refactor+feat: allow subsystems to send only declared messages, generate graphviz (#5314)

Closes #3774
Closes #3826

polkadot/Cargo.lock

@@ -7028,10 +7028,14 @@ version = "0.9.19"
 dependencies = [
  "assert_matches",
  "expander 0.0.6",
+ "petgraph",
+ "polkadot-overseer-gen",
  "proc-macro-crate",
  "proc-macro2",
  "quote",
  "syn",
+ "thiserror",
+ "tracing-gum",
 ]
 
 [[package]]
@@ -7400,6 +7404,7 @@ dependencies = [
  "polkadot-node-primitives",
  "polkadot-node-subsystem",
  "polkadot-node-subsystem-test-helpers",
+ "polkadot-node-subsystem-types",
  "polkadot-node-subsystem-util",
  "polkadot-overseer",
  "polkadot-parachain",

polkadot/bridges/.config/lingua.dic

@@ -16,6 +16,7 @@ Best/MS
 BlockId
 BlockNumber
 BridgeStorage
+clonable
 CLI/MS
 Chain1
 Chain2
@@ -177,6 +178,7 @@ plancks
 polkadot/MS
 pov-block/MS
 precommit
+proc-macro/MS
 prometheus
 proxying
 provisioner/MS

polkadot/core-primitives/src/lib.rs

@@ -60,7 +60,7 @@ pub type ChainId = u32;
 /// A hash of some data used by the relay chain.
 pub type Hash = sp_core::H256;
 
-/// Unit type wrapper around [`Hash`] that represents a candidate hash.
+/// Unit type wrapper around [`type@Hash`] that represents a candidate hash.
 ///
 /// This type is produced by [`CandidateReceipt::hash`].
 ///

polkadot/node/collation-generation/src/lib.rs

@@ -22,9 +22,9 @@ use futures::{channel::mpsc, future::FutureExt, join, select, sink::SinkExt, str
 use parity_scale_codec::Encode;
 use polkadot_node_primitives::{AvailableData, CollationGenerationConfig, PoV};
 use polkadot_node_subsystem::{
-	messages::{AllMessages, CollationGenerationMessage, CollatorProtocolMessage},
+	messages::{CollationGenerationMessage, CollatorProtocolMessage},
 	overseer, ActiveLeavesUpdate, FromOverseer, OverseerSignal, SpawnedSubsystem, SubsystemContext,
-	SubsystemError, SubsystemResult, SubsystemSender,
+	SubsystemError, SubsystemResult,
 };
 use polkadot_node_subsystem_util::{
 	request_availability_cores, request_persisted_validation_data, request_validation_code,
@@ -54,6 +54,7 @@ pub struct CollationGenerationSubsystem {
 	metrics: Metrics,
 }
 
+#[overseer::contextbounds(CollationGeneration, prefix = self::overseer)]
 impl CollationGenerationSubsystem {
 	/// Create a new instance of the `CollationGenerationSubsystem`.
 	pub fn new(metrics: Metrics) -> Self {
@@ -71,11 +72,7 @@ impl CollationGenerationSubsystem {
 	///
 	/// If `err_tx` is not `None`, errors are forwarded onto that channel as they occur.
 	/// Otherwise, most are logged and then discarded.
-	async fn run<Context>(mut self, mut ctx: Context)
-	where
-		Context: SubsystemContext<Message = CollationGenerationMessage>,
-		Context: overseer::SubsystemContext<Message = CollationGenerationMessage>,
-	{
+	async fn run<Context>(mut self, mut ctx: Context) {
 		// when we activate new leaves, we spawn a bunch of sub-tasks, each of which is
 		// expected to generate precisely one message. We don't want to block the main loop
 		// at any point waiting for them all, so instead, we create a channel on which they can
@@ -108,12 +105,8 @@ impl CollationGenerationSubsystem {
 		&mut self,
 		incoming: SubsystemResult<FromOverseer<<Context as SubsystemContext>::Message>>,
 		ctx: &mut Context,
-		sender: &mpsc::Sender<AllMessages>,
-	) -> bool
-	where
-		Context: SubsystemContext<Message = CollationGenerationMessage>,
-		Context: overseer::SubsystemContext<Message = CollationGenerationMessage>,
-	{
+		sender: &mpsc::Sender<overseer::CollationGenerationOutgoingMessages>,
+	) -> bool {
 		match incoming {
 			Ok(FromOverseer::Signal(OverseerSignal::ActiveLeaves(ActiveLeavesUpdate {
 				activated,
@@ -162,11 +155,8 @@ impl CollationGenerationSubsystem {
 	}
 }
 
-impl<Context> overseer::Subsystem<Context, SubsystemError> for CollationGenerationSubsystem
-where
-	Context: SubsystemContext<Message = CollationGenerationMessage>,
-	Context: overseer::SubsystemContext<Message = CollationGenerationMessage>,
-{
+#[overseer::subsystem(CollationGeneration, error=SubsystemError, prefix=self::overseer)]
+impl<Context> CollationGenerationSubsystem {
 	fn start(self, ctx: Context) -> SpawnedSubsystem {
 		let future = async move {
 			self.run(ctx).await;
@@ -178,12 +168,13 @@ where
 	}
 }
 
-async fn handle_new_activations<Context: SubsystemContext>(
+#[overseer::contextbounds(CollationGeneration, prefix = self::overseer)]
+async fn handle_new_activations<Context>(
 	config: Arc<CollationGenerationConfig>,
 	activated: impl IntoIterator<Item = Hash>,
 	ctx: &mut Context,
 	metrics: Metrics,
-	sender: &mpsc::Sender<AllMessages>,
+	sender: &mpsc::Sender<overseer::CollationGenerationOutgoingMessages>,
 ) -> crate::error::Result<()> {
 	// follow the procedure from the guide:
 	// https://w3f.github.io/parachain-implementers-guide/node/collators/collation-generation.html
@@ -393,9 +384,10 @@ async fn handle_new_activations<Context: SubsystemContext>(
 					metrics.on_collation_generated();
 
 					if let Err(err) = task_sender
-						.send(AllMessages::CollatorProtocol(
-							CollatorProtocolMessage::DistributeCollation(ccr, pov, result_sender),
-						))
+						.send(
+							CollatorProtocolMessage::DistributeCollation(ccr, pov, result_sender)
+								.into(),
+						)
 						.await
 					{
 						gum::warn!(
@@ -417,7 +409,7 @@ async fn obtain_current_validation_code_hash(
 	relay_parent: Hash,
 	para_id: ParaId,
 	assumption: OccupiedCoreAssumption,
-	sender: &mut impl SubsystemSender,
+	sender: &mut impl overseer::CollationGenerationSenderTrait,
 ) -> Result<Option<ValidationCodeHash>, crate::error::Error> {
 	use polkadot_node_subsystem::RuntimeApiError;
 

polkadot/node/collation-generation/src/tests.rs

@@ -296,7 +296,7 @@ mod handle_new_activations {
 			*subsystem_sent_messages.lock().await = rx.collect().await;
 		});
 
-		let sent_messages = Arc::try_unwrap(sent_messages)
+		let mut sent_messages = Arc::try_unwrap(sent_messages)
 			.expect("subsystem should have shut down by now")
 			.into_inner();
 
@@ -328,7 +328,7 @@ mod handle_new_activations {
 		};
 
 		assert_eq!(sent_messages.len(), 1);
-		match &sent_messages[0] {
+		match AllMessages::from(sent_messages.pop().unwrap()) {
 			AllMessages::CollatorProtocol(CollatorProtocolMessage::DistributeCollation(
 				CandidateReceipt { descriptor, .. },
 				_pov,
@@ -356,7 +356,7 @@ mod handle_new_activations {
 					expect_descriptor.erasure_root = descriptor.erasure_root.clone();
 					expect_descriptor
 				};
-				assert_eq!(descriptor, &expect_descriptor);
+				assert_eq!(descriptor, expect_descriptor);
 			},
 			_ => panic!("received wrong message type"),
 		}
@@ -470,11 +470,13 @@ mod handle_new_activations {
 
 		assert_eq!(sent_messages.len(), 1);
 		match &sent_messages[0] {
-			AllMessages::CollatorProtocol(CollatorProtocolMessage::DistributeCollation(
-				CandidateReceipt { descriptor, .. },
-				_pov,
-				..,
-			)) => {
+			overseer::CollationGenerationOutgoingMessages::CollatorProtocolMessage(
+				CollatorProtocolMessage::DistributeCollation(
+					CandidateReceipt { descriptor, .. },
+					_pov,
+					..,
+				),
+			) => {
 				assert_eq!(expect_validation_code_hash, descriptor.validation_code_hash);
 			},
 			_ => panic!("received wrong message type"),

polkadot/node/core/approval-voting/src/import.rs

@@ -38,7 +38,7 @@ use polkadot_node_subsystem::{
 		ApprovalDistributionMessage, ChainApiMessage, ChainSelectionMessage, RuntimeApiMessage,
 		RuntimeApiRequest,
 	},
-	overseer, RuntimeApiError, SubsystemContext, SubsystemError, SubsystemResult,
+	overseer, RuntimeApiError, SubsystemError, SubsystemResult,
 };
 use polkadot_node_subsystem_util::{
 	determine_new_blocks,
@@ -107,8 +107,9 @@ enum ImportedBlockInfoError {
 }
 
 /// Computes information about the imported block. Returns an error if the info couldn't be extracted.
-async fn imported_block_info(
-	ctx: &mut (impl SubsystemContext + overseer::SubsystemContext),
+#[overseer::contextbounds(ApprovalVoting, prefix = self::overseer)]
+async fn imported_block_info<Context>(
+	ctx: &mut Context,
 	env: ImportedBlockInfoEnv<'_>,
 	block_hash: Hash,
 	block_header: &Header,
@@ -319,10 +320,11 @@ pub struct BlockImportedCandidates {
 ///   * and return information about all candidates imported under each block.
 ///
 /// It is the responsibility of the caller to schedule wakeups for each block.
-pub(crate) async fn handle_new_head(
-	ctx: &mut (impl SubsystemContext + overseer::SubsystemContext),
+#[overseer::contextbounds(ApprovalVoting, prefix = self::overseer)]
+pub(crate) async fn handle_new_head<Context, B: Backend>(
+	ctx: &mut Context,
 	state: &mut State,
-	db: &mut OverlayedBackend<'_, impl Backend>,
+	db: &mut OverlayedBackend<'_, B>,
 	head: Hash,
 	finalized_number: &Option<BlockNumber>,
 ) -> SubsystemResult<Vec<BlockImportedCandidates>> {
@@ -609,7 +611,7 @@ pub(crate) mod tests {
 	use assert_matches::assert_matches;
 	use merlin::Transcript;
 	use polkadot_node_primitives::approval::{VRFOutput, VRFProof};
-	use polkadot_node_subsystem::messages::AllMessages;
+	use polkadot_node_subsystem::messages::{AllMessages, ApprovalVotingMessage};
 	use polkadot_node_subsystem_test_helpers::make_subsystem_context;
 	use polkadot_node_subsystem_util::database::Database;
 	use polkadot_primitives::v2::{Id as ParaId, SessionInfo, ValidatorIndex};
@@ -724,7 +726,8 @@ pub(crate) mod tests {
 	#[test]
 	fn imported_block_info_is_good() {
 		let pool = TaskExecutor::new();
-		let (mut ctx, mut handle) = make_subsystem_context::<(), _>(pool.clone());
+		let (mut ctx, mut handle) =
+			make_subsystem_context::<ApprovalVotingMessage, _>(pool.clone());
 
 		let session = 5;
 		let session_info = dummy_session_info(session);
@@ -847,7 +850,8 @@ pub(crate) mod tests {
 	#[test]
 	fn imported_block_info_fails_if_no_babe_vrf() {
 		let pool = TaskExecutor::new();
-		let (mut ctx, mut handle) = make_subsystem_context::<(), _>(pool.clone());
+		let (mut ctx, mut handle) =
+			make_subsystem_context::<ApprovalVotingMessage, _>(pool.clone());
 
 		let session = 5;
 		let session_info = dummy_session_info(session);
@@ -950,7 +954,8 @@ pub(crate) mod tests {
 	#[test]
 	fn imported_block_info_fails_if_ancient_session() {
 		let pool = TaskExecutor::new();
-		let (mut ctx, mut handle) = make_subsystem_context::<(), _>(pool.clone());
+		let (mut ctx, mut handle) =
+			make_subsystem_context::<ApprovalVotingMessage, _>(pool.clone());
 
 		let session = 5;
 
@@ -1027,7 +1032,7 @@ pub(crate) mod tests {
 	#[test]
 	fn imported_block_info_extracts_force_approve() {
 		let pool = TaskExecutor::new();
-		let (mut ctx, mut handle) = make_subsystem_context::<(), _>(pool.clone());
+		let (mut ctx, mut handle) = make_subsystem_context(pool.clone());
 
 		let session = 5;
 		let session_info = dummy_session_info(session);
@@ -1158,7 +1163,8 @@ pub(crate) mod tests {
 		let mut overlay_db = OverlayedBackend::new(&db);
 
 		let pool = TaskExecutor::new();
-		let (mut ctx, mut handle) = make_subsystem_context::<(), _>(pool.clone());
+		let (mut ctx, mut handle) =
+			make_subsystem_context::<ApprovalVotingMessage, _>(pool.clone());
 
 		let session = 5;
 		let irrelevant = 666;

polkadot/node/core/approval-voting/src/lib.rs

@@ -37,9 +37,8 @@ use polkadot_node_subsystem::{
 		ChainSelectionMessage, DisputeCoordinatorMessage, HighestApprovedAncestorBlock,
 		RuntimeApiMessage, RuntimeApiRequest,
 	},
-	overseer::{self, SubsystemSender as _},
-	FromOverseer, OverseerSignal, SpawnedSubsystem, SubsystemContext, SubsystemError,
-	SubsystemResult, SubsystemSender,
+	overseer, FromOverseer, OverseerSignal, SpawnedSubsystem, SubsystemError, SubsystemResult,
+	SubsystemSender,
 };
 use polkadot_node_subsystem_util::{
 	database::Database,
@@ -355,11 +354,8 @@ impl ApprovalVotingSubsystem {
 	}
 }
 
-impl<Context> overseer::Subsystem<Context, SubsystemError> for ApprovalVotingSubsystem
-where
-	Context: SubsystemContext<Message = ApprovalVotingMessage>,
-	Context: overseer::SubsystemContext<Message = ApprovalVotingMessage>,
-{
+#[overseer::subsystem(ApprovalVoting, error = SubsystemError, prefix = self::overseer)]
+impl<Context: Send> ApprovalVotingSubsystem {
 	fn start(self, ctx: Context) -> SpawnedSubsystem {
 		let backend = DbBackend::new(self.db.clone(), self.db_config);
 		let future = run::<DbBackend, Context>(
@@ -597,27 +593,34 @@ struct State {
 	assignment_criteria: Box<dyn AssignmentCriteria + Send + Sync>,
 }
 
+#[overseer::contextbounds(ApprovalVoting, prefix = self::overseer)]
 impl State {
 	fn session_info(&self, i: SessionIndex) -> Option<&SessionInfo> {
 		self.session_window.as_ref().and_then(|w| w.session_info(i))
 	}
 
 	/// Bring `session_window` up to date.
-	pub async fn cache_session_info_for_head(
+	pub async fn cache_session_info_for_head<Context>(
 		&mut self,
-		ctx: &mut (impl SubsystemContext + overseer::SubsystemContext),
+		ctx: &mut Context,
 		head: Hash,
-	) -> Result<Option<SessionWindowUpdate>, SessionsUnavailable> {
+	) -> Result<Option<SessionWindowUpdate>, SessionsUnavailable>
+	where
+		<Context as overseer::SubsystemContext>::Sender: Sized + Send,
+	{
 		let session_window = self.session_window.take();
 		match session_window {
 			None => {
+				let sender = ctx.sender().clone();
 				self.session_window =
-					Some(RollingSessionWindow::new(ctx, APPROVAL_SESSIONS, head).await?);
+					Some(RollingSessionWindow::new(sender, APPROVAL_SESSIONS, head).await?);
 				Ok(None)
 			},
 			Some(mut session_window) => {
-				let r =
-					session_window.cache_session_info_for_head(ctx, head).await.map(Option::Some);
+				let r = session_window
+					.cache_session_info_for_head(ctx.sender(), head)
+					.await
+					.map(Option::Some);
 				self.session_window = Some(session_window);
 				r
 			},
@@ -701,6 +704,7 @@ enum Action {
 	Conclude,
 }
 
+#[overseer::contextbounds(ApprovalVoting, prefix = self::overseer)]
 async fn run<B, Context>(
 	mut ctx: Context,
 	mut subsystem: ApprovalVotingSubsystem,
@@ -709,8 +713,6 @@ async fn run<B, Context>(
 	mut backend: B,
 ) -> SubsystemResult<()>
 where
-	Context: SubsystemContext<Message = ApprovalVotingMessage>,
-	Context: overseer::SubsystemContext<Message = ApprovalVotingMessage>,
 	B: Backend,
 {
 	let mut state = State {
@@ -848,9 +850,9 @@ where
 // 	https://github.com/paritytech/polkadot/issues/3311
 //
 // returns `true` if any of the actions was a `Conclude` command.
-async fn handle_actions(
-	ctx: &mut (impl SubsystemContext<Message = ApprovalVotingMessage>
-	          + overseer::SubsystemContext<Message = ApprovalVotingMessage>),
+#[overseer::contextbounds(ApprovalVoting, prefix = self::overseer)]
+async fn handle_actions<Context>(
+	ctx: &mut Context,
 	state: &mut State,
 	overlayed_db: &mut OverlayedBackend<'_, impl Backend>,
 	metrics: &Metrics,
@@ -868,7 +870,6 @@ async fn handle_actions(
 			Action::ScheduleWakeup { block_hash, block_number, candidate_hash, tick } =>
 				wakeups.schedule(block_hash, block_number, candidate_hash, tick),
 			Action::IssueApproval(candidate_hash, approval_request) => {
-				let mut sender = ctx.sender().clone();
 				// Note that the IssueApproval action will create additional
 				// actions that will need to all be processed before we can
 				// handle the next action in the set passed to the ambient
@@ -881,7 +882,7 @@ async fn handle_actions(
 				// Note that chaining these iterators is O(n) as we must consume
 				// the prior iterator.
 				let next_actions: Vec<Action> = issue_approval(
-					&mut sender,
+					ctx,
 					state,
 					overlayed_db,
 					metrics,
@@ -1086,9 +1087,9 @@ fn distribution_messages_for_activation(
 }
 
 // Handle an incoming signal from the overseer. Returns true if execution should conclude.
-async fn handle_from_overseer(
-	ctx: &mut (impl SubsystemContext<Message = ApprovalVotingMessage>
-	          + overseer::SubsystemContext<Message = ApprovalVotingMessage>),
+#[overseer::contextbounds(ApprovalVoting, prefix = self::overseer)]
+async fn handle_from_overseer<Context>(
+	ctx: &mut Context,
 	state: &mut State,
 	db: &mut OverlayedBackend<'_, impl Backend>,
 	metrics: &Metrics,
@@ -1197,8 +1198,9 @@ async fn handle_from_overseer(
 	Ok(actions)
 }
 
-async fn handle_approved_ancestor(
-	ctx: &mut (impl SubsystemContext + overseer::SubsystemContext),
+#[overseer::contextbounds(ApprovalVoting, prefix = self::overseer)]
+async fn handle_approved_ancestor<Context>(
+	ctx: &mut Context,
 	db: &OverlayedBackend<'_, impl Backend>,
 	target: Hash,
 	lower_bound: BlockNumber,
@@ -2147,9 +2149,9 @@ fn process_wakeup(
 // Launch approval work, returning an `AbortHandle` which corresponds to the background task
 // spawned. When the background work is no longer needed, the `AbortHandle` should be dropped
 // to cancel the background work and any requests it has spawned.
-async fn launch_approval(
-	ctx: &mut (impl SubsystemContext<Message = ApprovalVotingMessage>
-	          + overseer::SubsystemContext<Message = ApprovalVotingMessage>),
+#[overseer::contextbounds(ApprovalVoting, prefix = self::overseer)]
+async fn launch_approval<Context>(
+	ctx: &mut Context,
 	metrics: Metrics,
 	session_index: SessionIndex,
 	candidate: CandidateReceipt,
@@ -2242,15 +2244,12 @@ async fn launch_approval(
 						);
 
 						sender
-							.send_message(
-								DisputeCoordinatorMessage::IssueLocalStatement(
-									session_index,
-									candidate_hash,
-									candidate.clone(),
-									false,
-								)
-								.into(),
-							)
+							.send_message(DisputeCoordinatorMessage::IssueLocalStatement(
+								session_index,
+								candidate_hash,
+								candidate.clone(),
+								false,
+							))
 							.await;
 						metrics_guard.take().on_approval_invalid();
 					},
@@ -2281,17 +2280,14 @@ async fn launch_approval(
 		let (val_tx, val_rx) = oneshot::channel();
 
 		sender
-			.send_message(
-				CandidateValidationMessage::ValidateFromExhaustive(
-					available_data.validation_data,
-					validation_code,
-					candidate.clone(),
-					available_data.pov,
-					APPROVAL_EXECUTION_TIMEOUT,
-					val_tx,
-				)
-				.into(),
-			)
+			.send_message(CandidateValidationMessage::ValidateFromExhaustive(
+				available_data.validation_data,
+				validation_code,
+				candidate.clone(),
+				available_data.pov,
+				APPROVAL_EXECUTION_TIMEOUT,
+				val_tx,
+			))
 			.await;
 
 		match val_rx.await {
@@ -2309,15 +2305,12 @@ async fn launch_approval(
 				} else {
 					// Commitments mismatch - issue a dispute.
 					sender
-						.send_message(
-							DisputeCoordinatorMessage::IssueLocalStatement(
-								session_index,
-								candidate_hash,
-								candidate.clone(),
-								false,
-							)
-							.into(),
-						)
+						.send_message(DisputeCoordinatorMessage::IssueLocalStatement(
+							session_index,
+							candidate_hash,
+							candidate.clone(),
+							false,
+						))
 						.await;
 
 					metrics_guard.take().on_approval_invalid();
@@ -2334,15 +2327,12 @@ async fn launch_approval(
 				);
 
 				sender
-					.send_message(
-						DisputeCoordinatorMessage::IssueLocalStatement(
-							session_index,
-							candidate_hash,
-							candidate.clone(),
-							false,
-						)
-						.into(),
-					)
+					.send_message(DisputeCoordinatorMessage::IssueLocalStatement(
+						session_index,
+						candidate_hash,
+						candidate.clone(),
+						false,
+					))
 					.await;
 
 				metrics_guard.take().on_approval_invalid();
@@ -2368,8 +2358,9 @@ async fn launch_approval(
 
 // Issue and import a local approval vote. Should only be invoked after approval checks
 // have been done.
-async fn issue_approval(
-	ctx: &mut impl SubsystemSender,
+#[overseer::contextbounds(ApprovalVoting, prefix = self::overseer)]
+async fn issue_approval<Context>(
+	ctx: &mut Context,
 	state: &mut State,
 	db: &mut OverlayedBackend<'_, impl Backend>,
 	metrics: &Metrics,
@@ -2527,15 +2518,14 @@ async fn issue_approval(
 	metrics.on_approval_produced();
 
 	// dispatch to approval distribution.
-	ctx.send_unbounded_message(
-		ApprovalDistributionMessage::DistributeApproval(IndirectSignedApprovalVote {
+	ctx.send_unbounded_message(ApprovalDistributionMessage::DistributeApproval(
+		IndirectSignedApprovalVote {
 			block_hash,
 			candidate_index: candidate_index as _,
 			validator: validator_index,
 			signature: sig,
-		})
-		.into(),
-	);
+		},
+	));
 
 	// dispatch to dispute coordinator.
 	actions.extend(inform_disputes_action);

polkadot/node/core/av-store/src/lib.rs

@@ -36,8 +36,7 @@ use polkadot_node_primitives::{AvailableData, ErasureChunk};
 use polkadot_node_subsystem::{
 	errors::{ChainApiError, RuntimeApiError},
 	messages::{AvailabilityStoreMessage, ChainApiMessage},
-	overseer, ActiveLeavesUpdate, FromOverseer, OverseerSignal, SpawnedSubsystem, SubsystemContext,
-	SubsystemError,
+	overseer, ActiveLeavesUpdate, FromOverseer, OverseerSignal, SpawnedSubsystem, SubsystemError,
 };
 use polkadot_node_subsystem_util as util;
 use polkadot_primitives::v2::{
@@ -519,23 +518,17 @@ impl KnownUnfinalizedBlocks {
 	}
 }
 
-impl<Context> overseer::Subsystem<Context, SubsystemError> for AvailabilityStoreSubsystem
-where
-	Context: SubsystemContext<Message = AvailabilityStoreMessage>,
-	Context: overseer::SubsystemContext<Message = AvailabilityStoreMessage>,
-{
+#[overseer::subsystem(AvailabilityStore, error=SubsystemError, prefix=self::overseer)]
+impl<Context> AvailabilityStoreSubsystem {
 	fn start(self, ctx: Context) -> SpawnedSubsystem {
-		let future = run(self, ctx).map(|_| Ok(())).boxed();
+		let future = run::<Context>(self, ctx).map(|_| Ok(())).boxed();
 
 		SpawnedSubsystem { name: "availability-store-subsystem", future }
 	}
 }
 
-async fn run<Context>(mut subsystem: AvailabilityStoreSubsystem, mut ctx: Context)
-where
-	Context: SubsystemContext<Message = AvailabilityStoreMessage>,
-	Context: overseer::SubsystemContext<Message = AvailabilityStoreMessage>,
-{
+#[overseer::contextbounds(AvailabilityStore, prefix = self::overseer)]
+async fn run<Context>(mut subsystem: AvailabilityStoreSubsystem, mut ctx: Context) {
 	let mut next_pruning = Delay::new(subsystem.pruning_config.pruning_interval).fuse();
 
 	loop {
@@ -556,15 +549,12 @@ where
 	}
 }
 
+#[overseer::contextbounds(AvailabilityStore, prefix = self::overseer)]
 async fn run_iteration<Context>(
 	ctx: &mut Context,
 	subsystem: &mut AvailabilityStoreSubsystem,
 	mut next_pruning: &mut future::Fuse<Delay>,
-) -> Result<bool, Error>
-where
-	Context: SubsystemContext<Message = AvailabilityStoreMessage>,
-	Context: overseer::SubsystemContext<Message = AvailabilityStoreMessage>,
-{
+) -> Result<bool, Error> {
 	select! {
 		incoming = ctx.recv().fuse() => {
 			match incoming.map_err(|_| Error::ContextChannelClosed)? {
@@ -608,15 +598,12 @@ where
 	Ok(false)
 }
 
+#[overseer::contextbounds(AvailabilityStore, prefix = self::overseer)]
 async fn process_block_activated<Context>(
 	ctx: &mut Context,
 	subsystem: &mut AvailabilityStoreSubsystem,
 	activated: Hash,
-) -> Result<(), Error>
-where
-	Context: SubsystemContext<Message = AvailabilityStoreMessage>,
-	Context: overseer::SubsystemContext<Message = AvailabilityStoreMessage>,
-{
+) -> Result<(), Error> {
 	let now = subsystem.clock.now()?;
 
 	let block_header = {
@@ -663,6 +650,7 @@ where
 	Ok(())
 }
 
+#[overseer::contextbounds(AvailabilityStore, prefix = self::overseer)]
 async fn process_new_head<Context>(
 	ctx: &mut Context,
 	db: &Arc<dyn Database>,
@@ -672,11 +660,7 @@ async fn process_new_head<Context>(
 	now: Duration,
 	hash: Hash,
 	header: Header,
-) -> Result<(), Error>
-where
-	Context: SubsystemContext<Message = AvailabilityStoreMessage>,
-	Context: overseer::SubsystemContext<Message = AvailabilityStoreMessage>,
-{
+) -> Result<(), Error> {
 	let candidate_events = util::request_candidate_events(hash, ctx.sender()).await.await??;
 
 	// We need to request the number of validators based on the parent state,
@@ -814,16 +798,13 @@ macro_rules! peek_num {
 	};
 }
 
+#[overseer::contextbounds(AvailabilityStore, prefix = self::overseer)]
 async fn process_block_finalized<Context>(
 	ctx: &mut Context,
 	subsystem: &AvailabilityStoreSubsystem,
 	finalized_hash: Hash,
 	finalized_number: BlockNumber,
-) -> Result<(), Error>
-where
-	Context: SubsystemContext<Message = AvailabilityStoreMessage>,
-	Context: overseer::SubsystemContext<Message = AvailabilityStoreMessage>,
-{
+) -> Result<(), Error> {
 	let now = subsystem.clock.now()?;
 
 	let mut next_possible_batch = 0;

polkadot/node/core/av-store/src/tests.rs

@@ -309,13 +309,13 @@ fn store_chunk_works() {
 		let chunk_msg =
 			AvailabilityStoreMessage::StoreChunk { candidate_hash, chunk: chunk.clone(), tx };
 
-		overseer_send(&mut virtual_overseer, chunk_msg.into()).await;
+		overseer_send(&mut virtual_overseer, chunk_msg).await;
 		assert_eq!(rx.await.unwrap(), Ok(()));
 
 		let (tx, rx) = oneshot::channel();
 		let query_chunk = AvailabilityStoreMessage::QueryChunk(candidate_hash, validator_index, tx);
 
-		overseer_send(&mut virtual_overseer, query_chunk.into()).await;
+		overseer_send(&mut virtual_overseer, query_chunk).await;
 
 		assert_eq!(rx.await.unwrap().unwrap(), chunk);
 		virtual_overseer
@@ -341,13 +341,13 @@ fn store_chunk_does_nothing_if_no_entry_already() {
 		let chunk_msg =
 			AvailabilityStoreMessage::StoreChunk { candidate_hash, chunk: chunk.clone(), tx };
 
-		overseer_send(&mut virtual_overseer, chunk_msg.into()).await;
+		overseer_send(&mut virtual_overseer, chunk_msg).await;
 		assert_eq!(rx.await.unwrap(), Err(()));
 
 		let (tx, rx) = oneshot::channel();
 		let query_chunk = AvailabilityStoreMessage::QueryChunk(candidate_hash, validator_index, tx);
 
-		overseer_send(&mut virtual_overseer, query_chunk.into()).await;
+		overseer_send(&mut virtual_overseer, query_chunk).await;
 
 		assert!(rx.await.unwrap().is_none());
 		virtual_overseer

polkadot/node/core/backing/src/lib.rs

@@ -37,13 +37,12 @@ use polkadot_node_primitives::{
 use polkadot_node_subsystem::{
 	jaeger,
 	messages::{
-		AllMessages, AvailabilityDistributionMessage, AvailabilityStoreMessage,
-		CandidateBackingMessage, CandidateValidationMessage, CollatorProtocolMessage,
-		DisputeCoordinatorMessage, ProvisionableData, ProvisionerMessage, RuntimeApiRequest,
-		StatementDistributionMessage,
+		AvailabilityDistributionMessage, AvailabilityStoreMessage, CandidateBackingMessage,
+		CandidateValidationMessage, CollatorProtocolMessage, DisputeCoordinatorMessage,
+		ProvisionableData, ProvisionerMessage, RuntimeApiRequest, StatementDistributionMessage,
 	},
 	overseer, ActiveLeavesUpdate, FromOverseer, OverseerSignal, PerLeafSpan, SpawnedSubsystem,
-	Stage, SubsystemContext, SubsystemError, SubsystemSender,
+	Stage, SubsystemError,
 };
 use polkadot_node_subsystem_util::{
 	self as util, request_from_runtime, request_session_index_for_child, request_validator_groups,
@@ -131,10 +130,10 @@ impl CandidateBackingSubsystem {
 	}
 }
 
-impl<Context> overseer::Subsystem<Context, SubsystemError> for CandidateBackingSubsystem
+#[overseer::subsystem(CandidateBacking, error = SubsystemError, prefix = self::overseer)]
+impl<Context> CandidateBackingSubsystem
 where
-	Context: SubsystemContext<Message = CandidateBackingMessage>,
-	Context: overseer::SubsystemContext<Message = CandidateBackingMessage>,
+	Context: Send + Sync,
 {
 	fn start(self, ctx: Context) -> SpawnedSubsystem {
 		let future = async move {
@@ -148,15 +147,12 @@ where
 	}
 }
 
+#[overseer::contextbounds(CandidateBacking, prefix = self::overseer)]
 async fn run<Context>(
 	mut ctx: Context,
 	keystore: SyncCryptoStorePtr,
 	metrics: Metrics,
-) -> FatalResult<()>
-where
-	Context: SubsystemContext<Message = CandidateBackingMessage>,
-	Context: overseer::SubsystemContext<Message = CandidateBackingMessage>,
-{
+) -> FatalResult<()> {
 	let (background_validation_tx, mut background_validation_rx) = mpsc::channel(16);
 	let mut jobs = HashMap::new();
 
@@ -180,6 +176,7 @@ where
 	Ok(())
 }
 
+#[overseer::contextbounds(CandidateBacking, prefix = self::overseer)]
 async fn run_iteration<Context>(
 	ctx: &mut Context,
 	keystore: SyncCryptoStorePtr,
@@ -187,11 +184,7 @@ async fn run_iteration<Context>(
 	jobs: &mut HashMap<Hash, JobAndSpan<Context>>,
 	background_validation_tx: mpsc::Sender<(Hash, ValidatedCandidateCommand)>,
 	background_validation_rx: &mut mpsc::Receiver<(Hash, ValidatedCandidateCommand)>,
-) -> Result<(), Error>
-where
-	Context: SubsystemContext<Message = CandidateBackingMessage>,
-	Context: overseer::SubsystemContext<Message = CandidateBackingMessage>,
-{
+) -> Result<(), Error> {
 	loop {
 		futures::select!(
 			validated_command = background_validation_rx.next().fuse() => {
@@ -225,16 +218,13 @@ where
 	}
 }
 
+#[overseer::contextbounds(CandidateBacking, prefix = self::overseer)]
 async fn handle_validated_candidate_command<Context>(
 	ctx: &mut Context,
 	jobs: &mut HashMap<Hash, JobAndSpan<Context>>,
 	relay_parent: Hash,
 	command: ValidatedCandidateCommand,
-) -> Result<(), Error>
-where
-	Context: SubsystemContext<Message = CandidateBackingMessage>,
-	Context: overseer::SubsystemContext<Message = CandidateBackingMessage>,
-{
+) -> Result<(), Error> {
 	if let Some(job) = jobs.get_mut(&relay_parent) {
 		job.job.handle_validated_candidate_command(&job.span, ctx, command).await?;
 	} else {
@@ -245,15 +235,12 @@ where
 	Ok(())
 }
 
+#[overseer::contextbounds(CandidateBacking, prefix = self::overseer)]
 async fn handle_communication<Context>(
 	ctx: &mut Context,
 	jobs: &mut HashMap<Hash, JobAndSpan<Context>>,
 	message: CandidateBackingMessage,
-) -> Result<(), Error>
-where
-	Context: SubsystemContext<Message = CandidateBackingMessage>,
-	Context: overseer::SubsystemContext<Message = CandidateBackingMessage>,
-{
+) -> Result<(), Error> {
 	match message {
 		CandidateBackingMessage::Second(relay_parent, candidate, pov) => {
 			if let Some(job) = jobs.get_mut(&relay_parent) {
@@ -274,6 +261,7 @@ where
 	Ok(())
 }
 
+#[overseer::contextbounds(CandidateBacking, prefix = self::overseer)]
 async fn handle_active_leaves_update<Context>(
 	ctx: &mut Context,
 	update: ActiveLeavesUpdate,
@@ -281,11 +269,7 @@ async fn handle_active_leaves_update<Context>(
 	keystore: &SyncCryptoStorePtr,
 	background_validation_tx: &mpsc::Sender<(Hash, ValidatedCandidateCommand)>,
 	metrics: &Metrics,
-) -> Result<(), Error>
-where
-	Context: SubsystemContext<Message = CandidateBackingMessage>,
-	Context: overseer::SubsystemContext<Message = CandidateBackingMessage>,
-{
+) -> Result<(), Error> {
 	for deactivated in update.deactivated {
 		jobs.remove(&deactivated);
 	}
@@ -578,22 +562,19 @@ fn table_attested_to_backed(
 }
 
 async fn store_available_data(
-	sender: &mut impl SubsystemSender,
+	sender: &mut impl overseer::CandidateBackingSenderTrait,
 	n_validators: u32,
 	candidate_hash: CandidateHash,
 	available_data: AvailableData,
 ) -> Result<(), Error> {
 	let (tx, rx) = oneshot::channel();
 	sender
-		.send_message(
-			AvailabilityStoreMessage::StoreAvailableData {
-				candidate_hash,
-				n_validators,
-				available_data,
-				tx,
-			}
-			.into(),
-		)
+		.send_message(AvailabilityStoreMessage::StoreAvailableData {
+			candidate_hash,
+			n_validators,
+			available_data,
+			tx,
+		})
 		.await;
 
 	let _ = rx.await.map_err(Error::StoreAvailableData)?;
@@ -605,8 +586,9 @@ async fn store_available_data(
 //
 // This will compute the erasure root internally and compare it to the expected erasure root.
 // This returns `Err()` iff there is an internal error. Otherwise, it returns either `Ok(Ok(()))` or `Ok(Err(_))`.
+
 async fn make_pov_available(
-	sender: &mut impl SubsystemSender,
+	sender: &mut impl overseer::CandidateBackingSenderTrait,
 	n_validators: usize,
 	pov: Arc<PoV>,
 	candidate_hash: CandidateHash,
@@ -639,7 +621,7 @@ async fn make_pov_available(
 }
 
 async fn request_pov(
-	sender: &mut impl SubsystemSender,
+	sender: &mut impl overseer::CandidateBackingSenderTrait,
 	relay_parent: Hash,
 	from_validator: ValidatorIndex,
 	candidate_hash: CandidateHash,
@@ -647,16 +629,13 @@ async fn request_pov(
 ) -> Result<Arc<PoV>, Error> {
 	let (tx, rx) = oneshot::channel();
 	sender
-		.send_message(
-			AvailabilityDistributionMessage::FetchPoV {
-				relay_parent,
-				from_validator,
-				candidate_hash,
-				pov_hash,
-				tx,
-			}
-			.into(),
-		)
+		.send_message(AvailabilityDistributionMessage::FetchPoV {
+			relay_parent,
+			from_validator,
+			candidate_hash,
+			pov_hash,
+			tx,
+		})
 		.await;
 
 	let pov = rx.await.map_err(|_| Error::FetchPoV)?;
@@ -664,22 +643,19 @@ async fn request_pov(
 }
 
 async fn request_candidate_validation(
-	sender: &mut impl SubsystemSender,
+	sender: &mut impl overseer::CandidateBackingSenderTrait,
 	candidate_receipt: CandidateReceipt,
 	pov: Arc<PoV>,
 ) -> Result<ValidationResult, Error> {
 	let (tx, rx) = oneshot::channel();
 
 	sender
-		.send_message(
-			CandidateValidationMessage::ValidateFromChainState(
-				candidate_receipt,
-				pov,
-				BACKING_EXECUTION_TIMEOUT,
-				tx,
-			)
-			.into(),
-		)
+		.send_message(CandidateValidationMessage::ValidateFromChainState(
+			candidate_receipt,
+			pov,
+			BACKING_EXECUTION_TIMEOUT,
+			tx,
+		))
 		.await;
 
 	match rx.await {
@@ -692,7 +668,7 @@ async fn request_candidate_validation(
 type BackgroundValidationResult =
 	Result<(CandidateReceipt, CandidateCommitments, Arc<PoV>), CandidateReceipt>;
 
-struct BackgroundValidationParams<S: overseer::SubsystemSender<AllMessages>, F> {
+struct BackgroundValidationParams<S: overseer::CandidateBackingSenderTrait, F> {
 	sender: S,
 	tx_command: mpsc::Sender<(Hash, ValidatedCandidateCommand)>,
 	candidate: CandidateReceipt,
@@ -705,7 +681,7 @@ struct BackgroundValidationParams<S: overseer::SubsystemSender<AllMessages>, F>
 
 async fn validate_and_make_available(
 	params: BackgroundValidationParams<
-		impl SubsystemSender,
+		impl overseer::CandidateBackingSenderTrait,
 		impl Fn(BackgroundValidationResult) -> ValidatedCandidateCommand + Sync,
 	>,
 ) -> Result<(), Error> {
@@ -809,11 +785,8 @@ async fn validate_and_make_available(
 
 struct ValidatorIndexOutOfBounds;
 
-impl<Context> CandidateBackingJob<Context>
-where
-	Context: SubsystemContext,
-	Context: overseer::SubsystemContext,
-{
+#[overseer::contextbounds(CandidateBacking, prefix = self::overseer)]
+impl<Context> CandidateBackingJob<Context> {
 	async fn handle_validated_candidate_command(
 		&mut self,
 		root_span: &jaeger::Span,
@@ -896,7 +869,7 @@ where
 		&mut self,
 		ctx: &mut Context,
 		params: BackgroundValidationParams<
-			impl SubsystemSender,
+			impl overseer::CandidateBackingSenderTrait,
 			impl Fn(BackgroundValidationResult) -> ValidatedCandidateCommand + Send + 'static + Sync,
 		>,
 	) -> Result<(), Error> {
@@ -1001,7 +974,7 @@ where
 	}
 
 	/// Check if there have happened any new misbehaviors and issue necessary messages.
-	fn issue_new_misbehaviors(&mut self, ctx: &mut Context) {
+	fn issue_new_misbehaviors(&mut self, sender: &mut impl overseer::CandidateBackingSenderTrait) {
 		// collect the misbehaviors to avoid double mutable self borrow issues
 		let misbehaviors: Vec<_> = self.table.drain_misbehaviors().collect();
 		for (validator_id, report) in misbehaviors {
@@ -1010,7 +983,7 @@ where
 			//
 			// Misbehaviors are bounded by the number of validators and
 			// the block production protocol.
-			ctx.send_unbounded_message(ProvisionerMessage::ProvisionableData(
+			sender.send_unbounded_message(ProvisionerMessage::ProvisionableData(
 				self.parent,
 				ProvisionableData::MisbehaviorReport(self.parent, validator_id, report),
 			));
@@ -1042,7 +1015,7 @@ where
 		};
 
 		if let Err(ValidatorIndexOutOfBounds) = self
-			.dispatch_new_statement_to_dispute_coordinator(ctx, candidate_hash, &statement)
+			.dispatch_new_statement_to_dispute_coordinator(ctx.sender(), candidate_hash, &statement)
 			.await
 		{
 			gum::warn!(
@@ -1101,7 +1074,7 @@ where
 			None
 		};
 
-		self.issue_new_misbehaviors(ctx);
+		self.issue_new_misbehaviors(ctx.sender());
 
 		// It is important that the child span is dropped before its parent span (`unbacked_span`)
 		drop(import_statement_span);
@@ -1123,8 +1096,8 @@ where
 	/// the networking component responsible for feeding statements to the backing subsystem
 	/// is meant to check the signature and provenance of all statements before submission.
 	async fn dispatch_new_statement_to_dispute_coordinator(
-		&mut self,
-		ctx: &mut Context,
+		&self,
+		sender: &mut impl overseer::CandidateBackingSenderTrait,
 		candidate_hash: CandidateHash,
 		statement: &SignedFullStatement,
 	) -> Result<(), ValidatorIndexOutOfBounds> {
@@ -1157,14 +1130,15 @@ where
 		if let (Some(candidate_receipt), Some(dispute_statement)) =
 			(maybe_candidate_receipt, maybe_signed_dispute_statement)
 		{
-			ctx.send_message(DisputeCoordinatorMessage::ImportStatements {
-				candidate_hash,
-				candidate_receipt,
-				session: self.session_index,
-				statements: vec![(dispute_statement, validator_index)],
-				pending_confirmation: None,
-			})
-			.await;
+			sender
+				.send_message(DisputeCoordinatorMessage::ImportStatements {
+					candidate_hash,
+					candidate_receipt,
+					session: self.session_index,
+					statements: vec![(dispute_statement, validator_index)],
+					pending_confirmation: None,
+				})
+				.await;
 		}
 
 		Ok(())

polkadot/node/core/backing/src/tests.rs

@@ -23,7 +23,10 @@ use assert_matches::assert_matches;
 use futures::{future, Future};
 use polkadot_node_primitives::{BlockData, InvalidCandidate};
 use polkadot_node_subsystem::{
-	messages::{CollatorProtocolMessage, RuntimeApiMessage, RuntimeApiRequest, ValidationFailed},
+	messages::{
+		AllMessages, CollatorProtocolMessage, RuntimeApiMessage, RuntimeApiRequest,
+		ValidationFailed,
+	},
 	ActivatedLeaf, ActiveLeavesUpdate, FromOverseer, LeafStatus, OverseerSignal,
 };
 use polkadot_node_subsystem_test_helpers as test_helpers;

polkadot/node/core/bitfield-signing/src/lib.rs

@@ -34,7 +34,7 @@ use polkadot_node_subsystem::{
 		AvailabilityStoreMessage, BitfieldDistributionMessage, BitfieldSigningMessage,
 		RuntimeApiMessage, RuntimeApiRequest,
 	},
-	ActivatedLeaf, LeafStatus, PerLeafSpan, SubsystemSender,
+	overseer, ActivatedLeaf, LeafStatus, PerLeafSpan, SubsystemSender,
 };
 use polkadot_node_subsystem_util::{self as util, JobSender, JobSubsystem, JobTrait, Validator};
 use polkadot_primitives::v2::{AvailabilityBitfield, CoreState, Hash, ValidatorIndex};
@@ -53,7 +53,7 @@ const JOB_DELAY: Duration = Duration::from_millis(1500);
 const LOG_TARGET: &str = "parachain::bitfield-signing";
 
 /// Each `BitfieldSigningJob` prepares a signed bitfield for a single relay parent.
-pub struct BitfieldSigningJob;
+pub struct BitfieldSigningJob<Sender>(std::marker::PhantomData<Sender>);
 
 /// Errors we may encounter in the course of executing the `BitfieldSigningSubsystem`.
 #[derive(Debug, thiserror::Error)]
@@ -83,7 +83,7 @@ pub enum Error {
 async fn get_core_availability(
 	core: &CoreState,
 	validator_idx: ValidatorIndex,
-	sender: &Mutex<&mut impl SubsystemSender>,
+	sender: &Mutex<&mut impl SubsystemSender<overseer::BitfieldSigningOutgoingMessages>>,
 	span: &jaeger::Span,
 ) -> Result<bool, Error> {
 	if let &CoreState::Occupied(ref core) = core {
@@ -122,7 +122,7 @@ async fn get_core_availability(
 /// delegates to the v1 runtime API
 async fn get_availability_cores(
 	relay_parent: Hash,
-	sender: &mut impl SubsystemSender,
+	sender: &mut impl SubsystemSender<overseer::BitfieldSigningOutgoingMessages>,
 ) -> Result<Vec<CoreState>, Error> {
 	let (tx, rx) = oneshot::channel();
 	sender
@@ -146,7 +146,7 @@ async fn construct_availability_bitfield(
 	relay_parent: Hash,
 	span: &jaeger::Span,
 	validator_idx: ValidatorIndex,
-	sender: &mut impl SubsystemSender,
+	sender: &mut impl SubsystemSender<overseer::BitfieldSigningOutgoingMessages>,
 ) -> Result<AvailabilityBitfield, Error> {
 	// get the set of availability cores from the runtime
 	let availability_cores = {
@@ -182,8 +182,13 @@ async fn construct_availability_bitfield(
 	Ok(AvailabilityBitfield(core_bits))
 }
 
-impl JobTrait for BitfieldSigningJob {
+impl<Sender> JobTrait for BitfieldSigningJob<Sender>
+where
+	Sender: overseer::BitfieldSigningSenderTrait + Unpin,
+{
 	type ToJob = BitfieldSigningMessage;
+	type OutgoingMessages = overseer::BitfieldSigningOutgoingMessages;
+	type Sender = Sender;
 	type Error = Error;
 	type RunArgs = SyncCryptoStorePtr;
 	type Metrics = Metrics;
@@ -191,12 +196,12 @@ impl JobTrait for BitfieldSigningJob {
 	const NAME: &'static str = "bitfield-signing-job";
 
 	/// Run a job for the parent block indicated
-	fn run<S: SubsystemSender>(
+	fn run(
 		leaf: ActivatedLeaf,
 		keystore: Self::RunArgs,
 		metrics: Self::Metrics,
 		_receiver: mpsc::Receiver<BitfieldSigningMessage>,
-		mut sender: JobSender<S>,
+		mut sender: JobSender<Sender>,
 	) -> Pin<Box<dyn Future<Output = Result<(), Self::Error>> + Send>> {
 		let metrics = metrics.clone();
 		async move {
@@ -286,4 +291,5 @@ impl JobTrait for BitfieldSigningJob {
 }
 
 /// `BitfieldSigningSubsystem` manages a number of bitfield signing jobs.
-pub type BitfieldSigningSubsystem<Spawner> = JobSubsystem<BitfieldSigningJob, Spawner>;
+pub type BitfieldSigningSubsystem<Spawner, Sender> =
+	JobSubsystem<BitfieldSigningJob<Sender>, Spawner>;

polkadot/node/core/candidate-validation/src/lib.rs

@@ -35,8 +35,8 @@ use polkadot_node_subsystem::{
 		CandidateValidationMessage, PreCheckOutcome, RuntimeApiMessage, RuntimeApiRequest,
 		ValidationFailed,
 	},
-	overseer, FromOverseer, OverseerSignal, SpawnedSubsystem, SubsystemContext, SubsystemError,
-	SubsystemResult, SubsystemSender,
+	overseer, FromOverseer, OverseerSignal, SpawnedSubsystem, SubsystemError, SubsystemResult,
+	SubsystemSender,
 };
 use polkadot_parachain::primitives::{ValidationParams, ValidationResult as WasmValidationResult};
 use polkadot_primitives::v2::{
@@ -93,11 +93,8 @@ impl CandidateValidationSubsystem {
 	}
 }
 
-impl<Context> overseer::Subsystem<Context, SubsystemError> for CandidateValidationSubsystem
-where
-	Context: SubsystemContext<Message = CandidateValidationMessage>,
-	Context: overseer::SubsystemContext<Message = CandidateValidationMessage>,
-{
+#[overseer::subsystem(CandidateValidation, error=SubsystemError, prefix=self::overseer)]
+impl<Context> CandidateValidationSubsystem {
 	fn start(self, ctx: Context) -> SpawnedSubsystem {
 		let future = run(
 			ctx,
@@ -112,17 +109,14 @@ where
 	}
 }
 
+#[overseer::contextbounds(CandidateValidation, prefix = self::overseer)]
 async fn run<Context>(
 	mut ctx: Context,
 	metrics: Metrics,
 	pvf_metrics: polkadot_node_core_pvf::Metrics,
 	cache_path: PathBuf,
 	program_path: PathBuf,
-) -> SubsystemResult<()>
-where
-	Context: SubsystemContext<Message = CandidateValidationMessage>,
-	Context: overseer::SubsystemContext<Message = CandidateValidationMessage>,
-{
+) -> SubsystemResult<()> {
 	let (validation_host, task) = polkadot_node_core_pvf::start(
 		polkadot_node_core_pvf::Config::new(cache_path, program_path),
 		pvf_metrics,
@@ -235,7 +229,7 @@ async fn runtime_api_request<T, Sender>(
 	receiver: oneshot::Receiver<Result<T, RuntimeApiError>>,
 ) -> Result<T, RuntimeRequestFailed>
 where
-	Sender: SubsystemSender,
+	Sender: SubsystemSender<RuntimeApiMessage>,
 {
 	sender
 		.send_message(RuntimeApiMessage::Request(relay_parent, request).into())
@@ -268,7 +262,7 @@ async fn request_validation_code_by_hash<Sender>(
 	validation_code_hash: ValidationCodeHash,
 ) -> Result<Option<ValidationCode>, RuntimeRequestFailed>
 where
-	Sender: SubsystemSender,
+	Sender: SubsystemSender<RuntimeApiMessage>,
 {
 	let (tx, rx) = oneshot::channel();
 	runtime_api_request(
@@ -287,7 +281,7 @@ async fn precheck_pvf<Sender>(
 	validation_code_hash: ValidationCodeHash,
 ) -> PreCheckOutcome
 where
-	Sender: SubsystemSender,
+	Sender: SubsystemSender<RuntimeApiMessage>,
 {
 	let validation_code =
 		match request_validation_code_by_hash(sender, relay_parent, validation_code_hash).await {
@@ -342,7 +336,7 @@ async fn check_assumption_validation_data<Sender>(
 	assumption: OccupiedCoreAssumption,
 ) -> AssumptionCheckOutcome
 where
-	Sender: SubsystemSender,
+	Sender: SubsystemSender<RuntimeApiMessage>,
 {
 	let validation_data = {
 		let (tx, rx) = oneshot::channel();
@@ -386,7 +380,7 @@ async fn find_assumed_validation_data<Sender>(
 	descriptor: &CandidateDescriptor,
 ) -> AssumptionCheckOutcome
 where
-	Sender: SubsystemSender,
+	Sender: SubsystemSender<RuntimeApiMessage>,
 {
 	// The candidate descriptor has a `persisted_validation_data_hash` which corresponds to
 	// one of up to two possible values that we can derive from the state of the
@@ -421,7 +415,7 @@ pub async fn find_validation_data<Sender>(
 	descriptor: &CandidateDescriptor,
 ) -> Result<Option<(PersistedValidationData, ValidationCode)>, ValidationFailed>
 where
-	Sender: SubsystemSender,
+	Sender: SubsystemSender<RuntimeApiMessage>,
 {
 	match find_assumed_validation_data(sender, &descriptor).await {
 		AssumptionCheckOutcome::Matches(validation_data, validation_code) =>
@@ -446,7 +440,7 @@ async fn validate_from_chain_state<Sender>(
 	metrics: &Metrics,
 ) -> Result<ValidationResult, ValidationFailed>
 where
-	Sender: SubsystemSender,
+	Sender: SubsystemSender<RuntimeApiMessage>,
 {
 	let mut new_sender = sender.clone();
 	let (validation_data, validation_code) =

polkadot/node/core/chain-api/src/lib.rs

@@ -39,7 +39,7 @@ use sp_blockchain::HeaderBackend;
 
 use polkadot_node_subsystem::{
 	messages::ChainApiMessage, overseer, FromOverseer, OverseerSignal, SpawnedSubsystem,
-	SubsystemContext, SubsystemError, SubsystemResult,
+	SubsystemError, SubsystemResult,
 };
 use polkadot_primitives::v2::{Block, BlockId};
 
@@ -64,11 +64,10 @@ impl<Client> ChainApiSubsystem<Client> {
 	}
 }
 
-impl<Client, Context> overseer::Subsystem<Context, SubsystemError> for ChainApiSubsystem<Client>
+#[overseer::subsystem(ChainApi, error = SubsystemError, prefix = self::overseer)]
+impl<Client, Context> ChainApiSubsystem<Client>
 where
 	Client: HeaderBackend<Block> + AuxStore + 'static,
-	Context: SubsystemContext<Message = ChainApiMessage>,
-	Context: overseer::SubsystemContext<Message = ChainApiMessage>,
 {
 	fn start(self, ctx: Context) -> SpawnedSubsystem {
 		let future = run::<Client, Context>(ctx, self)
@@ -78,14 +77,13 @@ where
 	}
 }
 
+#[overseer::contextbounds(ChainApi, prefix = self::overseer)]
 async fn run<Client, Context>(
 	mut ctx: Context,
 	subsystem: ChainApiSubsystem<Client>,
 ) -> SubsystemResult<()>
 where
 	Client: HeaderBackend<Block> + AuxStore,
-	Context: SubsystemContext<Message = ChainApiMessage>,
-	Context: overseer::SubsystemContext<Message = ChainApiMessage>,
 {
 	loop {
 		match ctx.recv().await? {

polkadot/node/core/chain-selection/src/lib.rs

@@ -20,7 +20,8 @@ use polkadot_node_primitives::BlockWeight;
 use polkadot_node_subsystem::{
 	errors::ChainApiError,
 	messages::{ChainApiMessage, ChainSelectionMessage},
-	overseer, FromOverseer, OverseerSignal, SpawnedSubsystem, SubsystemContext, SubsystemError,
+	overseer::{self, SubsystemSender},
+	FromOverseer, OverseerSignal, SpawnedSubsystem, SubsystemError,
 };
 use polkadot_node_subsystem_util::database::Database;
 use polkadot_primitives::v2::{BlockNumber, ConsensusLog, Hash, Header};
@@ -328,11 +329,8 @@ impl ChainSelectionSubsystem {
 	}
 }
 
-impl<Context> overseer::Subsystem<Context, SubsystemError> for ChainSelectionSubsystem
-where
-	Context: SubsystemContext<Message = ChainSelectionMessage>,
-	Context: overseer::SubsystemContext<Message = ChainSelectionMessage>,
-{
+#[overseer::subsystem(ChainSelection, error = SubsystemError, prefix = self::overseer)]
+impl<Context> ChainSelectionSubsystem {
 	fn start(self, ctx: Context) -> SpawnedSubsystem {
 		let backend = db_backend::v1::DbBackend::new(
 			self.db,
@@ -348,14 +346,13 @@ where
 	}
 }
 
+#[overseer::contextbounds(ChainSelection, prefix = self::overseer)]
 async fn run<Context, B>(
 	mut ctx: Context,
 	mut backend: B,
 	stagnant_check_interval: StagnantCheckInterval,
 	clock: Box<dyn Clock + Send + Sync>,
 ) where
-	Context: SubsystemContext<Message = ChainSelectionMessage>,
-	Context: overseer::SubsystemContext<Message = ChainSelectionMessage>,
 	B: Backend,
 {
 	loop {
@@ -363,7 +360,7 @@ async fn run<Context, B>(
 		match res {
 			Err(e) => {
 				e.trace();
-				// All errors right now are considered fatal:
+				// All errors are considered fatal right now:
 				break
 			},
 			Ok(()) => {
@@ -379,6 +376,7 @@ async fn run<Context, B>(
 //
 // A return value of `Ok` indicates that an exit should be made, while non-fatal errors
 // lead to another call to this function.
+#[overseer::contextbounds(ChainSelection, prefix = self::overseer)]
 async fn run_until_error<Context, B>(
 	ctx: &mut Context,
 	backend: &mut B,
@@ -386,8 +384,6 @@ async fn run_until_error<Context, B>(
 	clock: &(dyn Clock + Sync),
 ) -> Result<(), Error>
 where
-	Context: SubsystemContext<Message = ChainSelectionMessage>,
-	Context: overseer::SubsystemContext<Message = ChainSelectionMessage>,
 	B: Backend,
 {
 	let mut stagnant_check_stream = stagnant_check_interval.timeout_stream();
@@ -402,7 +398,7 @@ where
 					FromOverseer::Signal(OverseerSignal::ActiveLeaves(update)) => {
 						for leaf in update.activated {
 							let write_ops = handle_active_leaf(
-								ctx,
+								ctx.sender(),
 								&*backend,
 								clock.timestamp_now() + STAGNANT_TIMEOUT,
 								leaf.hash,
@@ -419,7 +415,7 @@ where
 							handle_approved_block(backend, hash)?
 						}
 						ChainSelectionMessage::Leaves(tx) => {
-							let leaves = load_leaves(ctx, &*backend).await?;
+							let leaves = load_leaves(ctx.sender(), &*backend).await?;
 							let _ = tx.send(leaves);
 						}
 						ChainSelectionMessage::BestLeafContaining(required, tx) => {
@@ -446,11 +442,11 @@ where
 }
 
 async fn fetch_finalized(
-	ctx: &mut impl SubsystemContext,
+	sender: &mut impl SubsystemSender<ChainApiMessage>,
 ) -> Result<Option<(Hash, BlockNumber)>, Error> {
 	let (number_tx, number_rx) = oneshot::channel();
 
-	ctx.send_message(ChainApiMessage::FinalizedBlockNumber(number_tx)).await;
+	sender.send_message(ChainApiMessage::FinalizedBlockNumber(number_tx)).await;
 
 	let number = match number_rx.await? {
 		Ok(number) => number,
@@ -462,7 +458,7 @@ async fn fetch_finalized(
 
 	let (hash_tx, hash_rx) = oneshot::channel();
 
-	ctx.send_message(ChainApiMessage::FinalizedBlockHash(number, hash_tx)).await;
+	sender.send_message(ChainApiMessage::FinalizedBlockHash(number, hash_tx)).await;
 
 	match hash_rx.await? {
 		Err(err) => {
@@ -478,11 +474,11 @@ async fn fetch_finalized(
 }
 
 async fn fetch_header(
-	ctx: &mut impl SubsystemContext,
+	sender: &mut impl SubsystemSender<ChainApiMessage>,
 	hash: Hash,
 ) -> Result<Option<Header>, Error> {
 	let (tx, rx) = oneshot::channel();
-	ctx.send_message(ChainApiMessage::BlockHeader(hash, tx)).await;
+	sender.send_message(ChainApiMessage::BlockHeader(hash, tx)).await;
 
 	Ok(rx.await?.unwrap_or_else(|err| {
 		gum::warn!(target: LOG_TARGET, ?hash, ?err, "Missing hash for finalized block number");
@@ -491,11 +487,11 @@ async fn fetch_header(
 }
 
 async fn fetch_block_weight(
-	ctx: &mut impl SubsystemContext,
+	sender: &mut impl overseer::SubsystemSender<ChainApiMessage>,
 	hash: Hash,
 ) -> Result<Option<BlockWeight>, Error> {
 	let (tx, rx) = oneshot::channel();
-	ctx.send_message(ChainApiMessage::BlockWeight(hash, tx)).await;
+	sender.send_message(ChainApiMessage::BlockWeight(hash, tx)).await;
 
 	let res = rx.await?;
 
@@ -507,7 +503,7 @@ async fn fetch_block_weight(
 
 // Handle a new active leaf.
 async fn handle_active_leaf(
-	ctx: &mut impl SubsystemContext,
+	sender: &mut impl overseer::ChainSelectionSenderTrait,
 	backend: &impl Backend,
 	stagnant_at: Timestamp,
 	hash: Hash,
@@ -519,10 +515,10 @@ async fn handle_active_leaf(
 			// tree.
 			l.saturating_sub(1)
 		},
-		None => fetch_finalized(ctx).await?.map_or(1, |(_, n)| n),
+		None => fetch_finalized(sender).await?.map_or(1, |(_, n)| n),
 	};
 
-	let header = match fetch_header(ctx, hash).await? {
+	let header = match fetch_header(sender, hash).await? {
 		None => {
 			gum::warn!(target: LOG_TARGET, ?hash, "Missing header for new head");
 			return Ok(Vec::new())
@@ -531,7 +527,7 @@ async fn handle_active_leaf(
 	};
 
 	let new_blocks = polkadot_node_subsystem_util::determine_new_blocks(
-		ctx.sender(),
+		sender,
 		|h| backend.load_block_entry(h).map(|b| b.is_some()),
 		hash,
 		&header,
@@ -544,7 +540,7 @@ async fn handle_active_leaf(
 	// determine_new_blocks gives blocks in descending order.
 	// for this, we want ascending order.
 	for (hash, header) in new_blocks.into_iter().rev() {
-		let weight = match fetch_block_weight(ctx, hash).await? {
+		let weight = match fetch_block_weight(sender, hash).await? {
 			None => {
 				gum::warn!(
 					target: LOG_TARGET,
@@ -654,13 +650,13 @@ fn detect_stagnant(backend: &mut impl Backend, now: Timestamp) -> Result<(), Err
 // Load the leaves from the backend. If there are no leaves, then return
 // the finalized block.
 async fn load_leaves(
-	ctx: &mut impl SubsystemContext,
+	sender: &mut impl overseer::SubsystemSender<ChainApiMessage>,
 	backend: &impl Backend,
 ) -> Result<Vec<Hash>, Error> {
 	let leaves: Vec<_> = backend.load_leaves()?.into_hashes_descending().collect();
 
 	if leaves.is_empty() {
-		Ok(fetch_finalized(ctx).await?.map_or(Vec::new(), |(h, _)| vec![h]))
+		Ok(fetch_finalized(sender).await?.map_or(Vec::new(), |(h, _)| vec![h]))
 	} else {
 		Ok(leaves)
 	}

polkadot/node/core/dispute-coordinator/src/initialized.rs

@@ -34,7 +34,7 @@ use polkadot_node_subsystem::{
 		BlockDescription, DisputeCoordinatorMessage, DisputeDistributionMessage,
 		ImportStatementsResult,
 	},
-	overseer, ActivatedLeaf, ActiveLeavesUpdate, FromOverseer, OverseerSignal, SubsystemContext,
+	overseer, ActivatedLeaf, ActiveLeavesUpdate, FromOverseer, OverseerSignal,
 };
 use polkadot_node_subsystem_util::rolling_session_window::{
 	RollingSessionWindow, SessionWindowUpdate, SessionsUnavailable,
@@ -83,6 +83,7 @@ pub struct Initialized {
 	error: Option<SessionsUnavailable>,
 }
 
+#[overseer::contextbounds(DisputeCoordinator, prefix = self::overseer)]
 impl Initialized {
 	/// Make initialized subsystem, ready to `run`.
 	pub fn new(
@@ -123,8 +124,6 @@ impl Initialized {
 		clock: Box<dyn Clock>,
 	) -> FatalResult<()>
 	where
-		Context: overseer::SubsystemContext<Message = DisputeCoordinatorMessage>,
-		Context: SubsystemContext<Message = DisputeCoordinatorMessage>,
 		B: Backend,
 	{
 		loop {
@@ -161,8 +160,6 @@ impl Initialized {
 		clock: &dyn Clock,
 	) -> Result<()>
 	where
-		Context: overseer::SubsystemContext<Message = DisputeCoordinatorMessage>,
-		Context: SubsystemContext<Message = DisputeCoordinatorMessage>,
 		B: Backend,
 	{
 		for (priority, request) in participations.drain(..) {
@@ -253,10 +250,9 @@ impl Initialized {
 		}
 	}
 
-	async fn process_active_leaves_update(
+	async fn process_active_leaves_update<Context>(
 		&mut self,
-		ctx: &mut (impl SubsystemContext<Message = DisputeCoordinatorMessage>
-		          + overseer::SubsystemContext<Message = DisputeCoordinatorMessage>),
+		ctx: &mut Context,
 		overlay_db: &mut OverlayedBackend<'_, impl Backend>,
 		update: ActiveLeavesUpdate,
 		now: u64,
@@ -268,7 +264,7 @@ impl Initialized {
 		if let Some(new_leaf) = update.activated {
 			match self
 				.rolling_session_window
-				.cache_session_info_for_head(ctx, new_leaf.hash)
+				.cache_session_info_for_head(ctx.sender(), new_leaf.hash)
 				.await
 			{
 				Err(e) => {
@@ -318,10 +314,9 @@ impl Initialized {
 
 	/// Scrapes on-chain votes (backing votes and concluded disputes) for a active leaf of the
 	/// relay chain.
-	async fn process_on_chain_votes(
+	async fn process_on_chain_votes<Context>(
 		&mut self,
-		ctx: &mut (impl SubsystemContext<Message = DisputeCoordinatorMessage>
-		          + overseer::SubsystemContext<Message = DisputeCoordinatorMessage>),
+		ctx: &mut Context,
 		overlay_db: &mut OverlayedBackend<'_, impl Backend>,
 		votes: ScrapedOnChainVotes,
 		now: u64,
@@ -497,9 +492,9 @@ impl Initialized {
 		Ok(())
 	}
 
-	async fn handle_incoming(
+	async fn handle_incoming<Context>(
 		&mut self,
-		ctx: &mut impl SubsystemContext,
+		ctx: &mut Context,
 		overlay_db: &mut OverlayedBackend<'_, impl Backend>,
 		message: DisputeCoordinatorMessage,
 		now: Timestamp,
@@ -634,9 +629,9 @@ impl Initialized {
 		Ok(())
 	}
 
-	async fn handle_import_statements(
+	async fn handle_import_statements<Context>(
 		&mut self,
-		ctx: &mut impl SubsystemContext,
+		ctx: &mut Context,
 		overlay_db: &mut OverlayedBackend<'_, impl Backend>,
 		candidate_hash: CandidateHash,
 		candidate_receipt: MaybeCandidateReceipt,
@@ -923,9 +918,9 @@ impl Initialized {
 		Ok(ImportStatementsResult::ValidImport)
 	}
 
-	async fn issue_local_statement(
+	async fn issue_local_statement<Context>(
 		&mut self,
-		ctx: &mut impl SubsystemContext,
+		ctx: &mut Context,
 		overlay_db: &mut OverlayedBackend<'_, impl Backend>,
 		candidate_hash: CandidateHash,
 		candidate_receipt: CandidateReceipt,
@@ -1054,10 +1049,10 @@ enum MuxedMessage {
 	Participation(participation::WorkerMessage),
 }
 
+#[overseer::contextbounds(DisputeCoordinator, prefix = self::overseer)]
 impl MuxedMessage {
-	async fn receive(
-		ctx: &mut (impl SubsystemContext<Message = DisputeCoordinatorMessage>
-		          + overseer::SubsystemContext<Message = DisputeCoordinatorMessage>),
+	async fn receive<Context>(
+		ctx: &mut Context,
 		from_sender: &mut participation::WorkerMessageReceiver,
 	) -> FatalResult<Self> {
 		// We are only fusing here to make `select` happy, in reality we will quit if the stream

polkadot/node/core/dispute-coordinator/src/lib.rs

@@ -32,8 +32,7 @@ use sc_keystore::LocalKeystore;
 
 use polkadot_node_primitives::{CandidateVotes, DISPUTE_WINDOW};
 use polkadot_node_subsystem::{
-	messages::DisputeCoordinatorMessage, overseer, ActivatedLeaf, FromOverseer, OverseerSignal,
-	SpawnedSubsystem, SubsystemContext, SubsystemError,
+	overseer, ActivatedLeaf, FromOverseer, OverseerSignal, SpawnedSubsystem, SubsystemError,
 };
 use polkadot_node_subsystem_util::{
 	database::Database, rolling_session_window::RollingSessionWindow,
@@ -124,11 +123,8 @@ impl Config {
 	}
 }
 
-impl<Context> overseer::Subsystem<Context, SubsystemError> for DisputeCoordinatorSubsystem
-where
-	Context: SubsystemContext<Message = DisputeCoordinatorMessage>,
-	Context: overseer::SubsystemContext<Message = DisputeCoordinatorMessage>,
-{
+#[overseer::subsystem(DisputeCoordinator, error=SubsystemError, prefix=self::overseer)]
+impl<Context: Send> DisputeCoordinatorSubsystem {
 	fn start(self, ctx: Context) -> SpawnedSubsystem {
 		let future = async {
 			let backend = DbBackend::new(self.store.clone(), self.config.column_config());
@@ -142,6 +138,7 @@ where
 	}
 }
 
+#[overseer::contextbounds(DisputeCoordinator, prefix = self::overseer)]
 impl DisputeCoordinatorSubsystem {
 	/// Create a new instance of the subsystem.
 	pub fn new(
@@ -161,8 +158,6 @@ impl DisputeCoordinatorSubsystem {
 		clock: Box<dyn Clock>,
 	) -> FatalResult<()>
 	where
-		Context: overseer::SubsystemContext<Message = DisputeCoordinatorMessage>,
-		Context: SubsystemContext<Message = DisputeCoordinatorMessage>,
 		B: Backend + 'static,
 	{
 		let res = self.initialize(&mut ctx, backend, &*clock).await?;
@@ -194,8 +189,6 @@ impl DisputeCoordinatorSubsystem {
 		)>,
 	>
 	where
-		Context: overseer::SubsystemContext<Message = DisputeCoordinatorMessage>,
-		Context: SubsystemContext<Message = DisputeCoordinatorMessage>,
 		B: Backend + 'static,
 	{
 		loop {
@@ -260,11 +253,7 @@ impl DisputeCoordinatorSubsystem {
 		Vec<ScrapedOnChainVotes>,
 		SpamSlots,
 		ChainScraper,
-	)>
-	where
-		Context: overseer::SubsystemContext<Message = DisputeCoordinatorMessage>,
-		Context: SubsystemContext<Message = DisputeCoordinatorMessage>,
-	{
+	)> {
 		// Prune obsolete disputes:
 		db::v1::note_current_session(overlay_db, rolling_session_window.latest_session())?;
 
@@ -358,17 +347,15 @@ impl DisputeCoordinatorSubsystem {
 }
 
 /// Wait for `ActiveLeavesUpdate` on startup, returns `None` if `Conclude` signal came first.
+#[overseer::contextbounds(DisputeCoordinator, prefix = self::overseer)]
 async fn get_rolling_session_window<Context>(
 	ctx: &mut Context,
-) -> Result<Option<(ActivatedLeaf, RollingSessionWindow)>>
-where
-	Context: overseer::SubsystemContext<Message = DisputeCoordinatorMessage>,
-	Context: SubsystemContext<Message = DisputeCoordinatorMessage>,
-{
-	if let Some(leaf) = wait_for_first_leaf(ctx).await? {
+) -> Result<Option<(ActivatedLeaf, RollingSessionWindow)>> {
+	if let Some(leaf) = { wait_for_first_leaf(ctx) }.await? {
+		let sender = ctx.sender().clone();
 		Ok(Some((
 			leaf.clone(),
-			RollingSessionWindow::new(ctx, DISPUTE_WINDOW, leaf.hash)
+			RollingSessionWindow::new(sender, DISPUTE_WINDOW, leaf.hash)
 				.await
 				.map_err(JfyiError::RollingSessionWindow)?,
 		)))
@@ -378,11 +365,8 @@ where
 }
 
 /// Wait for `ActiveLeavesUpdate`, returns `None` if `Conclude` signal came first.
-async fn wait_for_first_leaf<Context>(ctx: &mut Context) -> Result<Option<ActivatedLeaf>>
-where
-	Context: overseer::SubsystemContext<Message = DisputeCoordinatorMessage>,
-	Context: SubsystemContext<Message = DisputeCoordinatorMessage>,
-{
+#[overseer::contextbounds(DisputeCoordinator, prefix = self::overseer)]
+async fn wait_for_first_leaf<Context>(ctx: &mut Context) -> Result<Option<ActivatedLeaf>> {
 	loop {
 		match ctx.recv().await? {
 			FromOverseer::Signal(OverseerSignal::Conclude) => return Ok(None),

polkadot/node/core/dispute-coordinator/src/participation/mod.rs

@@ -28,7 +28,7 @@ use futures_timer::Delay;
 use polkadot_node_primitives::{ValidationResult, APPROVAL_EXECUTION_TIMEOUT};
 use polkadot_node_subsystem::{
 	messages::{AvailabilityRecoveryMessage, AvailabilityStoreMessage, CandidateValidationMessage},
-	ActiveLeavesUpdate, RecoveryError, SubsystemContext, SubsystemSender,
+	overseer, ActiveLeavesUpdate, RecoveryError,
 };
 use polkadot_node_subsystem_util::runtime::get_validation_code_by_hash;
 use polkadot_primitives::v2::{BlockNumber, CandidateHash, CandidateReceipt, Hash, SessionIndex};
@@ -123,6 +123,7 @@ impl WorkerMessage {
 	}
 }
 
+#[overseer::contextbounds(DisputeCoordinator, prefix = self::overseer)]
 impl Participation {
 	/// Get ready for managing dispute participation requests.
 	///
@@ -144,7 +145,7 @@ impl Participation {
 	/// `on_active_leaves_update`, the participation will be launched right away.
 	///
 	/// Returns: false, if queues are already full.
-	pub async fn queue_participation<Context: SubsystemContext>(
+	pub async fn queue_participation<Context>(
 		&mut self,
 		ctx: &mut Context,
 		priority: ParticipationPriority,
@@ -174,7 +175,7 @@ impl Participation {
 	///
 	/// Returns: The received `ParticipationStatement` or a fatal error, in case
 	/// something went wrong when dequeuing more requests (tasks could not be spawned).
-	pub async fn get_participation_result<Context: SubsystemContext>(
+	pub async fn get_participation_result<Context>(
 		&mut self,
 		ctx: &mut Context,
 		msg: WorkerMessage,
@@ -190,7 +191,7 @@ impl Participation {
 	///
 	/// Make sure we to dequeue participations if that became possible and update most recent
 	/// block.
-	pub async fn process_active_leaves_update<Context: SubsystemContext>(
+	pub async fn process_active_leaves_update<Context>(
 		&mut self,
 		ctx: &mut Context,
 		update: &ActiveLeavesUpdate,
@@ -212,7 +213,8 @@ impl Participation {
 	}
 
 	/// Dequeue until `MAX_PARALLEL_PARTICIPATIONS` is reached.
-	async fn dequeue_until_capacity<Context: SubsystemContext>(
+
+	async fn dequeue_until_capacity<Context>(
 		&mut self,
 		ctx: &mut Context,
 		recent_head: Hash,
@@ -228,7 +230,7 @@ impl Participation {
 	}
 
 	/// Fork a participation task in the background.
-	fn fork_participation<Context: SubsystemContext>(
+	fn fork_participation<Context>(
 		&mut self,
 		ctx: &mut Context,
 		req: ParticipationRequest,
@@ -248,7 +250,7 @@ impl Participation {
 
 async fn participate(
 	mut result_sender: WorkerMessageSender,
-	mut sender: impl SubsystemSender,
+	mut sender: impl overseer::DisputeCoordinatorSenderTrait,
 	block_hash: Hash,
 	req: ParticipationRequest,
 ) {
@@ -259,15 +261,12 @@ async fn participate(
 	// available data
 	let (recover_available_data_tx, recover_available_data_rx) = oneshot::channel();
 	sender
-		.send_message(
-			AvailabilityRecoveryMessage::RecoverAvailableData(
-				req.candidate_receipt().clone(),
-				req.session(),
-				None,
-				recover_available_data_tx,
-			)
-			.into(),
-		)
+		.send_message(AvailabilityRecoveryMessage::RecoverAvailableData(
+			req.candidate_receipt().clone(),
+			req.session(),
+			None,
+			recover_available_data_tx,
+		))
 		.await;
 
 	let available_data = match recover_available_data_rx.await {
@@ -326,15 +325,12 @@ async fn participate(
 	// in the dispute
 	let (store_available_data_tx, store_available_data_rx) = oneshot::channel();
 	sender
-		.send_message(
-			AvailabilityStoreMessage::StoreAvailableData {
-				candidate_hash: *req.candidate_hash(),
-				n_validators: req.n_validators() as u32,
-				available_data: available_data.clone(),
-				tx: store_available_data_tx,
-			}
-			.into(),
-		)
+		.send_message(AvailabilityStoreMessage::StoreAvailableData {
+			candidate_hash: *req.candidate_hash(),
+			n_validators: req.n_validators() as u32,
+			available_data: available_data.clone(),
+			tx: store_available_data_tx,
+		})
 		.await;
 
 	match store_available_data_rx.await {
@@ -364,17 +360,14 @@ async fn participate(
 	// same level of leeway.
 	let (validation_tx, validation_rx) = oneshot::channel();
 	sender
-		.send_message(
-			CandidateValidationMessage::ValidateFromExhaustive(
-				available_data.validation_data,
-				validation_code,
-				req.candidate_receipt().clone(),
-				available_data.pov,
-				APPROVAL_EXECUTION_TIMEOUT,
-				validation_tx,
-			)
-			.into(),
-		)
+		.send_message(CandidateValidationMessage::ValidateFromExhaustive(
+			available_data.validation_data,
+			validation_code,
+			req.candidate_receipt().clone(),
+			available_data.pov,
+			APPROVAL_EXECUTION_TIMEOUT,
+			validation_tx,
+		))
 		.await;
 
 	// we cast votes (either positive or negative) depending on the outcome of

polkadot/node/core/dispute-coordinator/src/participation/queues/mod.rs

@@ -20,7 +20,7 @@ use std::{
 };
 
 use futures::channel::oneshot;
-use polkadot_node_subsystem::{messages::ChainApiMessage, SubsystemSender};
+use polkadot_node_subsystem::{messages::ChainApiMessage, overseer};
 use polkadot_primitives::v2::{BlockNumber, CandidateHash, CandidateReceipt, Hash, SessionIndex};
 
 use crate::{
@@ -163,7 +163,7 @@ impl Queues {
 	/// Returns error in case a queue was found full already.
 	pub async fn queue(
 		&mut self,
-		sender: &mut impl SubsystemSender,
+		sender: &mut impl overseer::DisputeCoordinatorSenderTrait,
 		priority: ParticipationPriority,
 		req: ParticipationRequest,
 	) -> Result<()> {
@@ -305,7 +305,7 @@ impl CandidateComparator {
 	///		`Ok(None)` in case we could not lookup the candidate's relay parent, returns a
 	///		`FatalError` in case the chain API call fails with an unexpected error.
 	pub async fn new(
-		sender: &mut impl SubsystemSender,
+		sender: &mut impl overseer::DisputeCoordinatorSenderTrait,
 		candidate: &CandidateReceipt,
 	) -> FatalResult<Option<Self>> {
 		let candidate_hash = candidate.hash();
@@ -350,11 +350,11 @@ impl Ord for CandidateComparator {
 }
 
 async fn get_block_number(
-	sender: &mut impl SubsystemSender,
+	sender: &mut impl overseer::DisputeCoordinatorSenderTrait,
 	relay_parent: Hash,
 ) -> FatalResult<Option<BlockNumber>> {
 	let (tx, rx) = oneshot::channel();
-	sender.send_message(ChainApiMessage::BlockNumber(relay_parent, tx).into()).await;
+	sender.send_message(ChainApiMessage::BlockNumber(relay_parent, tx)).await;
 	rx.await
 		.map_err(|_| FatalError::ChainApiSenderDropped)?
 		.map_err(FatalError::ChainApiAncestors)

polkadot/node/core/dispute-coordinator/src/participation/tests.rs

@@ -53,16 +53,15 @@ pub fn make_our_subsystem_context<S>(
 	make_subsystem_context(spawn)
 }
 
-async fn participate(
-	ctx: &mut impl SubsystemContext,
-	participation: &mut Participation,
-) -> Result<()> {
+#[overseer::contextbounds(DisputeCoordinator, prefix = self::overseer)]
+async fn participate<Context>(ctx: &mut Context, participation: &mut Participation) -> Result<()> {
 	let commitments = CandidateCommitments::default();
 	participate_with_commitments_hash(ctx, participation, commitments.hash()).await
 }
 
-async fn participate_with_commitments_hash(
-	ctx: &mut impl SubsystemContext,
+#[overseer::contextbounds(DisputeCoordinator, prefix = self::overseer)]
+async fn participate_with_commitments_hash<Context>(
+	ctx: &mut Context,
 	participation: &mut Participation,
 	commitments_hash: Hash,
 ) -> Result<()> {
@@ -81,8 +80,9 @@ async fn participate_with_commitments_hash(
 		.await
 }
 
-async fn activate_leaf(
-	ctx: &mut impl SubsystemContext,
+#[overseer::contextbounds(DisputeCoordinator, prefix = self::overseer)]
+async fn activate_leaf<Context>(
+	ctx: &mut Context,
 	participation: &mut Participation,
 	block_number: BlockNumber,
 ) -> FatalResult<()> {

polkadot/node/core/dispute-coordinator/src/scraping/mod.rs

@@ -21,7 +21,8 @@ use lru::LruCache;
 
 use polkadot_node_primitives::MAX_FINALITY_LAG;
 use polkadot_node_subsystem::{
-	messages::ChainApiMessage, ActivatedLeaf, ActiveLeavesUpdate, ChainApiError, SubsystemSender,
+	messages::ChainApiMessage, overseer, ActivatedLeaf, ActiveLeavesUpdate, ChainApiError,
+	SubsystemSender,
 };
 use polkadot_node_subsystem_util::runtime::{get_candidate_events, get_on_chain_votes};
 use polkadot_primitives::v2::{
@@ -81,10 +82,13 @@ impl ChainScraper {
 	/// Create a properly initialized `OrderingProvider`.
 	///
 	/// Returns: `Self` and any scraped votes.
-	pub async fn new<Sender: SubsystemSender>(
+	pub async fn new<Sender>(
 		sender: &mut Sender,
 		initial_head: ActivatedLeaf,
-	) -> Result<(Self, Vec<ScrapedOnChainVotes>)> {
+	) -> Result<(Self, Vec<ScrapedOnChainVotes>)>
+	where
+		Sender: overseer::DisputeCoordinatorSenderTrait,
+	{
 		let mut s = Self {
 			included_candidates: HashSet::new(),
 			candidates_by_block_number: BTreeMap::new(),
@@ -106,11 +110,14 @@ impl ChainScraper {
 	/// and updates current heads, so we can query candidates for all non finalized blocks.
 	///
 	/// Returns: On chain vote for the leaf and any ancestors we might not yet have seen.
-	pub async fn process_active_leaves_update<Sender: SubsystemSender>(
+	pub async fn process_active_leaves_update<Sender>(
 		&mut self,
 		sender: &mut Sender,
 		update: &ActiveLeavesUpdate,
-	) -> crate::error::Result<Vec<ScrapedOnChainVotes>> {
+	) -> crate::error::Result<Vec<ScrapedOnChainVotes>>
+	where
+		Sender: overseer::DisputeCoordinatorSenderTrait,
+	{
 		let activated = match update.activated.as_ref() {
 			Some(activated) => activated,
 			None => return Ok(Vec::new()),
@@ -160,12 +167,15 @@ impl ChainScraper {
 	/// Process candidate events of a block.
 	///
 	/// Keep track of all included candidates.
-	async fn process_candidate_events(
+	async fn process_candidate_events<Sender>(
 		&mut self,
-		sender: &mut impl SubsystemSender,
+		sender: &mut Sender,
 		block_number: BlockNumber,
 		block_hash: Hash,
-	) -> Result<()> {
+	) -> Result<()>
+	where
+		Sender: overseer::DisputeCoordinatorSenderTrait,
+	{
 		// Get included events:
 		let included =
 			get_candidate_events(sender, block_hash)
@@ -196,12 +206,15 @@ impl ChainScraper {
 	/// either at the block present in cache or at the last finalized block.
 	///
 	/// Both `head` and the latest finalized block are **not** included in the result.
-	async fn get_unfinalized_block_ancestors<Sender: SubsystemSender>(
+	async fn get_unfinalized_block_ancestors<Sender>(
 		&mut self,
 		sender: &mut Sender,
 		mut head: Hash,
 		mut head_number: BlockNumber,
-	) -> Result<Vec<Hash>> {
+	) -> Result<Vec<Hash>>
+	where
+		Sender: overseer::DisputeCoordinatorSenderTrait,
+	{
 		let target_ancestor = get_finalized_block_number(sender).await?;
 
 		let mut ancestors = Vec::new();
@@ -256,26 +269,29 @@ impl ChainScraper {
 	}
 }
 
-async fn get_finalized_block_number(sender: &mut impl SubsystemSender) -> FatalResult<BlockNumber> {
+async fn get_finalized_block_number<Sender>(sender: &mut Sender) -> FatalResult<BlockNumber>
+where
+	Sender: overseer::DisputeCoordinatorSenderTrait,
+{
 	let (number_tx, number_rx) = oneshot::channel();
 	send_message_fatal(sender, ChainApiMessage::FinalizedBlockNumber(number_tx), number_rx).await
 }
 
-async fn get_block_ancestors(
-	sender: &mut impl SubsystemSender,
+async fn get_block_ancestors<Sender>(
+	sender: &mut Sender,
 	head: Hash,
 	num_ancestors: BlockNumber,
-) -> FatalResult<Vec<Hash>> {
+) -> FatalResult<Vec<Hash>>
+where
+	Sender: overseer::DisputeCoordinatorSenderTrait,
+{
 	let (tx, rx) = oneshot::channel();
 	sender
-		.send_message(
-			ChainApiMessage::Ancestors {
-				hash: head,
-				k: num_ancestors as usize,
-				response_channel: tx,
-			}
-			.into(),
-		)
+		.send_message(ChainApiMessage::Ancestors {
+			hash: head,
+			k: num_ancestors as usize,
+			response_channel: tx,
+		})
 		.await;
 
 	rx.await
@@ -289,9 +305,9 @@ async fn send_message_fatal<Sender, Response>(
 	receiver: oneshot::Receiver<std::result::Result<Response, ChainApiError>>,
 ) -> FatalResult<Response>
 where
-	Sender: SubsystemSender,
+	Sender: SubsystemSender<ChainApiMessage>,
 {
-	sender.send_message(message.into()).await;
+	sender.send_message(message).await;
 
 	receiver
 		.await

polkadot/node/core/provisioner/src/lib.rs

@@ -32,7 +32,7 @@ use polkadot_node_subsystem::{
 		CandidateBackingMessage, ChainApiMessage, DisputeCoordinatorMessage, ProvisionableData,
 		ProvisionerInherentData, ProvisionerMessage,
 	},
-	ActivatedLeaf, LeafStatus, PerLeafSpan, SubsystemSender,
+	overseer, ActivatedLeaf, LeafStatus, PerLeafSpan,
 };
 use polkadot_node_subsystem_util::{
 	request_availability_cores, request_persisted_validation_data, JobSender, JobSubsystem,
@@ -95,8 +95,12 @@ impl InherentAfter {
 	}
 }
 
+/// Provisioner run arguments.
+#[derive(Debug, Clone, Copy)]
+pub struct ProvisionerConfig;
+
 /// A per-relay-parent job for the provisioning subsystem.
-pub struct ProvisionerJob {
+pub struct ProvisionerJob<Sender> {
 	leaf: ActivatedLeaf,
 	receiver: mpsc::Receiver<ProvisionerMessage>,
 	backed_candidates: Vec<CandidateReceipt>,
@@ -104,14 +108,16 @@ pub struct ProvisionerJob {
 	metrics: Metrics,
 	inherent_after: InherentAfter,
 	awaiting_inherent: Vec<oneshot::Sender<ProvisionerInherentData>>,
+	_phantom: std::marker::PhantomData<Sender>,
 }
 
-/// Provisioner run arguments.
-#[derive(Debug, Clone, Copy)]
-pub struct ProvisionerConfig;
-
-impl JobTrait for ProvisionerJob {
+impl<Sender> JobTrait for ProvisionerJob<Sender>
+where
+	Sender: overseer::ProvisionerSenderTrait + std::marker::Unpin,
+{
 	type ToJob = ProvisionerMessage;
+	type OutgoingMessages = overseer::ProvisionerOutgoingMessages;
+	type Sender = Sender;
 	type Error = Error;
 	type RunArgs = ProvisionerConfig;
 	type Metrics = Metrics;
@@ -121,12 +127,12 @@ impl JobTrait for ProvisionerJob {
 	/// Run a job for the parent block indicated
 	//
 	// this function is in charge of creating and executing the job's main loop
-	fn run<S: SubsystemSender>(
+	fn run(
 		leaf: ActivatedLeaf,
 		_: Self::RunArgs,
 		metrics: Self::Metrics,
 		receiver: mpsc::Receiver<ProvisionerMessage>,
-		mut sender: JobSender<S>,
+		mut sender: JobSender<Sender>,
 	) -> Pin<Box<dyn Future<Output = Result<(), Self::Error>> + Send>> {
 		let span = leaf.span.clone();
 		async move {
@@ -139,7 +145,10 @@ impl JobTrait for ProvisionerJob {
 	}
 }
 
-impl ProvisionerJob {
+impl<Sender> ProvisionerJob<Sender>
+where
+	Sender: overseer::ProvisionerSenderTrait,
+{
 	fn new(
 		leaf: ActivatedLeaf,
 		metrics: Metrics,
@@ -153,14 +162,11 @@ impl ProvisionerJob {
 			metrics,
 			inherent_after: InherentAfter::new_from_now(),
 			awaiting_inherent: Vec::new(),
+			_phantom: std::marker::PhantomData::<Sender>::default(),
 		}
 	}
 
-	async fn run_loop(
-		mut self,
-		sender: &mut impl SubsystemSender,
-		span: PerLeafSpan,
-	) -> Result<(), Error> {
+	async fn run_loop(mut self, sender: &mut Sender, span: PerLeafSpan) -> Result<(), Error> {
 		loop {
 			futures::select! {
 				msg = self.receiver.next() => match msg {
@@ -197,7 +203,7 @@ impl ProvisionerJob {
 
 	async fn send_inherent_data(
 		&mut self,
-		sender: &mut impl SubsystemSender,
+		sender: &mut Sender,
 		return_senders: Vec<oneshot::Sender<ProvisionerInherentData>>,
 	) {
 		if let Err(err) = send_inherent_data(
@@ -275,7 +281,7 @@ async fn send_inherent_data(
 	bitfields: &[SignedAvailabilityBitfield],
 	candidates: &[CandidateReceipt],
 	return_senders: Vec<oneshot::Sender<ProvisionerInherentData>>,
-	from_job: &mut impl SubsystemSender,
+	from_job: &mut impl overseer::ProvisionerSenderTrait,
 	metrics: &Metrics,
 ) -> Result<(), Error> {
 	let availability_cores = request_availability_cores(leaf.hash, from_job)
@@ -394,7 +400,7 @@ async fn select_candidates(
 	bitfields: &[SignedAvailabilityBitfield],
 	candidates: &[CandidateReceipt],
 	relay_parent: Hash,
-	sender: &mut impl SubsystemSender,
+	sender: &mut impl overseer::ProvisionerSenderTrait,
 ) -> Result<Vec<BackedCandidate>, Error> {
 	let block_number = get_block_number_under_construction(relay_parent, sender).await?;
 
@@ -472,14 +478,11 @@ async fn select_candidates(
 	// now get the backed candidates corresponding to these candidate receipts
 	let (tx, rx) = oneshot::channel();
 	sender
-		.send_message(
-			CandidateBackingMessage::GetBackedCandidates(
-				relay_parent,
-				selected_candidates.clone(),
-				tx,
-			)
-			.into(),
-		)
+		.send_message(CandidateBackingMessage::GetBackedCandidates(
+			relay_parent,
+			selected_candidates.clone(),
+			tx,
+		))
 		.await;
 	let mut candidates = rx.await.map_err(|err| Error::CanceledBackedCandidates(err))?;
 
@@ -530,10 +533,10 @@ async fn select_candidates(
 /// in the event of an invalid `relay_parent`, returns `Ok(0)`
 async fn get_block_number_under_construction(
 	relay_parent: Hash,
-	sender: &mut impl SubsystemSender,
+	sender: &mut impl overseer::ProvisionerSenderTrait,
 ) -> Result<BlockNumber, Error> {
 	let (tx, rx) = oneshot::channel();
-	sender.send_message(ChainApiMessage::BlockNumber(relay_parent, tx).into()).await;
+	sender.send_message(ChainApiMessage::BlockNumber(relay_parent, tx)).await;
 
 	match rx.await.map_err(|err| Error::CanceledBlockNumber(err))? {
 		Ok(Some(n)) => Ok(n + 1),
@@ -591,7 +594,7 @@ enum RequestType {
 
 /// Request open disputes identified by `CandidateHash` and the `SessionIndex`.
 async fn request_disputes(
-	sender: &mut impl SubsystemSender,
+	sender: &mut impl overseer::ProvisionerSenderTrait,
 	active_or_recent: RequestType,
 ) -> Vec<(SessionIndex, CandidateHash)> {
 	let (tx, rx) = oneshot::channel();
@@ -600,7 +603,7 @@ async fn request_disputes(
 		RequestType::Active => DisputeCoordinatorMessage::ActiveDisputes(tx),
 	};
 	// Bounded by block production - `ProvisionerMessage::RequestInherentData`.
-	sender.send_unbounded_message(msg.into());
+	sender.send_unbounded_message(msg);
 
 	let recent_disputes = match rx.await {
 		Ok(r) => r,
@@ -614,14 +617,15 @@ async fn request_disputes(
 
 /// Request the relevant dispute statements for a set of disputes identified by `CandidateHash` and the `SessionIndex`.
 async fn request_votes(
-	sender: &mut impl SubsystemSender,
+	sender: &mut impl overseer::ProvisionerSenderTrait,
 	disputes_to_query: Vec<(SessionIndex, CandidateHash)>,
 ) -> Vec<(SessionIndex, CandidateHash, CandidateVotes)> {
 	let (tx, rx) = oneshot::channel();
 	// Bounded by block production - `ProvisionerMessage::RequestInherentData`.
-	sender.send_unbounded_message(
-		DisputeCoordinatorMessage::QueryCandidateVotes(disputes_to_query, tx).into(),
-	);
+	sender.send_unbounded_message(DisputeCoordinatorMessage::QueryCandidateVotes(
+		disputes_to_query,
+		tx,
+	));
 
 	match rx.await {
 		Ok(v) => v,
@@ -665,7 +669,7 @@ fn extend_by_random_subset_without_repetition(
 const MAX_DISPUTES_FORWARDED_TO_RUNTIME: usize = 1_000;
 
 async fn select_disputes(
-	sender: &mut impl SubsystemSender,
+	sender: &mut impl overseer::ProvisionerSenderTrait,
 	metrics: &metrics::Metrics,
 	_leaf: &ActivatedLeaf,
 ) -> Result<MultiDisputeStatementSet, Error> {
@@ -804,4 +808,4 @@ async fn select_disputes(
 }
 
 /// The provisioner subsystem.
-pub type ProvisionerSubsystem<Spawner> = JobSubsystem<ProvisionerJob, Spawner>;
+pub type ProvisionerSubsystem<Spawner, Sender> = JobSubsystem<ProvisionerJob<Sender>, Spawner>;

polkadot/node/core/provisioner/src/onchain_disputes.rs

@@ -15,14 +15,17 @@
 // along with Polkadot.  If not, see <http://www.gnu.org/licenses/>.
 
 use crate::error::GetOnchainDisputesError;
-use polkadot_node_subsystem::SubsystemSender;
+use polkadot_node_subsystem::overseer;
 use polkadot_primitives::v2::{CandidateHash, DisputeState, Hash, SessionIndex};
 use std::collections::HashMap;
 
-pub async fn get_onchain_disputes(
-	_sender: &mut impl SubsystemSender,
+pub async fn get_onchain_disputes<Sender>(
+	_sender: &mut Sender,
 	_relay_parent: Hash,
-) -> Result<HashMap<(SessionIndex, CandidateHash), DisputeState>, GetOnchainDisputesError> {
+) -> Result<HashMap<(SessionIndex, CandidateHash), DisputeState>, GetOnchainDisputesError>
+where
+	Sender: overseer::ProvisionerSenderTrait,
+{
 	let _onchain = Result::<
 		HashMap<(SessionIndex, CandidateHash), DisputeState>,
 		GetOnchainDisputesError,
@@ -46,8 +49,8 @@ mod staging_impl {
 	};
 
 	/// Gets the on-chain disputes at a given block number and returns them as a `HashSet` so that searching in them is cheap.
-	pub async fn get_onchain_disputes(
-		sender: &mut impl SubsystemSender,
+	pub async fn get_onchain_disputes<Sender>(
+		sender: &mut Sender,
 		relay_parent: Hash,
 	) -> Result<HashMap<(SessionIndex, CandidateHash), DisputeState>, GetOnchainDisputesError> {
 		gum::trace!(target: LOG_TARGET, ?relay_parent, "Fetching on-chain disputes");

polkadot/node/core/pvf-checker/src/lib.rs

@@ -22,9 +22,9 @@
 use futures::{channel::oneshot, future::BoxFuture, prelude::*, stream::FuturesUnordered};
 
 use polkadot_node_subsystem::{
-	messages::{CandidateValidationMessage, PreCheckOutcome, PvfCheckerMessage},
-	overseer, ActiveLeavesUpdate, FromOverseer, OverseerSignal, SpawnedSubsystem, SubsystemContext,
-	SubsystemError, SubsystemResult, SubsystemSender,
+	messages::{CandidateValidationMessage, PreCheckOutcome, PvfCheckerMessage, RuntimeApiMessage},
+	overseer, ActiveLeavesUpdate, FromOverseer, OverseerSignal, SpawnedSubsystem, SubsystemError,
+	SubsystemResult, SubsystemSender,
 };
 use polkadot_primitives::v2::{
 	BlockNumber, Hash, PvfCheckStatement, SessionIndex, ValidationCodeHash, ValidatorId,
@@ -60,11 +60,8 @@ impl PvfCheckerSubsystem {
 	}
 }
 
-impl<Context> overseer::Subsystem<Context, SubsystemError> for PvfCheckerSubsystem
-where
-	Context: SubsystemContext<Message = PvfCheckerMessage>,
-	Context: overseer::SubsystemContext<Message = PvfCheckerMessage>,
-{
+#[overseer::subsystem(PvfChecker, error=SubsystemError, prefix = self::overseer)]
+impl<Context> PvfCheckerSubsystem {
 	fn start(self, ctx: Context) -> SpawnedSubsystem {
 		if self.enabled {
 			let future = run(ctx, self.keystore, self.metrics)
@@ -123,15 +120,12 @@ struct State {
 		FuturesUnordered<BoxFuture<'static, Option<(PreCheckOutcome, ValidationCodeHash)>>>,
 }
 
+#[overseer::contextbounds(PvfChecker, prefix = self::overseer)]
 async fn run<Context>(
 	mut ctx: Context,
 	keystore: SyncCryptoStorePtr,
 	metrics: Metrics,
-) -> SubsystemResult<()>
-where
-	Context: SubsystemContext<Message = PvfCheckerMessage>,
-	Context: overseer::SubsystemContext<Message = PvfCheckerMessage>,
-{
+) -> SubsystemResult<()> {
 	let mut state = State {
 		credentials: None,
 		recent_block: None,
@@ -179,7 +173,7 @@ where
 /// Handle an incoming PVF pre-check result from the candidate-validation subsystem.
 async fn handle_pvf_check(
 	state: &mut State,
-	sender: &mut impl SubsystemSender,
+	sender: &mut impl overseer::PvfCheckerSenderTrait,
 	keystore: &SyncCryptoStorePtr,
 	metrics: &Metrics,
 	outcome: PreCheckOutcome,
@@ -247,7 +241,7 @@ struct Conclude;
 
 async fn handle_from_overseer(
 	state: &mut State,
-	sender: &mut impl SubsystemSender,
+	sender: &mut impl overseer::PvfCheckerSenderTrait,
 	keystore: &SyncCryptoStorePtr,
 	metrics: &Metrics,
 	from_overseer: FromOverseer<PvfCheckerMessage>,
@@ -273,7 +267,7 @@ async fn handle_from_overseer(
 
 async fn handle_leaves_update(
 	state: &mut State,
-	sender: &mut impl SubsystemSender,
+	sender: &mut impl overseer::PvfCheckerSenderTrait,
 	keystore: &SyncCryptoStorePtr,
 	metrics: &Metrics,
 	update: ActiveLeavesUpdate,
@@ -355,7 +349,7 @@ struct ActivationEffect {
 /// Returns `None` if the PVF pre-checking runtime API is not supported for the given leaf hash.
 async fn examine_activation(
 	state: &mut State,
-	sender: &mut impl SubsystemSender,
+	sender: &mut impl overseer::PvfCheckerSenderTrait,
 	keystore: &SyncCryptoStorePtr,
 	leaf_hash: Hash,
 	leaf_number: BlockNumber,
@@ -414,7 +408,7 @@ async fn examine_activation(
 /// Checks the active validators for the given leaf. If we have a signing key for one of them,
 /// returns the [`SigningCredentials`].
 async fn check_signing_credentials(
-	sender: &mut impl SubsystemSender,
+	sender: &mut impl SubsystemSender<RuntimeApiMessage>,
 	keystore: &SyncCryptoStorePtr,
 	leaf: Hash,
 ) -> Option<SigningCredentials> {
@@ -443,7 +437,7 @@ async fn check_signing_credentials(
 ///
 /// If the validator already voted for the given code, this function does nothing.
 async fn sign_and_submit_pvf_check_statement(
-	sender: &mut impl SubsystemSender,
+	sender: &mut impl overseer::PvfCheckerSenderTrait,
 	keystore: &SyncCryptoStorePtr,
 	voted: &mut HashSet<ValidationCodeHash>,
 	credentials: &SigningCredentials,
@@ -535,7 +529,7 @@ async fn sign_and_submit_pvf_check_statement(
 /// into the `currently_checking` set.
 async fn initiate_precheck(
 	state: &mut State,
-	sender: &mut impl SubsystemSender,
+	sender: &mut impl overseer::PvfCheckerSenderTrait,
 	relay_parent: Hash,
 	validation_code_hash: ValidationCodeHash,
 	metrics: &Metrics,
@@ -544,9 +538,7 @@ async fn initiate_precheck(
 
 	let (tx, rx) = oneshot::channel();
 	sender
-		.send_message(
-			CandidateValidationMessage::PreCheck(relay_parent, validation_code_hash, tx).into(),
-		)
+		.send_message(CandidateValidationMessage::PreCheck(relay_parent, validation_code_hash, tx))
 		.await;
 
 	let timer = metrics.time_pre_check_judgement();

polkadot/node/core/pvf-checker/src/runtime_api.rs

@@ -26,7 +26,7 @@ use polkadot_primitives::v2::{
 };
 
 pub(crate) async fn session_index_for_child(
-	sender: &mut impl SubsystemSender,
+	sender: &mut impl SubsystemSender<RuntimeApiMessage>,
 	relay_parent: Hash,
 ) -> Result<SessionIndex, RuntimeRequestError> {
 	let (tx, rx) = oneshot::channel();
@@ -34,7 +34,7 @@ pub(crate) async fn session_index_for_child(
 }
 
 pub(crate) async fn validators(
-	sender: &mut impl SubsystemSender,
+	sender: &mut impl SubsystemSender<RuntimeApiMessage>,
 	relay_parent: Hash,
 ) -> Result<Vec<ValidatorId>, RuntimeRequestError> {
 	let (tx, rx) = oneshot::channel();
@@ -42,7 +42,7 @@ pub(crate) async fn validators(
 }
 
 pub(crate) async fn submit_pvf_check_statement(
-	sender: &mut impl SubsystemSender,
+	sender: &mut impl SubsystemSender<RuntimeApiMessage>,
 	relay_parent: Hash,
 	stmt: PvfCheckStatement,
 	signature: ValidatorSignature,
@@ -58,7 +58,7 @@ pub(crate) async fn submit_pvf_check_statement(
 }
 
 pub(crate) async fn pvfs_require_precheck(
-	sender: &mut impl SubsystemSender,
+	sender: &mut impl SubsystemSender<RuntimeApiMessage>,
 	relay_parent: Hash,
 ) -> Result<Vec<ValidationCodeHash>, RuntimeRequestError> {
 	let (tx, rx) = oneshot::channel();
@@ -73,7 +73,7 @@ pub(crate) enum RuntimeRequestError {
 }
 
 pub(crate) async fn runtime_api_request<T>(
-	sender: &mut impl SubsystemSender,
+	sender: &mut impl SubsystemSender<RuntimeApiMessage>,
 	relay_parent: Hash,
 	request: RuntimeApiRequest,
 	receiver: oneshot::Receiver<Result<T, RuntimeApiSubsystemError>>,

polkadot/node/core/runtime-api/src/lib.rs

@@ -25,8 +25,7 @@
 use polkadot_node_subsystem::{
 	errors::RuntimeApiError,
 	messages::{RuntimeApiMessage, RuntimeApiRequest as Request},
-	overseer, FromOverseer, OverseerSignal, SpawnedSubsystem, SubsystemContext, SubsystemError,
-	SubsystemResult,
+	overseer, FromOverseer, OverseerSignal, SpawnedSubsystem, SubsystemError, SubsystemResult,
 };
 use polkadot_primitives::{
 	runtime_api::ParachainHost,
@@ -92,12 +91,11 @@ impl<Client> RuntimeApiSubsystem<Client> {
 	}
 }
 
-impl<Client, Context> overseer::Subsystem<Context, SubsystemError> for RuntimeApiSubsystem<Client>
+#[overseer::subsystem(RuntimeApi, error = SubsystemError, prefix = self::overseer)]
+impl<Client, Context> RuntimeApiSubsystem<Client>
 where
 	Client: ProvideRuntimeApi<Block> + Send + 'static + Sync,
 	Client::Api: ParachainHost<Block> + BabeApi<Block> + AuthorityDiscoveryApi<Block>,
-	Context: SubsystemContext<Message = RuntimeApiMessage>,
-	Context: overseer::SubsystemContext<Message = RuntimeApiMessage>,
 {
 	fn start(self, ctx: Context) -> SpawnedSubsystem {
 		SpawnedSubsystem { future: run(ctx, self).boxed(), name: "runtime-api-subsystem" }
@@ -333,6 +331,7 @@ where
 	}
 }
 
+#[overseer::contextbounds(RuntimeApi, prefix = self::overseer)]
 async fn run<Client, Context>(
 	mut ctx: Context,
 	mut subsystem: RuntimeApiSubsystem<Client>,
@@ -340,8 +339,6 @@ async fn run<Client, Context>(
 where
 	Client: ProvideRuntimeApi<Block> + Send + Sync + 'static,
 	Client::Api: ParachainHost<Block> + BabeApi<Block> + AuthorityDiscoveryApi<Block>,
-	Context: SubsystemContext<Message = RuntimeApiMessage>,
-	Context: overseer::SubsystemContext<Message = RuntimeApiMessage>,
 {
 	loop {
 		select! {

polkadot/node/malus/src/interceptor.rs

@@ -21,16 +21,18 @@
 //! messages on the overseer level.
 
 use polkadot_node_subsystem::*;
-pub use polkadot_node_subsystem::{messages::AllMessages, overseer, FromOverseer};
+pub use polkadot_node_subsystem::{messages, messages::*, overseer, FromOverseer};
 use std::{future::Future, pin::Pin};
 
 /// Filter incoming and outgoing messages.
 pub trait MessageInterceptor<Sender>: Send + Sync + Clone + 'static
 where
-	Sender: overseer::SubsystemSender<Self::Message> + Clone + 'static,
+	Sender: overseer::SubsystemSender<<Self::Message as overseer::AssociateOutgoing>::OutgoingMessages>
+		+ Clone
+		+ 'static,
 {
 	/// The message type the original subsystem handles incoming.
-	type Message: Send + 'static;
+	type Message: overseer::AssociateOutgoing + Send + 'static;
 
 	/// Filter messages that are to be received by
 	/// the subsystem.
@@ -46,7 +48,10 @@ where
 	}
 
 	/// Modify outgoing messages.
-	fn intercept_outgoing(&self, msg: AllMessages) -> Option<AllMessages> {
+	fn intercept_outgoing(
+		&self,
+		msg: <Self::Message as overseer::AssociateOutgoing>::OutgoingMessages,
+	) -> Option<<Self::Message as overseer::AssociateOutgoing>::OutgoingMessages> {
 		Some(msg)
 	}
 }
@@ -59,13 +64,26 @@ pub struct InterceptedSender<Sender, Fil> {
 }
 
 #[async_trait::async_trait]
-impl<Sender, Fil> overseer::SubsystemSender<AllMessages> for InterceptedSender<Sender, Fil>
+impl<OutgoingMessage, Sender, Fil> overseer::SubsystemSender<OutgoingMessage> for InterceptedSender<Sender, Fil>
 where
-	Sender: overseer::SubsystemSender<AllMessages>
-		+ overseer::SubsystemSender<<Fil as MessageInterceptor<Sender>>::Message>,
+	OutgoingMessage: overseer::AssociateOutgoing + Send + 'static,
+	Sender: overseer::SubsystemSender<OutgoingMessage>
+		+ overseer::SubsystemSender<
+				<
+					<Fil as MessageInterceptor<Sender>>::Message as overseer::AssociateOutgoing
+				>::OutgoingMessages
+			>,
 	Fil: MessageInterceptor<Sender>,
+	<Fil as MessageInterceptor<Sender>>::Message: overseer::AssociateOutgoing,
+	<
+		<Fil as MessageInterceptor<Sender>>::Message as overseer::AssociateOutgoing
+	>::OutgoingMessages:
+		From<OutgoingMessage>,
 {
-	async fn send_message(&mut self, msg: AllMessages) {
+	async fn send_message(&mut self, msg: OutgoingMessage) {
+		let msg = <
+					<<Fil as MessageInterceptor<Sender>>::Message as overseer::AssociateOutgoing
+				>::OutgoingMessages as From<OutgoingMessage>>::from(msg);
 		if let Some(msg) = self.message_filter.intercept_outgoing(msg) {
 			self.inner.send_message(msg).await;
 		}
@@ -73,7 +91,7 @@ where
 
 	async fn send_messages<T>(&mut self, msgs: T)
 	where
-		T: IntoIterator<Item = AllMessages> + Send,
+		T: IntoIterator<Item = OutgoingMessage> + Send,
 		T::IntoIter: Send,
 	{
 		for msg in msgs {
@@ -81,7 +99,10 @@ where
 		}
 	}
 
-	fn send_unbounded_message(&mut self, msg: AllMessages) {
+	fn send_unbounded_message(&mut self, msg: OutgoingMessage) {
+		let msg = <
+					<<Fil as MessageInterceptor<Sender>>::Message as overseer::AssociateOutgoing
+				>::OutgoingMessages as From<OutgoingMessage>>::from(msg);
 		if let Some(msg) = self.message_filter.intercept_outgoing(msg) {
 			self.inner.send_unbounded_message(msg);
 		}
@@ -91,11 +112,16 @@ where
 /// A subsystem context, that filters the outgoing messages.
 pub struct InterceptedContext<Context, Fil>
 where
-	Context: overseer::SubsystemContext + SubsystemContext,
+	Context: overseer::SubsystemContext<Error=SubsystemError, Signal=OverseerSignal>,
 	Fil: MessageInterceptor<<Context as overseer::SubsystemContext>::Sender>,
-	<Context as overseer::SubsystemContext>::Sender: overseer::SubsystemSender<
-		<Fil as MessageInterceptor<<Context as overseer::SubsystemContext>::Sender>>::Message,
-	>,
+	<Context as overseer::SubsystemContext>::Sender:
+		overseer::SubsystemSender<
+			<
+				<
+					Fil as MessageInterceptor<<Context as overseer::SubsystemContext>::Sender>
+				>::Message as overseer::AssociateOutgoing
+			>::OutgoingMessages,
+		>,
 {
 	inner: Context,
 	message_filter: Fil,
@@ -104,14 +130,15 @@ where
 
 impl<Context, Fil> InterceptedContext<Context, Fil>
 where
-	Context: overseer::SubsystemContext + SubsystemContext,
+	Context: overseer::SubsystemContext<Error=SubsystemError,Signal=OverseerSignal>,
 	Fil: MessageInterceptor<
 		<Context as overseer::SubsystemContext>::Sender,
 		Message = <Context as overseer::SubsystemContext>::Message,
 	>,
+	<Context as overseer::SubsystemContext>::Message: overseer::AssociateOutgoing,
 	<Context as overseer::SubsystemContext>::Sender: overseer::SubsystemSender<
-		<Fil as MessageInterceptor<<Context as overseer::SubsystemContext>::Sender>>::Message,
-	>,
+		<<Context as overseer::SubsystemContext>::Message as overseer::AssociateOutgoing>::OutgoingMessages
+	>
 {
 	pub fn new(mut inner: Context, message_filter: Fil) -> Self {
 		let sender = InterceptedSender::<<Context as overseer::SubsystemContext>::Sender, Fil> {
@@ -125,22 +152,27 @@ where
 #[async_trait::async_trait]
 impl<Context, Fil> overseer::SubsystemContext for InterceptedContext<Context, Fil>
 where
-	Context: overseer::SubsystemContext + SubsystemContext,
+	Context: overseer::SubsystemContext<Error=SubsystemError,Signal=OverseerSignal>,
+	<Context as overseer::SubsystemContext>::Message:
+		overseer::AssociateOutgoing,
+	<Context as overseer::SubsystemContext>::Sender:
+		overseer::SubsystemSender<
+			<<Context as overseer::SubsystemContext>::Message as overseer::AssociateOutgoing>::OutgoingMessages
+		>,
+	InterceptedSender<<Context as overseer::SubsystemContext>::Sender, Fil>:
+		overseer::SubsystemSender<
+			<<Context as overseer::SubsystemContext>::Message as overseer::AssociateOutgoing>::OutgoingMessages
+		>,
 	Fil: MessageInterceptor<
 		<Context as overseer::SubsystemContext>::Sender,
 		Message = <Context as overseer::SubsystemContext>::Message,
 	>,
-	<Context as overseer::SubsystemContext>::AllMessages:
-		From<<Context as overseer::SubsystemContext>::Message>,
-	<Context as overseer::SubsystemContext>::Sender: overseer::SubsystemSender<
-		<Fil as MessageInterceptor<<Context as overseer::SubsystemContext>::Sender>>::Message,
-	>,
 {
 	type Message = <Context as overseer::SubsystemContext>::Message;
 	type Sender = InterceptedSender<<Context as overseer::SubsystemContext>::Sender, Fil>;
-	type Error = <Context as overseer::SubsystemContext>::Error;
-	type AllMessages = <Context as overseer::SubsystemContext>::AllMessages;
-	type Signal = <Context as overseer::SubsystemContext>::Signal;
+	type Error = SubsystemError;
+	type OutgoingMessages = <<Context as overseer::SubsystemContext>::Message as overseer::AssociateOutgoing>::OutgoingMessages;
+	type Signal = OverseerSignal;
 
 	async fn try_recv(&mut self) -> Result<Option<FromOverseer<Self::Message>>, ()> {
 		loop {
@@ -200,16 +232,28 @@ impl<Sub, Interceptor> InterceptedSubsystem<Sub, Interceptor> {
 
 impl<Context, Sub, Interceptor> overseer::Subsystem<Context, SubsystemError> for InterceptedSubsystem<Sub, Interceptor>
 where
-	Context: overseer::SubsystemContext + SubsystemContext + Sync + Send,
-	Sub: overseer::Subsystem<InterceptedContext<Context, Interceptor>, SubsystemError>,
-	InterceptedContext<Context, Interceptor>: overseer::SubsystemContext + SubsystemContext,
-	Interceptor: MessageInterceptor<
-		<Context as overseer::SubsystemContext>::Sender,
-		Message = <Context as overseer::SubsystemContext>::Message,
-	>,
-	<Context as overseer::SubsystemContext>::Sender: overseer::SubsystemSender<
-		<Interceptor as MessageInterceptor<<Context as overseer::SubsystemContext>::Sender>>::Message,
-	>,
+	Context:
+		overseer::SubsystemContext<Error=SubsystemError,Signal=OverseerSignal> + Sync + Send,
+	InterceptedContext<Context, Interceptor>:
+		overseer::SubsystemContext<Error=SubsystemError,Signal=OverseerSignal>,
+	Sub:
+		overseer::Subsystem<InterceptedContext<Context, Interceptor>, SubsystemError>,
+	Interceptor:
+		MessageInterceptor<
+			<Context as overseer::SubsystemContext>::Sender,
+			Message = <Context as overseer::SubsystemContext>::Message,
+		>,
+	// <Context as overseer::SubsystemContext>::Sender:
+	// 	overseer::SubsystemSender<
+	// 		<Interceptor as MessageInterceptor<<Context as overseer::SubsystemContext>::Sender>>::Message,
+	// 	>,
+	<Context as overseer::SubsystemContext>::Message:
+		overseer::AssociateOutgoing,
+	<Context as overseer::SubsystemContext>::Sender:
+		overseer::SubsystemSender<
+				<<Context as overseer::SubsystemContext>::Message as overseer::AssociateOutgoing
+			>::OutgoingMessages
+		>,
 {
 	fn start(self, ctx: Context) -> SpawnedSubsystem {
 		let ctx = InterceptedContext::new(ctx, self.message_interceptor);

polkadot/node/malus/src/tests.rs

@@ -19,8 +19,8 @@ use super::*;
 use polkadot_node_subsystem_test_helpers::*;
 
 use polkadot_node_subsystem::{
-	messages::{AllMessages, AvailabilityStoreMessage},
-	overseer::{dummy::DummySubsystem, gen::TimeoutExt, Subsystem},
+	messages::AvailabilityStoreMessage,
+	overseer::{dummy::DummySubsystem, gen::TimeoutExt, Subsystem, AssociateOutgoing},
 	SubsystemError,
 };
 
@@ -29,8 +29,7 @@ struct BlackHoleInterceptor;
 
 impl<Sender> MessageInterceptor<Sender> for BlackHoleInterceptor
 where
-	Sender: overseer::SubsystemSender<AllMessages>
-		+ overseer::SubsystemSender<AvailabilityStoreMessage>
+	Sender: overseer::AvailabilityStoreSenderTrait
 		+ Clone
 		+ 'static,
 {
@@ -53,8 +52,7 @@ struct PassInterceptor;
 
 impl<Sender> MessageInterceptor<Sender> for PassInterceptor
 where
-	Sender: overseer::SubsystemSender<AllMessages>
-		+ overseer::SubsystemSender<AvailabilityStoreMessage>
+	Sender: overseer::AvailabilityStoreSenderTrait
 		+ Clone
 		+ 'static,
 {
@@ -68,8 +66,8 @@ async fn overseer_send<T: Into<AllMessages>>(overseer: &mut TestSubsystemContext
 fn launch_harness<F, M, Sub, G>(test_gen: G)
 where
 	F: Future<Output = TestSubsystemContextHandle<M>> + Send,
-	M: Into<AllMessages> + std::fmt::Debug + Send + 'static,
-	AllMessages: From<M>,
+	M: AssociateOutgoing + std::fmt::Debug + Send + 'static,
+	// <M as AssociateOutgoing>::OutgoingMessages: From<M>,
 	Sub: Subsystem<TestSubsystemContext<M, sp_core::testing::TaskExecutor>, SubsystemError>,
 	G: Fn(TestSubsystemContextHandle<M>) -> (F, Sub),
 {

polkadot/node/malus/src/variants/common.rs

@@ -131,11 +131,7 @@ where
 		subsystem_sender: Sender,
 		response_sender: oneshot::Sender<Result<ValidationResult, ValidationFailed>>,
 	) where
-		Sender: overseer::SubsystemSender<AllMessages>
-			+ overseer::SubsystemSender<CandidateValidationMessage>
-			+ Clone
-			+ Send
-			+ 'static,
+		Sender: overseer::CandidateValidationSenderTrait + Clone + Send + 'static,
 	{
 		let _candidate_descriptor = candidate_descriptor.clone();
 		let mut subsystem_sender = subsystem_sender.clone();
@@ -200,11 +196,7 @@ fn create_validation_response(
 
 impl<Sender, Spawner> MessageInterceptor<Sender> for ReplaceValidationResult<Spawner>
 where
-	Sender: overseer::SubsystemSender<CandidateValidationMessage>
-		+ overseer::SubsystemSender<AllMessages>
-		+ Clone
-		+ Send
-		+ 'static,
+	Sender: overseer::CandidateValidationSenderTrait + Clone + Send + 'static,
 	Spawner: SpawnNamed + Clone + 'static,
 {
 	type Message = CandidateValidationMessage;
@@ -336,7 +328,10 @@ where
 		}
 	}
 
-	fn intercept_outgoing(&self, msg: AllMessages) -> Option<AllMessages> {
+	fn intercept_outgoing(
+		&self,
+		msg: overseer::CandidateValidationOutgoingMessages,
+	) -> Option<overseer::CandidateValidationOutgoingMessages> {
 		Some(msg)
 	}
 }

polkadot/node/malus/src/variants/suggest_garbage_candidate.rs

@@ -71,11 +71,7 @@ struct NoteCandidate<Spawner> {
 
 impl<Sender, Spawner> MessageInterceptor<Sender> for NoteCandidate<Spawner>
 where
-	Sender: overseer::SubsystemSender<AllMessages>
-		+ overseer::SubsystemSender<CandidateBackingMessage>
-		+ Clone
-		+ Send
-		+ 'static,
+	Sender: overseer::CandidateBackingSenderTrait + Clone + Send + 'static,
 	Spawner: SpawnNamed + Clone + 'static,
 {
 	type Message = CandidateBackingMessage;
@@ -219,20 +215,21 @@ where
 		}
 	}
 
-	fn intercept_outgoing(&self, msg: AllMessages) -> Option<AllMessages> {
+	fn intercept_outgoing(
+		&self,
+		msg: overseer::CandidateBackingOutgoingMessages,
+	) -> Option<overseer::CandidateBackingOutgoingMessages> {
 		let msg = match msg {
-			AllMessages::CollatorProtocol(CollatorProtocolMessage::Seconded(
-				relay_parent,
-				statement,
-			)) => {
+			overseer::CandidateBackingOutgoingMessages::CollatorProtocolMessage(
+				CollatorProtocolMessage::Seconded(relay_parent, statement),
+			) => {
 				// `parachain::collator-protocol: received an unexpected `CollationSeconded`: unknown statement statement=...`
 				// TODO: Fix this error. We get this on colaltors because `malicious backing` creates a candidate that gets backed/included.
 				// It is harmless for test parachain collators, but it will prevent cumulus based collators to make progress
 				// as they wait for the relay chain to confirm the seconding of the collation.
-				AllMessages::CollatorProtocol(CollatorProtocolMessage::Seconded(
-					relay_parent,
-					statement,
-				))
+				overseer::CandidateBackingOutgoingMessages::CollatorProtocolMessage(
+					CollatorProtocolMessage::Seconded(relay_parent, statement),
+				)
 			},
 			msg => msg,
 		};

polkadot/node/metrics/src/lib.rs

@@ -41,7 +41,7 @@ pub fn logger_hook() -> impl FnOnce(&mut sc_cli::LoggerBuilder, &sc_service::Con
 	|_logger_builder, _config| {}
 }
 
-/// This module reexports Prometheus types and defines the [`Metrics`] trait.
+/// This module reexports Prometheus types and defines the [`Metrics`](metrics::Metrics) trait.
 pub mod metrics {
 	/// Reexport Substrate Prometheus types.
 	pub use substrate_prometheus_endpoint as prometheus;

polkadot/node/network/approval-distribution/src/lib.rs

@@ -34,8 +34,7 @@ use polkadot_node_subsystem::{
 		ApprovalCheckResult, ApprovalDistributionMessage, ApprovalVotingMessage,
 		AssignmentCheckResult, NetworkBridgeEvent, NetworkBridgeMessage,
 	},
-	overseer, ActiveLeavesUpdate, FromOverseer, OverseerSignal, SpawnedSubsystem, SubsystemContext,
-	SubsystemError,
+	overseer, ActiveLeavesUpdate, FromOverseer, OverseerSignal, SpawnedSubsystem, SubsystemError,
 };
 use polkadot_primitives::v2::{
 	BlockNumber, CandidateIndex, Hash, SessionIndex, ValidatorIndex, ValidatorSignature,
@@ -321,11 +320,11 @@ enum PendingMessage {
 	Approval(IndirectSignedApprovalVote),
 }
 
+#[overseer::contextbounds(ApprovalDistribution, prefix = self::overseer)]
 impl State {
-	async fn handle_network_msg(
+	async fn handle_network_msg<Context>(
 		&mut self,
-		ctx: &mut (impl SubsystemContext<Message = ApprovalDistributionMessage>
-		          + overseer::SubsystemContext<Message = ApprovalDistributionMessage>),
+		ctx: &mut Context,
 		metrics: &Metrics,
 		event: NetworkBridgeEvent<net_protocol::ApprovalDistributionMessage>,
 		rng: &mut (impl CryptoRng + Rng),
@@ -377,10 +376,9 @@ impl State {
 		}
 	}
 
-	async fn handle_new_blocks(
+	async fn handle_new_blocks<Context>(
 		&mut self,
-		ctx: &mut (impl SubsystemContext<Message = ApprovalDistributionMessage>
-		          + overseer::SubsystemContext<Message = ApprovalDistributionMessage>),
+		ctx: &mut Context,
 		metrics: &Metrics,
 		metas: Vec<BlockApprovalMeta>,
 		rng: &mut (impl CryptoRng + Rng),
@@ -421,11 +419,12 @@ impl State {
 		);
 
 		{
+			let sender = ctx.sender();
 			for (peer_id, view) in self.peer_views.iter() {
 				let intersection = view.iter().filter(|h| new_hashes.contains(h));
 				let view_intersection = View::new(intersection.cloned(), view.finalized_number);
 				Self::unify_with_peer(
-					ctx,
+					sender,
 					metrics,
 					&mut self.blocks,
 					&self.topologies,
@@ -496,10 +495,9 @@ impl State {
 		self.enable_aggression(ctx, Resend::Yes, metrics).await;
 	}
 
-	async fn handle_new_session_topology(
+	async fn handle_new_session_topology<Context>(
 		&mut self,
-		ctx: &mut (impl SubsystemContext<Message = ApprovalDistributionMessage>
-		          + overseer::SubsystemContext<Message = ApprovalDistributionMessage>),
+		ctx: &mut Context,
 		session: SessionIndex,
 		topology: SessionGridTopology,
 	) {
@@ -520,15 +518,16 @@ impl State {
 		.await;
 	}
 
-	async fn process_incoming_peer_message(
+	async fn process_incoming_peer_message<Context, R>(
 		&mut self,
-		ctx: &mut (impl SubsystemContext<Message = ApprovalDistributionMessage>
-		          + overseer::SubsystemContext<Message = ApprovalDistributionMessage>),
+		ctx: &mut Context,
 		metrics: &Metrics,
 		peer_id: PeerId,
 		msg: protocol_v1::ApprovalDistributionMessage,
-		rng: &mut (impl CryptoRng + Rng),
-	) {
+		rng: &mut R,
+	) where
+		R: CryptoRng + Rng,
+	{
 		match msg {
 			protocol_v1::ApprovalDistributionMessage::Assignments(assignments) => {
 				gum::trace!(
@@ -612,15 +611,16 @@ impl State {
 
 	// handle a peer view change: requires that the peer is already connected
 	// and has an entry in the `PeerData` struct.
-	async fn handle_peer_view_change(
+	async fn handle_peer_view_change<Context, R>(
 		&mut self,
-		ctx: &mut (impl SubsystemContext<Message = ApprovalDistributionMessage>
-		          + overseer::SubsystemContext<Message = ApprovalDistributionMessage>),
+		ctx: &mut Context,
 		metrics: &Metrics,
 		peer_id: PeerId,
 		view: View,
-		rng: &mut (impl CryptoRng + Rng),
-	) {
+		rng: &mut R,
+	) where
+		R: CryptoRng + Rng,
+	{
 		gum::trace!(target: LOG_TARGET, ?view, "Peer view change");
 		let finalized_number = view.finalized_number;
 		let old_view =
@@ -646,7 +646,7 @@ impl State {
 		}
 
 		Self::unify_with_peer(
-			ctx,
+			ctx.sender(),
 			metrics,
 			&mut self.blocks,
 			&self.topologies,
@@ -658,10 +658,9 @@ impl State {
 		.await;
 	}
 
-	async fn handle_block_finalized(
+	async fn handle_block_finalized<Context>(
 		&mut self,
-		ctx: &mut (impl SubsystemContext<Message = ApprovalDistributionMessage>
-		          + overseer::SubsystemContext<Message = ApprovalDistributionMessage>),
+		ctx: &mut Context,
 		metrics: &Metrics,
 		finalized_number: BlockNumber,
 	) {
@@ -687,16 +686,17 @@ impl State {
 		self.enable_aggression(ctx, Resend::No, metrics).await;
 	}
 
-	async fn import_and_circulate_assignment(
+	async fn import_and_circulate_assignment<Context, R>(
 		&mut self,
-		ctx: &mut (impl SubsystemContext<Message = ApprovalDistributionMessage>
-		          + overseer::SubsystemContext<Message = ApprovalDistributionMessage>),
+		ctx: &mut Context,
 		metrics: &Metrics,
 		source: MessageSource,
 		assignment: IndirectAssignmentCert,
 		claimed_candidate_index: CandidateIndex,
-		rng: &mut (impl CryptoRng + Rng),
-	) {
+		rng: &mut R,
+	) where
+		R: CryptoRng + Rng,
+	{
 		let block_hash = assignment.block_hash.clone();
 		let validator_index = assignment.validator;
 
@@ -712,7 +712,7 @@ impl State {
 						"Unexpected assignment",
 					);
 					if !self.recent_outdated_blocks.is_recent_outdated(&block_hash) {
-						modify_reputation(ctx, peer_id, COST_UNEXPECTED_MESSAGE).await;
+						modify_reputation(ctx.sender(), peer_id, COST_UNEXPECTED_MESSAGE).await;
 					}
 				}
 				return
@@ -737,7 +737,7 @@ impl State {
 								?message_subject,
 								"Duplicate assignment",
 							);
-							modify_reputation(ctx, peer_id, COST_DUPLICATE_MESSAGE).await;
+							modify_reputation(ctx.sender(), peer_id, COST_DUPLICATE_MESSAGE).await;
 						}
 						return
 					}
@@ -749,13 +749,13 @@ impl State {
 						?message_subject,
 						"Assignment from a peer is out of view",
 					);
-					modify_reputation(ctx, peer_id.clone(), COST_UNEXPECTED_MESSAGE).await;
+					modify_reputation(ctx.sender(), peer_id.clone(), COST_UNEXPECTED_MESSAGE).await;
 				},
 			}
 
 			// if the assignment is known to be valid, reward the peer
 			if entry.knowledge.contains(&message_subject, message_kind) {
-				modify_reputation(ctx, peer_id.clone(), BENEFIT_VALID_MESSAGE).await;
+				modify_reputation(ctx.sender(), peer_id.clone(), BENEFIT_VALID_MESSAGE).await;
 				if let Some(peer_knowledge) = entry.known_by.get_mut(&peer_id) {
 					gum::trace!(target: LOG_TARGET, ?peer_id, ?message_subject, "Known assignment");
 					peer_knowledge.received.insert(message_subject, message_kind);
@@ -791,7 +791,8 @@ impl State {
 			);
 			match result {
 				AssignmentCheckResult::Accepted => {
-					modify_reputation(ctx, peer_id.clone(), BENEFIT_VALID_MESSAGE_FIRST).await;
+					modify_reputation(ctx.sender(), peer_id.clone(), BENEFIT_VALID_MESSAGE_FIRST)
+						.await;
 					entry.knowledge.known_messages.insert(message_subject.clone(), message_kind);
 					if let Some(peer_knowledge) = entry.known_by.get_mut(&peer_id) {
 						peer_knowledge.received.insert(message_subject.clone(), message_kind);
@@ -819,7 +820,8 @@ impl State {
 						?peer_id,
 						"Got an assignment too far in the future",
 					);
-					modify_reputation(ctx, peer_id, COST_ASSIGNMENT_TOO_FAR_IN_THE_FUTURE).await;
+					modify_reputation(ctx.sender(), peer_id, COST_ASSIGNMENT_TOO_FAR_IN_THE_FUTURE)
+						.await;
 					return
 				},
 				AssignmentCheckResult::Bad(error) => {
@@ -830,7 +832,7 @@ impl State {
 						%error,
 						"Got a bad assignment from peer",
 					);
-					modify_reputation(ctx, peer_id, COST_INVALID_MESSAGE).await;
+					modify_reputation(ctx.sender(), peer_id, COST_INVALID_MESSAGE).await;
 					return
 				},
 			}
@@ -946,10 +948,9 @@ impl State {
 		}
 	}
 
-	async fn import_and_circulate_approval(
+	async fn import_and_circulate_approval<Context>(
 		&mut self,
-		ctx: &mut (impl SubsystemContext<Message = ApprovalDistributionMessage>
-		          + overseer::SubsystemContext<Message = ApprovalDistributionMessage>),
+		ctx: &mut Context,
 		metrics: &Metrics,
 		source: MessageSource,
 		vote: IndirectSignedApprovalVote,
@@ -963,7 +964,7 @@ impl State {
 			_ => {
 				if let Some(peer_id) = source.peer_id() {
 					if !self.recent_outdated_blocks.is_recent_outdated(&block_hash) {
-						modify_reputation(ctx, peer_id, COST_UNEXPECTED_MESSAGE).await;
+						modify_reputation(ctx.sender(), peer_id, COST_UNEXPECTED_MESSAGE).await;
 					}
 				}
 				return
@@ -982,7 +983,7 @@ impl State {
 					?message_subject,
 					"Unknown approval assignment",
 				);
-				modify_reputation(ctx, peer_id, COST_UNEXPECTED_MESSAGE).await;
+				modify_reputation(ctx.sender(), peer_id, COST_UNEXPECTED_MESSAGE).await;
 				return
 			}
 
@@ -999,7 +1000,7 @@ impl State {
 								"Duplicate approval",
 							);
 
-							modify_reputation(ctx, peer_id, COST_DUPLICATE_MESSAGE).await;
+							modify_reputation(ctx.sender(), peer_id, COST_DUPLICATE_MESSAGE).await;
 						}
 						return
 					}
@@ -1011,14 +1012,14 @@ impl State {
 						?message_subject,
 						"Approval from a peer is out of view",
 					);
-					modify_reputation(ctx, peer_id.clone(), COST_UNEXPECTED_MESSAGE).await;
+					modify_reputation(ctx.sender(), peer_id.clone(), COST_UNEXPECTED_MESSAGE).await;
 				},
 			}
 
 			// if the approval is known to be valid, reward the peer
 			if entry.knowledge.contains(&message_subject, message_kind) {
 				gum::trace!(target: LOG_TARGET, ?peer_id, ?message_subject, "Known approval");
-				modify_reputation(ctx, peer_id.clone(), BENEFIT_VALID_MESSAGE).await;
+				modify_reputation(ctx.sender(), peer_id.clone(), BENEFIT_VALID_MESSAGE).await;
 				if let Some(peer_knowledge) = entry.known_by.get_mut(&peer_id) {
 					peer_knowledge.received.insert(message_subject.clone(), message_kind);
 				}
@@ -1049,7 +1050,8 @@ impl State {
 			);
 			match result {
 				ApprovalCheckResult::Accepted => {
-					modify_reputation(ctx, peer_id.clone(), BENEFIT_VALID_MESSAGE_FIRST).await;
+					modify_reputation(ctx.sender(), peer_id.clone(), BENEFIT_VALID_MESSAGE_FIRST)
+						.await;
 
 					entry.knowledge.insert(message_subject.clone(), message_kind);
 					if let Some(peer_knowledge) = entry.known_by.get_mut(&peer_id) {
@@ -1057,7 +1059,7 @@ impl State {
 					}
 				},
 				ApprovalCheckResult::Bad(error) => {
-					modify_reputation(ctx, peer_id, COST_INVALID_MESSAGE).await;
+					modify_reputation(ctx.sender(), peer_id, COST_INVALID_MESSAGE).await;
 					gum::info!(
 						target: LOG_TARGET,
 						?peer_id,
@@ -1209,8 +1211,7 @@ impl State {
 	}
 
 	async fn unify_with_peer(
-		ctx: &mut (impl SubsystemContext<Message = ApprovalDistributionMessage>
-		          + overseer::SubsystemContext<Message = ApprovalDistributionMessage>),
+		sender: &mut impl overseer::ApprovalDistributionSenderTrait,
 		metrics: &Metrics,
 		entries: &mut HashMap<Hash, BlockEntry>,
 		topologies: &SessionGridTopologies,
@@ -1326,13 +1327,14 @@ impl State {
 				"Sending assignments to unified peer",
 			);
 
-			ctx.send_message(NetworkBridgeMessage::SendValidationMessage(
-				vec![peer_id.clone()],
-				Versioned::V1(protocol_v1::ValidationProtocol::ApprovalDistribution(
-					protocol_v1::ApprovalDistributionMessage::Assignments(assignments_to_send),
-				)),
-			))
-			.await;
+			sender
+				.send_message(NetworkBridgeMessage::SendValidationMessage(
+					vec![peer_id.clone()],
+					Versioned::V1(protocol_v1::ValidationProtocol::ApprovalDistribution(
+						protocol_v1::ApprovalDistributionMessage::Assignments(assignments_to_send),
+					)),
+				))
+				.await;
 		}
 
 		if !approvals_to_send.is_empty() {
@@ -1343,20 +1345,20 @@ impl State {
 				"Sending approvals to unified peer",
 			);
 
-			ctx.send_message(NetworkBridgeMessage::SendValidationMessage(
-				vec![peer_id],
-				Versioned::V1(protocol_v1::ValidationProtocol::ApprovalDistribution(
-					protocol_v1::ApprovalDistributionMessage::Approvals(approvals_to_send),
-				)),
-			))
-			.await;
+			sender
+				.send_message(NetworkBridgeMessage::SendValidationMessage(
+					vec![peer_id],
+					Versioned::V1(protocol_v1::ValidationProtocol::ApprovalDistribution(
+						protocol_v1::ApprovalDistributionMessage::Approvals(approvals_to_send),
+					)),
+				))
+				.await;
 		}
 	}
 
-	async fn enable_aggression(
+	async fn enable_aggression<Context>(
 		&mut self,
-		ctx: &mut (impl SubsystemContext<Message = ApprovalDistributionMessage>
-		          + overseer::SubsystemContext<Message = ApprovalDistributionMessage>),
+		ctx: &mut Context,
 		resend: Resend,
 		metrics: &Metrics,
 	) {
@@ -1457,14 +1459,17 @@ impl State {
 //
 // Note that the required routing of a message can be modified even if the
 // topology is unknown yet.
-async fn adjust_required_routing_and_propagate(
-	ctx: &mut (impl SubsystemContext<Message = ApprovalDistributionMessage>
-	          + overseer::SubsystemContext<Message = ApprovalDistributionMessage>),
+#[overseer::contextbounds(ApprovalDistribution, prefix = self::overseer)]
+async fn adjust_required_routing_and_propagate<Context, BlockFilter, RoutingModifier>(
+	ctx: &mut Context,
 	blocks: &mut HashMap<Hash, BlockEntry>,
 	topologies: &SessionGridTopologies,
-	block_filter: impl Fn(&mut BlockEntry) -> bool,
-	routing_modifier: impl Fn(&mut RequiredRouting, bool, &ValidatorIndex),
-) {
+	block_filter: BlockFilter,
+	routing_modifier: RoutingModifier,
+) where
+	BlockFilter: Fn(&mut BlockEntry) -> bool,
+	RoutingModifier: Fn(&mut RequiredRouting, bool, &ValidatorIndex),
+{
 	let mut peer_assignments = HashMap::new();
 	let mut peer_approvals = HashMap::new();
 
@@ -1566,8 +1571,7 @@ async fn adjust_required_routing_and_propagate(
 
 /// Modify the reputation of a peer based on its behavior.
 async fn modify_reputation(
-	ctx: &mut (impl SubsystemContext<Message = ApprovalDistributionMessage>
-	          + overseer::SubsystemContext<Message = ApprovalDistributionMessage>),
+	sender: &mut impl overseer::ApprovalDistributionSenderTrait,
 	peer_id: PeerId,
 	rep: Rep,
 ) {
@@ -1578,20 +1582,17 @@ async fn modify_reputation(
 		"Reputation change for peer",
 	);
 
-	ctx.send_message(NetworkBridgeMessage::ReportPeer(peer_id, rep)).await;
+	sender.send_message(NetworkBridgeMessage::ReportPeer(peer_id, rep)).await;
 }
 
+#[overseer::contextbounds(ApprovalDistribution, prefix = self::overseer)]
 impl ApprovalDistribution {
 	/// Create a new instance of the [`ApprovalDistribution`] subsystem.
 	pub fn new(metrics: Metrics) -> Self {
 		Self { metrics }
 	}
 
-	async fn run<Context>(self, ctx: Context)
-	where
-		Context: SubsystemContext<Message = ApprovalDistributionMessage>,
-		Context: overseer::SubsystemContext<Message = ApprovalDistributionMessage>,
-	{
+	async fn run<Context>(self, ctx: Context) {
 		let mut state = State::default();
 
 		// According to the docs of `rand`, this is a ChaCha12 RNG in practice
@@ -1606,10 +1607,7 @@ impl ApprovalDistribution {
 		mut ctx: Context,
 		state: &mut State,
 		rng: &mut (impl CryptoRng + Rng),
-	) where
-		Context: SubsystemContext<Message = ApprovalDistributionMessage>,
-		Context: overseer::SubsystemContext<Message = ApprovalDistributionMessage>,
-	{
+	) {
 		loop {
 			let message = match ctx.recv().await {
 				Ok(message) => message,
@@ -1644,10 +1642,7 @@ impl ApprovalDistribution {
 		msg: ApprovalDistributionMessage,
 		metrics: &Metrics,
 		rng: &mut (impl CryptoRng + Rng),
-	) where
-		Context: SubsystemContext<Message = ApprovalDistributionMessage>,
-		Context: overseer::SubsystemContext<Message = ApprovalDistributionMessage>,
-	{
+	) {
 		match msg {
 			ApprovalDistributionMessage::NetworkBridgeUpdate(event) => {
 				state.handle_network_msg(ctx, metrics, event, rng).await;
@@ -1690,11 +1685,8 @@ impl ApprovalDistribution {
 	}
 }
 
-impl<Context> overseer::Subsystem<Context, SubsystemError> for ApprovalDistribution
-where
-	Context: SubsystemContext<Message = ApprovalDistributionMessage>,
-	Context: overseer::SubsystemContext<Message = ApprovalDistributionMessage>,
-{
+#[overseer::subsystem(ApprovalDistribution, error=SubsystemError, prefix=self::overseer)]
+impl<Context> ApprovalDistribution {
 	fn start(self, ctx: Context) -> SpawnedSubsystem {
 		let future = self.run(ctx).map(|_| Ok(())).boxed();
 

polkadot/node/network/availability-distribution/src/lib.rs

@@ -21,7 +21,7 @@ use sp_keystore::SyncCryptoStorePtr;
 use polkadot_node_network_protocol::request_response::{v1, IncomingRequestReceiver};
 use polkadot_node_subsystem::{
 	messages::AvailabilityDistributionMessage, overseer, FromOverseer, OverseerSignal,
-	SpawnedSubsystem, SubsystemContext, SubsystemError,
+	SpawnedSubsystem, SubsystemError,
 };
 
 /// Error and [`Result`] type for this subsystem.
@@ -68,11 +68,8 @@ pub struct IncomingRequestReceivers {
 	pub chunk_req_receiver: IncomingRequestReceiver<v1::ChunkFetchingRequest>,
 }
 
-impl<Context> overseer::Subsystem<Context, SubsystemError> for AvailabilityDistributionSubsystem
-where
-	Context: SubsystemContext<Message = AvailabilityDistributionMessage>,
-	Context: overseer::SubsystemContext<Message = AvailabilityDistributionMessage>,
-{
+#[overseer::subsystem(AvailabilityDistribution, error=SubsystemError, prefix=self::overseer)]
+impl<Context> AvailabilityDistributionSubsystem {
 	fn start(self, ctx: Context) -> SpawnedSubsystem {
 		let future = self
 			.run(ctx)
@@ -83,6 +80,7 @@ where
 	}
 }
 
+#[overseer::contextbounds(AvailabilityDistribution, prefix = self::overseer)]
 impl AvailabilityDistributionSubsystem {
 	/// Create a new instance of the availability distribution.
 	pub fn new(
@@ -95,11 +93,7 @@ impl AvailabilityDistributionSubsystem {
 	}
 
 	/// Start processing work as passed on from the Overseer.
-	async fn run<Context>(self, mut ctx: Context) -> std::result::Result<(), FatalError>
-	where
-		Context: SubsystemContext<Message = AvailabilityDistributionMessage>,
-		Context: overseer::SubsystemContext<Message = AvailabilityDistributionMessage>,
-	{
+	async fn run<Context>(self, mut ctx: Context) -> std::result::Result<(), FatalError> {
 		let Self { mut runtime, recvs, metrics } = self;
 
 		let IncomingRequestReceivers { pov_req_receiver, chunk_req_receiver } = recvs;

polkadot/node/network/availability-distribution/src/pov_requester/mod.rs

@@ -27,7 +27,7 @@ use polkadot_node_primitives::PoV;
 use polkadot_node_subsystem::{
 	jaeger,
 	messages::{IfDisconnected, NetworkBridgeMessage},
-	SubsystemContext,
+	overseer,
 };
 use polkadot_node_subsystem_util::runtime::RuntimeInfo;
 use polkadot_primitives::v2::{AuthorityDiscoveryId, CandidateHash, Hash, ValidatorIndex};
@@ -39,6 +39,7 @@ use crate::{
 };
 
 /// Start background worker for taking care of fetching the requested `PoV` from the network.
+#[overseer::contextbounds(AvailabilityDistribution, prefix = self::overseer)]
 pub async fn fetch_pov<Context>(
 	ctx: &mut Context,
 	runtime: &mut RuntimeInfo,
@@ -48,10 +49,7 @@ pub async fn fetch_pov<Context>(
 	pov_hash: Hash,
 	tx: oneshot::Sender<PoV>,
 	metrics: Metrics,
-) -> Result<()>
-where
-	Context: SubsystemContext,
-{
+) -> Result<()> {
 	let info = &runtime.get_session_info(ctx.sender(), parent).await?.session_info;
 	let authority_id = info
 		.discovery_keys

polkadot/node/network/availability-distribution/src/requester/fetch_task/mod.rs

@@ -30,8 +30,8 @@ use polkadot_node_network_protocol::request_response::{
 use polkadot_node_primitives::ErasureChunk;
 use polkadot_node_subsystem::{
 	jaeger,
-	messages::{AllMessages, AvailabilityStoreMessage, IfDisconnected, NetworkBridgeMessage},
-	SubsystemContext,
+	messages::{AvailabilityStoreMessage, IfDisconnected, NetworkBridgeMessage},
+	overseer,
 };
 use polkadot_primitives::v2::{
 	AuthorityDiscoveryId, BlakeTwo256, CandidateHash, GroupIndex, Hash, HashT, OccupiedCore,
@@ -84,7 +84,7 @@ enum FetchedState {
 /// Messages sent from `FetchTask`s to be handled/forwarded.
 pub enum FromFetchTask {
 	/// Message to other subsystem.
-	Message(AllMessages),
+	Message(overseer::AvailabilityDistributionOutgoingMessages),
 
 	/// Concluded with result.
 	///
@@ -171,14 +171,12 @@ impl FetchTaskConfig {
 	}
 }
 
+#[overseer::contextbounds(AvailabilityDistribution, prefix = self::overseer)]
 impl FetchTask {
 	/// Start fetching a chunk.
 	///
 	/// A task handling the fetching of the configured chunk will be spawned.
-	pub async fn start<Context>(config: FetchTaskConfig, ctx: &mut Context) -> Result<Self>
-	where
-		Context: SubsystemContext,
-	{
+	pub async fn start<Context>(config: FetchTaskConfig, ctx: &mut Context) -> Result<Self> {
 		let FetchTaskConfig { prepared_running, live_in } = config;
 
 		if let Some(running) = prepared_running {
@@ -333,9 +331,10 @@ impl RunningTask {
 		let requests = Requests::ChunkFetchingV1(full_request);
 
 		self.sender
-			.send(FromFetchTask::Message(AllMessages::NetworkBridge(
-				NetworkBridgeMessage::SendRequests(vec![requests], IfDisconnected::ImmediateError),
-			)))
+			.send(FromFetchTask::Message(
+				NetworkBridgeMessage::SendRequests(vec![requests], IfDisconnected::ImmediateError)
+					.into(),
+			))
 			.await
 			.map_err(|_| TaskError::ShuttingDown)?;
 
@@ -413,13 +412,14 @@ impl RunningTask {
 		let (tx, rx) = oneshot::channel();
 		let r = self
 			.sender
-			.send(FromFetchTask::Message(AllMessages::AvailabilityStore(
+			.send(FromFetchTask::Message(
 				AvailabilityStoreMessage::StoreChunk {
 					candidate_hash: self.request.candidate_hash,
 					chunk,
 					tx,
-				},
-			)))
+				}
+				.into(),
+			))
 			.await;
 		if let Err(err) = r {
 			gum::error!(target: LOG_TARGET, err= ?err, "Storing erasure chunk failed, system shutting down?");

polkadot/node/network/availability-distribution/src/requester/fetch_task/tests.rs

@@ -227,7 +227,11 @@ impl TestRun {
 
 	/// Returns true, if after processing of the given message it would be OK for the stream to
 	/// end.
-	async fn handle_message(&self, msg: AllMessages) -> bool {
+	async fn handle_message(
+		&self,
+		msg: overseer::AvailabilityDistributionOutgoingMessages,
+	) -> bool {
+		let msg = AllMessages::from(msg);
 		match msg {
 			AllMessages::NetworkBridge(NetworkBridgeMessage::SendRequests(
 				reqs,

polkadot/node/network/availability-distribution/src/requester/mod.rs

@@ -33,8 +33,8 @@ use futures::{
 };
 
 use polkadot_node_subsystem::{
-	messages::{AllMessages, ChainApiMessage},
-	ActivatedLeaf, ActiveLeavesUpdate, LeafStatus, SubsystemContext,
+	messages::{ChainApiMessage, RuntimeApiMessage},
+	overseer, ActivatedLeaf, ActiveLeavesUpdate, LeafStatus,
 };
 use polkadot_node_subsystem_util::runtime::{get_occupied_cores, RuntimeInfo};
 use polkadot_primitives::v2::{CandidateHash, Hash, OccupiedCore, SessionIndex};
@@ -78,6 +78,7 @@ pub struct Requester {
 	metrics: Metrics,
 }
 
+#[overseer::contextbounds(AvailabilityDistribution, prefix = self::overseer)]
 impl Requester {
 	/// How many ancestors of the leaf should we consider along with it.
 	pub(crate) const LEAF_ANCESTRY_LEN_WITHIN_SESSION: usize = 3;
@@ -99,10 +100,7 @@ impl Requester {
 		ctx: &mut Context,
 		runtime: &mut RuntimeInfo,
 		update: ActiveLeavesUpdate,
-	) -> Result<()>
-	where
-		Context: SubsystemContext,
-	{
+	) -> Result<()> {
 		gum::trace!(target: LOG_TARGET, ?update, "Update fetching heads");
 		let ActiveLeavesUpdate { activated, deactivated } = update;
 		// Stale leaves happen after a reversion - we don't want to re-run availability there.
@@ -125,13 +123,11 @@ impl Requester {
 		ctx: &mut Context,
 		runtime: &mut RuntimeInfo,
 		new_head: ActivatedLeaf,
-	) -> Result<()>
-	where
-		Context: SubsystemContext,
-	{
+	) -> Result<()> {
+		let sender = &mut ctx.sender().clone();
 		let ActivatedLeaf { hash: leaf, .. } = new_head;
 		let (leaf_session_index, ancestors_in_session) = get_block_ancestors_in_same_session(
-			ctx,
+			sender,
 			runtime,
 			leaf,
 			Self::LEAF_ANCESTRY_LEN_WITHIN_SESSION,
@@ -139,7 +135,7 @@ impl Requester {
 		.await?;
 		// Also spawn or bump tasks for candidates in ancestry in the same session.
 		for hash in std::iter::once(leaf).chain(ancestors_in_session) {
-			let cores = get_occupied_cores(ctx, hash).await?;
+			let cores = get_occupied_cores(sender, hash).await?;
 			gum::trace!(
 				target: LOG_TARGET,
 				occupied_cores = ?cores,
@@ -177,15 +173,12 @@ impl Requester {
 	/// passed in leaf might be some later block where the candidate is still pending availability.
 	async fn add_cores<Context>(
 		&mut self,
-		ctx: &mut Context,
+		context: &mut Context,
 		runtime: &mut RuntimeInfo,
 		leaf: Hash,
 		leaf_session_index: SessionIndex,
 		cores: impl IntoIterator<Item = OccupiedCore>,
-	) -> Result<()>
-	where
-		Context: SubsystemContext,
-	{
+	) -> Result<()> {
 		for core in cores {
 			match self.fetches.entry(core.candidate_hash) {
 				Entry::Occupied(mut e) =>
@@ -200,7 +193,7 @@ impl Requester {
 					let task_cfg = self
 						.session_cache
 						.with_session_info(
-							ctx,
+							context,
 							runtime,
 							// We use leaf here, the relay_parent must be in the same session as the
 							// leaf. This is guaranteed by runtime which ensures that cores are cleared
@@ -221,7 +214,7 @@ impl Requester {
 						});
 
 					if let Ok(Some(task_cfg)) = task_cfg {
-						e.insert(FetchTask::start(task_cfg, ctx).await?);
+						e.insert(FetchTask::start(task_cfg, context).await?);
 					}
 					// Not a validator, nothing to do.
 				},
@@ -232,9 +225,9 @@ impl Requester {
 }
 
 impl Stream for Requester {
-	type Item = AllMessages;
+	type Item = overseer::AvailabilityDistributionOutgoingMessages;
 
-	fn poll_next(mut self: Pin<&mut Self>, ctx: &mut Context) -> Poll<Option<AllMessages>> {
+	fn poll_next(mut self: Pin<&mut Self>, ctx: &mut Context) -> Poll<Option<Self::Item>> {
 		loop {
 			match Pin::new(&mut self.rx).poll_next(ctx) {
 				Poll::Ready(Some(FromFetchTask::Message(m))) => return Poll::Ready(Some(m)),
@@ -257,26 +250,27 @@ impl Stream for Requester {
 /// Requests up to `limit` ancestor hashes of relay parent in the same session.
 ///
 /// Also returns session index of the `head`.
-async fn get_block_ancestors_in_same_session<Context>(
-	ctx: &mut Context,
+async fn get_block_ancestors_in_same_session<Sender>(
+	sender: &mut Sender,
 	runtime: &mut RuntimeInfo,
 	head: Hash,
 	limit: usize,
 ) -> Result<(SessionIndex, Vec<Hash>)>
 where
-	Context: SubsystemContext,
+	Sender:
+		overseer::SubsystemSender<RuntimeApiMessage> + overseer::SubsystemSender<ChainApiMessage>,
 {
 	// The order is parent, grandparent, ...
 	//
 	// `limit + 1` since a session index for the last element in ancestry
 	// is obtained through its parent. It always gets truncated because
 	// `session_ancestry_len` can only be incremented `ancestors.len() - 1` times.
-	let mut ancestors = get_block_ancestors(ctx, head, limit + 1).await?;
+	let mut ancestors = get_block_ancestors(sender, head, limit + 1).await?;
 	let mut ancestors_iter = ancestors.iter();
 
 	// `head` is the child of the first block in `ancestors`, request its session index.
 	let head_session_index = match ancestors_iter.next() {
-		Some(parent) => runtime.get_session_index_for_child(ctx.sender(), *parent).await?,
+		Some(parent) => runtime.get_session_index_for_child(sender, *parent).await?,
 		None => {
 			// No first element, i.e. empty.
 			return Ok((0, ancestors))
@@ -287,7 +281,7 @@ where
 	// The first parent is skipped.
 	for parent in ancestors_iter {
 		// Parent is the i-th ancestor, request session index for its child -- (i-1)th element.
-		let session_index = runtime.get_session_index_for_child(ctx.sender(), *parent).await?;
+		let session_index = runtime.get_session_index_for_child(sender, *parent).await?;
 		if session_index == head_session_index {
 			session_ancestry_len += 1;
 		} else {
@@ -302,21 +296,22 @@ where
 }
 
 /// Request up to `limit` ancestor hashes of relay parent from the Chain API.
-async fn get_block_ancestors<Context>(
-	ctx: &mut Context,
+async fn get_block_ancestors<Sender>(
+	sender: &mut Sender,
 	relay_parent: Hash,
 	limit: usize,
 ) -> Result<Vec<Hash>>
 where
-	Context: SubsystemContext,
+	Sender: overseer::SubsystemSender<ChainApiMessage>,
 {
 	let (tx, rx) = oneshot::channel();
-	ctx.send_message(ChainApiMessage::Ancestors {
-		hash: relay_parent,
-		k: limit,
-		response_channel: tx,
-	})
-	.await;
+	sender
+		.send_message(ChainApiMessage::Ancestors {
+			hash: relay_parent,
+			k: limit,
+			response_channel: tx,
+		})
+		.await;
 
 	let ancestors = rx
 		.await

polkadot/node/network/availability-distribution/src/requester/session_cache.rs

@@ -19,7 +19,7 @@ use std::collections::HashSet;
 use lru::LruCache;
 use rand::{seq::SliceRandom, thread_rng};
 
-use polkadot_node_subsystem::SubsystemContext;
+use polkadot_node_subsystem::overseer;
 use polkadot_node_subsystem_util::runtime::RuntimeInfo;
 use polkadot_primitives::v2::{
 	AuthorityDiscoveryId, GroupIndex, Hash, SessionIndex, ValidatorIndex,
@@ -79,6 +79,7 @@ pub struct BadValidators {
 	pub bad_validators: Vec<AuthorityDiscoveryId>,
 }
 
+#[overseer::contextbounds(AvailabilityDistribution, prefix = self::overseer)]
 impl SessionCache {
 	/// Create a new `SessionCache`.
 	pub fn new() -> Self {
@@ -103,7 +104,6 @@ impl SessionCache {
 		with_info: F,
 	) -> Result<Option<R>>
 	where
-		Context: SubsystemContext,
 		F: FnOnce(&SessionInfo) -> R,
 	{
 		if let Some(o_info) = self.session_info_cache.get(&session_index) {
@@ -178,10 +178,7 @@ impl SessionCache {
 		runtime: &mut RuntimeInfo,
 		relay_parent: Hash,
 		session_index: SessionIndex,
-	) -> Result<Option<SessionInfo>>
-	where
-		Context: SubsystemContext,
-	{
+	) -> Result<Option<SessionInfo>> {
 		let info = runtime
 			.get_session_info_by_index(ctx.sender(), relay_parent, session_index)
 			.await?;

polkadot/node/network/availability-distribution/src/responder.rs

@@ -43,7 +43,7 @@ pub async fn run_pov_receiver<Sender>(
 	mut receiver: IncomingRequestReceiver<v1::PoVFetchingRequest>,
 	metrics: Metrics,
 ) where
-	Sender: SubsystemSender,
+	Sender: SubsystemSender<AvailabilityStoreMessage>,
 {
 	loop {
 		match receiver.recv(|| vec![COST_INVALID_REQUEST]).await.into_nested() {
@@ -71,7 +71,7 @@ pub async fn run_chunk_receiver<Sender>(
 	mut receiver: IncomingRequestReceiver<v1::ChunkFetchingRequest>,
 	metrics: Metrics,
 ) where
-	Sender: SubsystemSender,
+	Sender: SubsystemSender<AvailabilityStoreMessage>,
 {
 	loop {
 		match receiver.recv(|| vec![COST_INVALID_REQUEST]).await.into_nested() {
@@ -105,7 +105,7 @@ pub async fn answer_pov_request_log<Sender>(
 	req: IncomingRequest<v1::PoVFetchingRequest>,
 	metrics: &Metrics,
 ) where
-	Sender: SubsystemSender,
+	Sender: SubsystemSender<AvailabilityStoreMessage>,
 {
 	let res = answer_pov_request(sender, req).await;
 	match res {
@@ -130,7 +130,7 @@ pub async fn answer_chunk_request_log<Sender>(
 	metrics: &Metrics,
 ) -> ()
 where
-	Sender: SubsystemSender,
+	Sender: SubsystemSender<AvailabilityStoreMessage>,
 {
 	let res = answer_chunk_request(sender, req).await;
 	match res {
@@ -154,7 +154,7 @@ pub async fn answer_pov_request<Sender>(
 	req: IncomingRequest<v1::PoVFetchingRequest>,
 ) -> Result<bool>
 where
-	Sender: SubsystemSender,
+	Sender: SubsystemSender<AvailabilityStoreMessage>,
 {
 	let _span = jaeger::Span::new(req.payload.candidate_hash, "answer-pov-request");
 
@@ -182,7 +182,7 @@ pub async fn answer_chunk_request<Sender>(
 	req: IncomingRequest<v1::ChunkFetchingRequest>,
 ) -> Result<bool>
 where
-	Sender: SubsystemSender,
+	Sender: SubsystemSender<AvailabilityStoreMessage>,
 {
 	let span = jaeger::Span::new(req.payload.candidate_hash, "answer-chunk-request");
 
@@ -217,7 +217,7 @@ async fn query_chunk<Sender>(
 	validator_index: ValidatorIndex,
 ) -> std::result::Result<Option<ErasureChunk>, JfyiError>
 where
-	Sender: SubsystemSender,
+	Sender: SubsystemSender<AvailabilityStoreMessage>,
 {
 	let (tx, rx) = oneshot::channel();
 	sender
@@ -245,7 +245,7 @@ async fn query_available_data<Sender>(
 	candidate_hash: CandidateHash,
 ) -> Result<Option<AvailableData>>
 where
-	Sender: SubsystemSender,
+	Sender: SubsystemSender<AvailabilityStoreMessage>,
 {
 	let (tx, rx) = oneshot::channel();
 	sender

polkadot/node/network/availability-recovery/src/lib.rs

@@ -51,9 +51,8 @@ use polkadot_node_subsystem::{
 	errors::RecoveryError,
 	jaeger,
 	messages::{AvailabilityRecoveryMessage, AvailabilityStoreMessage, NetworkBridgeMessage},
-	overseer::{self, Subsystem},
-	ActiveLeavesUpdate, FromOverseer, OverseerSignal, SpawnedSubsystem, SubsystemContext,
-	SubsystemError, SubsystemResult, SubsystemSender,
+	overseer, ActiveLeavesUpdate, FromOverseer, OverseerSignal, SpawnedSubsystem, SubsystemError,
+	SubsystemResult,
 };
 use polkadot_node_subsystem_util::request_session_info;
 use polkadot_primitives::v2::{
@@ -156,8 +155,8 @@ enum Source {
 
 /// A stateful reconstruction of availability data in reference to
 /// a candidate hash.
-struct RecoveryTask<S> {
-	sender: S,
+struct RecoveryTask<Sender> {
+	sender: Sender,
 
 	/// The parameters of the recovery process.
 	params: RecoveryParams,
@@ -177,7 +176,7 @@ impl RequestFromBackers {
 	async fn run(
 		&mut self,
 		params: &RecoveryParams,
-		sender: &mut impl SubsystemSender,
+		sender: &mut impl overseer::AvailabilityRecoverySenderTrait,
 	) -> Result<AvailableData, RecoveryError> {
 		gum::trace!(
 			target: LOG_TARGET,
@@ -199,13 +198,10 @@ impl RequestFromBackers {
 			);
 
 			sender
-				.send_message(
-					NetworkBridgeMessage::SendRequests(
-						vec![Requests::AvailableDataFetchingV1(req)],
-						IfDisconnected::ImmediateError,
-					)
-					.into(),
-				)
+				.send_message(NetworkBridgeMessage::SendRequests(
+					vec![Requests::AvailableDataFetchingV1(req)],
+					IfDisconnected::ImmediateError,
+				))
 				.await;
 
 			match response.await {
@@ -298,11 +294,13 @@ impl RequestChunksFromValidators {
 		)
 	}
 
-	async fn launch_parallel_requests(
+	async fn launch_parallel_requests<Sender>(
 		&mut self,
 		params: &RecoveryParams,
-		sender: &mut impl SubsystemSender,
-	) {
+		sender: &mut Sender,
+	) where
+		Sender: overseer::AvailabilityRecoverySenderTrait,
+	{
 		let num_requests = self.get_desired_request_count(params.threshold);
 		let candidate_hash = &params.candidate_hash;
 		let already_requesting_count = self.requesting_chunks.len();
@@ -358,9 +356,10 @@ impl RequestChunksFromValidators {
 		}
 
 		sender
-			.send_message(
-				NetworkBridgeMessage::SendRequests(requests, IfDisconnected::ImmediateError).into(),
-			)
+			.send_message(NetworkBridgeMessage::SendRequests(
+				requests,
+				IfDisconnected::ImmediateError,
+			))
 			.await;
 	}
 
@@ -483,20 +482,21 @@ impl RequestChunksFromValidators {
 		}
 	}
 
-	async fn run(
+	async fn run<Sender>(
 		&mut self,
 		params: &RecoveryParams,
-		sender: &mut impl SubsystemSender,
-	) -> Result<AvailableData, RecoveryError> {
+		sender: &mut Sender,
+	) -> Result<AvailableData, RecoveryError>
+	where
+		Sender: overseer::AvailabilityRecoverySenderTrait,
+	{
 		let metrics = &params.metrics;
 
 		// First query the store for any chunks we've got.
 		{
 			let (tx, rx) = oneshot::channel();
 			sender
-				.send_message(
-					AvailabilityStoreMessage::QueryAllChunks(params.candidate_hash, tx).into(),
-				)
+				.send_message(AvailabilityStoreMessage::QueryAllChunks(params.candidate_hash, tx))
 				.await;
 
 			match rx.await {
@@ -646,16 +646,19 @@ fn reconstructed_data_matches_root(
 	branches.root() == *expected_root
 }
 
-impl<S: SubsystemSender> RecoveryTask<S> {
+impl<Sender> RecoveryTask<Sender>
+where
+	Sender: overseer::AvailabilityRecoverySenderTrait,
+{
 	async fn run(mut self) -> Result<AvailableData, RecoveryError> {
 		// First just see if we have the data available locally.
 		{
 			let (tx, rx) = oneshot::channel();
 			self.sender
-				.send_message(
-					AvailabilityStoreMessage::QueryAvailableData(self.params.candidate_hash, tx)
-						.into(),
-				)
+				.send_message(AvailabilityStoreMessage::QueryAvailableData(
+					self.params.candidate_hash,
+					tx,
+				))
 				.await;
 
 			match rx.await {
@@ -799,11 +802,8 @@ impl Default for State {
 	}
 }
 
-impl<Context> Subsystem<Context, SubsystemError> for AvailabilityRecoverySubsystem
-where
-	Context: SubsystemContext<Message = AvailabilityRecoveryMessage>,
-	Context: overseer::SubsystemContext<Message = AvailabilityRecoveryMessage>,
-{
+#[overseer::subsystem(AvailabilityRecovery, error=SubsystemError, prefix=self::overseer)]
+impl<Context> AvailabilityRecoverySubsystem {
 	fn start(self, ctx: Context) -> SpawnedSubsystem {
 		let future = self
 			.run(ctx)
@@ -832,6 +832,7 @@ async fn handle_signal(state: &mut State, signal: OverseerSignal) -> SubsystemRe
 }
 
 /// Machinery around launching recovery tasks into the background.
+#[overseer::contextbounds(AvailabilityRecovery, prefix = self::overseer)]
 async fn launch_recovery_task<Context>(
 	state: &mut State,
 	ctx: &mut Context,
@@ -840,11 +841,7 @@ async fn launch_recovery_task<Context>(
 	backing_group: Option<GroupIndex>,
 	response_sender: oneshot::Sender<Result<AvailableData, RecoveryError>>,
 	metrics: &Metrics,
-) -> error::Result<()>
-where
-	Context: SubsystemContext<Message = AvailabilityRecoveryMessage>,
-	Context: overseer::SubsystemContext<Message = AvailabilityRecoveryMessage>,
-{
+) -> error::Result<()> {
 	let candidate_hash = receipt.hash();
 
 	let params = RecoveryParams {
@@ -885,6 +882,7 @@ where
 }
 
 /// Handles an availability recovery request.
+#[overseer::contextbounds(AvailabilityRecovery, prefix = self::overseer)]
 async fn handle_recover<Context>(
 	state: &mut State,
 	ctx: &mut Context,
@@ -893,11 +891,7 @@ async fn handle_recover<Context>(
 	backing_group: Option<GroupIndex>,
 	response_sender: oneshot::Sender<Result<AvailableData, RecoveryError>>,
 	metrics: &Metrics,
-) -> error::Result<()>
-where
-	Context: SubsystemContext<Message = AvailabilityRecoveryMessage>,
-	Context: overseer::SubsystemContext<Message = AvailabilityRecoveryMessage>,
-{
+) -> error::Result<()> {
 	let candidate_hash = receipt.hash();
 
 	let span = jaeger::Span::new(candidate_hash, "availbility-recovery")
@@ -953,14 +947,11 @@ where
 }
 
 /// Queries a chunk from av-store.
+#[overseer::contextbounds(AvailabilityRecovery, prefix = self::overseer)]
 async fn query_full_data<Context>(
 	ctx: &mut Context,
 	candidate_hash: CandidateHash,
-) -> error::Result<Option<AvailableData>>
-where
-	Context: SubsystemContext<Message = AvailabilityRecoveryMessage>,
-	Context: overseer::SubsystemContext<Message = AvailabilityRecoveryMessage>,
-{
+) -> error::Result<Option<AvailableData>> {
 	let (tx, rx) = oneshot::channel();
 	ctx.send_message(AvailabilityStoreMessage::QueryAvailableData(candidate_hash, tx))
 		.await;
@@ -968,6 +959,7 @@ where
 	Ok(rx.await.map_err(error::Error::CanceledQueryFullData)?)
 }
 
+#[overseer::contextbounds(AvailabilityRecovery, prefix = self::overseer)]
 impl AvailabilityRecoverySubsystem {
 	/// Create a new instance of `AvailabilityRecoverySubsystem` which starts with a fast path to
 	/// request data from backers.
@@ -986,11 +978,7 @@ impl AvailabilityRecoverySubsystem {
 		Self { fast_path: false, req_receiver, metrics }
 	}
 
-	async fn run<Context>(self, mut ctx: Context) -> SubsystemResult<()>
-	where
-		Context: SubsystemContext<Message = AvailabilityRecoveryMessage>,
-		Context: overseer::SubsystemContext<Message = AvailabilityRecoveryMessage>,
-	{
+	async fn run<Context>(self, mut ctx: Context) -> SubsystemResult<()> {
 		let mut state = State::default();
 		let Self { fast_path, mut req_receiver, metrics } = self;
 

polkadot/node/network/bitfield-distribution/src/lib.rs

@@ -31,7 +31,7 @@ use polkadot_node_network_protocol::{
 };
 use polkadot_node_subsystem::{
 	jaeger, messages::*, overseer, ActiveLeavesUpdate, FromOverseer, OverseerSignal, PerLeafSpan,
-	SpawnedSubsystem, SubsystemContext, SubsystemError, SubsystemResult,
+	SpawnedSubsystem, SubsystemError, SubsystemResult,
 };
 use polkadot_node_subsystem_util::{self as util};
 use polkadot_primitives::v2::{
@@ -204,6 +204,7 @@ pub struct BitfieldDistribution {
 	metrics: Metrics,
 }
 
+#[overseer::contextbounds(BitfieldDistribution, prefix = self::overseer)]
 impl BitfieldDistribution {
 	/// Create a new instance of the `BitfieldDistribution` subsystem.
 	pub fn new(metrics: Metrics) -> Self {
@@ -211,11 +212,7 @@ impl BitfieldDistribution {
 	}
 
 	/// Start processing work as passed on from the Overseer.
-	async fn run<Context>(self, ctx: Context)
-	where
-		Context: SubsystemContext<Message = BitfieldDistributionMessage>,
-		Context: overseer::SubsystemContext<Message = BitfieldDistributionMessage>,
-	{
+	async fn run<Context>(self, ctx: Context) {
 		let mut state = ProtocolState::default();
 		let mut rng = rand::rngs::StdRng::from_entropy();
 		self.run_inner(ctx, &mut state, &mut rng).await
@@ -226,10 +223,7 @@ impl BitfieldDistribution {
 		mut ctx: Context,
 		state: &mut ProtocolState,
 		rng: &mut (impl CryptoRng + Rng),
-	) where
-		Context: SubsystemContext<Message = BitfieldDistributionMessage>,
-		Context: overseer::SubsystemContext<Message = BitfieldDistributionMessage>,
-	{
+	) {
 		// work: process incoming messages from the overseer and process accordingly.
 
 		loop {
@@ -316,17 +310,20 @@ impl BitfieldDistribution {
 }
 
 /// Modify the reputation of a peer based on its behavior.
-async fn modify_reputation<Context>(ctx: &mut Context, relay_parent: Hash, peer: PeerId, rep: Rep)
-where
-	Context: SubsystemContext<Message = BitfieldDistributionMessage>,
-{
+async fn modify_reputation(
+	sender: &mut impl overseer::BitfieldDistributionSenderTrait,
+	relay_parent: Hash,
+	peer: PeerId,
+	rep: Rep,
+) {
 	gum::trace!(target: LOG_TARGET, ?relay_parent, ?rep, %peer, "reputation change");
 
-	ctx.send_message(NetworkBridgeMessage::ReportPeer(peer, rep)).await
+	sender.send_message(NetworkBridgeMessage::ReportPeer(peer, rep)).await
 }
 /// Distribute a given valid and signature checked bitfield message.
 ///
 /// For this variant the source is this node.
+#[overseer::contextbounds(BitfieldDistribution, prefix=self::overseer)]
 async fn handle_bitfield_distribution<Context>(
 	ctx: &mut Context,
 	state: &mut ProtocolState,
@@ -334,9 +331,7 @@ async fn handle_bitfield_distribution<Context>(
 	relay_parent: Hash,
 	signed_availability: SignedAvailabilityBitfield,
 	rng: &mut (impl CryptoRng + Rng),
-) where
-	Context: SubsystemContext<Message = BitfieldDistributionMessage>,
-{
+) {
 	let _timer = metrics.time_handle_bitfield_distribution();
 
 	// Ignore anything the overseer did not tell this subsystem to work on
@@ -389,6 +384,7 @@ async fn handle_bitfield_distribution<Context>(
 /// Distribute a given valid and signature checked bitfield message.
 ///
 /// Can be originated by another subsystem or received via network from another peer.
+#[overseer::contextbounds(BitfieldDistribution, prefix=self::overseer)]
 async fn relay_message<Context>(
 	ctx: &mut Context,
 	job_data: &mut PerRelayParentData,
@@ -398,9 +394,7 @@ async fn relay_message<Context>(
 	message: BitfieldGossipMessage,
 	required_routing: RequiredRouting,
 	rng: &mut (impl CryptoRng + Rng),
-) where
-	Context: SubsystemContext<Message = BitfieldDistributionMessage>,
-{
+) {
 	let relay_parent = message.relay_parent;
 	let span = job_data.span.child("relay-msg");
 
@@ -478,6 +472,7 @@ async fn relay_message<Context>(
 }
 
 /// Handle an incoming message from a peer.
+#[overseer::contextbounds(BitfieldDistribution, prefix=self::overseer)]
 async fn process_incoming_peer_message<Context>(
 	ctx: &mut Context,
 	state: &mut ProtocolState,
@@ -485,9 +480,7 @@ async fn process_incoming_peer_message<Context>(
 	origin: PeerId,
 	message: protocol_v1::BitfieldDistributionMessage,
 	rng: &mut (impl CryptoRng + Rng),
-) where
-	Context: SubsystemContext<Message = BitfieldDistributionMessage>,
-{
+) {
 	let protocol_v1::BitfieldDistributionMessage::Bitfield(relay_parent, bitfield) = message;
 	gum::trace!(
 		target: LOG_TARGET,
@@ -497,7 +490,7 @@ async fn process_incoming_peer_message<Context>(
 	);
 	// we don't care about this, not part of our view.
 	if !state.view.contains(&relay_parent) {
-		modify_reputation(ctx, relay_parent, origin, COST_NOT_IN_VIEW).await;
+		modify_reputation(ctx.sender(), relay_parent, origin, COST_NOT_IN_VIEW).await;
 		return
 	}
 
@@ -506,7 +499,7 @@ async fn process_incoming_peer_message<Context>(
 	let job_data: &mut _ = if let Some(ref mut job_data) = job_data {
 		job_data
 	} else {
-		modify_reputation(ctx, relay_parent, origin, COST_NOT_IN_VIEW).await;
+		modify_reputation(ctx.sender(), relay_parent, origin, COST_NOT_IN_VIEW).await;
 		return
 	};
 
@@ -523,7 +516,7 @@ async fn process_incoming_peer_message<Context>(
 	let validator_set = &job_data.validator_set;
 	if validator_set.is_empty() {
 		gum::trace!(target: LOG_TARGET, ?relay_parent, ?origin, "Validator set is empty",);
-		modify_reputation(ctx, relay_parent, origin, COST_MISSING_PEER_SESSION_KEY).await;
+		modify_reputation(ctx.sender(), relay_parent, origin, COST_MISSING_PEER_SESSION_KEY).await;
 		return
 	}
 
@@ -533,7 +526,7 @@ async fn process_incoming_peer_message<Context>(
 	let validator = if let Some(validator) = validator_set.get(validator_index.0 as usize) {
 		validator.clone()
 	} else {
-		modify_reputation(ctx, relay_parent, origin, COST_VALIDATOR_INDEX_INVALID).await;
+		modify_reputation(ctx.sender(), relay_parent, origin, COST_VALIDATOR_INDEX_INVALID).await;
 		return
 	};
 
@@ -546,7 +539,7 @@ async fn process_incoming_peer_message<Context>(
 		received_set.insert(validator.clone());
 	} else {
 		gum::trace!(target: LOG_TARGET, ?validator_index, ?origin, "Duplicate message");
-		modify_reputation(ctx, relay_parent, origin, COST_PEER_DUPLICATE_MESSAGE).await;
+		modify_reputation(ctx.sender(), relay_parent, origin, COST_PEER_DUPLICATE_MESSAGE).await;
 		return
 	};
 
@@ -560,13 +553,13 @@ async fn process_incoming_peer_message<Context>(
 			"already received a message for validator",
 		);
 		if old_message.signed_availability.as_unchecked() == &bitfield {
-			modify_reputation(ctx, relay_parent, origin, BENEFIT_VALID_MESSAGE).await;
+			modify_reputation(ctx.sender(), relay_parent, origin, BENEFIT_VALID_MESSAGE).await;
 		}
 		return
 	}
 	let signed_availability = match bitfield.try_into_checked(&signing_context, &validator) {
 		Err(_) => {
-			modify_reputation(ctx, relay_parent, origin, COST_SIGNATURE_INVALID).await;
+			modify_reputation(ctx.sender(), relay_parent, origin, COST_SIGNATURE_INVALID).await;
 			return
 		},
 		Ok(bitfield) => bitfield,
@@ -592,20 +585,19 @@ async fn process_incoming_peer_message<Context>(
 	)
 	.await;
 
-	modify_reputation(ctx, relay_parent, origin, BENEFIT_VALID_MESSAGE_FIRST).await
+	modify_reputation(ctx.sender(), relay_parent, origin, BENEFIT_VALID_MESSAGE_FIRST).await
 }
 
 /// Deal with network bridge updates and track what needs to be tracked
 /// which depends on the message type received.
+#[overseer::contextbounds(BitfieldDistribution, prefix=self::overseer)]
 async fn handle_network_msg<Context>(
 	ctx: &mut Context,
 	state: &mut ProtocolState,
 	metrics: &Metrics,
 	bridge_message: NetworkBridgeEvent<net_protocol::BitfieldDistributionMessage>,
 	rng: &mut (impl CryptoRng + Rng),
-) where
-	Context: SubsystemContext<Message = BitfieldDistributionMessage>,
-{
+) {
 	let _timer = metrics.time_handle_network_msg();
 
 	match bridge_message {
@@ -677,15 +669,14 @@ fn handle_our_view_change(state: &mut ProtocolState, view: OurView) {
 
 // Send the difference between two views which were not sent
 // to that particular peer.
+#[overseer::contextbounds(BitfieldDistribution, prefix=self::overseer)]
 async fn handle_peer_view_change<Context>(
 	ctx: &mut Context,
 	state: &mut ProtocolState,
 	origin: PeerId,
 	view: View,
 	rng: &mut (impl CryptoRng + Rng),
-) where
-	Context: SubsystemContext<Message = BitfieldDistributionMessage>,
-{
+) {
 	let added = state
 		.peer_views
 		.entry(origin.clone())
@@ -736,15 +727,14 @@ async fn handle_peer_view_change<Context>(
 }
 
 /// Send a gossip message and track it in the per relay parent data.
+#[overseer::contextbounds(BitfieldDistribution, prefix=self::overseer)]
 async fn send_tracked_gossip_message<Context>(
 	ctx: &mut Context,
 	state: &mut ProtocolState,
 	dest: PeerId,
 	validator: ValidatorId,
 	message: BitfieldGossipMessage,
-) where
-	Context: SubsystemContext<Message = BitfieldDistributionMessage>,
-{
+) {
 	let job_data = if let Some(job_data) = state.per_relay_parent.get_mut(&message.relay_parent) {
 		job_data
 	} else {
@@ -773,11 +763,8 @@ async fn send_tracked_gossip_message<Context>(
 	.await;
 }
 
-impl<Context> overseer::Subsystem<Context, SubsystemError> for BitfieldDistribution
-where
-	Context: SubsystemContext<Message = BitfieldDistributionMessage>,
-	Context: overseer::SubsystemContext<Message = BitfieldDistributionMessage>,
-{
+#[overseer::subsystem(BitfieldDistribution, error=SubsystemError, prefix=self::overseer)]
+impl<Context> BitfieldDistribution {
 	fn start(self, ctx: Context) -> SpawnedSubsystem {
 		let future = self.run(ctx).map(|_| Ok(())).boxed();
 
@@ -786,13 +773,11 @@ where
 }
 
 /// Query our validator set and signing context for a particular relay parent.
+#[overseer::contextbounds(BitfieldDistribution, prefix=self::overseer)]
 async fn query_basics<Context>(
 	ctx: &mut Context,
 	relay_parent: Hash,
-) -> SubsystemResult<Option<(Vec<ValidatorId>, SigningContext)>>
-where
-	Context: SubsystemContext<Message = BitfieldDistributionMessage>,
-{
+) -> SubsystemResult<Option<(Vec<ValidatorId>, SigningContext)>> {
 	let (validators_tx, validators_rx) = oneshot::channel();
 	let (session_tx, session_rx) = oneshot::channel();
 

polkadot/node/network/bridge/src/lib.rs

@@ -33,17 +33,18 @@ use polkadot_node_network_protocol::{
 	v1 as protocol_v1, ObservedRole, OurView, PeerId, ProtocolVersion,
 	UnifiedReputationChange as Rep, Versioned, View,
 };
+
 use polkadot_node_subsystem::{
 	errors::{SubsystemError, SubsystemResult},
 	messages::{
 		network_bridge_event::{NewGossipTopology, TopologyPeerInfo},
-		AllMessages, CollatorProtocolMessage, NetworkBridgeEvent, NetworkBridgeMessage,
+		ApprovalDistributionMessage, BitfieldDistributionMessage, CollatorProtocolMessage,
+		GossipSupportMessage, NetworkBridgeEvent, NetworkBridgeMessage,
+		StatementDistributionMessage,
 	},
 	overseer, ActivatedLeaf, ActiveLeavesUpdate, FromOverseer, OverseerSignal, SpawnedSubsystem,
-	SubsystemContext, SubsystemSender,
 };
-use polkadot_node_subsystem_util::metrics::{self, prometheus};
-use polkadot_overseer::gen::{OverseerError, Subsystem};
+use polkadot_overseer::gen::OverseerError;
 use polkadot_primitives::v2::{AuthorityDiscoveryId, BlockNumber, Hash, ValidatorIndex};
 
 /// Peer set info for network initialization.
@@ -67,6 +68,9 @@ use network::{send_message, Network};
 
 use crate::network::get_peer_id_by_authority_id;
 
+mod metrics;
+use self::metrics::Metrics;
+
 #[cfg(test)]
 mod tests;
 
@@ -83,206 +87,6 @@ const EMPTY_VIEW_COST: Rep = Rep::CostMajor("Peer sent us an empty view");
 // network bridge log target
 const LOG_TARGET: &'static str = "parachain::network-bridge";
 
-/// Metrics for the network bridge.
-#[derive(Clone, Default)]
-pub struct Metrics(Option<MetricsInner>);
-
-fn peer_set_label(peer_set: PeerSet, version: ProtocolVersion) -> &'static str {
-	// Higher level code is meant to protect against this ever happening.
-	peer_set.get_protocol_name_static(version).unwrap_or("<internal error>")
-}
-
-impl Metrics {
-	fn on_peer_connected(&self, peer_set: PeerSet, version: ProtocolVersion) {
-		self.0.as_ref().map(|metrics| {
-			metrics
-				.connected_events
-				.with_label_values(&[peer_set_label(peer_set, version)])
-				.inc()
-		});
-	}
-
-	fn on_peer_disconnected(&self, peer_set: PeerSet, version: ProtocolVersion) {
-		self.0.as_ref().map(|metrics| {
-			metrics
-				.disconnected_events
-				.with_label_values(&[peer_set_label(peer_set, version)])
-				.inc()
-		});
-	}
-
-	fn note_peer_count(&self, peer_set: PeerSet, version: ProtocolVersion, count: usize) {
-		self.0.as_ref().map(|metrics| {
-			metrics
-				.peer_count
-				.with_label_values(&[peer_set_label(peer_set, version)])
-				.set(count as u64)
-		});
-	}
-
-	fn on_notification_received(&self, peer_set: PeerSet, version: ProtocolVersion, size: usize) {
-		if let Some(metrics) = self.0.as_ref() {
-			metrics
-				.notifications_received
-				.with_label_values(&[peer_set_label(peer_set, version)])
-				.inc();
-
-			metrics
-				.bytes_received
-				.with_label_values(&[peer_set_label(peer_set, version)])
-				.inc_by(size as u64);
-		}
-	}
-
-	fn on_notification_sent(
-		&self,
-		peer_set: PeerSet,
-		version: ProtocolVersion,
-		size: usize,
-		to_peers: usize,
-	) {
-		if let Some(metrics) = self.0.as_ref() {
-			metrics
-				.notifications_sent
-				.with_label_values(&[peer_set_label(peer_set, version)])
-				.inc_by(to_peers as u64);
-
-			metrics
-				.bytes_sent
-				.with_label_values(&[peer_set_label(peer_set, version)])
-				.inc_by((size * to_peers) as u64);
-		}
-	}
-
-	fn note_desired_peer_count(&self, peer_set: PeerSet, size: usize) {
-		self.0.as_ref().map(|metrics| {
-			metrics
-				.desired_peer_count
-				.with_label_values(&[peer_set.get_default_protocol_name()])
-				.set(size as u64)
-		});
-	}
-
-	fn on_report_event(&self) {
-		if let Some(metrics) = self.0.as_ref() {
-			metrics.report_events.inc()
-		}
-	}
-}
-
-#[derive(Clone)]
-struct MetricsInner {
-	peer_count: prometheus::GaugeVec<prometheus::U64>,
-	connected_events: prometheus::CounterVec<prometheus::U64>,
-	disconnected_events: prometheus::CounterVec<prometheus::U64>,
-	desired_peer_count: prometheus::GaugeVec<prometheus::U64>,
-	report_events: prometheus::Counter<prometheus::U64>,
-
-	notifications_received: prometheus::CounterVec<prometheus::U64>,
-	notifications_sent: prometheus::CounterVec<prometheus::U64>,
-
-	bytes_received: prometheus::CounterVec<prometheus::U64>,
-	bytes_sent: prometheus::CounterVec<prometheus::U64>,
-}
-
-impl metrics::Metrics for Metrics {
-	fn try_register(
-		registry: &prometheus::Registry,
-	) -> std::result::Result<Self, prometheus::PrometheusError> {
-		let metrics = MetricsInner {
-			peer_count: prometheus::register(
-				prometheus::GaugeVec::new(
-					prometheus::Opts::new(
-						"polkadot_parachain_peer_count",
-						"The number of peers on a parachain-related peer-set",
-					),
-					&["protocol"]
-				)?,
-				registry,
-			)?,
-			connected_events: prometheus::register(
-				prometheus::CounterVec::new(
-					prometheus::Opts::new(
-						"polkadot_parachain_peer_connect_events_total",
-						"The number of peer connect events on a parachain notifications protocol",
-					),
-					&["protocol"]
-				)?,
-				registry,
-			)?,
-			disconnected_events: prometheus::register(
-				prometheus::CounterVec::new(
-					prometheus::Opts::new(
-						"polkadot_parachain_peer_disconnect_events_total",
-						"The number of peer disconnect events on a parachain notifications protocol",
-					),
-					&["protocol"]
-				)?,
-				registry,
-			)?,
-			desired_peer_count: prometheus::register(
-				prometheus::GaugeVec::new(
-					prometheus::Opts::new(
-						"polkadot_parachain_desired_peer_count",
-						"The number of peers that the local node is expected to connect to on a parachain-related peer-set (either including or not including unresolvable authorities, depending on whether `ConnectToValidators` or `ConnectToValidatorsResolved` was used.)",
-					),
-					&["protocol"]
-				)?,
-				registry,
-			)?,
-			report_events: prometheus::register(
-				prometheus::Counter::new(
-					"polkadot_parachain_network_report_events_total",
-					"The amount of reputation changes issued by subsystems",
-				)?,
-				registry,
-			)?,
-			notifications_received: prometheus::register(
-				prometheus::CounterVec::new(
-					prometheus::Opts::new(
-						"polkadot_parachain_notifications_received_total",
-						"The number of notifications received on a parachain protocol",
-					),
-					&["protocol"]
-				)?,
-				registry,
-			)?,
-			notifications_sent: prometheus::register(
-				prometheus::CounterVec::new(
-					prometheus::Opts::new(
-						"polkadot_parachain_notifications_sent_total",
-						"The number of notifications sent on a parachain protocol",
-					),
-					&["protocol"]
-				)?,
-				registry,
-			)?,
-			bytes_received: prometheus::register(
-				prometheus::CounterVec::new(
-					prometheus::Opts::new(
-						"polkadot_parachain_notification_bytes_received_total",
-						"The number of bytes received on a parachain notification protocol",
-					),
-					&["protocol"]
-				)?,
-				registry,
-			)?,
-			bytes_sent: prometheus::register(
-				prometheus::CounterVec::new(
-					prometheus::Opts::new(
-						"polkadot_parachain_notification_bytes_sent_total",
-						"The number of bytes sent on a parachain notification protocol",
-					),
-					&["protocol"]
-				)?,
-				registry,
-			)?,
-		};
-
-		Ok(Metrics(Some(metrics)))
-	}
-}
-
 /// Messages from and to the network.
 ///
 /// As transmitted to and received from subsystems.
@@ -320,12 +124,11 @@ impl<N, AD> NetworkBridge<N, AD> {
 	}
 }
 
-impl<Net, AD, Context> Subsystem<Context, SubsystemError> for NetworkBridge<Net, AD>
+#[overseer::subsystem(NetworkBridge, error = SubsystemError, prefix = self::overseer)]
+impl<Net, AD, Context> NetworkBridge<Net, AD>
 where
 	Net: Network + Sync,
 	AD: validator_discovery::AuthorityDiscovery + Clone,
-	Context: SubsystemContext<Message = NetworkBridgeMessage>
-		+ overseer::SubsystemContext<Message = NetworkBridgeMessage>,
 {
 	fn start(mut self, ctx: Context) -> SpawnedSubsystem {
 		// The stream of networking events has to be created at initialization, otherwise the
@@ -382,6 +185,7 @@ enum Mode {
 	Active,
 }
 
+#[overseer::contextbounds(NetworkBridge, prefix = self::overseer)]
 async fn handle_subsystem_messages<Context, N, AD>(
 	mut ctx: Context,
 	mut network_service: N,
@@ -391,8 +195,6 @@ async fn handle_subsystem_messages<Context, N, AD>(
 	metrics: Metrics,
 ) -> Result<(), UnexpectedAbort>
 where
-	Context: SubsystemContext<Message = NetworkBridgeMessage>,
-	Context: overseer::SubsystemContext<Message = NetworkBridgeMessage>,
 	N: Network,
 	AD: validator_discovery::AuthorityDiscovery + Clone,
 {
@@ -678,7 +480,7 @@ where
 }
 
 async fn handle_network_messages<AD: validator_discovery::AuthorityDiscovery>(
-	mut sender: impl SubsystemSender,
+	mut sender: impl overseer::NetworkBridgeSenderTrait,
 	mut network_service: impl Network,
 	network_stream: BoxStream<'static, NetworkEvent>,
 	mut authority_discovery_service: AD,
@@ -1031,6 +833,7 @@ async fn handle_network_messages<AD: validator_discovery::AuthorityDiscovery>(
 /// #fn is_send<T: Send>();
 /// #is_send::<parking_lot::MutexGuard<'static, ()>();
 /// ```
+#[overseer::contextbounds(NetworkBridge, prefix = self::overseer)]
 async fn run_network<N, AD, Context>(
 	bridge: NetworkBridge<N, AD>,
 	mut ctx: Context,
@@ -1039,8 +842,6 @@ async fn run_network<N, AD, Context>(
 where
 	N: Network,
 	AD: validator_discovery::AuthorityDiscovery + Clone,
-	Context: SubsystemContext<Message = NetworkBridgeMessage>
-		+ overseer::SubsystemContext<Message = NetworkBridgeMessage>,
 {
 	let shared = Shared::default();
 
@@ -1105,14 +906,17 @@ fn construct_view(
 	View::new(live_heads.take(MAX_VIEW_HEADS), finalized_number)
 }
 
-fn update_our_view(
-	net: &mut impl Network,
-	ctx: &mut impl SubsystemContext<Message = NetworkBridgeMessage, AllMessages = AllMessages>,
+#[overseer::contextbounds(NetworkBridge, prefix = self::overseer)]
+fn update_our_view<Net, Context>(
+	net: &mut Net,
+	ctx: &mut Context,
 	live_heads: &[ActivatedLeaf],
 	shared: &Shared,
 	finalized_number: BlockNumber,
 	metrics: &Metrics,
-) {
+) where
+	Net: Network,
+{
 	let new_view = construct_view(live_heads.iter().map(|v| v.hash), finalized_number);
 
 	let (validation_peers, collation_peers) = {
@@ -1238,54 +1042,79 @@ fn send_collation_message_v1(
 
 async fn dispatch_validation_event_to_all(
 	event: NetworkBridgeEvent<net_protocol::VersionedValidationProtocol>,
-	ctx: &mut impl SubsystemSender,
+	ctx: &mut impl overseer::NetworkBridgeSenderTrait,
 ) {
 	dispatch_validation_events_to_all(std::iter::once(event), ctx).await
 }
 
 async fn dispatch_collation_event_to_all(
 	event: NetworkBridgeEvent<net_protocol::VersionedCollationProtocol>,
-	ctx: &mut impl SubsystemSender,
+	ctx: &mut impl overseer::NetworkBridgeSenderTrait,
 ) {
 	dispatch_collation_events_to_all(std::iter::once(event), ctx).await
 }
 
 fn dispatch_validation_event_to_all_unbounded(
 	event: NetworkBridgeEvent<net_protocol::VersionedValidationProtocol>,
-	ctx: &mut impl SubsystemSender,
+	sender: &mut impl overseer::NetworkBridgeSenderTrait,
 ) {
-	for msg in AllMessages::dispatch_iter(event) {
-		ctx.send_unbounded_message(msg);
-	}
+	event
+		.focus()
+		.ok()
+		.map(StatementDistributionMessage::from)
+		.and_then(|msg| Some(sender.send_unbounded_message(msg)));
+	event
+		.focus()
+		.ok()
+		.map(BitfieldDistributionMessage::from)
+		.and_then(|msg| Some(sender.send_unbounded_message(msg)));
+	event
+		.focus()
+		.ok()
+		.map(ApprovalDistributionMessage::from)
+		.and_then(|msg| Some(sender.send_unbounded_message(msg)));
+	event
+		.focus()
+		.ok()
+		.map(GossipSupportMessage::from)
+		.and_then(|msg| Some(sender.send_unbounded_message(msg)));
 }
 
 fn dispatch_collation_event_to_all_unbounded(
 	event: NetworkBridgeEvent<net_protocol::VersionedCollationProtocol>,
-	ctx: &mut impl SubsystemSender,
+	sender: &mut impl overseer::NetworkBridgeSenderTrait,
 ) {
-	if let Some(msg) = event.focus().ok().map(CollatorProtocolMessage::NetworkBridgeUpdate) {
-		ctx.send_unbounded_message(msg.into());
+	if let Ok(msg) = event.focus() {
+		sender.send_unbounded_message(CollatorProtocolMessage::NetworkBridgeUpdate(msg))
 	}
 }
 
-async fn dispatch_validation_events_to_all<I>(events: I, ctx: &mut impl SubsystemSender)
-where
+async fn dispatch_validation_events_to_all<I>(
+	events: I,
+	sender: &mut impl overseer::NetworkBridgeSenderTrait,
+) where
 	I: IntoIterator<Item = NetworkBridgeEvent<net_protocol::VersionedValidationProtocol>>,
 	I::IntoIter: Send,
 {
-	ctx.send_messages(events.into_iter().flat_map(AllMessages::dispatch_iter)).await
+	for event in events {
+		sender
+			.send_messages(event.focus().map(StatementDistributionMessage::from))
+			.await;
+		sender.send_messages(event.focus().map(BitfieldDistributionMessage::from)).await;
+		sender.send_messages(event.focus().map(ApprovalDistributionMessage::from)).await;
+		sender.send_messages(event.focus().map(GossipSupportMessage::from)).await;
+	}
 }
 
-async fn dispatch_collation_events_to_all<I>(events: I, ctx: &mut impl SubsystemSender)
-where
+async fn dispatch_collation_events_to_all<I>(
+	events: I,
+	ctx: &mut impl overseer::NetworkBridgeSenderTrait,
+) where
 	I: IntoIterator<Item = NetworkBridgeEvent<net_protocol::VersionedCollationProtocol>>,
 	I::IntoIter: Send,
 {
 	let messages_for = |event: NetworkBridgeEvent<net_protocol::VersionedCollationProtocol>| {
-		event
-			.focus()
-			.ok()
-			.map(|m| AllMessages::CollatorProtocol(CollatorProtocolMessage::NetworkBridgeUpdate(m)))
+		event.focus().ok().map(|m| CollatorProtocolMessage::NetworkBridgeUpdate(m))
 	};
 
 	ctx.send_messages(events.into_iter().flat_map(messages_for)).await

polkadot/node/network/bridge/src/metrics.rs

@@ -0,0 +1,223 @@
+// Copyright 2022 Parity Technologies (UK) Ltd.
+// This file is part of Polkadot.
+
+// Polkadot is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Polkadot is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Polkadot.  If not, see <http://www.gnu.org/licenses/>.
+
+use super::{PeerSet, ProtocolVersion};
+use polkadot_node_subsystem_util::metrics::{self, prometheus};
+
+/// Metrics for the network bridge.
+#[derive(Clone, Default)]
+pub struct Metrics(pub(crate) Option<MetricsInner>);
+
+fn peer_set_label(peer_set: PeerSet, version: ProtocolVersion) -> &'static str {
+	// Higher level code is meant to protect against this ever happening.
+	peer_set.get_protocol_name_static(version).unwrap_or("<internal error>")
+}
+
+impl Metrics {
+	pub fn on_peer_connected(&self, peer_set: PeerSet, version: ProtocolVersion) {
+		self.0.as_ref().map(|metrics| {
+			metrics
+				.connected_events
+				.with_label_values(&[peer_set_label(peer_set, version)])
+				.inc()
+		});
+	}
+
+	pub fn on_peer_disconnected(&self, peer_set: PeerSet, version: ProtocolVersion) {
+		self.0.as_ref().map(|metrics| {
+			metrics
+				.disconnected_events
+				.with_label_values(&[peer_set_label(peer_set, version)])
+				.inc()
+		});
+	}
+
+	pub fn note_peer_count(&self, peer_set: PeerSet, version: ProtocolVersion, count: usize) {
+		self.0.as_ref().map(|metrics| {
+			metrics
+				.peer_count
+				.with_label_values(&[peer_set_label(peer_set, version)])
+				.set(count as u64)
+		});
+	}
+
+	pub fn on_notification_received(
+		&self,
+		peer_set: PeerSet,
+		version: ProtocolVersion,
+		size: usize,
+	) {
+		if let Some(metrics) = self.0.as_ref() {
+			metrics
+				.notifications_received
+				.with_label_values(&[peer_set_label(peer_set, version)])
+				.inc();
+
+			metrics
+				.bytes_received
+				.with_label_values(&[peer_set_label(peer_set, version)])
+				.inc_by(size as u64);
+		}
+	}
+
+	pub fn on_notification_sent(
+		&self,
+		peer_set: PeerSet,
+		version: ProtocolVersion,
+		size: usize,
+		to_peers: usize,
+	) {
+		if let Some(metrics) = self.0.as_ref() {
+			metrics
+				.notifications_sent
+				.with_label_values(&[peer_set_label(peer_set, version)])
+				.inc_by(to_peers as u64);
+
+			metrics
+				.bytes_sent
+				.with_label_values(&[peer_set_label(peer_set, version)])
+				.inc_by((size * to_peers) as u64);
+		}
+	}
+
+	pub fn note_desired_peer_count(&self, peer_set: PeerSet, size: usize) {
+		self.0.as_ref().map(|metrics| {
+			metrics
+				.desired_peer_count
+				.with_label_values(&[peer_set.get_default_protocol_name()])
+				.set(size as u64)
+		});
+	}
+
+	pub fn on_report_event(&self) {
+		if let Some(metrics) = self.0.as_ref() {
+			metrics.report_events.inc()
+		}
+	}
+}
+
+#[derive(Clone)]
+pub(crate) struct MetricsInner {
+	peer_count: prometheus::GaugeVec<prometheus::U64>,
+	connected_events: prometheus::CounterVec<prometheus::U64>,
+	disconnected_events: prometheus::CounterVec<prometheus::U64>,
+	desired_peer_count: prometheus::GaugeVec<prometheus::U64>,
+	report_events: prometheus::Counter<prometheus::U64>,
+
+	notifications_received: prometheus::CounterVec<prometheus::U64>,
+	notifications_sent: prometheus::CounterVec<prometheus::U64>,
+
+	bytes_received: prometheus::CounterVec<prometheus::U64>,
+	bytes_sent: prometheus::CounterVec<prometheus::U64>,
+}
+
+impl metrics::Metrics for Metrics {
+	fn try_register(
+		registry: &prometheus::Registry,
+	) -> std::result::Result<Self, prometheus::PrometheusError> {
+		let metrics = MetricsInner {
+			peer_count: prometheus::register(
+				prometheus::GaugeVec::new(
+					prometheus::Opts::new(
+						"polkadot_parachain_peer_count",
+						"The number of peers on a parachain-related peer-set",
+					),
+					&["protocol"]
+				)?,
+				registry,
+			)?,
+			connected_events: prometheus::register(
+				prometheus::CounterVec::new(
+					prometheus::Opts::new(
+						"polkadot_parachain_peer_connect_events_total",
+						"The number of peer connect events on a parachain notifications protocol",
+					),
+					&["protocol"]
+				)?,
+				registry,
+			)?,
+			disconnected_events: prometheus::register(
+				prometheus::CounterVec::new(
+					prometheus::Opts::new(
+						"polkadot_parachain_peer_disconnect_events_total",
+						"The number of peer disconnect events on a parachain notifications protocol",
+					),
+					&["protocol"]
+				)?,
+				registry,
+			)?,
+			desired_peer_count: prometheus::register(
+				prometheus::GaugeVec::new(
+					prometheus::Opts::new(
+						"polkadot_parachain_desired_peer_count",
+						"The number of peers that the local node is expected to connect to on a parachain-related peer-set (either including or not including unresolvable authorities, depending on whether `ConnectToValidators` or `ConnectToValidatorsResolved` was used.)",
+					),
+					&["protocol"]
+				)?,
+				registry,
+			)?,
+			report_events: prometheus::register(
+				prometheus::Counter::new(
+					"polkadot_parachain_network_report_events_total",
+					"The amount of reputation changes issued by subsystems",
+				)?,
+				registry,
+			)?,
+			notifications_received: prometheus::register(
+				prometheus::CounterVec::new(
+					prometheus::Opts::new(
+						"polkadot_parachain_notifications_received_total",
+						"The number of notifications received on a parachain protocol",
+					),
+					&["protocol"]
+				)?,
+				registry,
+			)?,
+			notifications_sent: prometheus::register(
+				prometheus::CounterVec::new(
+					prometheus::Opts::new(
+						"polkadot_parachain_notifications_sent_total",
+						"The number of notifications sent on a parachain protocol",
+					),
+					&["protocol"]
+				)?,
+				registry,
+			)?,
+			bytes_received: prometheus::register(
+				prometheus::CounterVec::new(
+					prometheus::Opts::new(
+						"polkadot_parachain_notification_bytes_received_total",
+						"The number of bytes received on a parachain notification protocol",
+					),
+					&["protocol"]
+				)?,
+				registry,
+			)?,
+			bytes_sent: prometheus::register(
+				prometheus::CounterVec::new(
+					prometheus::Opts::new(
+						"polkadot_parachain_notification_bytes_sent_total",
+						"The number of bytes sent on a parachain notification protocol",
+					),
+					&["protocol"]
+				)?,
+				registry,
+			)?,
+		};
+
+		Ok(Metrics(Some(metrics)))
+	}
+}

polkadot/node/network/bridge/src/tests.rs

@@ -34,8 +34,8 @@ use polkadot_node_network_protocol::{
 use polkadot_node_subsystem::{
 	jaeger,
 	messages::{
-		ApprovalDistributionMessage, BitfieldDistributionMessage, GossipSupportMessage,
-		StatementDistributionMessage,
+		AllMessages, ApprovalDistributionMessage, BitfieldDistributionMessage,
+		GossipSupportMessage, StatementDistributionMessage,
 	},
 	ActiveLeavesUpdate, FromOverseer, LeafStatus, OverseerSignal,
 };
@@ -313,8 +313,9 @@ async fn assert_sends_validation_event_to_all(
 	event: NetworkBridgeEvent<net_protocol::VersionedValidationProtocol>,
 	virtual_overseer: &mut TestSubsystemContextHandle<NetworkBridgeMessage>,
 ) {
-	// Ordering must match the enum variant order
-	// in `AllMessages`.
+	// Ordering must be consistent across:
+	// `fn dispatch_validation_event_to_all_unbounded`
+	// `dispatch_validation_events_to_all`
 	assert_matches!(
 		virtual_overseer.recv().await,
 		AllMessages::StatementDistribution(
@@ -1190,54 +1191,6 @@ fn send_messages_to_peers() {
 	});
 }
 
-#[test]
-fn spread_event_to_subsystems_is_up_to_date() {
-	// Number of subsystems expected to be interested in a network event,
-	// and hence the network event broadcasted to.
-	const EXPECTED_COUNT: usize = 4;
-
-	let mut cnt = 0_usize;
-	for msg in AllMessages::dispatch_iter(NetworkBridgeEvent::PeerDisconnected(PeerId::random())) {
-		match msg {
-			AllMessages::Empty => unreachable!("Nobody cares about the dummy"),
-			AllMessages::CandidateValidation(_) => unreachable!("Not interested in network events"),
-			AllMessages::CandidateBacking(_) => unreachable!("Not interested in network events"),
-			AllMessages::ChainApi(_) => unreachable!("Not interested in network events"),
-			AllMessages::CollatorProtocol(_) => unreachable!("Not interested in network events"),
-			AllMessages::StatementDistribution(_) => {
-				cnt += 1;
-			},
-			AllMessages::AvailabilityDistribution(_) =>
-				unreachable!("Not interested in network events"),
-			AllMessages::AvailabilityRecovery(_) =>
-				unreachable!("Not interested in network events"),
-			AllMessages::BitfieldDistribution(_) => {
-				cnt += 1;
-			},
-			AllMessages::BitfieldSigning(_) => unreachable!("Not interested in network events"),
-			AllMessages::Provisioner(_) => unreachable!("Not interested in network events"),
-			AllMessages::RuntimeApi(_) => unreachable!("Not interested in network events"),
-			AllMessages::AvailabilityStore(_) => unreachable!("Not interested in network events"),
-			AllMessages::NetworkBridge(_) => unreachable!("Not interested in network events"),
-			AllMessages::CollationGeneration(_) => unreachable!("Not interested in network events"),
-			AllMessages::ApprovalVoting(_) => unreachable!("Not interested in network events"),
-			AllMessages::ApprovalDistribution(_) => {
-				cnt += 1;
-			},
-			AllMessages::GossipSupport(_) => {
-				cnt += 1;
-			},
-			AllMessages::DisputeCoordinator(_) => unreachable!("Not interested in network events"),
-			AllMessages::DisputeDistribution(_) => unreachable!("Not interested in network events"),
-			AllMessages::ChainSelection(_) => unreachable!("Not interested in network events"),
-			AllMessages::PvfChecker(_) => unreachable!("Not interested in network events"),
-			// Add variants here as needed, `{ cnt += 1; }` for those that need to be
-			// notified, `unreachable!()` for those that should not.
-		}
-	}
-	assert_eq!(cnt, EXPECTED_COUNT);
-}
-
 #[test]
 fn our_view_updates_decreasing_order_and_limited_to_max() {
 	test_harness(done_syncing_oracle(), |test_harness| async move {

polkadot/node/network/collator-protocol/src/collator_side/mod.rs

@@ -38,8 +38,10 @@ use polkadot_node_network_protocol::{
 use polkadot_node_primitives::{CollationSecondedSignal, PoV, Statement};
 use polkadot_node_subsystem::{
 	jaeger,
-	messages::{CollatorProtocolMessage, NetworkBridgeEvent, NetworkBridgeMessage},
-	overseer, FromOverseer, OverseerSignal, PerLeafSpan, SubsystemContext,
+	messages::{
+		CollatorProtocolMessage, NetworkBridgeEvent, NetworkBridgeMessage, RuntimeApiMessage,
+	},
+	overseer, FromOverseer, OverseerSignal, PerLeafSpan,
 };
 use polkadot_node_subsystem_util::{
 	metrics::{self, prometheus},
@@ -360,6 +362,7 @@ impl State {
 /// or the relay-parent isn't in the active-leaves set, we ignore the message
 /// as it must be invalid in that case - although this indicates a logic error
 /// elsewhere in the node.
+#[overseer::contextbounds(CollatorProtocol, prefix = self::overseer)]
 async fn distribute_collation<Context>(
 	ctx: &mut Context,
 	runtime: &mut RuntimeInfo,
@@ -368,11 +371,7 @@ async fn distribute_collation<Context>(
 	receipt: CandidateReceipt,
 	pov: PoV,
 	result_sender: Option<oneshot::Sender<CollationSecondedSignal>>,
-) -> Result<()>
-where
-	Context: SubsystemContext<Message = CollatorProtocolMessage>,
-	Context: overseer::SubsystemContext<Message = CollatorProtocolMessage>,
-{
+) -> Result<()> {
 	let relay_parent = receipt.descriptor.relay_parent;
 
 	// This collation is not in the active-leaves set.
@@ -398,7 +397,7 @@ where
 
 	// Determine which core the para collated-on is assigned to.
 	// If it is not scheduled then ignore the message.
-	let (our_core, num_cores) = match determine_core(ctx, id, relay_parent).await? {
+	let (our_core, num_cores) = match determine_core(ctx.sender(), id, relay_parent).await? {
 		Some(core) => core,
 		None => {
 			gum::warn!(
@@ -461,16 +460,12 @@ where
 
 /// Get the Id of the Core that is assigned to the para being collated on if any
 /// and the total number of cores.
-async fn determine_core<Context>(
-	ctx: &mut Context,
+async fn determine_core(
+	sender: &mut impl overseer::SubsystemSender<RuntimeApiMessage>,
 	para_id: ParaId,
 	relay_parent: Hash,
-) -> Result<Option<(CoreIndex, usize)>>
-where
-	Context: SubsystemContext<Message = CollatorProtocolMessage>,
-	Context: overseer::SubsystemContext<Message = CollatorProtocolMessage>,
-{
-	let cores = get_availability_cores(ctx, relay_parent).await?;
+) -> Result<Option<(CoreIndex, usize)>> {
+	let cores = get_availability_cores(sender, relay_parent).await?;
 
 	for (idx, core) in cores.iter().enumerate() {
 		if let CoreState::Scheduled(occupied) = core {
@@ -493,17 +488,14 @@ struct GroupValidators {
 /// Figure out current group of validators assigned to the para being collated on.
 ///
 /// Returns [`ValidatorId`]'s of current group as determined based on the `relay_parent`.
+#[overseer::contextbounds(CollatorProtocol, prefix = self::overseer)]
 async fn determine_our_validators<Context>(
 	ctx: &mut Context,
 	runtime: &mut RuntimeInfo,
 	core_index: CoreIndex,
 	cores: usize,
 	relay_parent: Hash,
-) -> Result<GroupValidators>
-where
-	Context: SubsystemContext<Message = CollatorProtocolMessage>,
-	Context: overseer::SubsystemContext<Message = CollatorProtocolMessage>,
-{
+) -> Result<GroupValidators> {
 	let session_index = runtime.get_session_index_for_child(ctx.sender(), relay_parent).await?;
 	let info = &runtime
 		.get_session_info_by_index(ctx.sender(), relay_parent, session_index)
@@ -511,7 +503,7 @@ where
 		.session_info;
 	gum::debug!(target: LOG_TARGET, ?session_index, "Received session info");
 	let groups = &info.validator_groups;
-	let rotation_info = get_group_rotation_info(ctx, relay_parent).await?;
+	let rotation_info = get_group_rotation_info(ctx.sender(), relay_parent).await?;
 
 	let current_group_index = rotation_info.group_for_core(core_index, cores);
 	let current_validators = groups
@@ -530,11 +522,8 @@ where
 }
 
 /// Issue a `Declare` collation message to the given `peer`.
-async fn declare<Context>(ctx: &mut Context, state: &mut State, peer: PeerId)
-where
-	Context: SubsystemContext<Message = CollatorProtocolMessage>,
-	Context: overseer::SubsystemContext<Message = CollatorProtocolMessage>,
-{
+#[overseer::contextbounds(CollatorProtocol, prefix = self::overseer)]
+async fn declare<Context>(ctx: &mut Context, state: &mut State, peer: PeerId) {
 	let declare_signature_payload = protocol_v1::declare_signature_payload(&state.local_peer_id);
 
 	if let Some(para_id) = state.collating_on {
@@ -554,11 +543,11 @@ where
 
 /// Issue a connection request to a set of validators and
 /// revoke the previous connection request.
-async fn connect_to_validators<Context>(ctx: &mut Context, validator_ids: Vec<AuthorityDiscoveryId>)
-where
-	Context: SubsystemContext<Message = CollatorProtocolMessage>,
-	Context: overseer::SubsystemContext<Message = CollatorProtocolMessage>,
-{
+#[overseer::contextbounds(CollatorProtocol, prefix = self::overseer)]
+async fn connect_to_validators<Context>(
+	ctx: &mut Context,
+	validator_ids: Vec<AuthorityDiscoveryId>,
+) {
 	// ignore address resolution failure
 	// will reissue a new request on new collation
 	let (failed, _) = oneshot::channel();
@@ -574,15 +563,13 @@ where
 ///
 /// This will only advertise a collation if there exists one for the given `relay_parent` and the given `peer` is
 /// set as validator for our para at the given `relay_parent`.
+#[overseer::contextbounds(CollatorProtocol, prefix = self::overseer)]
 async fn advertise_collation<Context>(
 	ctx: &mut Context,
 	state: &mut State,
 	relay_parent: Hash,
 	peer: PeerId,
-) where
-	Context: SubsystemContext<Message = CollatorProtocolMessage>,
-	Context: overseer::SubsystemContext<Message = CollatorProtocolMessage>,
-{
+) {
 	let should_advertise = state
 		.our_validators_groups
 		.get(&relay_parent)
@@ -635,16 +622,13 @@ async fn advertise_collation<Context>(
 }
 
 /// The main incoming message dispatching switch.
+#[overseer::contextbounds(CollatorProtocol, prefix = self::overseer)]
 async fn process_msg<Context>(
 	ctx: &mut Context,
 	runtime: &mut RuntimeInfo,
 	state: &mut State,
 	msg: CollatorProtocolMessage,
-) -> Result<()>
-where
-	Context: SubsystemContext<Message = CollatorProtocolMessage>,
-	Context: overseer::SubsystemContext<Message = CollatorProtocolMessage>,
-{
+) -> Result<()> {
 	use CollatorProtocolMessage::*;
 
 	match msg {
@@ -748,17 +732,14 @@ async fn send_collation(
 }
 
 /// A networking messages switch.
+#[overseer::contextbounds(CollatorProtocol, prefix = self::overseer)]
 async fn handle_incoming_peer_message<Context>(
 	ctx: &mut Context,
 	runtime: &mut RuntimeInfo,
 	state: &mut State,
 	origin: PeerId,
 	msg: protocol_v1::CollatorProtocolMessage,
-) -> Result<()>
-where
-	Context: SubsystemContext<Message = CollatorProtocolMessage>,
-	Context: overseer::SubsystemContext<Message = CollatorProtocolMessage>,
-{
+) -> Result<()> {
 	use protocol_v1::CollatorProtocolMessage::*;
 
 	match msg {
@@ -831,15 +812,12 @@ where
 }
 
 /// Process an incoming network request for a collation.
+#[overseer::contextbounds(CollatorProtocol, prefix = self::overseer)]
 async fn handle_incoming_request<Context>(
 	ctx: &mut Context,
 	state: &mut State,
 	req: IncomingRequest<request_v1::CollationFetchingRequest>,
-) -> Result<()>
-where
-	Context: SubsystemContext<Message = CollatorProtocolMessage>,
-	Context: overseer::SubsystemContext<Message = CollatorProtocolMessage>,
-{
+) -> Result<()> {
 	let _span = state
 		.span_per_relay_parent
 		.get(&req.payload.relay_parent)
@@ -907,15 +885,13 @@ where
 }
 
 /// Our view has changed.
+#[overseer::contextbounds(CollatorProtocol, prefix = self::overseer)]
 async fn handle_peer_view_change<Context>(
 	ctx: &mut Context,
 	state: &mut State,
 	peer_id: PeerId,
 	view: View,
-) where
-	Context: SubsystemContext<Message = CollatorProtocolMessage>,
-	Context: overseer::SubsystemContext<Message = CollatorProtocolMessage>,
-{
+) {
 	let current = state.peer_views.entry(peer_id.clone()).or_default();
 
 	let added: Vec<Hash> = view.difference(&*current).cloned().collect();
@@ -928,16 +904,13 @@ async fn handle_peer_view_change<Context>(
 }
 
 /// Bridge messages switch.
+#[overseer::contextbounds(CollatorProtocol, prefix = self::overseer)]
 async fn handle_network_msg<Context>(
 	ctx: &mut Context,
 	runtime: &mut RuntimeInfo,
 	state: &mut State,
 	bridge_message: NetworkBridgeEvent<net_protocol::CollatorProtocolMessage>,
-) -> Result<()>
-where
-	Context: SubsystemContext<Message = CollatorProtocolMessage>,
-	Context: overseer::SubsystemContext<Message = CollatorProtocolMessage>,
-{
+) -> Result<()> {
 	use NetworkBridgeEvent::*;
 
 	match bridge_message {
@@ -1021,17 +994,14 @@ async fn handle_our_view_change(state: &mut State, view: OurView) -> Result<()>
 }
 
 /// The collator protocol collator side main loop.
+#[overseer::contextbounds(CollatorProtocol, prefix = crate::overseer)]
 pub(crate) async fn run<Context>(
 	mut ctx: Context,
 	local_peer_id: PeerId,
 	collator_pair: CollatorPair,
 	mut req_receiver: IncomingRequestReceiver<request_v1::CollationFetchingRequest>,
 	metrics: Metrics,
-) -> std::result::Result<(), FatalError>
-where
-	Context: SubsystemContext<Message = CollatorProtocolMessage>,
-	Context: overseer::SubsystemContext<Message = CollatorProtocolMessage>,
-{
+) -> std::result::Result<(), FatalError> {
 	use OverseerSignal::*;
 
 	let mut state = State::new(local_peer_id, collator_pair, metrics);

polkadot/node/network/collator-protocol/src/lib.rs

@@ -34,9 +34,7 @@ use polkadot_node_network_protocol::{
 use polkadot_primitives::v2::CollatorPair;
 
 use polkadot_node_subsystem::{
-	errors::SubsystemError,
-	messages::{CollatorProtocolMessage, NetworkBridgeMessage},
-	overseer, SpawnedSubsystem, SubsystemContext, SubsystemSender,
+	errors::SubsystemError, messages::NetworkBridgeMessage, overseer, SpawnedSubsystem,
 };
 
 mod error;
@@ -89,6 +87,7 @@ pub struct CollatorProtocolSubsystem {
 	protocol_side: ProtocolSide,
 }
 
+#[overseer::contextbounds(CollatorProtocol, prefix = self::overseer)]
 impl CollatorProtocolSubsystem {
 	/// Start the collator protocol.
 	/// If `id` is `Some` this is a collator side of the protocol.
@@ -98,11 +97,7 @@ impl CollatorProtocolSubsystem {
 		Self { protocol_side }
 	}
 
-	async fn run<Context>(self, ctx: Context) -> std::result::Result<(), error::FatalError>
-	where
-		Context: overseer::SubsystemContext<Message = CollatorProtocolMessage>,
-		Context: SubsystemContext<Message = CollatorProtocolMessage>,
-	{
+	async fn run<Context>(self, ctx: Context) -> std::result::Result<(), error::FatalError> {
 		match self.protocol_side {
 			ProtocolSide::Validator { keystore, eviction_policy, metrics } =>
 				validator_side::run(ctx, keystore, eviction_policy, metrics).await,
@@ -112,12 +107,8 @@ impl CollatorProtocolSubsystem {
 	}
 }
 
-impl<Context> overseer::Subsystem<Context, SubsystemError> for CollatorProtocolSubsystem
-where
-	Context: SubsystemContext<Message = CollatorProtocolMessage>,
-	Context: overseer::SubsystemContext<Message = CollatorProtocolMessage>,
-	<Context as SubsystemContext>::Sender: SubsystemSender,
-{
+#[overseer::subsystem(CollatorProtocol, error=SubsystemError, prefix=self::overseer)]
+impl<Context> CollatorProtocolSubsystem {
 	fn start(self, ctx: Context) -> SpawnedSubsystem {
 		let future = self
 			.run(ctx)
@@ -129,10 +120,11 @@ where
 }
 
 /// Modify the reputation of a peer based on its behavior.
-async fn modify_reputation<Context>(ctx: &mut Context, peer: PeerId, rep: Rep)
-where
-	Context: SubsystemContext,
-{
+async fn modify_reputation(
+	sender: &mut impl overseer::CollatorProtocolSenderTrait,
+	peer: PeerId,
+	rep: Rep,
+) {
 	gum::trace!(
 		target: LOG_TARGET,
 		rep = ?rep,
@@ -140,5 +132,5 @@ where
 		"reputation change for peer",
 	);
 
-	ctx.send_message(NetworkBridgeMessage::ReportPeer(peer, rep)).await;
+	sender.send_message(NetworkBridgeMessage::ReportPeer(peer, rep)).await;
 }

polkadot/node/network/collator-protocol/src/validator_side/mod.rs

@@ -48,9 +48,9 @@ use polkadot_node_subsystem::{
 	jaeger,
 	messages::{
 		CandidateBackingMessage, CollatorProtocolMessage, IfDisconnected, NetworkBridgeEvent,
-		NetworkBridgeMessage,
+		NetworkBridgeMessage, RuntimeApiMessage,
 	},
-	overseer, FromOverseer, OverseerSignal, PerLeafSpan, SubsystemContext, SubsystemSender,
+	overseer, FromOverseer, OverseerSignal, PerLeafSpan, SubsystemSender,
 };
 use polkadot_node_subsystem_util::metrics::{self, prometheus};
 use polkadot_primitives::v2::{CandidateReceipt, CollatorId, Hash, Id as ParaId};
@@ -362,7 +362,7 @@ struct ActiveParas {
 impl ActiveParas {
 	async fn assign_incoming(
 		&mut self,
-		sender: &mut impl SubsystemSender,
+		sender: &mut impl SubsystemSender<RuntimeApiMessage>,
 		keystore: &SyncCryptoStorePtr,
 		new_relay_parents: impl IntoIterator<Item = Hash>,
 	) {
@@ -630,25 +630,19 @@ fn collator_peer_id(
 	})
 }
 
-async fn disconnect_peer<Context>(ctx: &mut Context, peer_id: PeerId)
-where
-	Context: overseer::SubsystemContext<Message = CollatorProtocolMessage>,
-	Context: SubsystemContext<Message = CollatorProtocolMessage>,
-{
-	ctx.send_message(NetworkBridgeMessage::DisconnectPeer(peer_id, PeerSet::Collation))
+async fn disconnect_peer(sender: &mut impl overseer::CollatorProtocolSenderTrait, peer_id: PeerId) {
+	sender
+		.send_message(NetworkBridgeMessage::DisconnectPeer(peer_id, PeerSet::Collation))
 		.await
 }
 
 /// Another subsystem has requested to fetch collations on a particular leaf for some para.
-async fn fetch_collation<Context>(
-	ctx: &mut Context,
+async fn fetch_collation(
+	sender: &mut impl overseer::CollatorProtocolSenderTrait,
 	state: &mut State,
 	pc: PendingCollation,
 	id: CollatorId,
-) where
-	Context: overseer::SubsystemContext<Message = CollatorProtocolMessage>,
-	Context: SubsystemContext<Message = CollatorProtocolMessage>,
-{
+) {
 	let (tx, rx) = oneshot::channel();
 
 	let PendingCollation { relay_parent, para_id, peer_id, .. } = pc;
@@ -663,7 +657,7 @@ async fn fetch_collation<Context>(
 
 	if let Some(peer_data) = state.peer_data.get(&peer_id) {
 		if peer_data.has_advertised(&relay_parent) {
-			request_collation(ctx, state, relay_parent, para_id, peer_id, tx).await;
+			request_collation(sender, state, relay_parent, para_id, peer_id, tx).await;
 		} else {
 			gum::debug!(
 				target: LOG_TARGET,
@@ -687,51 +681,44 @@ async fn fetch_collation<Context>(
 }
 
 /// Report a collator for some malicious actions.
-async fn report_collator<Context>(
-	ctx: &mut Context,
+async fn report_collator(
+	sender: &mut impl overseer::CollatorProtocolSenderTrait,
 	peer_data: &HashMap<PeerId, PeerData>,
 	id: CollatorId,
-) where
-	Context: SubsystemContext<Message = CollatorProtocolMessage>,
-{
+) {
 	if let Some(peer_id) = collator_peer_id(peer_data, &id) {
-		modify_reputation(ctx, peer_id, COST_REPORT_BAD).await;
+		modify_reputation(sender, peer_id, COST_REPORT_BAD).await;
 	}
 }
 
 /// Some other subsystem has reported a collator as a good one, bump reputation.
-async fn note_good_collation<Context>(
-	ctx: &mut Context,
+async fn note_good_collation(
+	sender: &mut impl overseer::CollatorProtocolSenderTrait,
 	peer_data: &HashMap<PeerId, PeerData>,
 	id: CollatorId,
-) where
-	Context: overseer::SubsystemContext<Message = CollatorProtocolMessage>,
-	Context: SubsystemContext<Message = CollatorProtocolMessage>,
-{
+) {
 	if let Some(peer_id) = collator_peer_id(peer_data, &id) {
-		modify_reputation(ctx, peer_id, BENEFIT_NOTIFY_GOOD).await;
+		modify_reputation(sender, peer_id, BENEFIT_NOTIFY_GOOD).await;
 	}
 }
 
 /// Notify a collator that its collation got seconded.
-async fn notify_collation_seconded<Context>(
-	ctx: &mut Context,
+async fn notify_collation_seconded(
+	sender: &mut impl overseer::CollatorProtocolSenderTrait,
 	peer_id: PeerId,
 	relay_parent: Hash,
 	statement: SignedFullStatement,
-) where
-	Context: overseer::SubsystemContext<Message = CollatorProtocolMessage>,
-	Context: SubsystemContext<Message = CollatorProtocolMessage>,
-{
+) {
 	let wire_message =
 		protocol_v1::CollatorProtocolMessage::CollationSeconded(relay_parent, statement.into());
-	ctx.send_message(NetworkBridgeMessage::SendCollationMessage(
-		vec![peer_id],
-		Versioned::V1(protocol_v1::CollationProtocol::CollatorProtocol(wire_message)),
-	))
-	.await;
+	sender
+		.send_message(NetworkBridgeMessage::SendCollationMessage(
+			vec![peer_id],
+			Versioned::V1(protocol_v1::CollationProtocol::CollatorProtocol(wire_message)),
+		))
+		.await;
 
-	modify_reputation(ctx, peer_id, BENEFIT_NOTIFY_GOOD).await;
+	modify_reputation(sender, peer_id, BENEFIT_NOTIFY_GOOD).await;
 }
 
 /// A peer's view has changed. A number of things should be done:
@@ -754,17 +741,14 @@ async fn handle_peer_view_change(state: &mut State, peer_id: PeerId, view: View)
 ///  - Check if the requested collation is in our view.
 ///  - Update `PerRequest` records with the `result` field if necessary.
 /// And as such invocations of this function may rely on that.
-async fn request_collation<Context>(
-	ctx: &mut Context,
+async fn request_collation(
+	sender: &mut impl overseer::CollatorProtocolSenderTrait,
 	state: &mut State,
 	relay_parent: Hash,
 	para_id: ParaId,
 	peer_id: PeerId,
 	result: oneshot::Sender<(CandidateReceipt, PoV)>,
-) where
-	Context: overseer::SubsystemContext<Message = CollatorProtocolMessage>,
-	Context: SubsystemContext<Message = CollatorProtocolMessage>,
-{
+) {
 	if !state.view.contains(&relay_parent) {
 		gum::debug!(
 			target: LOG_TARGET,
@@ -815,29 +799,28 @@ async fn request_collation<Context>(
 		"Requesting collation",
 	);
 
-	ctx.send_message(NetworkBridgeMessage::SendRequests(
-		vec![requests],
-		IfDisconnected::ImmediateError,
-	))
-	.await;
+	sender
+		.send_message(NetworkBridgeMessage::SendRequests(
+			vec![requests],
+			IfDisconnected::ImmediateError,
+		))
+		.await;
 }
 
 /// Networking message has been received.
+#[overseer::contextbounds(CollatorProtocol, prefix = overseer)]
 async fn process_incoming_peer_message<Context>(
 	ctx: &mut Context,
 	state: &mut State,
 	origin: PeerId,
 	msg: protocol_v1::CollatorProtocolMessage,
-) where
-	Context: overseer::SubsystemContext<Message = CollatorProtocolMessage>,
-	Context: SubsystemContext<Message = CollatorProtocolMessage>,
-{
+) {
 	use protocol_v1::CollatorProtocolMessage::*;
 	use sp_runtime::traits::AppVerify;
 	match msg {
 		Declare(collator_id, para_id, signature) => {
 			if collator_peer_id(&state.peer_data, &collator_id).is_some() {
-				modify_reputation(ctx, origin, COST_UNEXPECTED_MESSAGE).await;
+				modify_reputation(ctx.sender(), origin, COST_UNEXPECTED_MESSAGE).await;
 				return
 			}
 
@@ -850,7 +833,7 @@ async fn process_incoming_peer_message<Context>(
 						?para_id,
 						"Unknown peer",
 					);
-					modify_reputation(ctx, origin, COST_UNEXPECTED_MESSAGE).await;
+					modify_reputation(ctx.sender(), origin, COST_UNEXPECTED_MESSAGE).await;
 					return
 				},
 			};
@@ -862,7 +845,7 @@ async fn process_incoming_peer_message<Context>(
 					?para_id,
 					"Peer is not in the collating state",
 				);
-				modify_reputation(ctx, origin, COST_UNEXPECTED_MESSAGE).await;
+				modify_reputation(ctx.sender(), origin, COST_UNEXPECTED_MESSAGE).await;
 				return
 			}
 
@@ -873,7 +856,7 @@ async fn process_incoming_peer_message<Context>(
 					?para_id,
 					"Signature verification failure",
 				);
-				modify_reputation(ctx, origin, COST_INVALID_SIGNATURE).await;
+				modify_reputation(ctx.sender(), origin, COST_INVALID_SIGNATURE).await;
 				return
 			}
 
@@ -896,9 +879,9 @@ async fn process_incoming_peer_message<Context>(
 					"Declared as collator for unneeded para",
 				);
 
-				modify_reputation(ctx, origin.clone(), COST_UNNEEDED_COLLATOR).await;
+				modify_reputation(ctx.sender(), origin.clone(), COST_UNNEEDED_COLLATOR).await;
 				gum::trace!(target: LOG_TARGET, "Disconnecting unneeded collator");
-				disconnect_peer(ctx, origin).await;
+				disconnect_peer(ctx.sender(), origin).await;
 			}
 		},
 		AdvertiseCollation(relay_parent) => {
@@ -914,7 +897,7 @@ async fn process_incoming_peer_message<Context>(
 					"Advertise collation out of view",
 				);
 
-				modify_reputation(ctx, origin, COST_UNEXPECTED_MESSAGE).await;
+				modify_reputation(ctx.sender(), origin, COST_UNEXPECTED_MESSAGE).await;
 				return
 			}
 
@@ -926,7 +909,7 @@ async fn process_incoming_peer_message<Context>(
 						?relay_parent,
 						"Advertise collation message has been received from an unknown peer",
 					);
-					modify_reputation(ctx, origin, COST_UNEXPECTED_MESSAGE).await;
+					modify_reputation(ctx.sender(), origin, COST_UNEXPECTED_MESSAGE).await;
 					return
 				},
 				Some(p) => p,
@@ -962,7 +945,8 @@ async fn process_incoming_peer_message<Context>(
 							collations.status = CollationStatus::Fetching;
 							collations.waiting_collation = Some(id.clone());
 
-							fetch_collation(ctx, state, pending_collation.clone(), id).await;
+							fetch_collation(ctx.sender(), state, pending_collation.clone(), id)
+								.await;
 						},
 						CollationStatus::Seconded => {
 							gum::trace!(
@@ -984,7 +968,7 @@ async fn process_incoming_peer_message<Context>(
 						"Invalid advertisement",
 					);
 
-					modify_reputation(ctx, origin, COST_UNEXPECTED_MESSAGE).await;
+					modify_reputation(ctx.sender(), origin, COST_UNEXPECTED_MESSAGE).await;
 				},
 			}
 		},
@@ -1011,16 +995,13 @@ async fn remove_relay_parent(state: &mut State, relay_parent: Hash) -> Result<()
 }
 
 /// Our view has changed.
+#[overseer::contextbounds(CollatorProtocol, prefix = self::overseer)]
 async fn handle_our_view_change<Context>(
 	ctx: &mut Context,
 	state: &mut State,
 	keystore: &SyncCryptoStorePtr,
 	view: OurView,
-) -> Result<()>
-where
-	Context: overseer::SubsystemContext<Message = CollatorProtocolMessage>,
-	Context: SubsystemContext<Message = CollatorProtocolMessage>,
-{
+) -> Result<()> {
 	let old_view = std::mem::replace(&mut state.view, view);
 
 	let added: HashMap<Hash, Arc<jaeger::Span>> = state
@@ -1061,7 +1042,7 @@ where
 					?para_id,
 					"Disconnecting peer on view change (not current parachain id)"
 				);
-				disconnect_peer(ctx, peer_id.clone()).await;
+				disconnect_peer(ctx.sender(), peer_id.clone()).await;
 			}
 		}
 	}
@@ -1070,16 +1051,13 @@ where
 }
 
 /// Bridge event switch.
+#[overseer::contextbounds(CollatorProtocol, prefix = self::overseer)]
 async fn handle_network_msg<Context>(
 	ctx: &mut Context,
 	state: &mut State,
 	keystore: &SyncCryptoStorePtr,
 	bridge_message: NetworkBridgeEvent<net_protocol::CollatorProtocolMessage>,
-) -> Result<()>
-where
-	Context: overseer::SubsystemContext<Message = CollatorProtocolMessage>,
-	Context: SubsystemContext<Message = CollatorProtocolMessage>,
-{
+) -> Result<()> {
 	use NetworkBridgeEvent::*;
 
 	match bridge_message {
@@ -1109,15 +1087,13 @@ where
 }
 
 /// The main message receiver switch.
+#[overseer::contextbounds(CollatorProtocol, prefix = self::overseer)]
 async fn process_msg<Context>(
 	ctx: &mut Context,
 	keystore: &SyncCryptoStorePtr,
 	msg: CollatorProtocolMessage,
 	state: &mut State,
-) where
-	Context: overseer::SubsystemContext<Message = CollatorProtocolMessage>,
-	Context: SubsystemContext<Message = CollatorProtocolMessage>,
-{
+) {
 	use CollatorProtocolMessage::*;
 
 	let _timer = state.metrics.time_process_msg();
@@ -1137,7 +1113,7 @@ async fn process_msg<Context>(
 			);
 		},
 		ReportCollator(id) => {
-			report_collator(ctx, &state.peer_data, id).await;
+			report_collator(ctx.sender(), &state.peer_data, id).await;
 		},
 		NetworkBridgeUpdate(event) => {
 			if let Err(e) = handle_network_msg(ctx, state, keystore, event).await {
@@ -1152,8 +1128,8 @@ async fn process_msg<Context>(
 			if let Some(collation_event) = state.pending_candidates.remove(&parent) {
 				let (collator_id, pending_collation) = collation_event;
 				let PendingCollation { relay_parent, peer_id, .. } = pending_collation;
-				note_good_collation(ctx, &state.peer_data, collator_id).await;
-				notify_collation_seconded(ctx, peer_id, relay_parent, stmt).await;
+				note_good_collation(ctx.sender(), &state.peer_data, collator_id).await;
+				notify_collation_seconded(ctx.sender(), peer_id, relay_parent, stmt).await;
 
 				if let Some(collations) = state.collations_per_relay_parent.get_mut(&parent) {
 					collations.status = CollationStatus::Seconded;
@@ -1184,7 +1160,7 @@ async fn process_msg<Context>(
 				Entry::Vacant(_) => return,
 			};
 
-			report_collator(ctx, &state.peer_data, id.clone()).await;
+			report_collator(ctx.sender(), &state.peer_data, id.clone()).await;
 
 			dequeue_next_collation_and_fetch(ctx, state, parent, id).await;
 		},
@@ -1211,16 +1187,13 @@ fn infinite_stream(every: Duration) -> impl FusedStream<Item = ()> {
 }
 
 /// The main run loop.
+#[overseer::contextbounds(CollatorProtocol, prefix = self::overseer)]
 pub(crate) async fn run<Context>(
 	mut ctx: Context,
 	keystore: SyncCryptoStorePtr,
 	eviction_policy: crate::CollatorEvictionPolicy,
 	metrics: Metrics,
-) -> std::result::Result<(), crate::error::FatalError>
-where
-	Context: overseer::SubsystemContext<Message = CollatorProtocolMessage>,
-	Context: SubsystemContext<Message = CollatorProtocolMessage>,
-{
+) -> std::result::Result<(), crate::error::FatalError> {
 	let mut state = State { metrics, ..Default::default() };
 
 	let next_inactivity_stream = infinite_stream(ACTIVITY_POLL);
@@ -1247,7 +1220,7 @@ where
 				}
 			}
 			_ = next_inactivity_stream.next() => {
-				disconnect_inactive_peers(&mut ctx, &eviction_policy, &state.peer_data).await;
+				disconnect_inactive_peers(ctx.sender(), &eviction_policy, &state.peer_data).await;
 			}
 			res = state.collation_fetches.select_next_some() => {
 				handle_collation_fetched_result(&mut ctx, &mut state, res).await;
@@ -1270,7 +1243,7 @@ where
 				).await;
 
 				for (peer_id, rep) in reputation_changes {
-					modify_reputation(&mut ctx, peer_id, rep).await;
+					modify_reputation(ctx.sender(), peer_id, rep).await;
 				}
 			},
 		}
@@ -1304,9 +1277,9 @@ async fn poll_requests(
 }
 
 /// Dequeue another collation and fetch.
-async fn dequeue_next_collation_and_fetch(
-	ctx: &mut (impl SubsystemContext<Message = CollatorProtocolMessage>
-	          + overseer::SubsystemContext<Message = CollatorProtocolMessage>),
+#[overseer::contextbounds(CollatorProtocol, prefix = self::overseer)]
+async fn dequeue_next_collation_and_fetch<Context>(
+	ctx: &mut Context,
 	state: &mut State,
 	relay_parent: Hash,
 	// The collator we tried to fetch from last.
@@ -1323,7 +1296,7 @@ async fn dequeue_next_collation_and_fetch(
 			?id,
 			"Successfully dequeued next advertisement - fetching ..."
 		);
-		fetch_collation(ctx, state, next, id).await;
+		fetch_collation(ctx.sender(), state, next, id).await;
 	} else {
 		gum::debug!(
 			target: LOG_TARGET,
@@ -1335,14 +1308,12 @@ async fn dequeue_next_collation_and_fetch(
 }
 
 /// Handle a fetched collation result.
+#[overseer::contextbounds(CollatorProtocol, prefix = self::overseer)]
 async fn handle_collation_fetched_result<Context>(
 	ctx: &mut Context,
 	state: &mut State,
 	(mut collation_event, res): PendingCollationFetch,
-) where
-	Context: overseer::SubsystemContext<Message = CollatorProtocolMessage>,
-	Context: SubsystemContext<Message = CollatorProtocolMessage>,
-{
+) {
 	// If no prior collation for this relay parent has been seconded, then
 	// memorize the `collation_event` for that `relay_parent`, such that we may
 	// notify the collator of their successful second backing
@@ -1380,12 +1351,13 @@ async fn handle_collation_fetched_result<Context>(
 
 	if let Entry::Vacant(entry) = state.pending_candidates.entry(relay_parent) {
 		collation_event.1.commitments_hash = Some(candidate_receipt.commitments_hash);
-		ctx.send_message(CandidateBackingMessage::Second(
-			relay_parent.clone(),
-			candidate_receipt,
-			pov,
-		))
-		.await;
+		ctx.sender()
+			.send_message(CandidateBackingMessage::Second(
+				relay_parent.clone(),
+				candidate_receipt,
+				pov,
+			))
+			.await;
 
 		entry.insert(collation_event);
 	} else {
@@ -1401,18 +1373,15 @@ async fn handle_collation_fetched_result<Context>(
 // This issues `NetworkBridge` notifications to disconnect from all inactive peers at the
 // earliest possible point. This does not yet clean up any metadata, as that will be done upon
 // receipt of the `PeerDisconnected` event.
-async fn disconnect_inactive_peers<Context>(
-	ctx: &mut Context,
+async fn disconnect_inactive_peers(
+	sender: &mut impl overseer::CollatorProtocolSenderTrait,
 	eviction_policy: &crate::CollatorEvictionPolicy,
 	peers: &HashMap<PeerId, PeerData>,
-) where
-	Context: overseer::SubsystemContext<Message = CollatorProtocolMessage>,
-	Context: SubsystemContext<Message = CollatorProtocolMessage>,
-{
+) {
 	for (peer, peer_data) in peers {
 		if peer_data.is_inactive(&eviction_policy) {
 			gum::trace!(target: LOG_TARGET, "Disconnecting inactive peer");
-			disconnect_peer(ctx, peer.clone()).await;
+			disconnect_peer(sender, peer.clone()).await;
 		}
 	}
 }

polkadot/node/network/dispute-distribution/src/lib.rs

@@ -33,7 +33,7 @@ use polkadot_node_network_protocol::request_response::{incoming::IncomingRequest
 use polkadot_node_primitives::DISPUTE_WINDOW;
 use polkadot_node_subsystem::{
 	messages::DisputeDistributionMessage, overseer, FromOverseer, OverseerSignal, SpawnedSubsystem,
-	SubsystemContext, SubsystemError,
+	SubsystemError,
 };
 use polkadot_node_subsystem_util::{runtime, runtime::RuntimeInfo};
 
@@ -114,12 +114,11 @@ pub struct DisputeDistributionSubsystem<AD> {
 	metrics: Metrics,
 }
 
-impl<Context, AD> overseer::Subsystem<Context, SubsystemError> for DisputeDistributionSubsystem<AD>
+#[overseer::subsystem(DisputeDistribution, error = SubsystemError, prefix = self::overseer)]
+impl<Context, AD> DisputeDistributionSubsystem<AD>
 where
-	Context: SubsystemContext<Message = DisputeDistributionMessage>
-		+ overseer::SubsystemContext<Message = DisputeDistributionMessage>
-		+ Sync
-		+ Send,
+	<Context as overseer::DisputeDistributionContextTrait>::Sender:
+		overseer::DisputeDistributionSenderTrait + Sync + Send,
 	AD: AuthorityDiscovery + Clone,
 {
 	fn start(self, ctx: Context) -> SpawnedSubsystem {
@@ -132,6 +131,7 @@ where
 	}
 }
 
+#[overseer::contextbounds(DisputeDistribution, prefix = self::overseer)]
 impl<AD> DisputeDistributionSubsystem<AD>
 where
 	AD: AuthorityDiscovery + Clone,
@@ -160,13 +160,7 @@ where
 	}
 
 	/// Start processing work as passed on from the Overseer.
-	async fn run<Context>(mut self, mut ctx: Context) -> std::result::Result<(), FatalError>
-	where
-		Context: SubsystemContext<Message = DisputeDistributionMessage>
-			+ overseer::SubsystemContext<Message = DisputeDistributionMessage>
-			+ Sync
-			+ Send,
-	{
+	async fn run<Context>(mut self, mut ctx: Context) -> std::result::Result<(), FatalError> {
 		let receiver = DisputesReceiver::new(
 			ctx.sender().clone(),
 			self.req_receiver
@@ -205,7 +199,7 @@ where
 	}
 
 	/// Handle overseer signals.
-	async fn handle_signals<Context: SubsystemContext>(
+	async fn handle_signals<Context>(
 		&mut self,
 		ctx: &mut Context,
 		signal: OverseerSignal,
@@ -221,7 +215,7 @@ where
 	}
 
 	/// Handle `DisputeDistributionMessage`s.
-	async fn handle_subsystem_message<Context: SubsystemContext>(
+	async fn handle_subsystem_message<Context>(
 		&mut self,
 		ctx: &mut Context,
 		msg: DisputeDistributionMessage,
@@ -243,10 +237,10 @@ enum MuxedMessage {
 	Sender(Option<TaskFinish>),
 }
 
+#[overseer::contextbounds(DisputeDistribution, prefix = self::overseer)]
 impl MuxedMessage {
-	async fn receive(
-		ctx: &mut (impl SubsystemContext<Message = DisputeDistributionMessage>
-		          + overseer::SubsystemContext<Message = DisputeDistributionMessage>),
+	async fn receive<Context>(
+		ctx: &mut Context,
 		from_sender: &mut mpsc::Receiver<TaskFinish>,
 	) -> Self {
 		// We are only fusing here to make `select` happy, in reality we will quit if the stream

polkadot/node/network/dispute-distribution/src/receiver/mod.rs

@@ -40,8 +40,8 @@ use polkadot_node_network_protocol::{
 };
 use polkadot_node_primitives::DISPUTE_WINDOW;
 use polkadot_node_subsystem::{
-	messages::{AllMessages, DisputeCoordinatorMessage, ImportStatementsResult},
-	SubsystemSender,
+	messages::{DisputeCoordinatorMessage, ImportStatementsResult},
+	overseer,
 };
 use polkadot_node_subsystem_util::{runtime, runtime::RuntimeInfo};
 
@@ -132,9 +132,10 @@ impl MuxedMessage {
 	}
 }
 
-impl<Sender: SubsystemSender, AD> DisputesReceiver<Sender, AD>
+impl<Sender, AD> DisputesReceiver<Sender, AD>
 where
 	AD: AuthorityDiscovery,
+	Sender: overseer::DisputeDistributionSenderTrait,
 {
 	/// Create a new receiver which can be `run`.
 	pub fn new(
@@ -265,15 +266,13 @@ where
 		let (pending_confirmation, confirmation_rx) = oneshot::channel();
 		let candidate_hash = candidate_receipt.hash();
 		self.sender
-			.send_message(AllMessages::DisputeCoordinator(
-				DisputeCoordinatorMessage::ImportStatements {
-					candidate_hash,
-					candidate_receipt,
-					session: valid_vote.0.session_index(),
-					statements: vec![valid_vote, invalid_vote],
-					pending_confirmation: Some(pending_confirmation),
-				},
-			))
+			.send_message(DisputeCoordinatorMessage::ImportStatements {
+				candidate_hash,
+				candidate_receipt,
+				session: valid_vote.0.session_index(),
+				statements: vec![valid_vote, invalid_vote],
+				pending_confirmation: Some(pending_confirmation),
+			})
 			.await;
 
 		self.pending_imports.push(peer, confirmation_rx, pending_response);

polkadot/node/network/dispute-distribution/src/sender/mod.rs

@@ -20,10 +20,7 @@ use futures::channel::{mpsc, oneshot};
 
 use polkadot_node_network_protocol::request_response::v1::DisputeRequest;
 use polkadot_node_primitives::{CandidateVotes, DisputeMessage, SignedDisputeStatement};
-use polkadot_node_subsystem::{
-	messages::{AllMessages, DisputeCoordinatorMessage},
-	ActiveLeavesUpdate, SubsystemContext,
-};
+use polkadot_node_subsystem::{messages::DisputeCoordinatorMessage, overseer, ActiveLeavesUpdate};
 use polkadot_node_subsystem_util::runtime::RuntimeInfo;
 use polkadot_primitives::v2::{CandidateHash, DisputeStatement, Hash, SessionIndex};
 
@@ -66,6 +63,7 @@ pub struct DisputeSender {
 	metrics: Metrics,
 }
 
+#[overseer::contextbounds(DisputeDistribution, prefix = self::overseer)]
 impl DisputeSender {
 	/// Create a new `DisputeSender` which can be used to start dispute sendings.
 	pub fn new(tx: mpsc::Sender<TaskFinish>, metrics: Metrics) -> Self {
@@ -79,7 +77,7 @@ impl DisputeSender {
 	}
 
 	/// Create a `SendTask` for a particular new dispute.
-	pub async fn start_sender<Context: SubsystemContext>(
+	pub async fn start_sender<Context>(
 		&mut self,
 		ctx: &mut Context,
 		runtime: &mut RuntimeInfo,
@@ -114,7 +112,7 @@ impl DisputeSender {
 	/// - Get new authorities to send messages to.
 	/// - Get rid of obsolete tasks and disputes.
 	/// - Get dispute sending started in case we missed one for some reason (e.g. on node startup)
-	pub async fn update_leaves<Context: SubsystemContext>(
+	pub async fn update_leaves<Context>(
 		&mut self,
 		ctx: &mut Context,
 		runtime: &mut RuntimeInfo,
@@ -179,7 +177,7 @@ impl DisputeSender {
 	/// Call `start_sender` on all passed in disputes.
 	///
 	/// Recover necessary votes for building up `DisputeMessage` and start sending for all of them.
-	async fn start_send_for_dispute<Context: SubsystemContext>(
+	async fn start_send_for_dispute<Context>(
 		&mut self,
 		ctx: &mut Context,
 		runtime: &mut RuntimeInfo,
@@ -303,7 +301,7 @@ impl DisputeSender {
 	/// Make active sessions correspond to currently active heads.
 	///
 	/// Returns: true if sessions changed.
-	async fn refresh_sessions<Context: SubsystemContext>(
+	async fn refresh_sessions<Context>(
 		&mut self,
 		ctx: &mut Context,
 		runtime: &mut RuntimeInfo,
@@ -321,7 +319,8 @@ impl DisputeSender {
 /// Retrieve the currently active sessions.
 ///
 /// List is all indices of all active sessions together with the head that was used for the query.
-async fn get_active_session_indices<Context: SubsystemContext>(
+#[overseer::contextbounds(DisputeDistribution, prefix = self::overseer)]
+async fn get_active_session_indices<Context>(
 	ctx: &mut Context,
 	runtime: &mut RuntimeInfo,
 	active_heads: &Vec<Hash>,
@@ -336,27 +335,29 @@ async fn get_active_session_indices<Context: SubsystemContext>(
 }
 
 /// Retrieve Set of active disputes from the dispute coordinator.
-async fn get_active_disputes<Context: SubsystemContext>(
+#[overseer::contextbounds(DisputeDistribution, prefix = self::overseer)]
+async fn get_active_disputes<Context>(
 	ctx: &mut Context,
 ) -> JfyiErrorResult<Vec<(SessionIndex, CandidateHash)>> {
 	let (tx, rx) = oneshot::channel();
+
 	// Caller scope is in `update_leaves` and this is bounded by fork count.
-	ctx.send_unbounded_message(AllMessages::DisputeCoordinator(
-		DisputeCoordinatorMessage::ActiveDisputes(tx),
-	));
+	ctx.send_unbounded_message(DisputeCoordinatorMessage::ActiveDisputes(tx));
 	rx.await.map_err(|_| JfyiError::AskActiveDisputesCanceled)
 }
 
 /// Get all locally available dispute votes for a given dispute.
-async fn get_candidate_votes<Context: SubsystemContext>(
+#[overseer::contextbounds(DisputeDistribution, prefix = self::overseer)]
+async fn get_candidate_votes<Context>(
 	ctx: &mut Context,
 	session_index: SessionIndex,
 	candidate_hash: CandidateHash,
 ) -> JfyiErrorResult<Option<CandidateVotes>> {
 	let (tx, rx) = oneshot::channel();
 	// Caller scope is in `update_leaves` and this is bounded by fork count.
-	ctx.send_unbounded_message(AllMessages::DisputeCoordinator(
-		DisputeCoordinatorMessage::QueryCandidateVotes(vec![(session_index, candidate_hash)], tx),
+	ctx.send_unbounded_message(DisputeCoordinatorMessage::QueryCandidateVotes(
+		vec![(session_index, candidate_hash)],
+		tx,
 	));
 	rx.await
 		.map(|v| v.get(0).map(|inner| inner.to_owned().2))

polkadot/node/network/dispute-distribution/src/sender/send_task.rs

@@ -26,10 +26,7 @@ use polkadot_node_network_protocol::{
 	},
 	IfDisconnected,
 };
-use polkadot_node_subsystem::{
-	messages::{AllMessages, NetworkBridgeMessage},
-	SubsystemContext,
-};
+use polkadot_node_subsystem::{messages::NetworkBridgeMessage, overseer};
 use polkadot_node_subsystem_util::{metrics, runtime::RuntimeInfo};
 use polkadot_primitives::v2::{
 	AuthorityDiscoveryId, CandidateHash, Hash, SessionIndex, ValidatorIndex,
@@ -100,9 +97,10 @@ impl TaskResult {
 	}
 }
 
+#[overseer::contextbounds(DisputeDistribution, prefix = self::overseer)]
 impl SendTask {
 	/// Initiates sending a dispute message to peers.
-	pub async fn new<Context: SubsystemContext>(
+	pub async fn new<Context>(
 		ctx: &mut Context,
 		runtime: &mut RuntimeInfo,
 		active_sessions: &HashMap<SessionIndex, Hash>,
@@ -120,7 +118,7 @@ impl SendTask {
 	///
 	/// This function is called at construction and should also be called whenever a session change
 	/// happens and on a regular basis to ensure we are retrying failed attempts.
-	pub async fn refresh_sends<Context: SubsystemContext>(
+	pub async fn refresh_sends<Context>(
 		&mut self,
 		ctx: &mut Context,
 		runtime: &mut RuntimeInfo,
@@ -197,7 +195,8 @@ impl SendTask {
 	///
 	/// This is all parachain validators of the session the candidate occurred and all authorities
 	/// of all currently active sessions, determined by currently active heads.
-	async fn get_relevant_validators<Context: SubsystemContext>(
+
+	async fn get_relevant_validators<Context>(
 		&self,
 		ctx: &mut Context,
 		runtime: &mut RuntimeInfo,
@@ -241,7 +240,8 @@ impl SendTask {
 /// Start sending of the given message to all given authorities.
 ///
 /// And spawn tasks for handling the response.
-async fn send_requests<Context: SubsystemContext>(
+#[overseer::contextbounds(DisputeDistribution, prefix = self::overseer)]
+async fn send_requests<Context>(
 	ctx: &mut Context,
 	tx: mpsc::Sender<TaskFinish>,
 	receivers: Vec<AuthorityDiscoveryId>,
@@ -271,7 +271,7 @@ async fn send_requests<Context: SubsystemContext>(
 	}
 
 	let msg = NetworkBridgeMessage::SendRequests(reqs, IfDisconnected::ImmediateError);
-	ctx.send_message(AllMessages::NetworkBridge(msg)).await;
+	ctx.send_message(msg).await;
 	Ok(statuses)
 }
 

polkadot/node/network/gossip-support/src/lib.rs

@@ -48,8 +48,7 @@ use polkadot_node_subsystem::{
 		GossipSupportMessage, NetworkBridgeEvent, NetworkBridgeMessage, RuntimeApiMessage,
 		RuntimeApiRequest,
 	},
-	overseer, ActiveLeavesUpdate, FromOverseer, OverseerSignal, SpawnedSubsystem, SubsystemContext,
-	SubsystemError,
+	overseer, ActiveLeavesUpdate, FromOverseer, OverseerSignal, SpawnedSubsystem, SubsystemError,
 };
 use polkadot_node_subsystem_util as util;
 use polkadot_primitives::v2::{
@@ -115,6 +114,7 @@ pub struct GossipSupport<AD> {
 	metrics: Metrics,
 }
 
+#[overseer::contextbounds(GossipSupport, prefix = self::overseer)]
 impl<AD> GossipSupport<AD>
 where
 	AD: AuthorityDiscovery,
@@ -138,11 +138,7 @@ where
 		}
 	}
 
-	async fn run<Context>(mut self, mut ctx: Context) -> Self
-	where
-		Context: SubsystemContext<Message = GossipSupportMessage>,
-		Context: overseer::SubsystemContext<Message = GossipSupportMessage>,
-	{
+	async fn run<Context>(mut self, mut ctx: Context) -> Self {
 		fn get_connectivity_check_delay() -> Delay {
 			Delay::new(LOW_CONNECTIVITY_WARN_DELAY)
 		}
@@ -178,7 +174,7 @@ where
 					gum::trace!(target: LOG_TARGET, "active leaves signal");
 
 					let leaves = activated.into_iter().map(|a| a.hash);
-					if let Err(e) = self.handle_active_leaves(&mut ctx, leaves).await {
+					if let Err(e) = self.handle_active_leaves(ctx.sender(), leaves).await {
 						gum::debug!(target: LOG_TARGET, error = ?e);
 					}
 				},
@@ -191,18 +187,13 @@ where
 	/// 1. Determine if the current session index has changed.
 	/// 2. If it has, determine relevant validators
 	///    and issue a connection request.
-	async fn handle_active_leaves<Context>(
+	async fn handle_active_leaves(
 		&mut self,
-		ctx: &mut Context,
+		sender: &mut impl overseer::GossipSupportSenderTrait,
 		leaves: impl Iterator<Item = Hash>,
-	) -> Result<(), util::Error>
-	where
-		Context: SubsystemContext<Message = GossipSupportMessage>,
-		Context: overseer::SubsystemContext<Message = GossipSupportMessage>,
-	{
+	) -> Result<(), util::Error> {
 		for leaf in leaves {
-			let current_index =
-				util::request_session_index_for_child(leaf, ctx.sender()).await.await??;
+			let current_index = util::request_session_index_for_child(leaf, sender).await.await??;
 			let since_failure = self.last_failure.map(|i| i.elapsed()).unwrap_or_default();
 			let force_request = since_failure >= BACKOFF_DURATION;
 			let leaf_session = Some((current_index, leaf));
@@ -216,7 +207,7 @@ where
 
 			if let Some((session_index, relay_parent)) = maybe_issue_connection {
 				let session_info =
-					util::request_session_info(leaf, session_index, ctx.sender()).await.await??;
+					util::request_session_info(leaf, session_index, sender).await.await??;
 
 				let session_info = match session_info {
 					Some(s) => s,
@@ -255,13 +246,13 @@ where
 				// by virtue of a new session being entered. Therefore we maintain
 				// connections to a much broader set of validators.
 				{
-					let mut connections = authorities_past_present_future(ctx, leaf).await?;
+					let mut connections = authorities_past_present_future(sender, leaf).await?;
 
 					// Remove all of our locally controlled validator indices so we don't connect to ourself.
 					// If we control none of them, don't issue connection requests - we're outside
 					// of the 'clique' of recent validators.
 					if remove_all_controlled(&self.keystore, &mut connections).await != 0 {
-						self.issue_connection_request(ctx, connections).await;
+						self.issue_connection_request(sender, connections).await;
 					}
 				}
 
@@ -273,7 +264,7 @@ where
 					self.update_authority_status_metrics(&session_info).await;
 
 					update_gossip_topology(
-						ctx,
+						sender,
 						our_index,
 						session_info.discovery_keys,
 						relay_parent,
@@ -317,13 +308,12 @@ where
 		}
 	}
 
-	async fn issue_connection_request<Context>(
+	async fn issue_connection_request<Sender>(
 		&mut self,
-		ctx: &mut Context,
+		sender: &mut Sender,
 		authorities: Vec<AuthorityDiscoveryId>,
 	) where
-		Context: SubsystemContext<Message = GossipSupportMessage>,
-		Context: overseer::SubsystemContext<Message = GossipSupportMessage>,
+		Sender: overseer::GossipSupportSenderTrait,
 	{
 		let num = authorities.len();
 		let mut validator_addrs = Vec::with_capacity(authorities.len());
@@ -347,11 +337,12 @@ where
 		self.resolved_authorities = resolved;
 		gum::debug!(target: LOG_TARGET, %num, "Issuing a connection request");
 
-		ctx.send_message(NetworkBridgeMessage::ConnectToResolvedValidators {
-			validator_addrs,
-			peer_set: PeerSet::Validation,
-		})
-		.await;
+		sender
+			.send_message(NetworkBridgeMessage::ConnectToResolvedValidators {
+				validator_addrs,
+				peer_set: PeerSet::Validation,
+			})
+			.await;
 
 		// issue another request for the same session
 		// if at least a third of the authorities were not resolved.
@@ -442,15 +433,11 @@ where
 }
 
 // Get the authorities of the past, present, and future.
-async fn authorities_past_present_future<Context>(
-	ctx: &mut Context,
+async fn authorities_past_present_future(
+	sender: &mut impl overseer::GossipSupportSenderTrait,
 	relay_parent: Hash,
-) -> Result<Vec<AuthorityDiscoveryId>, util::Error>
-where
-	Context: SubsystemContext<Message = GossipSupportMessage>,
-	Context: overseer::SubsystemContext<Message = GossipSupportMessage>,
-{
-	let authorities = util::request_authorities(relay_parent, ctx.sender()).await.await??;
+) -> Result<Vec<AuthorityDiscoveryId>, util::Error> {
+	let authorities = util::request_authorities(relay_parent, sender).await.await??;
 	gum::debug!(
 		target: LOG_TARGET,
 		authority_count = ?authorities.len(),
@@ -500,28 +487,25 @@ async fn remove_all_controlled(
 /// This limits the amount of gossip peers to 2 * `sqrt(len)` and ensures the diameter of 2.
 ///
 /// [web3]: https://research.web3.foundation/en/latest/polkadot/networking/3-avail-valid.html#topology
-async fn update_gossip_topology<Context>(
-	ctx: &mut Context,
+async fn update_gossip_topology(
+	sender: &mut impl overseer::GossipSupportSenderTrait,
 	our_index: usize,
 	authorities: Vec<AuthorityDiscoveryId>,
 	relay_parent: Hash,
 	session_index: SessionIndex,
-) -> Result<(), util::Error>
-where
-	Context: SubsystemContext<Message = GossipSupportMessage>,
-	Context: overseer::SubsystemContext<Message = GossipSupportMessage>,
-{
+) -> Result<(), util::Error> {
 	// retrieve BABE randomness
 	let random_seed = {
 		let (tx, rx) = oneshot::channel();
 
 		// TODO https://github.com/paritytech/polkadot/issues/5316:
 		// get the random seed from the `SessionInfo` instead.
-		ctx.send_message(RuntimeApiMessage::Request(
-			relay_parent,
-			RuntimeApiRequest::CurrentBabeEpoch(tx),
-		))
-		.await;
+		sender
+			.send_message(RuntimeApiMessage::Request(
+				relay_parent,
+				RuntimeApiRequest::CurrentBabeEpoch(tx),
+			))
+			.await;
 
 		let randomness = rx.await??.randomness;
 		let mut subject = [0u8; 40];
@@ -553,12 +537,13 @@ where
 		.map(|i| (authorities[i].clone(), ValidatorIndex::from(i as u32)))
 		.collect();
 
-	ctx.send_message(NetworkBridgeMessage::NewGossipTopology {
-		session: session_index,
-		our_neighbors_x: row_neighbors,
-		our_neighbors_y: column_neighbors,
-	})
-	.await;
+	sender
+		.send_message(NetworkBridgeMessage::NewGossipTopology {
+			session: session_index,
+			our_neighbors_x: row_neighbors,
+			our_neighbors_y: column_neighbors,
+		})
+		.await;
 
 	Ok(())
 }
@@ -596,10 +581,9 @@ fn matrix_neighbors(
 	}
 }
 
-impl<Context, AD> overseer::Subsystem<Context, SubsystemError> for GossipSupport<AD>
+#[overseer::subsystem(GossipSupport, error = SubsystemError, prefix = self::overseer)]
+impl<Context, AD> GossipSupport<AD>
 where
-	Context: SubsystemContext<Message = GossipSupportMessage>,
-	Context: overseer::SubsystemContext<Message = GossipSupportMessage>,
 	AD: AuthorityDiscovery + Clone,
 {
 	fn start(self, ctx: Context) -> SpawnedSubsystem {

polkadot/node/network/statement-distribution/src/lib.rs

@@ -38,11 +38,11 @@ use polkadot_node_subsystem_util::{self as util, rand, MIN_GOSSIP_PEERS};
 use polkadot_node_subsystem::{
 	jaeger,
 	messages::{
-		AllMessages, CandidateBackingMessage, NetworkBridgeEvent, NetworkBridgeMessage,
+		CandidateBackingMessage, NetworkBridgeEvent, NetworkBridgeMessage,
 		StatementDistributionMessage,
 	},
 	overseer, ActiveLeavesUpdate, FromOverseer, OverseerSignal, PerLeafSpan, SpawnedSubsystem,
-	SubsystemContext, SubsystemError,
+	SubsystemError,
 };
 use polkadot_primitives::v2::{
 	AuthorityDiscoveryId, CandidateHash, CommittedCandidateReceipt, CompactStatement, Hash,
@@ -127,12 +127,8 @@ pub struct StatementDistributionSubsystem<R> {
 	rng: R,
 }
 
-impl<Context, R: rand::Rng + Send + Sync + 'static> overseer::Subsystem<Context, SubsystemError>
-	for StatementDistributionSubsystem<R>
-where
-	Context: SubsystemContext<Message = StatementDistributionMessage>,
-	Context: overseer::SubsystemContext<Message = StatementDistributionMessage>,
-{
+#[overseer::subsystem(StatementDistribution, error=SubsystemError, prefix=self::overseer)]
+impl<Context, R: rand::Rng + Send + Sync + 'static> StatementDistributionSubsystem<R> {
 	fn start(self, ctx: Context) -> SpawnedSubsystem {
 		// Swallow error because failure is fatal to the node and we log with more precision
 		// within `run`.
@@ -630,10 +626,10 @@ enum MuxedMessage {
 	Responder(Option<ResponderMessage>),
 }
 
+#[overseer::contextbounds(StatementDistribution, prefix = self::overseer)]
 impl MuxedMessage {
-	async fn receive(
-		ctx: &mut (impl SubsystemContext<Message = StatementDistributionMessage>
-		          + overseer::SubsystemContext<Message = StatementDistributionMessage>),
+	async fn receive<Context>(
+		ctx: &mut Context,
 		from_requester: &mut mpsc::Receiver<RequesterMessage>,
 		from_responder: &mut mpsc::Receiver<ResponderMessage>,
 	) -> MuxedMessage {
@@ -890,11 +886,12 @@ fn check_statement_signature(
 /// circulates the statement to all peers who have not seen it yet, and
 /// sends all statements dependent on that statement to peers who could previously not receive
 /// them but now can.
-async fn circulate_statement_and_dependents(
+#[overseer::contextbounds(StatementDistribution, prefix=self::overseer)]
+async fn circulate_statement_and_dependents<Context>(
 	gossip_peers: &HashSet<PeerId>,
 	peers: &mut HashMap<PeerId, PeerData>,
 	active_heads: &mut HashMap<Hash, ActiveHeadData>,
-	ctx: &mut (impl SubsystemContext + overseer::SubsystemContext),
+	ctx: &mut Context,
 	relay_parent: Hash,
 	statement: SignedFullStatement,
 	priority_peers: Vec<PeerId>,
@@ -1006,10 +1003,11 @@ fn is_statement_large(statement: &SignedFullStatement) -> (bool, Option<usize>)
 
 /// Circulates a statement to all peers who have not seen it yet, and returns
 /// an iterator over peers who need to have dependent statements sent.
-async fn circulate_statement<'a>(
+#[overseer::contextbounds(StatementDistribution, prefix=self::overseer)]
+async fn circulate_statement<'a, Context>(
 	gossip_peers: &HashSet<PeerId>,
 	peers: &mut HashMap<PeerId, PeerData>,
-	ctx: &mut (impl SubsystemContext + overseer::SubsystemContext),
+	ctx: &mut Context,
 	relay_parent: Hash,
 	stored: StoredStatement<'a>,
 	mut priority_peers: Vec<PeerId>,
@@ -1081,10 +1079,10 @@ async fn circulate_statement<'a>(
 			statement = ?stored.statement,
 			"Sending statement",
 		);
-		ctx.send_message(AllMessages::NetworkBridge(NetworkBridgeMessage::SendValidationMessage(
+		ctx.send_message(NetworkBridgeMessage::SendValidationMessage(
 			peers_to_send.iter().map(|(p, _)| p.clone()).collect(),
 			payload,
-		)))
+		))
 		.await;
 	}
 
@@ -1095,10 +1093,11 @@ async fn circulate_statement<'a>(
 }
 
 /// Send all statements about a given candidate hash to a peer.
-async fn send_statements_about(
+#[overseer::contextbounds(StatementDistribution, prefix=self::overseer)]
+async fn send_statements_about<Context>(
 	peer: PeerId,
 	peer_data: &mut PeerData,
-	ctx: &mut (impl SubsystemContext + overseer::SubsystemContext),
+	ctx: &mut Context,
 	relay_parent: Hash,
 	candidate_hash: CandidateHash,
 	active_head: &ActiveHeadData,
@@ -1120,21 +1119,19 @@ async fn send_statements_about(
 			statement = ?statement.statement,
 			"Sending statement",
 		);
-		ctx.send_message(AllMessages::NetworkBridge(NetworkBridgeMessage::SendValidationMessage(
-			vec![peer.clone()],
-			payload,
-		)))
-		.await;
+		ctx.send_message(NetworkBridgeMessage::SendValidationMessage(vec![peer.clone()], payload))
+			.await;
 
 		metrics.on_statement_distributed();
 	}
 }
 
 /// Send all statements at a given relay-parent to a peer.
-async fn send_statements(
+#[overseer::contextbounds(StatementDistribution, prefix=self::overseer)]
+async fn send_statements<Context>(
 	peer: PeerId,
 	peer_data: &mut PeerData,
-	ctx: &mut (impl SubsystemContext + overseer::SubsystemContext),
+	ctx: &mut Context,
 	relay_parent: Hash,
 	active_head: &ActiveHeadData,
 	metrics: &Metrics,
@@ -1154,23 +1151,19 @@ async fn send_statements(
 			statement = ?statement.statement,
 			"Sending statement"
 		);
-		ctx.send_message(AllMessages::NetworkBridge(NetworkBridgeMessage::SendValidationMessage(
-			vec![peer.clone()],
-			payload,
-		)))
-		.await;
+		ctx.send_message(NetworkBridgeMessage::SendValidationMessage(vec![peer.clone()], payload))
+			.await;
 
 		metrics.on_statement_distributed();
 	}
 }
 
 async fn report_peer(
-	ctx: &mut (impl SubsystemContext + overseer::SubsystemContext),
+	sender: &mut impl overseer::StatementDistributionSenderTrait,
 	peer: PeerId,
 	rep: Rep,
 ) {
-	ctx.send_message(AllMessages::NetworkBridge(NetworkBridgeMessage::ReportPeer(peer, rep)))
-		.await
+	sender.send_message(NetworkBridgeMessage::ReportPeer(peer, rep)).await
 }
 
 /// If message contains a statement, then retrieve it, otherwise fork task to fetch it.
@@ -1180,11 +1173,12 @@ async fn report_peer(
 /// your statement.
 ///
 /// If the message was large, but the result has been fetched already that one is returned.
-async fn retrieve_statement_from_message<'a>(
+#[overseer::contextbounds(StatementDistribution, prefix=self::overseer)]
+async fn retrieve_statement_from_message<'a, Context>(
 	peer: PeerId,
 	message: protocol_v1::StatementDistributionMessage,
 	active_head: &'a mut ActiveHeadData,
-	ctx: &mut (impl SubsystemContext + overseer::SubsystemContext),
+	ctx: &mut Context,
 	req_sender: &mpsc::Sender<RequesterMessage>,
 	metrics: &Metrics,
 ) -> Option<UncheckedSignedFullStatement> {
@@ -1272,11 +1266,12 @@ async fn retrieve_statement_from_message<'a>(
 /// Launch request for a large statement and get tracking status.
 ///
 /// Returns `None` if spawning task failed.
-async fn launch_request(
+#[overseer::contextbounds(StatementDistribution, prefix=self::overseer)]
+async fn launch_request<Context>(
 	meta: StatementMetadata,
 	peer: PeerId,
 	req_sender: mpsc::Sender<RequesterMessage>,
-	ctx: &mut (impl SubsystemContext + overseer::SubsystemContext),
+	ctx: &mut Context,
 	metrics: &Metrics,
 ) -> Option<LargeStatementStatus> {
 	let (task, handle) =
@@ -1302,19 +1297,21 @@ async fn launch_request(
 }
 
 /// Handle incoming message and circulate it to peers, if we did not know it already.
-///
-async fn handle_incoming_message_and_circulate<'a>(
+#[overseer::contextbounds(StatementDistribution, prefix=self::overseer)]
+async fn handle_incoming_message_and_circulate<'a, Context, R>(
 	peer: PeerId,
 	gossip_peers: &HashSet<PeerId>,
 	peers: &mut HashMap<PeerId, PeerData>,
 	active_heads: &'a mut HashMap<Hash, ActiveHeadData>,
 	recent_outdated_heads: &RecentOutdatedHeads,
-	ctx: &mut (impl SubsystemContext + overseer::SubsystemContext),
+	ctx: &mut Context,
 	message: protocol_v1::StatementDistributionMessage,
 	req_sender: &mpsc::Sender<RequesterMessage>,
 	metrics: &Metrics,
-	rng: &mut impl rand::Rng,
-) {
+	rng: &mut R,
+) where
+	R: rand::Rng,
+{
 	let handled_incoming = match peers.get_mut(&peer) {
 		Some(data) =>
 			handle_incoming_message(
@@ -1360,12 +1357,13 @@ async fn handle_incoming_message_and_circulate<'a>(
 //
 // This function checks the signature and ensures the statement is compatible with our
 // view. It also notifies candidate backing if the statement was previously unknown.
-async fn handle_incoming_message<'a>(
+#[overseer::contextbounds(StatementDistribution, prefix=self::overseer)]
+async fn handle_incoming_message<'a, Context>(
 	peer: PeerId,
 	peer_data: &mut PeerData,
 	active_heads: &'a mut HashMap<Hash, ActiveHeadData>,
 	recent_outdated_heads: &RecentOutdatedHeads,
-	ctx: &mut (impl SubsystemContext + overseer::SubsystemContext),
+	ctx: &mut Context,
 	message: protocol_v1::StatementDistributionMessage,
 	req_sender: &mpsc::Sender<RequesterMessage>,
 	metrics: &Metrics,
@@ -1383,7 +1381,7 @@ async fn handle_incoming_message<'a>(
 			);
 
 			if !recent_outdated_heads.is_recent_outdated(&relay_parent) {
-				report_peer(ctx, peer, COST_UNEXPECTED_STATEMENT).await;
+				report_peer(ctx.sender(), peer, COST_UNEXPECTED_STATEMENT).await;
 			}
 
 			return None
@@ -1393,7 +1391,7 @@ async fn handle_incoming_message<'a>(
 	if let protocol_v1::StatementDistributionMessage::LargeStatement(_) = message {
 		if let Err(rep) = peer_data.receive_large_statement(&relay_parent) {
 			gum::debug!(target: LOG_TARGET, ?peer, ?message, ?rep, "Unexpected large statement.",);
-			report_peer(ctx, peer, rep).await;
+			report_peer(ctx.sender(), peer, rep).await;
 			return None
 		}
 	}
@@ -1434,16 +1432,16 @@ async fn handle_incoming_message<'a>(
 				// Report peer merely if this is not a duplicate out-of-view statement that
 				// was caused by a missing Seconded statement from this peer
 				if unexpected_count == 0_usize {
-					report_peer(ctx, peer, rep).await;
+					report_peer(ctx.sender(), peer, rep).await;
 				}
 			},
 			// This happens when we have an unexpected remote peer that announced Seconded
 			COST_UNEXPECTED_STATEMENT_REMOTE => {
 				metrics.on_unexpected_statement_seconded();
-				report_peer(ctx, peer, rep).await;
+				report_peer(ctx.sender(), peer, rep).await;
 			},
 			_ => {
-				report_peer(ctx, peer, rep).await;
+				report_peer(ctx.sender(), peer, rep).await;
 			},
 		}
 
@@ -1464,7 +1462,7 @@ async fn handle_incoming_message<'a>(
 				peer_data
 					.receive(&relay_parent, &fingerprint, max_message_count)
 					.expect("checked in `check_can_receive` above; qed");
-				report_peer(ctx, peer, BENEFIT_VALID_STATEMENT).await;
+				report_peer(ctx.sender(), peer, BENEFIT_VALID_STATEMENT).await;
 
 				return None
 			},
@@ -1474,7 +1472,7 @@ async fn handle_incoming_message<'a>(
 		match check_statement_signature(&active_head, relay_parent, unchecked_compact) {
 			Err(statement) => {
 				gum::debug!(target: LOG_TARGET, ?peer, ?statement, "Invalid statement signature");
-				report_peer(ctx, peer, COST_INVALID_SIGNATURE).await;
+				report_peer(ctx.sender(), peer, COST_INVALID_SIGNATURE).await;
 				return None
 			},
 			Ok(statement) => statement,
@@ -1500,7 +1498,7 @@ async fn handle_incoming_message<'a>(
 				is_large_statement,
 				"Full statement had bad payload."
 			);
-			report_peer(ctx, peer, COST_WRONG_HASH).await;
+			report_peer(ctx.sender(), peer, COST_WRONG_HASH).await;
 			return None
 		},
 		Ok(statement) => statement,
@@ -1539,7 +1537,7 @@ async fn handle_incoming_message<'a>(
 			unreachable!("checked in `is_useful_or_unknown` above; qed");
 		},
 		NotedStatement::Fresh(statement) => {
-			report_peer(ctx, peer, BENEFIT_VALID_STATEMENT_FIRST).await;
+			report_peer(ctx.sender(), peer, BENEFIT_VALID_STATEMENT_FIRST).await;
 
 			let mut _span = handle_incoming_span.child("notify-backing");
 
@@ -1557,16 +1555,19 @@ async fn handle_incoming_message<'a>(
 }
 
 /// Update a peer's view. Sends all newly unlocked statements based on the previous
-async fn update_peer_view_and_maybe_send_unlocked(
+#[overseer::contextbounds(StatementDistribution, prefix=self::overseer)]
+async fn update_peer_view_and_maybe_send_unlocked<Context, R>(
 	peer: PeerId,
 	gossip_peers: &HashSet<PeerId>,
 	peer_data: &mut PeerData,
-	ctx: &mut (impl SubsystemContext + overseer::SubsystemContext),
+	ctx: &mut Context,
 	active_heads: &HashMap<Hash, ActiveHeadData>,
 	new_view: View,
 	metrics: &Metrics,
-	rng: &mut impl rand::Rng,
-) {
+	rng: &mut R,
+) where
+	R: rand::Rng,
+{
 	let old_view = std::mem::replace(&mut peer_data.view, new_view);
 
 	// Remove entries for all relay-parents in the old view but not the new.
@@ -1596,18 +1597,21 @@ async fn update_peer_view_and_maybe_send_unlocked(
 	}
 }
 
-async fn handle_network_update(
+#[overseer::contextbounds(StatementDistribution, prefix=self::overseer)]
+async fn handle_network_update<Context, R>(
 	peers: &mut HashMap<PeerId, PeerData>,
 	gossip_peers: &mut HashSet<PeerId>,
 	authorities: &mut HashMap<AuthorityDiscoveryId, PeerId>,
 	active_heads: &mut HashMap<Hash, ActiveHeadData>,
 	recent_outdated_heads: &RecentOutdatedHeads,
-	ctx: &mut (impl SubsystemContext + overseer::SubsystemContext),
+	ctx: &mut Context,
 	req_sender: &mpsc::Sender<RequesterMessage>,
 	update: NetworkBridgeEvent<net_protocol::StatementDistributionMessage>,
 	metrics: &Metrics,
-	rng: &mut impl rand::Rng,
-) {
+	rng: &mut R,
+) where
+	R: rand::Rng,
+{
 	match update {
 		NetworkBridgeEvent::PeerConnected(peer, role, _, maybe_authority) => {
 			gum::trace!(target: LOG_TARGET, ?peer, ?role, "Peer connected");
@@ -1701,6 +1705,7 @@ async fn handle_network_update(
 	}
 }
 
+#[overseer::contextbounds(StatementDistribution, prefix = self::overseer)]
 impl<R: rand::Rng> StatementDistributionSubsystem<R> {
 	/// Create a new Statement Distribution Subsystem
 	pub fn new(
@@ -1712,11 +1717,7 @@ impl<R: rand::Rng> StatementDistributionSubsystem<R> {
 		Self { keystore, req_receiver: Some(req_receiver), metrics, rng }
 	}
 
-	async fn run(
-		mut self,
-		mut ctx: (impl SubsystemContext<Message = StatementDistributionMessage>
-		     + overseer::SubsystemContext<Message = StatementDistributionMessage>),
-	) -> std::result::Result<(), FatalError> {
+	async fn run<Context>(mut self, mut ctx: Context) -> std::result::Result<(), FatalError> {
 		let mut peers: HashMap<PeerId, PeerData> = HashMap::new();
 		let mut gossip_peers: HashSet<PeerId> = HashSet::new();
 		let mut authorities: HashMap<AuthorityDiscoveryId, PeerId> = HashMap::new();
@@ -1832,9 +1833,9 @@ impl<R: rand::Rng> StatementDistributionSubsystem<R> {
 		Ok(())
 	}
 
-	async fn handle_requester_message(
+	async fn handle_requester_message<Context>(
 		&mut self,
-		ctx: &mut impl SubsystemContext,
+		ctx: &mut Context,
 		gossip_peers: &HashSet<PeerId>,
 		peers: &mut HashMap<PeerId, PeerData>,
 		active_heads: &mut HashMap<Hash, ActiveHeadData>,
@@ -1851,9 +1852,9 @@ impl<R: rand::Rng> StatementDistributionSubsystem<R> {
 				bad_peers,
 			} => {
 				for bad in bad_peers {
-					report_peer(ctx, bad, COST_FETCH_FAIL).await;
+					report_peer(ctx.sender(), bad, COST_FETCH_FAIL).await;
 				}
-				report_peer(ctx, from_peer, BENEFIT_VALID_RESPONSE).await;
+				report_peer(ctx.sender(), from_peer, BENEFIT_VALID_RESPONSE).await;
 
 				let active_head = active_heads
 					.get_mut(&relay_parent)
@@ -1898,10 +1899,10 @@ impl<R: rand::Rng> StatementDistributionSubsystem<R> {
 				}
 			},
 			RequesterMessage::SendRequest(req) => {
-				ctx.send_message(AllMessages::NetworkBridge(NetworkBridgeMessage::SendRequests(
+				ctx.send_message(NetworkBridgeMessage::SendRequests(
 					vec![req],
 					IfDisconnected::ImmediateError,
-				)))
+				))
 				.await;
 			},
 			RequesterMessage::GetMorePeers { relay_parent, candidate_hash, tx } => {
@@ -1935,14 +1936,14 @@ impl<R: rand::Rng> StatementDistributionSubsystem<R> {
 					}
 				}
 			},
-			RequesterMessage::ReportPeer(peer, rep) => report_peer(ctx, peer, rep).await,
+			RequesterMessage::ReportPeer(peer, rep) => report_peer(ctx.sender(), peer, rep).await,
 		}
 		Ok(())
 	}
 
-	async fn handle_subsystem_message(
+	async fn handle_subsystem_message<Context>(
 		&mut self,
-		ctx: &mut (impl SubsystemContext + overseer::SubsystemContext),
+		ctx: &mut Context,
 		runtime: &mut RuntimeInfo,
 		peers: &mut HashMap<PeerId, PeerData>,
 		gossip_peers: &mut HashSet<PeerId>,

polkadot/node/network/statement-distribution/src/tests.rs

@@ -29,7 +29,7 @@ use polkadot_node_network_protocol::{
 use polkadot_node_primitives::{Statement, UncheckedSignedFullStatement};
 use polkadot_node_subsystem::{
 	jaeger,
-	messages::{network_bridge_event, RuntimeApiMessage, RuntimeApiRequest},
+	messages::{network_bridge_event, AllMessages, RuntimeApiMessage, RuntimeApiRequest},
 	ActivatedLeaf, LeafStatus,
 };
 use polkadot_node_subsystem_test_helpers::mock::make_ferdie_keystore;

polkadot/node/overseer/examples/minimal-example.rs

@@ -24,14 +24,12 @@ use std::time::Duration;
 
 use ::test_helpers::{dummy_candidate_descriptor, dummy_hash};
 use polkadot_node_primitives::{BlockData, PoV};
-use polkadot_node_subsystem_types::messages::{
-	CandidateBackingMessage, CandidateValidationMessage,
-};
+use polkadot_node_subsystem_types::messages::CandidateValidationMessage;
 use polkadot_overseer::{
 	self as overseer,
 	dummy::dummy_overseer_builder,
 	gen::{FromOverseer, SpawnedSubsystem},
-	AllMessages, HeadSupportsParachains, OverseerSignal, SubsystemError,
+	HeadSupportsParachains, SubsystemError,
 };
 use polkadot_primitives::v2::{CandidateReceipt, Hash};
 
@@ -46,15 +44,9 @@ impl HeadSupportsParachains for AlwaysSupportsParachains {
 
 struct Subsystem1;
 
+#[overseer::contextbounds(CandidateBacking, prefix = self::overseer)]
 impl Subsystem1 {
-	async fn run<Ctx>(mut ctx: Ctx) -> ()
-	where
-		Ctx: overseer::SubsystemContext<
-			Message = CandidateBackingMessage,
-			AllMessages = AllMessages,
-			Signal = OverseerSignal,
-		>,
-	{
+	async fn run<Context>(mut ctx: Context) {
 		'louy: loop {
 			match ctx.try_recv().await {
 				Ok(Some(msg)) => {
@@ -84,21 +76,14 @@ impl Subsystem1 {
 				Default::default(),
 				tx,
 			);
-			ctx.send_message(<Ctx as overseer::SubsystemContext>::AllMessages::from(msg))
-				.await;
+			ctx.send_message(msg).await;
 		}
 		()
 	}
 }
 
-impl<Context> overseer::Subsystem<Context, SubsystemError> for Subsystem1
-where
-	Context: overseer::SubsystemContext<
-		Message = CandidateBackingMessage,
-		AllMessages = AllMessages,
-		Signal = OverseerSignal,
-	>,
-{
+#[overseer::subsystem(CandidateBacking, error = SubsystemError, prefix = self::overseer)]
+impl<Context> Subsystem1 {
 	fn start(self, ctx: Context) -> SpawnedSubsystem<SubsystemError> {
 		let future = Box::pin(async move {
 			Self::run(ctx).await;
@@ -113,15 +98,9 @@ where
 
 struct Subsystem2;
 
+#[overseer::contextbounds(CandidateValidation, prefix = self::overseer)]
 impl Subsystem2 {
-	async fn run<Ctx>(mut ctx: Ctx)
-	where
-		Ctx: overseer::SubsystemContext<
-			Message = CandidateValidationMessage,
-			AllMessages = AllMessages,
-			Signal = OverseerSignal,
-		>,
-	{
+	async fn run<Context>(mut ctx: Context) -> () {
 		ctx.spawn(
 			"subsystem-2-job",
 			Box::pin(async {
@@ -151,14 +130,8 @@ impl Subsystem2 {
 	}
 }
 
-impl<Context> overseer::Subsystem<Context, SubsystemError> for Subsystem2
-where
-	Context: overseer::SubsystemContext<
-		Message = CandidateValidationMessage,
-		AllMessages = AllMessages,
-		Signal = OverseerSignal,
-	>,
-{
+#[overseer::subsystem(CandidateValidation, error = SubsystemError, prefix = self::overseer)]
+impl<Context> Subsystem2 {
 	fn start(self, ctx: Context) -> SpawnedSubsystem<SubsystemError> {
 		let future = Box::pin(async move {
 			Self::run(ctx).await;
@@ -181,6 +154,7 @@ fn main() {
 			.unwrap()
 			.replace_candidate_validation(|_| Subsystem2)
 			.replace_candidate_backing(|orig| orig)
+			.replace_candidate_backing(|_orig| Subsystem1)
 			.build()
 			.unwrap();
 

polkadot/node/overseer/overseer-gen/Cargo.toml

@@ -4,6 +4,7 @@ version = "0.9.19"
 authors = ["Parity Technologies <admin@parity.io>"]
 edition = "2021"
 description = "Generate an overseer including builder pattern and message wrapper from a single struct."
+autoexamples = false
 
 [dependencies]
 gum = { package = "tracing-gum", path = "../../gum" }
@@ -22,6 +23,16 @@ pin-project = "1.0"
 trybuild = "1.0.61"
 rustversion = "1.0.6"
 
+
+
+[[example]]
+name = "duo"
+crate-type = ["bin"]
+
+[[example]]
+name = "solo"
+crate-type = ["bin"]
+
 [features]
 default = []
 expand = ["polkadot-overseer-gen-proc-macro/expand"]

polkadot/node/overseer/overseer-gen/README.md

@@ -11,17 +11,20 @@ declarative.
 ```rust
     #[overlord(signal=SigSigSig, event=Event, gen=AllMessages, error=OverseerError)]
     pub struct Overseer {
-        #[subsystem(MsgA)]
+        #[subsystem(MsgA, sends: [MsgB])]
         sub_a: AwesomeSubSysA,
 
-        #[subsystem(MsgB)]
+        #[subsystem(MsgB, sends: [MsgA])]
         sub_b: AwesomeSubSysB,
     }
 ```
 
 * Each subsystem is annotated with `#[subsystem(_)]` where `MsgA` respectively `MsgB` are the messages
 being consumed by that particular subsystem. Each of those subsystems is required to implement the subsystem
-trait.
+trait with the correct trait bounds. Commonly this is achieved
+by using `#[subsystem]` and `#[contextbounds]` macro.
+  * `#[contextbounds(Foo, error=Yikes, prefix=wherethetraitsat)]` can applied to `impl`-blocks and `fn`-blocks. It will add additional trait bounds for the generic `Context` with `Context: FooContextTrait` for `<Context as FooContextTrait>::Sender: FooSenderTrait` besides a few more. Note that `Foo` here references the name of the subsystem as declared in `#[overlord(..)]` macro.
+  * `#[subsystem(Foo, error=Yikes, prefix=wherethetraitsat)]` is a extension to the above, implementing `trait Subsystem<Context, Yikes>`.
 * `error=` tells the overseer to use the user provided
 error type, if not provided a builtin one is used. Note that this is the one error type used throughout all calls, so make sure it does impl `From<E>` for all other error types `E` that are relevant to your application.
 * `event=` declares an external event type, that injects certain events
@@ -63,10 +66,10 @@ is not ready to be included in the Overseer:
 ```rust
     #[overlord(signal=SigSigSig, event=Event, gen=AllMessages, error=OverseerError)]
     pub struct Overseer {
-        #[subsystem(MsgA)]
+        #[subsystem(MsgA, sends: MsgB)]
         sub_a: AwesomeSubSysA,
 
-        #[subsystem(MsgB), wip]
+        #[subsystem(MsgB, sends: MsgA), wip]
         sub_b: AwesomeSubSysB, // This subsystem will not be required nor allowed to be set
     }
 ```

polkadot/node/overseer/overseer-gen/adr/01-adr.md

@@ -0,0 +1,21 @@
+# Limit outgoing messages
+
+## Status
+
+Accepted + implemented.
+
+## Context
+
+Previously, there was no way to limit and hence reason about a subset of subsystems, and if they form a cycle. Limiting the outgoing message types is a first step to create respective graphs and use classic graph algorithms to detect those and leave it to the user to resolve these.
+
+## Decision
+
+Annotate the `#[overlord]` inner `#[subsystem(..)]` annotation
+with an aditional set of outgoing messages and enforce this via more fine grained trait bounds on the `Sender` and `<Context>::Sender` bounds.
+
+## Consequences
+
+* A graph will be spawn for every compilation under the `OUT_DIR` of the crate where `#[overlord]` is specified.
+* Each subsystem has a consuming message which is often referred to as generic `M` (no change on that, is as before), but now we have trait `AssociateOutgoing { type OutgoingMessages = ..; }` which defines an outgoing helper `enum` that is generated with an ident constructed as `${Subsystem}OutgoingMessages` where `${Subsystem}` is the subsystem identifier as used in the overseer declaration. `${Subsystem}OutgoingMessages` is used throughout everywhere to constrain the outgoing messages (commonly referred to as `OutgoingMessage` generic bounded by `${Subsystem}OutgoingMessages: From<OutgoingMessage>` or `::OutgoingMessages: From`. It's what allows the construction of the graph and compile time verification.
+* `${Subsystem}SenderTrait` and `${Subsystem}ContextTrait` are accumulation traits or wrapper traits, that combine over all annotated M or `OutgoingMessages` from the overseer declaration or their respective outgoing types. It is usage convenience and assures consistency within a subsystem while also maintaining a single source of truth for which messages can be sent by a particular subsystem. Note that this is sidestepped for the test subsystem, which may consume `gen=AllMessages`, the global message wrapper type.
+* `Job`-based subsystems, being on their way out, are patched, but they now are generic over the `Sender` type, leaking that type.

polkadot/node/overseer/overseer-gen/examples/dummy.rs

@@ -1,143 +0,0 @@
-//! A dummy to be used with cargo expand
-
-use polkadot_node_network_protocol::WrongVariant;
-use polkadot_overseer_gen::*;
-use std::collections::HashMap;
-
-/// Concrete subsystem implementation for `MsgStrukt` msg type.
-#[derive(Default)]
-pub struct AwesomeSubSys;
-
-impl ::polkadot_overseer_gen::Subsystem<XxxSubsystemContext<MsgStrukt>, Yikes> for AwesomeSubSys {
-	fn start(self, _ctx: XxxSubsystemContext<MsgStrukt>) -> SpawnedSubsystem<Yikes> {
-		unimplemented!("starting yay!")
-	}
-}
-
-#[derive(Default)]
-pub struct GoblinTower;
-
-impl ::polkadot_overseer_gen::Subsystem<XxxSubsystemContext<Plinko>, Yikes> for GoblinTower {
-	fn start(self, _ctx: XxxSubsystemContext<Plinko>) -> SpawnedSubsystem<Yikes> {
-		unimplemented!("welcum")
-	}
-}
-
-/// A signal sent by the overseer.
-#[derive(Debug, Clone)]
-pub struct SigSigSig;
-
-/// The external event.
-#[derive(Debug, Clone)]
-pub struct EvX;
-
-impl EvX {
-	pub fn focus<'a, T>(&'a self) -> Result<EvX, ()> {
-		unimplemented!("dispatch")
-	}
-}
-
-#[derive(Debug, Clone, Copy)]
-pub struct Yikes;
-
-impl std::fmt::Display for Yikes {
-	fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-		writeln!(f, "yikes!")
-	}
-}
-
-impl std::error::Error for Yikes {}
-
-impl From<polkadot_overseer_gen::OverseerError> for Yikes {
-	fn from(_: polkadot_overseer_gen::OverseerError) -> Yikes {
-		Yikes
-	}
-}
-
-impl From<polkadot_overseer_gen::mpsc::SendError> for Yikes {
-	fn from(_: polkadot_overseer_gen::mpsc::SendError) -> Yikes {
-		Yikes
-	}
-}
-
-#[derive(Debug, Clone)]
-pub struct MsgStrukt(u8);
-
-#[derive(Debug, Clone, Copy)]
-pub struct Plinko;
-
-impl From<NetworkMsg> for MsgStrukt {
-	fn from(_event: NetworkMsg) -> Self {
-		MsgStrukt(1u8)
-	}
-}
-
-#[derive(Debug, Clone, Copy)]
-pub enum NetworkMsg {
-	A,
-	B,
-	C,
-}
-
-impl NetworkMsg {
-	fn focus(&self) -> Result<Self, WrongVariant> {
-		Ok(match self {
-			Self::B => return Err(WrongVariant),
-			Self::A | Self::C => self.clone(),
-		})
-	}
-}
-
-#[overlord(signal=SigSigSig, event=EvX, error=Yikes, network=NetworkMsg, gen=AllMessages)]
-struct Xxx<T> {
-	#[subsystem(MsgStrukt)]
-	sub0: AwesomeSubSys,
-
-	#[subsystem(no_dispatch, blocking, Plinko)]
-	plinkos: GoblinTower,
-
-	i_like_pi: f64,
-	i_like_generic: T,
-	i_like_hash: HashMap<f64, f64>,
-}
-
-#[derive(Debug, Clone)]
-struct DummySpawner;
-
-impl SpawnNamed for DummySpawner {
-	fn spawn_blocking(
-		&self,
-		task_name: &'static str,
-		subsystem_name: Option<&'static str>,
-		_future: futures::future::BoxFuture<'static, ()>,
-	) {
-		unimplemented!("spawn blocking {} {}", task_name, subsystem_name.unwrap_or("default"))
-	}
-
-	fn spawn(
-		&self,
-		task_name: &'static str,
-		subsystem_name: Option<&'static str>,
-		_future: futures::future::BoxFuture<'static, ()>,
-	) {
-		unimplemented!("spawn {} {}", task_name, subsystem_name.unwrap_or("default"))
-	}
-}
-
-#[derive(Debug, Clone)]
-struct DummyCtx;
-
-fn main() {
-	let (overseer, _handle): (Xxx<_, f64>, _) = Xxx::builder()
-		.sub0(AwesomeSubSys::default())
-		.plinkos(GoblinTower::default())
-		.i_like_pi(::std::f64::consts::PI)
-		.i_like_generic(42.0)
-		.i_like_hash(HashMap::new())
-		.spawner(DummySpawner)
-		.build()
-		.unwrap();
-	assert_eq!(overseer.i_like_pi.floor() as i8, 3);
-	assert_eq!(overseer.i_like_generic.floor() as i8, 42);
-	assert_eq!(overseer.i_like_hash.len() as i8, 0);
-}

polkadot/node/overseer/overseer-gen/examples/duo.rs

@@ -0,0 +1,89 @@
+#![allow(dead_code)] // overseer events are not used
+
+//! A dummy to be used with cargo expand
+
+use polkadot_overseer_gen::{self as overseer, SpawnNamed, *};
+use std::collections::HashMap;
+mod misc;
+
+pub use self::misc::*;
+
+/// Concrete subsystem implementation for `MsgStrukt` msg type.
+#[derive(Default)]
+pub struct AwesomeSubSys;
+
+#[overseer::subsystem(Awesome, error=Yikes)]
+impl<Context> AwesomeSubSys {
+	fn start(self, mut ctx: Context) -> SpawnedSubsystem<Yikes> {
+		let mut sender = ctx.sender().clone();
+		ctx.spawn(
+			"AwesomeSubsys",
+			Box::pin(async move {
+				sender.send_message(Plinko).await;
+			}),
+		)
+		.unwrap();
+		unimplemented!("starting yay!")
+	}
+}
+
+#[derive(Default)]
+pub struct Fortified;
+
+#[overseer::subsystem(GoblinTower, error=Yikes)]
+impl<Context> Fortified {
+	fn start(self, mut ctx: Context) -> SpawnedSubsystem<Yikes> {
+		let mut sender = ctx.sender().clone();
+		ctx.spawn(
+			"GoblinTower",
+			Box::pin(async move {
+				sender.send_message(MsgStrukt(8u8)).await;
+			}),
+		)
+		.unwrap();
+		unimplemented!("welcum")
+	}
+}
+
+#[overlord(signal=SigSigSig, event=EvX, error=Yikes, gen=AllMessages)]
+struct Duo<T> {
+	#[subsystem(consumes: MsgStrukt, sends: [Plinko])]
+	sub0: Awesome,
+
+	#[subsystem(blocking, consumes: Plinko, sends: [MsgStrukt])]
+	plinkos: GoblinTower,
+
+	i_like_pi: f64,
+	i_like_generic: T,
+	i_like_hash: HashMap<f64, f64>,
+}
+
+fn main() {
+	use futures::{executor, pin_mut};
+
+	executor::block_on(async move {
+		let (overseer, _handle): (Duo<_, f64>, _) = Duo::builder()
+			.sub0(AwesomeSubSys::default())
+			.plinkos(Fortified::default())
+			.i_like_pi(::std::f64::consts::PI)
+			.i_like_generic(42.0)
+			.i_like_hash(HashMap::new())
+			.spawner(DummySpawner)
+			.build()
+			.unwrap();
+
+		assert_eq!(overseer.i_like_pi.floor() as i8, 3);
+		assert_eq!(overseer.i_like_generic.floor() as i8, 42);
+		assert_eq!(overseer.i_like_hash.len() as i8, 0);
+
+		let overseer_fut = overseer
+			.running_subsystems
+			.into_future()
+			.timeout(std::time::Duration::from_millis(300))
+			.fuse();
+
+		pin_mut!(overseer_fut);
+
+		overseer_fut.await
+	});
+}

polkadot/node/overseer/overseer-gen/examples/misc.rs

@@ -0,0 +1,69 @@
+use polkadot_overseer_gen::{SpawnNamed, *};
+
+#[derive(Debug, Clone, Copy)]
+pub enum SigSigSig {
+	Conclude,
+	Foo,
+}
+
+#[derive(Debug, Clone)]
+pub struct DummySpawner;
+
+impl SpawnNamed for DummySpawner {
+	fn spawn_blocking(
+		&self,
+		task_name: &'static str,
+		subsystem_name: Option<&'static str>,
+		_future: futures::future::BoxFuture<'static, ()>,
+	) {
+		unimplemented!("spawn blocking {} {}", task_name, subsystem_name.unwrap_or("default"))
+	}
+
+	fn spawn(
+		&self,
+		task_name: &'static str,
+		subsystem_name: Option<&'static str>,
+		_future: futures::future::BoxFuture<'static, ()>,
+	) {
+		unimplemented!("spawn {} {}", task_name, subsystem_name.unwrap_or("default"))
+	}
+}
+
+/// The external event.
+#[derive(Debug, Clone)]
+pub struct EvX;
+
+impl EvX {
+	pub fn focus<'a, T>(&'a self) -> Result<EvX, ()> {
+		unimplemented!("focus")
+	}
+}
+
+#[derive(Debug, Clone, Copy)]
+pub struct Yikes;
+
+impl std::fmt::Display for Yikes {
+	fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+		writeln!(f, "yikes!")
+	}
+}
+
+impl std::error::Error for Yikes {}
+
+impl From<polkadot_overseer_gen::OverseerError> for Yikes {
+	fn from(_: polkadot_overseer_gen::OverseerError) -> Yikes {
+		Yikes
+	}
+}
+
+impl From<polkadot_overseer_gen::mpsc::SendError> for Yikes {
+	fn from(_: polkadot_overseer_gen::mpsc::SendError) -> Yikes {
+		Yikes
+	}
+}
+
+#[derive(Debug, Clone)]
+pub struct MsgStrukt(pub u8);
+
+#[derive(Debug, Clone, Copy)]
+pub struct Plinko;

polkadot/node/overseer/overseer-gen/examples/solo.rs

@@ -0,0 +1,54 @@
+#![allow(dead_code)] // overseer events are not used
+
+//! A minimal demo to be used with cargo expand.
+
+use polkadot_overseer_gen::{self as overseer, SpawnNamed, *};
+mod misc;
+
+pub use self::misc::*;
+
+#[overlord(signal=SigSigSig, event=EvX, error=Yikes, gen=AllMessages)]
+struct Solo<T> {
+	#[subsystem(consumes: Plinko, sends: [MsgStrukt])]
+	goblin_tower: GoblinTower,
+}
+
+#[derive(Default)]
+pub struct Fortified;
+
+#[overseer::subsystem(GoblinTower, error=Yikes)]
+impl<Context> Fortified {
+	fn start(self, mut ctx: Context) -> SpawnedSubsystem<Yikes> {
+		let mut sender = ctx.sender().clone();
+		ctx.spawn(
+			"GoblinTower",
+			Box::pin(async move {
+				sender.send_message(MsgStrukt(8u8)).await;
+			}),
+		)
+		.unwrap();
+		unimplemented!("welcum")
+	}
+}
+
+fn main() {
+	use futures::{executor, pin_mut};
+
+	executor::block_on(async move {
+		let (overseer, _handle): (Solo<_>, _) = Solo::builder()
+			.goblin_tower(Fortified::default())
+			.spawner(DummySpawner)
+			.build()
+			.unwrap();
+
+		let overseer_fut = overseer
+			.running_subsystems
+			.into_future()
+			.timeout(std::time::Duration::from_millis(300))
+			.fuse();
+
+		pin_mut!(overseer_fut);
+
+		overseer_fut.await
+	});
+}

polkadot/node/overseer/overseer-gen/proc-macro/Cargo.toml

@@ -17,12 +17,19 @@ quote = "1.0.18"
 proc-macro2 = "1.0.37"
 proc-macro-crate = "1.1.3"
 expander = { version = "0.0.6", default-features = false }
+petgraph = "0.6.0"
 
 [dev-dependencies]
 assert_matches = "1.5.0"
+polkadot-overseer-gen = { path = "../" }
+thiserror = "1"
+gum = { package = "tracing-gum", path = "../../../gum" }
 
 [features]
-default = []
+default = ["graph", "expand"]
 # write the expanded version to a `overlord-expansion.[a-f0-9]{10}.rs`
 # in the `OUT_DIR` as defined by `cargo` for the `expander` crate.
 expand = []
+# Create directional message consuming / outgoing graph.
+# Generates: `${OUT_DIR}/${overseer|lowercase}-subsystem-messaging.dot`
+graph = []

polkadot/node/overseer/overseer-gen/proc-macro/build.rs

@@ -0,0 +1,3 @@
+fn main() {
+	// populate OUT_DIR
+}

polkadot/node/overseer/overseer-gen/proc-macro/src/impl_builder.rs

@@ -103,7 +103,7 @@ pub(crate) fn impl_builder(info: &OverseerInfo) -> proc_macro2::TokenStream {
 		info.subsystems().iter().filter(|ssf| !ssf.wip).enumerate().map(|(idx, ssf)| {
 			let field_name = &ssf.name;
 			let field_type = &ssf.generic;
-			let subsystem_consumes = &ssf.consumes;
+			let subsystem_consumes = &ssf.message_to_consume;
 			// Remove state generic for the item to be replaced. It sufficient to know `field_type` for
 			// that since we always move from `Init<#field_type>` to `Init<NEW>`.
 			let impl_subsystem_state_generics = recollect_without_idx(&subsystem_passthrough_state_generics[..], idx);
@@ -130,19 +130,28 @@ pub(crate) fn impl_builder(info: &OverseerInfo) -> proc_macro2::TokenStream {
 			// see the loop below.
 			let to_keep_subsystem_name = recollect_without_idx(&subsystem_name[..], idx);
 
+			let subsystem_sender_trait = format_ident!("{}SenderTrait", field_type);
+			let _subsystem_ctx_trait = format_ident!("{}ContextTrait", field_type);
+
+			let builder_where_clause = quote!{
+				#field_type : #support_crate::Subsystem< #subsystem_ctx_name< #subsystem_consumes >, #error_ty>,
+				< #subsystem_ctx_name < #subsystem_consumes > as #support_crate :: SubsystemContext>::Sender:
+					#subsystem_sender_trait,
+			};
+
 			// Create the field init `fn`
 			quote! {
 				impl <InitStateSpawner, #field_type, #( #impl_subsystem_state_generics, )* #( #baggage_passthrough_state_generics, )*>
 				#builder <InitStateSpawner, #( #current_state_generics, )* #( #baggage_passthrough_state_generics, )*>
 				where
-					#field_type : Subsystem<#subsystem_ctx_name<#subsystem_consumes>, #error_ty>,
+					#builder_where_clause
 				{
 					/// Specify the subsystem in the builder directly
 					pub fn #field_name (self, var: #field_type ) ->
 						#builder <InitStateSpawner, #( #post_setter_state_generics, )* #( #baggage_passthrough_state_generics, )*>
 					{
 						#builder {
-							#field_name: Init::<#field_type>::Value(var),
+							#field_name: Init::< #field_type >::Value(var),
 							#(
 								#to_keep_subsystem_name: self. #to_keep_subsystem_name,
 							)*
@@ -158,7 +167,7 @@ pub(crate) fn impl_builder(info: &OverseerInfo) -> proc_macro2::TokenStream {
 					/// Specify the the initialization function for a subsystem
 					pub fn #field_name_with<'a, F>(self, subsystem_init_fn: F ) ->
 						#builder <InitStateSpawner, #( #post_setter_state_generics, )* #( #baggage_passthrough_state_generics, )*>
-						where
+					where
 						F: 'static + FnOnce(#handle) ->
 							::std::result::Result<#field_type, #error_ty>,
 					{
@@ -185,7 +194,7 @@ pub(crate) fn impl_builder(info: &OverseerInfo) -> proc_macro2::TokenStream {
 				impl <InitStateSpawner, #field_type, #( #impl_subsystem_state_generics, )* #( #baggage_passthrough_state_generics, )*>
 				#builder <InitStateSpawner, #( #post_setter_state_generics, )* #( #baggage_passthrough_state_generics, )*>
 				where
-					#field_type : Subsystem<#subsystem_ctx_name<#subsystem_consumes>, #error_ty>,
+					#builder_where_clause
 				{
 					/// Replace a subsystem by another implementation for the
 					/// consumable message type.
@@ -301,6 +310,28 @@ pub(crate) fn impl_builder(info: &OverseerInfo) -> proc_macro2::TokenStream {
 		S, #( #baggage_generic_ty, )* #( #subsystem_generics, )*
 	};
 
+	let builder_where_clause = info
+		.subsystems()
+		.iter()
+		.map(|ssf| {
+			let field_type = &ssf.generic;
+			let consumes = &ssf.message_to_consume;
+			let subsystem_sender_trait = format_ident!("{}SenderTrait", ssf.generic);
+			let subsystem_ctx_trait = format_ident!("{}ContextTrait", ssf.generic);
+			quote! {
+				#field_type:
+					#support_crate::Subsystem< #subsystem_ctx_name < #consumes>, #error_ty>,
+				<#subsystem_ctx_name< #consumes > as #subsystem_ctx_trait>::Sender:
+					#subsystem_sender_trait,
+				#subsystem_ctx_name< #consumes >:
+					#subsystem_ctx_trait,
+			}
+		})
+		.fold(TokenStream::new(), |mut ts, addendum| {
+			ts.extend(addendum);
+			ts
+		});
+
 	let mut ts = quote! {
 		/// Convenience alias.
 		type SubsystemInitFn<T> = Box<dyn FnOnce(#handle) -> ::std::result::Result<T, #error_ty> >;
@@ -332,14 +363,15 @@ pub(crate) fn impl_builder(info: &OverseerInfo) -> proc_macro2::TokenStream {
 			}
 		}
 
-		impl<S, #( #baggage_generic_ty, )*> #overseer_name <S, #( #baggage_generic_ty, )*> where #spawner_where_clause {
+		impl<S #(, #baggage_generic_ty )*> #overseer_name <S #(, #baggage_generic_ty)*>
+		where
+			#spawner_where_clause,
+		{
 			/// Create a new overseer utilizing the builder.
 			pub fn builder< #( #subsystem_generics),* >() ->
-				#builder<Missing<S> #(, Missing<#field_type> )* >
+				#builder<Missing<S> #(, Missing< #field_type > )* >
 			where
-				#(
-					#subsystem_generics : Subsystem<#subsystem_ctx_name< #consumes >, #error_ty>,
-				)*
+				#builder_where_clause
 			{
 				#builder :: new()
 			}
@@ -398,7 +430,8 @@ pub(crate) fn impl_builder(info: &OverseerInfo) -> proc_macro2::TokenStream {
 
 	ts.extend(quote!{
 		/// Builder pattern to create compile time safe construction path.
-		pub struct #builder <InitStateSpawner, #( #subsystem_passthrough_state_generics, )* #( #baggage_passthrough_state_generics, )*> {
+		pub struct #builder <InitStateSpawner, #( #subsystem_passthrough_state_generics, )* #( #baggage_passthrough_state_generics, )*>
+		{
 			#(
 				#subsystem_name: #subsystem_passthrough_state_generics,
 			)*
@@ -445,7 +478,7 @@ pub(crate) fn impl_builder(info: &OverseerInfo) -> proc_macro2::TokenStream {
 		impl<S, #( #subsystem_passthrough_state_generics, )* #( #baggage_passthrough_state_generics, )*>
 			#builder<Missing<S>, #( #subsystem_passthrough_state_generics, )* #( #baggage_passthrough_state_generics, )*>
 		where
-			#spawner_where_clause
+			#spawner_where_clause,
 		{
 			/// The `spawner` to use for spawning tasks.
 			pub fn spawner(self, spawner: S) -> #builder<
@@ -490,6 +523,12 @@ pub(crate) fn impl_builder(info: &OverseerInfo) -> proc_macro2::TokenStream {
 		}
 	});
 
+	// Create the string literals for spawn.
+	let subsystem_name_str_literal = subsystem_name
+		.iter()
+		.map(|ident| proc_macro2::Literal::string(ident.to_string().replace("_", "-").as_str()))
+		.collect::<Vec<_>>();
+
 	ts.extend(quote! {
 		/// Type used to represent a builder where all fields are initialized and the overseer could be constructed.
 		pub type #initialized_builder<#initialized_builder_generics> = #builder<Init<S>, #( Init<#field_type>, )*>;
@@ -498,9 +537,7 @@ pub(crate) fn impl_builder(info: &OverseerInfo) -> proc_macro2::TokenStream {
 		impl<#initialized_builder_generics> #initialized_builder<#initialized_builder_generics>
 		where
 			#spawner_where_clause,
-			#(
-				#subsystem_generics : Subsystem<#subsystem_ctx_name< #consumes >, #error_ty>,
-			)*
+			#builder_where_clause
 		{
 			/// Complete the construction and create the overseer type.
 			pub fn build(self)
@@ -577,17 +614,12 @@ pub(crate) fn impl_builder(info: &OverseerInfo) -> proc_macro2::TokenStream {
 						self.signal_capacity.unwrap_or(SIGNAL_CHANNEL_CAPACITY)
 					);
 
-					// Generate subsystem name based on overseer field name.
-					let subsystem_string = String::from(stringify!(#subsystem_name));
-					// Convert owned `snake case` string to a `kebab case` static str.
-					let subsystem_static_str = Box::leak(subsystem_string.replace("_", "-").into_boxed_str());
-
 					let ctx = #subsystem_ctx_name::< #consumes >::new(
 						signal_rx,
 						message_rx,
 						channels_out.clone(),
 						to_overseer_tx.clone(),
-						subsystem_static_str
+						#subsystem_name_str_literal
 					);
 
 					let #subsystem_name: OverseenSubsystem< #consumes > =
@@ -598,7 +630,7 @@ pub(crate) fn impl_builder(info: &OverseerInfo) -> proc_macro2::TokenStream {
 							unbounded_meter,
 							ctx,
 							#subsystem_name,
-							subsystem_static_str,
+							#subsystem_name_str_literal,
 							&mut running_subsystems,
 						)?;
 				)*

polkadot/node/overseer/overseer-gen/proc-macro/src/impl_channels_out.rs

@@ -65,6 +65,7 @@ pub(crate) fn impl_channels_out_struct(info: &OverseerInfo) -> Result<proc_macro
 				signals_received: usize,
 				message: #message_wrapper,
 			) {
+
 				let res: ::std::result::Result<_, _> = match message {
 				#(
 					#message_wrapper :: #consumes_variant ( inner ) => {
@@ -79,6 +80,13 @@ pub(crate) fn impl_channels_out_struct(info: &OverseerInfo) -> Result<proc_macro
 				)*
 					// dummy message type
 					#message_wrapper :: Empty => Ok(()),
+
+					#[allow(unreachable_patterns)]
+					// And everything that's not WIP but no subsystem consumes it
+					unused_msg => {
+						#support_crate :: gum :: warn!("Nothing consumes {:?}", unused_msg);
+						Ok(())
+					}
 				};
 
 				if let Err(subsystem_name) = res {
@@ -110,7 +118,14 @@ pub(crate) fn impl_channels_out_struct(info: &OverseerInfo) -> Result<proc_macro
 					#message_wrapper :: #unconsumes_variant ( _ ) => Ok(()),
 				)*
 					// dummy message type
-					#message_wrapper :: Empty => Ok(())
+					#message_wrapper :: Empty => Ok(()),
+
+					// And everything that's not WIP but no subsystem consumes it
+					#[allow(unreachable_patterns)]
+					unused_msg => {
+						#support_crate :: gum :: warn!("Nothing consumes {:?}", unused_msg);
+						Ok(())
+					}
 				};
 
 				if let Err(subsystem_name) = res {

polkadot/node/overseer/overseer-gen/proc-macro/src/impl_dispatch.rs

@@ -1,70 +0,0 @@
-// Copyright 2021 Parity Technologies (UK) Ltd.
-// This file is part of Polkadot.
-
-// Polkadot is free software: you can redistribute it and/or modify
-// it under the terms of the GNU General Public License as published by
-// the Free Software Foundation, either version 3 of the License, or
-// (at your option) any later version.
-
-// Polkadot is distributed in the hope that it will be useful,
-// but WITHOUT ANY WARRANTY; without even the implied warranty of
-// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-// GNU General Public License for more details.
-
-// You should have received a copy of the GNU General Public License
-// along with Polkadot.  If not, see <http://www.gnu.org/licenses/>.
-
-use super::*;
-use proc_macro2::{Ident, TokenStream};
-use quote::quote;
-use syn::Path;
-
-pub(crate) fn impl_dispatch(info: &OverseerInfo) -> TokenStream {
-	let message_wrapper = &info.message_wrapper;
-
-	let dispatchable_variant = info
-		.subsystems()
-		.into_iter()
-		.filter(|ssf| !ssf.no_dispatch)
-		.filter(|ssf| !ssf.wip)
-		.map(|ssf| ssf.generic.clone())
-		.collect::<Vec<Ident>>();
-
-	let dispatchable_message = info
-		.subsystems()
-		.into_iter()
-		.filter(|ssf| !ssf.no_dispatch)
-		.filter(|ssf| !ssf.wip)
-		.map(|ssf| ssf.consumes.clone())
-		.collect::<Vec<Path>>();
-
-	let mut ts = TokenStream::new();
-	if let Some(extern_network_ty) = &info.extern_network_ty.clone() {
-		ts.extend(quote! {
-			impl #message_wrapper {
-				/// Generated dispatch iterator generator.
-				pub fn dispatch_iter(extern_msg: #extern_network_ty) -> impl Iterator<Item=Self> + Send {
-					[
-					#(
-						extern_msg
-							// focuses on a `NetworkBridgeEvent< protocol_v1::* >`
-							// TODO do not require this to be hardcoded, either externalize or ...
-							// https://github.com/paritytech/polkadot/issues/3427
-							.focus()
-							.ok()
-							.map(|event| {
-								#message_wrapper :: #dispatchable_variant (
-									// the inner type of the enum variant
-									#dispatchable_message :: from( event )
-								)
-							}),
-					)*
-					]
-					.into_iter()
-					.filter_map(|x: Option<_>| x)
-				}
-			}
-		});
-	}
-	ts
-}

polkadot/node/overseer/overseer-gen/proc-macro/src/impl_message_wrapper.rs

@@ -21,7 +21,7 @@ use super::*;
 
 /// Generates the wrapper type enum.
 pub(crate) fn impl_message_wrapper_enum(info: &OverseerInfo) -> Result<proc_macro2::TokenStream> {
-	let consumes = info.consumes();
+	let consumes = info.any_message();
 	let consumes_variant = info.variant_names();
 
 	let outgoing = &info.outgoing_ty;
@@ -52,7 +52,8 @@ pub(crate) fn impl_message_wrapper_enum(info: &OverseerInfo) -> Result<proc_macr
 	};
 
 	let ts = quote! {
-		/// Generated message type wrapper
+		/// Generated message type wrapper over all possible messages
+		/// used by any subsystem.
 		#[allow(missing_docs)]
 		#[derive(Debug)]
 		pub enum #message_wrapper {

polkadot/node/overseer/overseer-gen/proc-macro/src/impl_misc.rs

@@ -1,259 +0,0 @@
-// Copyright 2021 Parity Technologies (UK) Ltd.
-// This file is part of Polkadot.
-
-// Polkadot is free software: you can redistribute it and/or modify
-// it under the terms of the GNU General Public License as published by
-// the Free Software Foundation, either version 3 of the License, or
-// (at your option) any later version.
-
-// Polkadot is distributed in the hope that it will be useful,
-// but WITHOUT ANY WARRANTY; without even the implied warranty of
-// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-// GNU General Public License for more details.
-
-// You should have received a copy of the GNU General Public License
-// along with Polkadot.  If not, see <http://www.gnu.org/licenses/>.
-
-use quote::quote;
-use syn::Ident;
-
-use super::*;
-
-/// Implement a builder pattern for the `Overseer`-type,
-/// which acts as the gateway to constructing the overseer.
-pub(crate) fn impl_misc(info: &OverseerInfo) -> proc_macro2::TokenStream {
-	let overseer_name = info.overseer_name.clone();
-	let subsystem_sender_name =
-		Ident::new(&(overseer_name.to_string() + "SubsystemSender"), overseer_name.span());
-	let subsystem_ctx_name =
-		Ident::new(&(overseer_name.to_string() + "SubsystemContext"), overseer_name.span());
-	let consumes = &info.consumes();
-	let signal = &info.extern_signal_ty;
-	let wrapper_message = &info.message_wrapper;
-	let error_ty = &info.extern_error_ty;
-	let support_crate = info.support_crate_name();
-
-	let ts = quote! {
-		/// Connector to send messages towards all subsystems,
-		/// while tracking the which signals where already received.
-		#[derive(Debug, Clone)]
-		pub struct #subsystem_sender_name {
-			/// Collection of channels to all subsystems.
-			channels: ChannelsOut,
-			/// Systemwide tick for which signals were received by all subsystems.
-			signals_received: SignalsReceived,
-		}
-
-		/// implementation for wrapping message type...
-		#[#support_crate ::async_trait]
-		impl SubsystemSender< #wrapper_message > for #subsystem_sender_name {
-			async fn send_message(&mut self, msg: #wrapper_message) {
-				self.channels.send_and_log_error(self.signals_received.load(), msg).await;
-			}
-
-			async fn send_messages<T>(&mut self, msgs: T)
-			where
-				T: IntoIterator<Item = #wrapper_message> + Send,
-				T::IntoIter: Send,
-			{
-				// This can definitely be optimized if necessary.
-				for msg in msgs {
-					self.send_message(msg).await;
-				}
-			}
-
-			fn send_unbounded_message(&mut self, msg: #wrapper_message) {
-				self.channels.send_unbounded_and_log_error(self.signals_received.load(), msg);
-			}
-		}
-
-		// ... but also implement for all individual messages to avoid
-		// the necessity for manual wrapping, and do the conversion
-		// based on the generated `From::from` impl for the individual variants.
-		#(
-		#[#support_crate ::async_trait]
-		impl SubsystemSender< #consumes > for #subsystem_sender_name {
-			async fn send_message(&mut self, msg: #consumes) {
-				self.channels.send_and_log_error(self.signals_received.load(), #wrapper_message ::from ( msg )).await;
-			}
-
-			async fn send_messages<T>(&mut self, msgs: T)
-			where
-				T: IntoIterator<Item = #consumes> + Send,
-				T::IntoIter: Send,
-			{
-				// This can definitely be optimized if necessary.
-				for msg in msgs {
-					self.send_message(msg).await;
-				}
-			}
-
-			fn send_unbounded_message(&mut self, msg: #consumes) {
-				self.channels.send_unbounded_and_log_error(self.signals_received.load(), #wrapper_message ::from ( msg ));
-			}
-		}
-		)*
-
-		/// A context type that is given to the [`Subsystem`] upon spawning.
-		/// It can be used by [`Subsystem`] to communicate with other [`Subsystem`]s
-		/// or to spawn it's [`SubsystemJob`]s.
-		///
-		/// [`Overseer`]: struct.Overseer.html
-		/// [`Subsystem`]: trait.Subsystem.html
-		/// [`SubsystemJob`]: trait.SubsystemJob.html
-		#[derive(Debug)]
-		#[allow(missing_docs)]
-		pub struct #subsystem_ctx_name<M>{
-			signals: #support_crate ::metered::MeteredReceiver< #signal >,
-			messages: SubsystemIncomingMessages<M>,
-			to_subsystems: #subsystem_sender_name,
-			to_overseer: #support_crate ::metered::UnboundedMeteredSender<
-				#support_crate ::ToOverseer
-				>,
-			signals_received: SignalsReceived,
-			pending_incoming: Option<(usize, M)>,
-			name: &'static str
-		}
-
-		impl<M> #subsystem_ctx_name<M> {
-			/// Create a new context.
-			fn new(
-				signals: #support_crate ::metered::MeteredReceiver< #signal >,
-				messages: SubsystemIncomingMessages<M>,
-				to_subsystems: ChannelsOut,
-				to_overseer: #support_crate ::metered::UnboundedMeteredSender<#support_crate:: ToOverseer>,
-				name: &'static str
-			) -> Self {
-				let signals_received = SignalsReceived::default();
-				#subsystem_ctx_name {
-					signals,
-					messages,
-					to_subsystems: #subsystem_sender_name {
-						channels: to_subsystems,
-						signals_received: signals_received.clone(),
-					},
-					to_overseer,
-					signals_received,
-					pending_incoming: None,
-					name
-				}
-			}
-
-			fn name(&self) -> &'static str {
-				self.name
-			}
-		}
-
-		#[#support_crate ::async_trait]
-		impl<M: std::fmt::Debug + Send + 'static> #support_crate ::SubsystemContext for #subsystem_ctx_name<M>
-		where
-			#subsystem_sender_name: #support_crate ::SubsystemSender< #wrapper_message >,
-			#wrapper_message: From<M>,
-		{
-			type Message = M;
-			type Signal = #signal;
-			type Sender = #subsystem_sender_name;
-			type AllMessages = #wrapper_message;
-			type Error = #error_ty;
-
-			async fn try_recv(&mut self) -> ::std::result::Result<Option<FromOverseer<M, #signal>>, ()> {
-				match #support_crate ::poll!(self.recv()) {
-					#support_crate ::Poll::Ready(msg) => Ok(Some(msg.map_err(|_| ())?)),
-					#support_crate ::Poll::Pending => Ok(None),
-				}
-			}
-
-			async fn recv(&mut self) -> ::std::result::Result<FromOverseer<M, #signal>, #error_ty> {
-				loop {
-					// If we have a message pending an overseer signal, we only poll for signals
-					// in the meantime.
-					if let Some((needs_signals_received, msg)) = self.pending_incoming.take() {
-						if needs_signals_received <= self.signals_received.load() {
-							return Ok(#support_crate ::FromOverseer::Communication { msg });
-						} else {
-							self.pending_incoming = Some((needs_signals_received, msg));
-
-							// wait for next signal.
-							let signal = self.signals.next().await
-								.ok_or(#support_crate ::OverseerError::Context(
-									"Signal channel is terminated and empty."
-									.to_owned()
-								))?;
-
-							self.signals_received.inc();
-							return Ok(#support_crate ::FromOverseer::Signal(signal))
-						}
-					}
-
-					let mut await_message = self.messages.next().fuse();
-					let mut await_signal = self.signals.next().fuse();
-					let signals_received = self.signals_received.load();
-					let pending_incoming = &mut self.pending_incoming;
-
-					// Otherwise, wait for the next signal or incoming message.
-					let from_overseer = #support_crate ::futures::select_biased! {
-						signal = await_signal => {
-							let signal = signal
-								.ok_or(#support_crate ::OverseerError::Context(
-									"Signal channel is terminated and empty."
-									.to_owned()
-								))?;
-
-							#support_crate ::FromOverseer::Signal(signal)
-						}
-						msg = await_message => {
-							let packet = msg
-								.ok_or(#support_crate ::OverseerError::Context(
-									"Message channel is terminated and empty."
-									.to_owned()
-								))?;
-
-							if packet.signals_received > signals_received {
-								// wait until we've received enough signals to return this message.
-								*pending_incoming = Some((packet.signals_received, packet.message));
-								continue;
-							} else {
-								// we know enough to return this message.
-								#support_crate ::FromOverseer::Communication { msg: packet.message}
-							}
-						}
-					};
-
-					if let #support_crate ::FromOverseer::Signal(_) = from_overseer {
-						self.signals_received.inc();
-					}
-
-					return Ok(from_overseer);
-				}
-			}
-
-			fn sender(&mut self) -> &mut Self::Sender {
-				&mut self.to_subsystems
-			}
-
-			fn spawn(&mut self, name: &'static str, s: Pin<Box<dyn Future<Output = ()> + Send>>)
-				-> ::std::result::Result<(), #error_ty>
-			{
-				self.to_overseer.unbounded_send(#support_crate ::ToOverseer::SpawnJob {
-					name,
-					subsystem: Some(self.name()),
-					s,
-				}).map_err(|_| #support_crate ::OverseerError::TaskSpawn(name))?;
-				Ok(())
-			}
-
-			fn spawn_blocking(&mut self, name: &'static str, s: Pin<Box<dyn Future<Output = ()> + Send>>)
-				-> ::std::result::Result<(), #error_ty>
-			{
-				self.to_overseer.unbounded_send(#support_crate ::ToOverseer::SpawnBlockingJob {
-					name,
-					subsystem: Some(self.name()),
-					s,
-				}).map_err(|_| #support_crate ::OverseerError::TaskSpawn(name))?;
-				Ok(())
-			}
-		}
-	};
-
-	ts
-}

polkadot/node/overseer/overseer-gen/proc-macro/src/impl_overseer.rs

@@ -37,7 +37,7 @@ pub(crate) fn impl_overseer_struct(info: &OverseerInfo) -> proc_macro2::TokenStr
 			S: #support_crate ::SpawnNamed,
 	};
 	// TODO add `where ..` clauses for baggage types
-	// TODO https://github.com/paritytech/polkadot/issues/3427
+	// TODO <https://github.com/paritytech/polkadot/issues/3427>
 
 	let consumes = &info.consumes_without_wip();
 	let consumes_variant = &info.variant_names_without_wip();
@@ -148,6 +148,12 @@ pub(crate) fn impl_overseer_struct(info: &OverseerInfo) -> proc_macro2::TokenStr
 						#message_wrapper :: #unconsumes_variant ( _ ) => {}
 					)*
 					#message_wrapper :: Empty => {}
+
+					// And everything that's not WIP but no subsystem consumes it
+					#[allow(unreachable_patterns)]
+					unused_msg => {
+						#support_crate :: gum :: warn!("Nothing consumes {:?}", unused_msg);
+					}
 				}
 				Ok(())
 			}

polkadot/node/overseer/overseer-gen/proc-macro/src/impl_subsystem_ctx_sender.rs

@@ -0,0 +1,712 @@
+// Copyright 2022 Parity Technologies (UK) Ltd.
+// This file is part of Polkadot.
+
+// Polkadot is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Polkadot is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Polkadot.  If not, see <http://www.gnu.org/licenses/>.
+
+use proc_macro2::TokenStream;
+use quote::quote;
+use syn::{Ident, Path, Result, Type};
+
+use petgraph::{
+	dot::{self, Dot},
+	graph::NodeIndex,
+	visit::EdgeRef,
+	Direction,
+};
+use std::collections::HashMap;
+
+use super::*;
+
+/// Render a graphviz (aka dot graph) to a file.
+fn graphviz(
+	graph: &petgraph::Graph<Ident, Path>,
+	dest: &mut impl std::io::Write,
+) -> std::io::Result<()> {
+	let config = &[dot::Config::EdgeNoLabel, dot::Config::NodeNoLabel][..];
+	let dot = Dot::with_attr_getters(
+		graph,
+		config,
+		&|_graph, edge| -> String {
+			format!(
+				r#"label="{}""#,
+				edge.weight().get_ident().expect("Must have a trailing identifier. qed")
+			)
+		},
+		&|_graph, (_node_index, subsystem_name)| -> String {
+			format!(r#"label="{}""#, subsystem_name,)
+		},
+	);
+	dest.write_all(format!("{:?}", &dot).as_bytes())?;
+	Ok(())
+}
+
+/// Generates all subsystem types and related accumulation traits.
+pub(crate) fn impl_subsystem_types_all(info: &OverseerInfo) -> Result<TokenStream> {
+	let mut ts = TokenStream::new();
+
+	let overseer_name = &info.overseer_name;
+	let span = overseer_name.span();
+	let all_messages_wrapper = &info.message_wrapper;
+	let support_crate = info.support_crate_name();
+	let signal_ty = &info.extern_signal_ty;
+	let error_ty = &info.extern_error_ty;
+
+	// create a directed graph with all the subsystems as nodes and the messages as edges
+	// key is always the message path, values are node indices in the graph and the subsystem generic identifier
+	// store the message path and the source sender, both in the graph as well as identifier
+	let mut outgoing_lut = HashMap::<&Path, Vec<(Ident, NodeIndex)>>::with_capacity(128);
+	// same for consuming the incoming messages
+	let mut consuming_lut = HashMap::<&Path, (Ident, NodeIndex)>::with_capacity(128);
+
+	// Ident = Node = subsystem generic names
+	// Path = Edge = messages
+	let mut graph = petgraph::Graph::<Ident, Path>::new();
+
+	// prepare the full index of outgoing and source subsystems
+	for ssf in info.subsystems() {
+		let node_index = graph.add_node(ssf.generic.clone());
+		for outgoing in ssf.messages_to_send.iter() {
+			outgoing_lut
+				.entry(outgoing)
+				.or_default()
+				.push((ssf.generic.clone(), node_index));
+		}
+		consuming_lut.insert(&ssf.message_to_consume, (ssf.generic.clone(), node_index));
+	}
+
+	for (message_ty, (_consuming_subsystem_ident, consuming_node_index)) in consuming_lut.iter() {
+		// match the outgoing ones that were registered above with the consumed message
+		if let Some(origin_subsystems) = outgoing_lut.get(message_ty) {
+			for (_origin_subsystem_ident, sending_node_index) in origin_subsystems.iter() {
+				graph.add_edge(*sending_node_index, *consuming_node_index, (*message_ty).clone());
+			}
+		}
+	}
+
+	// All outgoing edges are now usable to derive everything we need
+	for node_index in graph.node_indices() {
+		let subsystem_name = graph[node_index].to_string();
+		let outgoing_wrapper = Ident::new(&(subsystem_name + "OutgoingMessages"), span);
+
+		// cannot be a hashmap, duplicate keys and sorting required
+		// maps outgoing messages to the subsystem that consumes it
+		let outgoing_to_consumer = graph
+			.edges_directed(node_index, Direction::Outgoing)
+			.map(|edge| {
+				let message_ty = edge.weight();
+				let subsystem_generic_consumer = graph[edge.target()].clone();
+				Ok((to_variant(message_ty, span.clone())?, subsystem_generic_consumer))
+			})
+			.collect::<Result<Vec<(Ident, Ident)>>>()?;
+
+		// Split it for usage with quote
+		let outgoing_variant = outgoing_to_consumer.iter().map(|x| x.0.clone()).collect::<Vec<_>>();
+		let subsystem_generic = outgoing_to_consumer.into_iter().map(|x| x.1).collect::<Vec<_>>();
+
+		ts.extend(quote! {
+			impl ::std::convert::From< #outgoing_wrapper > for #all_messages_wrapper {
+				fn from(message: #outgoing_wrapper) -> Self {
+					match message {
+					#(
+						#outgoing_wrapper :: #outgoing_variant ( msg ) => #all_messages_wrapper :: #subsystem_generic ( msg ),
+					)*
+						#outgoing_wrapper :: Empty => #all_messages_wrapper :: Empty,
+						// And everything that's not WIP but no subsystem consumes it
+						#[allow(unreachable_patterns)]
+						unused_msg => {
+							#support_crate :: gum :: warn!("Nothing consumes {:?}", unused_msg);
+							#all_messages_wrapper :: Empty
+						}
+					}
+				}
+			}
+		})
+	}
+
+	// Dump the graph to file.
+	if cfg!(feature = "graph") || true {
+		let path = std::path::PathBuf::from(env!("OUT_DIR"))
+			.join(overseer_name.to_string().to_lowercase() + "-subsystem-messaging.dot");
+		if let Err(e) = std::fs::OpenOptions::new()
+			.truncate(true)
+			.create(true)
+			.write(true)
+			.open(&path)
+			.and_then(|mut f| graphviz(&graph, &mut f))
+		{
+			eprintln!("Failed to write dot graph to {}: {:?}", path.display(), e);
+		} else {
+			println!("Wrote dot graph to {}", path.display());
+		}
+	}
+
+	let subsystem_sender_name = &Ident::new(&(overseer_name.to_string() + "Sender"), span);
+	let subsystem_ctx_name = &Ident::new(&(overseer_name.to_string() + "SubsystemContext"), span);
+	ts.extend(impl_subsystem_context(info, &subsystem_sender_name, &subsystem_ctx_name));
+
+	ts.extend(impl_associate_outgoing_messages_trait(&all_messages_wrapper));
+
+	ts.extend(impl_subsystem_sender(
+		support_crate,
+		info.subsystems().iter().map(|ssf| {
+			let outgoing_wrapper =
+				Ident::new(&(ssf.generic.to_string() + "OutgoingMessages"), span);
+			outgoing_wrapper
+		}),
+		&all_messages_wrapper,
+		&subsystem_sender_name,
+	));
+
+	// Create all subsystem specific types, one by one
+	for ssf in info.subsystems() {
+		let subsystem_name = ssf.generic.to_string();
+		let outgoing_wrapper = &Ident::new(&(subsystem_name.clone() + "OutgoingMessages"), span);
+
+		let subsystem_ctx_trait = &Ident::new(&(subsystem_name.clone() + "ContextTrait"), span);
+		let subsystem_sender_trait = &Ident::new(&(subsystem_name.clone() + "SenderTrait"), span);
+
+		ts.extend(impl_per_subsystem_helper_traits(
+			info,
+			subsystem_ctx_name,
+			subsystem_ctx_trait,
+			subsystem_sender_name,
+			subsystem_sender_trait,
+			&ssf.message_to_consume,
+			&ssf.messages_to_send,
+			outgoing_wrapper,
+		));
+
+		ts.extend(impl_associate_outgoing_messages(&ssf.message_to_consume, &outgoing_wrapper));
+
+		ts.extend(impl_wrapper_enum(&outgoing_wrapper, ssf.messages_to_send.as_slice())?);
+	}
+
+	// impl the emtpy tuple handling for tests
+	let empty_tuple: Type = parse_quote! { () };
+	ts.extend(impl_subsystem_context_trait_for(
+		empty_tuple.clone(),
+		&[],
+		empty_tuple,
+		all_messages_wrapper,
+		subsystem_ctx_name,
+		subsystem_sender_name,
+		support_crate,
+		signal_ty,
+		error_ty,
+	));
+
+	Ok(ts)
+}
+
+/// Extract the final component of the message type path as used in the `#[subsystem(consumes: path::to::Foo)]` annotation.
+fn to_variant(path: &Path, span: Span) -> Result<Ident> {
+	let ident = path
+		.segments
+		.last()
+		.ok_or_else(|| syn::Error::new(span, "Path is empty, but it must end with an identifier"))
+		.map(|segment| segment.ident.clone())?;
+	Ok(ident)
+}
+
+/// Converts the outgoing message types to variants.
+///
+/// Note: Commonly this is `${X}Message` becomes `${X}OutgoingMessages::${X}Message`
+/// where for `AllMessages` it would be `AllMessages::${X}`.
+fn to_variants(message_types: &[Path], span: Span) -> Result<Vec<Ident>> {
+	let variants: Vec<_> =
+		Result::from_iter(message_types.into_iter().map(|path| to_variant(path, span.clone())))?;
+	Ok(variants)
+}
+
+/// Generates the wrapper type enum, no bells or whistles.
+pub(crate) fn impl_wrapper_enum(wrapper: &Ident, message_types: &[Path]) -> Result<TokenStream> {
+	// The message types are path based, each of them must finish with a type
+	// and as such we do this upfront.
+	let variants = to_variants(message_types, wrapper.span())?;
+
+	let ts = quote! {
+		#[allow(missing_docs)]
+		#[derive(Debug)]
+		pub enum #wrapper {
+			#(
+				#variants ( #message_types ),
+			)*
+			Empty,
+		}
+
+		#(
+			impl ::std::convert::From< #message_types > for #wrapper {
+				fn from(message: #message_types) -> Self {
+					#wrapper :: #variants ( message )
+				}
+			}
+		)*
+
+		// Useful for unit and integration tests:
+		impl ::std::convert::From< () > for #wrapper {
+			fn from(_message: ()) -> Self {
+				#wrapper :: Empty
+			}
+		}
+	};
+	Ok(ts)
+}
+
+/// Create the subsystem sender type and implements `trait SubsystemSender`
+/// for the `#outgoing_wrappers: From<OutgoingMessage>` with the proper associated types.
+pub(crate) fn impl_subsystem_sender(
+	support_crate: &Path,
+	outgoing_wrappers: impl IntoIterator<Item = Ident>,
+	all_messages_wrapper: &Ident,
+	subsystem_sender_name: &Ident,
+) -> TokenStream {
+	let mut ts = quote! {
+		/// Connector to send messages towards all subsystems,
+		/// while tracking the which signals where already received.
+		#[derive(Debug)]
+		pub struct #subsystem_sender_name < OutgoingWrapper > {
+			/// Collection of channels to all subsystems.
+			channels: ChannelsOut,
+			/// Systemwide tick for which signals were received by all subsystems.
+			signals_received: SignalsReceived,
+			/// Keep that marker around.
+			_phantom: ::core::marker::PhantomData< OutgoingWrapper >,
+		}
+
+		// can't derive due to `PhantomData` and `OutgoingWrapper` not being
+		// bounded by `Clone`.
+		impl<OutgoingWrapper> std::clone::Clone for #subsystem_sender_name < OutgoingWrapper > {
+			fn clone(&self) -> Self {
+				Self {
+					channels: self.channels.clone(),
+					signals_received: self.signals_received.clone(),
+					_phantom: ::core::marker::PhantomData::default(),
+				}
+			}
+		}
+	};
+
+	// Create the same for a wrapping enum:
+	//
+	// 1. subsystem specific `*OutgoingMessages`-type
+	// 2. overseer-global-`AllMessages`-type
+	let wrapped = |outgoing_wrapper: &TokenStream| {
+		quote! {
+			#[#support_crate ::async_trait]
+			impl<OutgoingMessage> SubsystemSender< OutgoingMessage > for #subsystem_sender_name < #outgoing_wrapper >
+			where
+				OutgoingMessage: Send + 'static,
+				#outgoing_wrapper: ::std::convert::From<OutgoingMessage> + Send,
+				#all_messages_wrapper: ::std::convert::From< #outgoing_wrapper > + Send,
+			{
+				async fn send_message(&mut self, msg: OutgoingMessage)
+				{
+					self.channels.send_and_log_error(
+						self.signals_received.load(),
+						<#all_messages_wrapper as ::std::convert::From<_>> ::from (
+							<#outgoing_wrapper as ::std::convert::From<_>> :: from ( msg )
+						)
+					).await;
+				}
+
+				async fn send_messages<I>(&mut self, msgs: I)
+				where
+					I: IntoIterator<Item=OutgoingMessage> + Send,
+					I::IntoIter: Iterator<Item=OutgoingMessage> + Send,
+				{
+					for msg in msgs {
+						self.send_message( msg ).await;
+					}
+				}
+
+				fn send_unbounded_message(&mut self, msg: OutgoingMessage)
+				{
+					self.channels.send_unbounded_and_log_error(
+						self.signals_received.load(),
+						<#all_messages_wrapper as ::std::convert::From<_>> ::from (
+							<#outgoing_wrapper as ::std::convert::From<_>> :: from ( msg )
+						)
+					);
+				}
+			}
+		}
+	};
+
+	for outgoing_wrapper in outgoing_wrappers {
+		ts.extend(wrapped(&quote! {
+			#outgoing_wrapper
+		}));
+	}
+
+	ts.extend(wrapped(&quote! {
+		()
+	}));
+
+	ts
+}
+
+/// Define the `trait AssociateOutgoing` and implement it for  `#all_messages_wrapper` and `()`.
+pub(crate) fn impl_associate_outgoing_messages_trait(all_messages_wrapper: &Ident) -> TokenStream {
+	quote! {
+		/// Binds a generated type covering all declared outgoing messages,
+		/// which implements `#generated_outgoing: From<M>` for all annotated types
+		/// of a particular subsystem.
+		///
+		/// Note: This works because there is a 1?:1 relation between consumed messages and subsystems.
+		pub trait AssociateOutgoing: ::std::fmt::Debug + Send {
+			/// The associated _outgoing_ messages for a subsystem that _consumes_ the message `Self`.
+			type OutgoingMessages: Into< #all_messages_wrapper > + ::std::fmt::Debug + Send;
+		}
+
+		// Helper for tests, where nothing is ever sent.
+		impl AssociateOutgoing for () {
+			type OutgoingMessages = ();
+		}
+
+		// Helper for tests, allows sending of arbitrary messages give
+		// an test context.
+		impl AssociateOutgoing for #all_messages_wrapper {
+			type OutgoingMessages = #all_messages_wrapper ;
+		}
+	}
+}
+
+/// Implement `AssociateOutgoing` for `#consumes` being handled by a particular subsystem.
+///
+/// Binds the outgoing messages to the inbound message.
+///
+/// Note: Works, since there is a 1:1 relation between inbound message type and subsystem declarations.
+/// Note: A workaround until default associated types work in `rustc`.
+pub(crate) fn impl_associate_outgoing_messages(
+	consumes: &Path,
+	outgoing_wrapper: &Ident,
+) -> TokenStream {
+	quote! {
+		impl AssociateOutgoing for #outgoing_wrapper {
+			type OutgoingMessages = #outgoing_wrapper;
+		}
+
+		impl AssociateOutgoing for #consumes {
+			type OutgoingMessages = #outgoing_wrapper;
+		}
+	}
+}
+
+/// Implement `trait SubsystemContext` for a particular subsystem context,
+/// that is generated by the proc-macro too.
+pub(crate) fn impl_subsystem_context_trait_for(
+	consumes: Type,
+	outgoing: &[Type],
+	outgoing_wrapper: Type,
+	all_messages_wrapper: &Ident,
+	subsystem_ctx_name: &Ident,
+	subsystem_sender_name: &Ident,
+	support_crate: &Path,
+	signal: &Path,
+	error_ty: &Path,
+) -> TokenStream {
+	// impl the subsystem context trait
+	let where_clause = quote! {
+		#consumes: AssociateOutgoing + ::std::fmt::Debug + Send + 'static,
+		#all_messages_wrapper: From< #outgoing_wrapper >,
+		#all_messages_wrapper: From< #consumes >,
+		#outgoing_wrapper: #( From< #outgoing > )+*,
+	};
+
+	quote! {
+		#[#support_crate ::async_trait]
+		impl #support_crate ::SubsystemContext for #subsystem_ctx_name < #consumes >
+		where
+			#where_clause
+		{
+			type Message = #consumes;
+			type Signal = #signal;
+			type OutgoingMessages = #outgoing_wrapper;
+			type Sender = #subsystem_sender_name < #outgoing_wrapper >;
+			type Error = #error_ty;
+
+			async fn try_recv(&mut self) -> ::std::result::Result<Option<FromOverseer< Self::Message, #signal>>, ()> {
+				match #support_crate ::poll!(self.recv()) {
+					#support_crate ::Poll::Ready(msg) => Ok(Some(msg.map_err(|_| ())?)),
+					#support_crate ::Poll::Pending => Ok(None),
+				}
+			}
+
+			async fn recv(&mut self) -> ::std::result::Result<FromOverseer<Self::Message, #signal>, #error_ty> {
+				loop {
+					// If we have a message pending an overseer signal, we only poll for signals
+					// in the meantime.
+					if let Some((needs_signals_received, msg)) = self.pending_incoming.take() {
+						if needs_signals_received <= self.signals_received.load() {
+							return Ok( #support_crate ::FromOverseer::Communication { msg });
+						} else {
+							self.pending_incoming = Some((needs_signals_received, msg));
+
+							// wait for next signal.
+							let signal = self.signals.next().await
+								.ok_or(#support_crate ::OverseerError::Context(
+									"Signal channel is terminated and empty."
+									.to_owned()
+								))?;
+
+							self.signals_received.inc();
+							return Ok( #support_crate ::FromOverseer::Signal(signal))
+						}
+					}
+
+					let mut await_message = self.messages.next().fuse();
+					let mut await_signal = self.signals.next().fuse();
+					let signals_received = self.signals_received.load();
+					let pending_incoming = &mut self.pending_incoming;
+
+					// Otherwise, wait for the next signal or incoming message.
+					let from_overseer = #support_crate ::futures::select_biased! {
+						signal = await_signal => {
+							let signal = signal
+								.ok_or( #support_crate ::OverseerError::Context(
+									"Signal channel is terminated and empty."
+									.to_owned()
+								))?;
+
+							#support_crate ::FromOverseer::Signal(signal)
+						}
+						msg = await_message => {
+							let packet = msg
+								.ok_or( #support_crate ::OverseerError::Context(
+									"Message channel is terminated and empty."
+									.to_owned()
+								))?;
+
+							if packet.signals_received > signals_received {
+								// wait until we've received enough signals to return this message.
+								*pending_incoming = Some((packet.signals_received, packet.message));
+								continue;
+							} else {
+								// we know enough to return this message.
+								#support_crate ::FromOverseer::Communication { msg: packet.message}
+							}
+						}
+					};
+
+					if let #support_crate ::FromOverseer::Signal(_) = from_overseer {
+						self.signals_received.inc();
+					}
+
+					return Ok(from_overseer);
+				}
+			}
+
+			fn sender(&mut self) -> &mut Self::Sender {
+				&mut self.to_subsystems
+			}
+
+			fn spawn(&mut self, name: &'static str, s: Pin<Box<dyn Future<Output = ()> + Send>>)
+				-> ::std::result::Result<(), #error_ty>
+			{
+				self.to_overseer.unbounded_send(#support_crate ::ToOverseer::SpawnJob {
+					name,
+					subsystem: Some(self.name()),
+					s,
+				}).map_err(|_| #support_crate ::OverseerError::TaskSpawn(name))?;
+				Ok(())
+			}
+
+			fn spawn_blocking(&mut self, name: &'static str, s: Pin<Box<dyn Future<Output = ()> + Send>>)
+				-> ::std::result::Result<(), #error_ty>
+			{
+				self.to_overseer.unbounded_send(#support_crate ::ToOverseer::SpawnBlockingJob {
+					name,
+					subsystem: Some(self.name()),
+					s,
+				}).map_err(|_| #support_crate ::OverseerError::TaskSpawn(name))?;
+				Ok(())
+			}
+		}
+	}
+}
+
+/// Implement the additional subsystem accumulation traits, for simplified usage,
+/// i.e. `${Subsystem}SenderTrait` and `${Subsystem}ContextTrait`.
+pub(crate) fn impl_per_subsystem_helper_traits(
+	info: &OverseerInfo,
+	subsystem_ctx_name: &Ident,
+	subsystem_ctx_trait: &Ident,
+	subsystem_sender_name: &Ident,
+	subsystem_sender_trait: &Ident,
+	consumes: &Path,
+	outgoing: &[Path],
+	outgoing_wrapper: &Ident,
+) -> TokenStream {
+	let all_messages_wrapper = &info.message_wrapper;
+	let signal_ty = &info.extern_signal_ty;
+	let error_ty = &info.extern_error_ty;
+	let support_crate = info.support_crate_name();
+
+	let mut ts = TokenStream::new();
+
+	// Create a helper trait bound of all outgoing messages, and the generated wrapper type
+	// for ease of use within subsystems:
+	let acc_sender_trait_bounds = quote! {
+		#support_crate ::SubsystemSender< #outgoing_wrapper >
+		#(
+			+ #support_crate ::SubsystemSender< #outgoing >
+		)*
+			+ #support_crate ::SubsystemSender< () >
+			+ Send
+			+ 'static
+	};
+
+	ts.extend(quote! {
+		/// A abstracting trait for usage with subsystems.
+		pub trait #subsystem_sender_trait : #acc_sender_trait_bounds
+		{}
+
+		impl<T> #subsystem_sender_trait for T
+		where
+			T: #acc_sender_trait_bounds
+		{}
+	});
+
+	// Create a helper accumulated per subsystem trait bound:
+	let where_clause = quote! {
+		#consumes: AssociateOutgoing + ::std::fmt::Debug + Send + 'static,
+		#all_messages_wrapper: From< #outgoing_wrapper >,
+		#all_messages_wrapper: From< #consumes >,
+		#all_messages_wrapper: From< () >,
+		#outgoing_wrapper: #( From< #outgoing > )+*,
+		#outgoing_wrapper: From< () >,
+	};
+
+	ts.extend(quote! {
+		/// Accumulative trait for a particular subsystem wrapper.
+		pub trait #subsystem_ctx_trait : SubsystemContext <
+			Message = #consumes,
+			Signal = #signal_ty,
+			OutgoingMessages = #outgoing_wrapper,
+			// Sender,
+			Error = #error_ty,
+		>
+		where
+			#where_clause
+			<Self as SubsystemContext>::Sender:
+				#subsystem_sender_trait
+				+ #acc_sender_trait_bounds,
+		{
+			/// Sender.
+			type Sender: #subsystem_sender_trait;
+		}
+
+		impl<T> #subsystem_ctx_trait for T
+		where
+			T: SubsystemContext <
+				Message = #consumes,
+				Signal = #signal_ty,
+				OutgoingMessages = #outgoing_wrapper,
+				// Sender
+				Error = #error_ty,
+			>,
+			#where_clause
+			<T as SubsystemContext>::Sender:
+				#subsystem_sender_trait
+				+ #acc_sender_trait_bounds,
+		{
+			type Sender = <T as SubsystemContext>::Sender;
+		}
+	});
+
+	ts.extend(impl_subsystem_context_trait_for(
+		parse_quote! { #consumes },
+		&Vec::from_iter(outgoing.iter().map(|path| {
+			parse_quote! { #path }
+		})),
+		parse_quote! { #outgoing_wrapper },
+		all_messages_wrapper,
+		subsystem_ctx_name,
+		subsystem_sender_name,
+		support_crate,
+		signal_ty,
+		error_ty,
+	));
+	ts
+}
+
+/// Generate the subsystem context type and provide `fn new` on it.
+///
+/// Note: The generated `fn new` is used by the [builder pattern](../impl_builder.rs).
+pub(crate) fn impl_subsystem_context(
+	info: &OverseerInfo,
+	subsystem_sender_name: &Ident,
+	subsystem_ctx_name: &Ident,
+) -> TokenStream {
+	let signal_ty = &info.extern_signal_ty;
+	let support_crate = info.support_crate_name();
+
+	let ts = quote! {
+		/// A context type that is given to the [`Subsystem`] upon spawning.
+		/// It can be used by [`Subsystem`] to communicate with other [`Subsystem`]s
+		/// or to spawn it's [`SubsystemJob`]s.
+		///
+		/// [`Overseer`]: struct.Overseer.html
+		/// [`Subsystem`]: trait.Subsystem.html
+		/// [`SubsystemJob`]: trait.SubsystemJob.html
+		#[derive(Debug)]
+		#[allow(missing_docs)]
+		pub struct #subsystem_ctx_name<M: AssociateOutgoing + Send + 'static> {
+			signals: #support_crate ::metered::MeteredReceiver< #signal_ty >,
+			messages: SubsystemIncomingMessages< M >,
+			to_subsystems: #subsystem_sender_name < <M as AssociateOutgoing>::OutgoingMessages >,
+			to_overseer: #support_crate ::metered::UnboundedMeteredSender<
+				#support_crate ::ToOverseer
+				>,
+			signals_received: SignalsReceived,
+			pending_incoming: Option<(usize, M)>,
+			name: &'static str
+		}
+
+		impl<M> #subsystem_ctx_name <M>
+		where
+			M: AssociateOutgoing + Send + 'static,
+		{
+			/// Create a new context.
+			fn new(
+				signals: #support_crate ::metered::MeteredReceiver< #signal_ty >,
+				messages: SubsystemIncomingMessages< M >,
+				to_subsystems: ChannelsOut,
+				to_overseer: #support_crate ::metered::UnboundedMeteredSender<#support_crate:: ToOverseer>,
+				name: &'static str
+			) -> Self {
+				let signals_received = SignalsReceived::default();
+				#subsystem_ctx_name :: <M> {
+					signals,
+					messages,
+					to_subsystems: #subsystem_sender_name :: < <M as AssociateOutgoing>::OutgoingMessages > {
+						channels: to_subsystems,
+						signals_received: signals_received.clone(),
+						_phantom: ::core::marker::PhantomData::default(),
+					},
+					to_overseer,
+					signals_received,
+					pending_incoming: None,
+					name
+				}
+			}
+
+			fn name(&self) -> &'static str {
+				self.name
+			}
+		}
+	};
+
+	ts
+}

polkadot/node/overseer/overseer-gen/proc-macro/src/lib.rs

@@ -14,33 +14,44 @@
 // You should have received a copy of the GNU General Public License
 // along with Polkadot.  If not, see <http://www.gnu.org/licenses/>.
 
-#![deny(unused_crate_dependencies)]
-
 use proc_macro2::{Ident, Span, TokenStream};
-use quote::{quote, ToTokens};
-use syn::{parse2, Result};
+use syn::{parse_quote, spanned::Spanned, Path};
 
 mod impl_builder;
 mod impl_channels_out;
-mod impl_dispatch;
 mod impl_message_wrapper;
-mod impl_misc;
 mod impl_overseer;
-mod parse_attr;
-mod parse_struct;
-
-use impl_builder::*;
-use impl_channels_out::*;
-use impl_dispatch::*;
-use impl_message_wrapper::*;
-use impl_misc::*;
-use impl_overseer::*;
-use parse_attr::*;
-use parse_struct::*;
+mod impl_subsystem_ctx_sender;
+mod overseer;
+mod parse;
+mod subsystem;
 
 #[cfg(test)]
 mod tests;
 
+use impl_builder::*;
+use impl_channels_out::*;
+use impl_message_wrapper::*;
+use impl_overseer::*;
+use impl_subsystem_ctx_sender::*;
+use parse::*;
+
+use self::{overseer::*, subsystem::*};
+
+/// Obtain the support crate `Path` as `TokenStream`.
+pub(crate) fn support_crate() -> Result<Path, proc_macro_crate::Error> {
+	Ok(if cfg!(test) {
+		parse_quote! {crate}
+	} else {
+		use proc_macro_crate::{crate_name, FoundCrate};
+		let crate_name = crate_name("polkadot-overseer-gen")?;
+		match crate_name {
+			FoundCrate::Itself => parse_quote! {crate},
+			FoundCrate::Name(name) => Ident::new(&name, Span::call_site()).into(),
+		}
+	})
+}
+
 #[proc_macro_attribute]
 pub fn overlord(
 	attr: proc_macro::TokenStream,
@@ -53,58 +64,26 @@ pub fn overlord(
 		.into()
 }
 
-pub(crate) fn impl_overseer_gen(
-	attr: TokenStream,
-	orig: TokenStream,
-) -> Result<proc_macro2::TokenStream> {
-	let args: AttrArgs = parse2(attr)?;
-	let message_wrapper = args.message_wrapper;
-
-	let of: OverseerGuts = parse2(orig)?;
-
-	let support_crate_name = if cfg!(test) {
-		quote! {crate}
-	} else {
-		use proc_macro_crate::{crate_name, FoundCrate};
-		let crate_name = crate_name("polkadot-overseer-gen")
-			.expect("Support crate polkadot-overseer-gen is present in `Cargo.toml`. qed");
-		match crate_name {
-			FoundCrate::Itself => quote! {crate},
-			FoundCrate::Name(name) => Ident::new(&name, Span::call_site()).to_token_stream(),
-		}
-	};
-	let info = OverseerInfo {
-		support_crate_name,
-		subsystems: of.subsystems,
-		baggage: of.baggage,
-		overseer_name: of.name,
-		message_wrapper,
-		message_channel_capacity: args.message_channel_capacity,
-		signal_channel_capacity: args.signal_channel_capacity,
-		extern_event_ty: args.extern_event_ty,
-		extern_signal_ty: args.extern_signal_ty,
-		extern_error_ty: args.extern_error_ty,
-		extern_network_ty: args.extern_network_ty,
-		outgoing_ty: args.outgoing_ty,
-	};
-
-	let mut additive = impl_overseer_struct(&info);
-	additive.extend(impl_builder(&info));
-
-	additive.extend(impl_overseen_subsystem(&info));
-	additive.extend(impl_channels_out_struct(&info));
-	additive.extend(impl_misc(&info));
-
-	additive.extend(impl_message_wrapper_enum(&info)?);
-	additive.extend(impl_dispatch(&info));
-
-	let ts = expander::Expander::new("overlord-expansion")
-		.add_comment("Generated overseer code by `#[overlord(..)]`".to_owned())
-		.dry(!cfg!(feature = "expand"))
-		.verbose(false)
-		.fmt(expander::Edition::_2021)
-		.write_to_out_dir(additive)
-		.expect("Expander does not fail due to IO in OUT_DIR. qed");
-
-	Ok(ts)
+#[proc_macro_attribute]
+pub fn subsystem(
+	attr: proc_macro::TokenStream,
+	item: proc_macro::TokenStream,
+) -> proc_macro::TokenStream {
+	let attr: TokenStream = attr.into();
+	let item: TokenStream = item.into();
+	impl_subsystem_context_trait_bounds(attr, item, MakeSubsystem::ImplSubsystemTrait)
+		.unwrap_or_else(|err| err.to_compile_error())
+		.into()
+}
+
+#[proc_macro_attribute]
+pub fn contextbounds(
+	attr: proc_macro::TokenStream,
+	item: proc_macro::TokenStream,
+) -> proc_macro::TokenStream {
+	let attr: TokenStream = attr.into();
+	let item: TokenStream = item.into();
+	impl_subsystem_context_trait_bounds(attr, item, MakeSubsystem::AddContextTraitBounds)
+		.unwrap_or_else(|err| err.to_compile_error())
+		.into()
 }

polkadot/node/overseer/overseer-gen/proc-macro/src/overseer.rs

@@ -0,0 +1,67 @@
+// Copyright 2022 Parity Technologies (UK) Ltd.
+// This file is part of Polkadot.
+
+// Polkadot is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Polkadot is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Polkadot.  If not, see <http://www.gnu.org/licenses/>.
+
+use proc_macro2::TokenStream;
+use syn::{parse2, Result};
+
+use super::{parse::*, *};
+
+pub(crate) fn impl_overseer_gen(
+	attr: TokenStream,
+	orig: TokenStream,
+) -> Result<proc_macro2::TokenStream> {
+	let args: OverseerAttrArgs = parse2(attr)?;
+	let message_wrapper = args.message_wrapper;
+
+	let of: OverseerGuts = parse2(orig)?;
+
+	let support_crate = support_crate().expect("The crate this macro is run for, includes the proc-macro support as dependency, otherwise it could not be run in the first place. qed");
+	let info = OverseerInfo {
+		support_crate,
+		subsystems: of.subsystems,
+		baggage: of.baggage,
+		overseer_name: of.name,
+		message_wrapper,
+		message_channel_capacity: args.message_channel_capacity,
+		signal_channel_capacity: args.signal_channel_capacity,
+		extern_event_ty: args.extern_event_ty,
+		extern_signal_ty: args.extern_signal_ty,
+		extern_error_ty: args.extern_error_ty,
+		outgoing_ty: args.outgoing_ty,
+	};
+
+	let mut additive = impl_overseer_struct(&info);
+	additive.extend(impl_builder(&info));
+
+	additive.extend(impl_overseen_subsystem(&info));
+	additive.extend(impl_channels_out_struct(&info));
+	additive.extend(impl_subsystem_types_all(&info)?);
+
+	additive.extend(impl_message_wrapper_enum(&info)?);
+
+	let ts = expander::Expander::new("overlord-expansion")
+		.add_comment("Generated overseer code by `#[overlord(..)]`".to_owned())
+		.dry(!cfg!(feature = "expand"))
+		.verbose(true)
+		// once all our needed format options are available on stable
+		// we should enabled this again, until then too many warnings
+		// are generated
+		// .fmt(expander::Edition::_2021)
+		.write_to_out_dir(additive)
+		.expect("Expander does not fail due to IO in OUT_DIR. qed");
+
+	Ok(ts)
+}

polkadot/node/overseer/overseer-gen/proc-macro/src/parse/mod.rs

@@ -0,0 +1,39 @@
+// Copyright 2022 Parity Technologies (UK) Ltd.
+// This file is part of Polkadot.
+
+// Polkadot is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Polkadot is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Polkadot.  If not, see <http://www.gnu.org/licenses/>.
+
+mod kw {
+	syn::custom_keyword!(event);
+	syn::custom_keyword!(signal);
+	syn::custom_keyword!(error);
+	syn::custom_keyword!(outgoing);
+	syn::custom_keyword!(gen);
+	syn::custom_keyword!(signal_capacity);
+	syn::custom_keyword!(message_capacity);
+	syn::custom_keyword!(subsystem);
+	syn::custom_keyword!(prefix);
+}
+
+mod parse_overseer_attr;
+mod parse_overseer_struct;
+
+mod parse_subsystem_attr;
+
+#[cfg(test)]
+mod tests;
+
+pub(crate) use self::{parse_overseer_attr::*, parse_overseer_struct::*};
+
+pub(crate) use self::parse_subsystem_attr::*;

polkadot/node/overseer/overseer-gen/proc-macro/src/parse/parse_overseer_attr.rs

@@ -14,6 +14,7 @@
 // You should have received a copy of the GNU General Public License
 // along with Polkadot.  If not, see <http://www.gnu.org/licenses/>.
 
+use super::kw;
 use proc_macro2::Span;
 use quote::{quote, ToTokens};
 use std::collections::{hash_map::RandomState, HashMap};
@@ -24,21 +25,9 @@ use syn::{
 	Error, Ident, LitInt, Path, Result, Token,
 };
 
-mod kw {
-	syn::custom_keyword!(event);
-	syn::custom_keyword!(signal);
-	syn::custom_keyword!(error);
-	syn::custom_keyword!(network);
-	syn::custom_keyword!(outgoing);
-	syn::custom_keyword!(gen);
-	syn::custom_keyword!(signal_capacity);
-	syn::custom_keyword!(message_capacity);
-}
-
 #[derive(Clone, Debug)]
 enum OverseerAttrItem {
 	ExternEventType { tag: kw::event, eq_token: Token![=], value: Path },
-	ExternNetworkType { tag: kw::network, eq_token: Token![=], value: Path },
 	ExternOverseerSignalType { tag: kw::signal, eq_token: Token![=], value: Path },
 	ExternErrorType { tag: kw::error, eq_token: Token![=], value: Path },
 	OutgoingType { tag: kw::outgoing, eq_token: Token![=], value: Path },
@@ -53,9 +42,6 @@ impl ToTokens for OverseerAttrItem {
 			Self::ExternEventType { tag, eq_token, value } => {
 				quote! { #tag #eq_token, #value }
 			},
-			Self::ExternNetworkType { tag, eq_token, value } => {
-				quote! { #tag #eq_token, #value }
-			},
 			Self::ExternOverseerSignalType { tag, eq_token, value } => {
 				quote! { #tag #eq_token, #value }
 			},
@@ -100,12 +86,6 @@ impl Parse for OverseerAttrItem {
 				eq_token: input.parse()?,
 				value: input.parse()?,
 			})
-		} else if lookahead.peek(kw::network) {
-			Ok(OverseerAttrItem::ExternNetworkType {
-				tag: input.parse::<kw::network>()?,
-				eq_token: input.parse()?,
-				value: input.parse()?,
-			})
 		} else if lookahead.peek(kw::outgoing) {
 			Ok(OverseerAttrItem::OutgoingType {
 				tag: input.parse::<kw::outgoing>()?,
@@ -138,15 +118,11 @@ impl Parse for OverseerAttrItem {
 
 /// Attribute arguments
 #[derive(Clone, Debug)]
-pub(crate) struct AttrArgs {
+pub(crate) struct OverseerAttrArgs {
 	pub(crate) message_wrapper: Ident,
 	pub(crate) extern_event_ty: Path,
 	pub(crate) extern_signal_ty: Path,
 	pub(crate) extern_error_ty: Path,
-	/// A external subsystem that both consumes and produces messages
-	/// but is not part of the band of subsystems, it's a mere proxy
-	/// to another entity that consumes/produces messages.
-	pub(crate) extern_network_ty: Option<Path>,
 	pub(crate) outgoing_ty: Option<Path>,
 	pub(crate) signal_channel_capacity: usize,
 	pub(crate) message_channel_capacity: usize,
@@ -170,7 +146,7 @@ macro_rules! extract_variant {
 	};
 }
 
-impl Parse for AttrArgs {
+impl Parse for OverseerAttrArgs {
 	fn parse(input: &ParseBuffer) -> Result<Self> {
 		let items: Punctuated<OverseerAttrItem, Token![,]> =
 			input.parse_terminated(OverseerAttrItem::parse)?;
@@ -198,18 +174,16 @@ impl Parse for AttrArgs {
 
 		let error = extract_variant!(unique, ExternErrorType; err = "Must declare the overseer error type via `error=..`.")?;
 		let event = extract_variant!(unique, ExternEventType; err = "Must declare the overseer event type via `event=..`.")?;
-		let signal = extract_variant!(unique, ExternOverseerSignalType; err = "Must declare the overseer signal type via `span=..`.")?;
+		let signal = extract_variant!(unique, ExternOverseerSignalType; err = "Must declare the overseer signal type via `signal=..`.")?;
 		let message_wrapper = extract_variant!(unique, MessageWrapperName; err = "Must declare the overseer generated wrapping message type via `gen=..`.")?;
-		let network = extract_variant!(unique, ExternNetworkType);
 		let outgoing = extract_variant!(unique, OutgoingType);
 
-		Ok(AttrArgs {
+		Ok(OverseerAttrArgs {
 			signal_channel_capacity,
 			message_channel_capacity,
 			extern_event_ty: event,
 			extern_signal_ty: signal,
 			extern_error_ty: error,
-			extern_network_ty: network,
 			outgoing_ty: outgoing,
 			message_wrapper,
 		})

polkadot/node/overseer/overseer-gen/proc-macro/src/parse/parse_overseer_struct.rs

@@ -17,32 +17,36 @@
 use proc_macro2::{Span, TokenStream};
 use std::collections::{hash_map::RandomState, HashMap, HashSet};
 use syn::{
+	parenthesized,
 	parse::{Parse, ParseStream},
 	punctuated::Punctuated,
 	spanned::Spanned,
-	AttrStyle, Attribute, Error, Field, FieldsNamed, GenericParam, Ident, ItemStruct, Path, Result,
-	Token, Type, Visibility,
+	token::Bracket,
+	AttrStyle, Error, Field, FieldsNamed, GenericParam, Ident, ItemStruct, Path, Result, Token,
+	Type, Visibility,
 };
 
 use quote::{quote, ToTokens};
 
 mod kw {
 	syn::custom_keyword!(wip);
-	syn::custom_keyword!(no_dispatch);
 	syn::custom_keyword!(blocking);
+	syn::custom_keyword!(consumes);
+	syn::custom_keyword!(sends);
 }
 
 #[derive(Clone, Debug)]
-enum SubSysAttrItem {
+pub(crate) enum SubSysAttrItem {
 	/// The subsystem is still a work in progress
 	/// and should not be communicated with.
 	Wip(kw::wip),
 	/// The subsystem is blocking and requires to be
 	/// spawned on an exclusive thread.
 	Blocking(kw::blocking),
-	/// External messages should not be - after being converted -
-	/// be dispatched to the annotated subsystem.
-	NoDispatch(kw::no_dispatch),
+	/// Message to be sent by this subsystem.
+	Sends(Sends),
+	/// Message to be consumed by this subsystem.
+	Consumes(Consumes),
 }
 
 impl Parse for SubSysAttrItem {
@@ -52,10 +56,10 @@ impl Parse for SubSysAttrItem {
 			Self::Wip(input.parse::<kw::wip>()?)
 		} else if lookahead.peek(kw::blocking) {
 			Self::Blocking(input.parse::<kw::blocking>()?)
-		} else if lookahead.peek(kw::no_dispatch) {
-			Self::NoDispatch(input.parse::<kw::no_dispatch>()?)
+		} else if lookahead.peek(kw::sends) {
+			Self::Sends(input.parse::<Sends>()?)
 		} else {
-			return Err(lookahead.error())
+			Self::Consumes(input.parse::<Consumes>()?)
 		})
 	}
 }
@@ -69,8 +73,11 @@ impl ToTokens for SubSysAttrItem {
 			Self::Blocking(blocking) => {
 				quote! { #blocking }
 			},
-			Self::NoDispatch(no_dispatch) => {
-				quote! { #no_dispatch }
+			Self::Sends(_) => {
+				quote! {}
+			},
+			Self::Consumes(_) => {
+				quote! {}
 			},
 		};
 		tokens.extend(ts.into_iter());
@@ -78,7 +85,7 @@ impl ToTokens for SubSysAttrItem {
 }
 
 /// A field of the struct annotated with
-/// `#[subsystem(no_dispatch, , A | B | C)]`
+/// `#[subsystem(A, B, C)]`
 #[derive(Clone, Debug)]
 pub(crate) struct SubSysField {
 	/// Name of the field.
@@ -87,11 +94,10 @@ pub(crate) struct SubSysField {
 	/// which is also used `#wrapper_message :: #variant` variant
 	/// part.
 	pub(crate) generic: Ident,
-	/// Type to be consumed by the subsystem.
-	pub(crate) consumes: Path,
-	/// If `no_dispatch` is present, if the message is incoming via
-	/// an `extern` `Event`, it will not be dispatched to all subsystems.
-	pub(crate) no_dispatch: bool,
+	/// Type of message to be consumed by the subsystem.
+	pub(crate) message_to_consume: Path,
+	/// Types of messages to be sent by the subsystem.
+	pub(crate) messages_to_send: Vec<Path>,
 	/// If the subsystem implementation is blocking execution and hence
 	/// has to be spawned on a separate thread or thread pool.
 	pub(crate) blocking: bool,
@@ -115,6 +121,15 @@ macro_rules! extract_variant {
 	($unique:expr, $variant:ident ; err = $err:expr) => {
 		extract_variant!($unique, $variant).ok_or_else(|| Error::new(Span::call_site(), $err))
 	};
+	($unique:expr, $variant:ident take) => {
+		$unique.values().find_map(|item| {
+			if let SubSysAttrItem::$variant(value) = item {
+				Some(value.clone())
+			} else {
+				None
+			}
+		})
+	};
 	($unique:expr, $variant:ident) => {
 		$unique.values().find_map(|item| {
 			if let SubSysAttrItem::$variant(_) = item {
@@ -126,57 +141,113 @@ macro_rules! extract_variant {
 	};
 }
 
-pub(crate) struct SubSystemTags {
+#[derive(Debug, Clone)]
+pub(crate) struct Sends {
 	#[allow(dead_code)]
-	pub(crate) attrs: Vec<Attribute>,
+	pub(crate) keyword_sends: kw::sends,
 	#[allow(dead_code)]
-	pub(crate) no_dispatch: bool,
-	/// The subsystem is in progress, only generate the `Wrapper` variant, but do not forward messages
-	/// and also not include the subsystem in the list of subsystems.
-	pub(crate) wip: bool,
-	pub(crate) blocking: bool,
+	pub(crate) colon: Token![:],
+	#[allow(dead_code)]
+	pub(crate) bracket: Option<Bracket>,
+	pub(crate) sends: Punctuated<Path, Token![,]>,
+}
+
+impl Parse for Sends {
+	fn parse(input: syn::parse::ParseStream) -> Result<Self> {
+		let content;
+		let keyword_sends = input.parse()?;
+		let colon = input.parse()?;
+		let (bracket, sends) = if !input.peek(syn::token::Bracket) {
+			let mut sends = Punctuated::new();
+			sends.push_value(input.parse::<Path>()?);
+			(None, sends)
+		} else {
+			let bracket = Some(syn::bracketed!(content in input));
+			let sends = Punctuated::parse_terminated(&content)?;
+			(bracket, sends)
+		};
+		Ok(Self { keyword_sends, colon, bracket, sends })
+	}
+}
+
+#[derive(Debug, Clone)]
+pub(crate) struct Consumes {
+	#[allow(dead_code)]
+	pub(crate) keyword_consumes: Option<kw::consumes>,
+	#[allow(dead_code)]
+	pub(crate) colon: Option<Token![:]>,
 	pub(crate) consumes: Path,
 }
 
-impl Parse for SubSystemTags {
+impl Parse for Consumes {
 	fn parse(input: syn::parse::ParseStream) -> Result<Self> {
-		let attrs = Attribute::parse_outer(input)?;
+		let lookahead = input.lookahead1();
+		Ok(if lookahead.peek(kw::consumes) {
+			Self {
+				keyword_consumes: Some(input.parse()?),
+				colon: input.parse()?,
+				consumes: input.parse()?,
+			}
+		} else {
+			Self { keyword_consumes: None, colon: None, consumes: input.parse()? }
+		})
+	}
+}
+
+/// Parses `(Foo, sends = [Bar, Baz])`
+/// including the `(` and `)`.
+#[derive(Debug, Clone)]
+pub(crate) struct SubSystemAttrItems {
+	/// The subsystem is in progress, only generate the `Wrapper` variant, but do not forward messages
+	/// and also not include the subsystem in the list of subsystems.
+	pub(crate) wip: bool,
+	/// If there are blocking components in the subsystem and hence it should be
+	/// spawned on a dedicated thread pool for such subssytems.
+	pub(crate) blocking: bool,
+	/// The message type being consumed by the subsystem.
+	pub(crate) consumes: Option<Consumes>,
+	pub(crate) sends: Option<Sends>,
+}
+
+impl Parse for SubSystemAttrItems {
+	fn parse(input: syn::parse::ParseStream) -> Result<Self> {
+		let span = input.span();
 
-		let input = input;
 		let content;
-		let _ = syn::parenthesized!(content in input);
+		let _paren_token = parenthesized!(content in input);
 
-		let mut items = Punctuated::new();
-		while let Ok(tag) = content.call(SubSysAttrItem::parse) {
-			items.push_value(tag);
-			items.push_punct(content.call(<Token![,]>::parse)?);
-		}
-
-		assert!(items.empty_or_trailing(), "Always followed by the message type to consume. qed");
-
-		let consumes = content.parse::<Path>()?;
+		let items = content.call(Punctuated::<SubSysAttrItem, Token![,]>::parse_terminated)?;
 
 		let mut unique = HashMap::<
 			std::mem::Discriminant<SubSysAttrItem>,
 			SubSysAttrItem,
 			RandomState,
 		>::default();
+
 		for item in items {
 			if let Some(first) = unique.insert(std::mem::discriminant(&item), item.clone()) {
-				let mut e = Error::new(
-					item.span(),
-					format!("Duplicate definition of subsystem attribute found"),
-				);
+				let mut e =
+					Error::new(item.span(), "Duplicate definition of subsystem attribute found");
 				e.combine(Error::new(first.span(), "previously defined here."));
 				return Err(e)
 			}
 		}
 
-		let no_dispatch = extract_variant!(unique, NoDispatch; default = false);
+		// A subsystem makes no sense if not one of them is provided
+		let sends = extract_variant!(unique, Sends take);
+		let consumes = extract_variant!(unique, Consumes take);
+		if sends.as_ref().map(|sends| sends.sends.is_empty()).unwrap_or(true) && consumes.is_none()
+		{
+			return Err(Error::new(
+				span,
+				"Must have at least one of `consumes: [..]` and `sends: [..]`.",
+			))
+		}
+
 		let blocking = extract_variant!(unique, Blocking; default = false);
 		let wip = extract_variant!(unique, Wip; default = false);
 
-		Ok(Self { attrs, no_dispatch, blocking, consumes, wip })
+		Ok(Self { blocking, wip, sends, consumes })
 	}
 }
 
@@ -192,7 +263,7 @@ pub(crate) struct BaggageField {
 #[derive(Clone, Debug)]
 pub(crate) struct OverseerInfo {
 	/// Where the support crate `::polkadot_overseer_gen` lives.
-	pub(crate) support_crate_name: TokenStream,
+	pub(crate) support_crate: Path,
 
 	/// Fields annotated with `#[subsystem(..)]`.
 	pub(crate) subsystems: Vec<SubSysField>,
@@ -216,11 +287,8 @@ pub(crate) struct OverseerInfo {
 	/// Incoming event type from the outer world, usually an external framework of some sort.
 	pub(crate) extern_event_ty: Path,
 
-	/// Incoming event type from an external entity, commonly from the network.
-	pub(crate) extern_network_ty: Option<Path>,
-
 	/// Type of messages that are sent to an external subsystem.
-	/// Merely here to be included during generation of `message_wrapper` type.
+	/// Merely here to be included during generation of `#message_wrapper` type.
 	pub(crate) outgoing_ty: Option<Path>,
 
 	/// Incoming event type from the outer world, commonly from the network.
@@ -228,8 +296,8 @@ pub(crate) struct OverseerInfo {
 }
 
 impl OverseerInfo {
-	pub(crate) fn support_crate_name(&self) -> &TokenStream {
-		&self.support_crate_name
+	pub(crate) fn support_crate_name(&self) -> &Path {
+		&self.support_crate
 	}
 
 	pub(crate) fn variant_names(&self) -> Vec<Ident> {
@@ -297,8 +365,11 @@ impl OverseerInfo {
 			.collect::<Vec<_>>()
 	}
 
-	pub(crate) fn consumes(&self) -> Vec<Path> {
-		self.subsystems.iter().map(|ssf| ssf.consumes.clone()).collect::<Vec<_>>()
+	pub(crate) fn any_message(&self) -> Vec<Path> {
+		self.subsystems
+			.iter()
+			.map(|ssf| ssf.message_to_consume.clone())
+			.collect::<Vec<_>>()
 	}
 
 	pub(crate) fn channel_names_without_wip(&self, suffix: &'static str) -> Vec<Ident> {
@@ -313,7 +384,7 @@ impl OverseerInfo {
 		self.subsystems
 			.iter()
 			.filter(|ssf| !ssf.wip)
-			.map(|ssf| ssf.consumes.clone())
+			.map(|ssf| ssf.message_to_consume.clone())
 			.collect::<Vec<_>>()
 	}
 }
@@ -341,7 +412,8 @@ impl OverseerGuts {
 		// for the builder pattern besides other places.
 		let mut unique_subsystem_idents = HashSet::<Ident>::new();
 		for Field { attrs, vis, ident, ty, .. } in fields.named.into_iter() {
-			let mut consumes =
+			// collect all subsystem annotations per field
+			let mut subsystem_attr =
 				attrs.iter().filter(|attr| attr.style == AttrStyle::Outer).filter_map(|attr| {
 					let span = attr.path.span();
 					attr.path.get_ident().filter(|ident| *ident == "subsystem").map(move |_ident| {
@@ -349,53 +421,75 @@ impl OverseerGuts {
 						(attr_tokens, span)
 					})
 				});
-			let ident =
-				ident.ok_or_else(|| Error::new(ty.span(), "Missing identifier for member. BUG"))?;
+			let ident = ident.ok_or_else(|| {
+				Error::new(
+					ty.span(),
+					"Missing identifier for field, only named fields are expceted.",
+				)
+			})?;
 
-			if let Some((attr_tokens, span)) = consumes.next() {
-				if let Some((_attr_tokens2, span2)) = consumes.next() {
+			// a `#[subsystem(..)]` annotation exists
+			if let Some((attr_tokens, span)) = subsystem_attr.next() {
+				if let Some((_attr_tokens2, span2)) = subsystem_attr.next() {
 					return Err({
 						let mut err = Error::new(span, "The first subsystem annotation is at");
 						err.combine(Error::new(span2, "but another here for the same field."));
 						err
 					})
 				}
-				let mut consumes_paths = Vec::with_capacity(attrs.len());
+
+				let span = attr_tokens.span();
+
 				let attr_tokens = attr_tokens.clone();
-				let variant: SubSystemTags = syn::parse2(attr_tokens.clone())?;
-				consumes_paths.push(variant.consumes);
+				let subsystem_attrs: SubSystemAttrItems = syn::parse2(attr_tokens.clone())?;
 
 				let field_ty = try_type_to_path(ty, span)?;
 				let generic = field_ty
 					.get_ident()
 					.ok_or_else(|| {
-						Error::new(field_ty.span(), "Must be an identifier, not a path.")
+						Error::new(
+							field_ty.span(),
+							"Must be an identifier, not a path. It will be used as a generic.",
+						)
 					})?
 					.clone();
+				// check for unique subsystem name, otherwise we'd create invalid code:
 				if let Some(previous) = unique_subsystem_idents.get(&generic) {
-					let mut e = Error::new(
-						generic.span(),
-						format!("Duplicate subsystem names `{}`", generic),
-					);
+					let mut e = Error::new(generic.span(), "Duplicate subsystem names");
 					e.combine(Error::new(previous.span(), "previously defined here."));
 					return Err(e)
 				}
 				unique_subsystem_idents.insert(generic.clone());
 
+				let SubSystemAttrItems { wip, blocking, consumes, sends, .. } = subsystem_attrs;
+
+				// messages to be sent
+				let sends = if let Some(sends) = sends {
+					Vec::from_iter(sends.sends.iter().cloned())
+				} else {
+					vec![]
+				};
+				// messages deemed for consumption
+				let consumes = if let Some(consumes) = consumes {
+					consumes.consumes
+				} else {
+					return Err(Error::new(span, "Must provide exactly one consuming message type"))
+				};
+
 				subsystems.push(SubSysField {
 					name: ident,
 					generic,
-					consumes: consumes_paths[0].clone(),
-					no_dispatch: variant.no_dispatch,
-					wip: variant.wip,
-					blocking: variant.blocking,
+					message_to_consume: consumes,
+					messages_to_send: sends,
+					wip,
+					blocking,
 				});
 			} else {
 				let field_ty = try_type_to_path(ty, ident.span())?;
 				let generic = field_ty
 					.get_ident()
 					.map(|ident| baggage_generics.contains(ident))
-					.unwrap_or_default();
+					.unwrap_or(false);
 				baggage.push(BaggageField { field_name: ident, generic, field_ty, vis });
 			}
 		}

polkadot/node/overseer/overseer-gen/proc-macro/src/parse/parse_subsystem_attr.rs

@@ -0,0 +1,144 @@
+// Copyright 2022 Parity Technologies (UK) Ltd.
+// This file is part of Polkadot.
+
+// Polkadot is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Polkadot is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Polkadot.  If not, see <http://www.gnu.org/licenses/>.
+
+use super::kw;
+use proc_macro2::Span;
+use quote::{quote, ToTokens};
+use std::collections::{hash_map::RandomState, HashMap};
+use syn::{
+	parse::{Parse, ParseBuffer},
+	punctuated::Punctuated,
+	spanned::Spanned,
+	Error, Ident, Path, Result, Token,
+};
+
+#[derive(Clone, Debug)]
+enum SubsystemAttrItem {
+	/// Error type provided by the user.
+	Error { tag: kw::error, eq_token: Token![=], value: Path },
+	/// For which slot in the overseer this should be plugged.
+	///
+	/// The subsystem implementation can and should have a different name
+	/// from the declared parameter type in the overseer.
+	Subsystem { tag: Option<kw::subsystem>, eq_token: Option<Token![=]>, value: Ident },
+	/// The prefix to apply when a subsystem is implemented in a different file/crate
+	/// than the overseer itself.
+	///
+	/// Important for `#[subsystem(..)]` to reference the traits correctly.
+	TraitPrefix { tag: kw::prefix, eq_token: Token![=], value: Path },
+}
+
+impl ToTokens for SubsystemAttrItem {
+	fn to_tokens(&self, tokens: &mut proc_macro2::TokenStream) {
+		let ts = match self {
+			Self::TraitPrefix { tag, eq_token, value } => {
+				quote! { #tag #eq_token, #value }
+			},
+			Self::Error { tag, eq_token, value } => {
+				quote! { #tag #eq_token, #value }
+			},
+			Self::Subsystem { tag, eq_token, value } => {
+				quote! { #tag #eq_token, #value }
+			},
+		};
+		tokens.extend(ts.into_iter());
+	}
+}
+
+impl Parse for SubsystemAttrItem {
+	fn parse(input: &ParseBuffer) -> Result<Self> {
+		let lookahead = input.lookahead1();
+		if lookahead.peek(kw::error) {
+			Ok(SubsystemAttrItem::Error {
+				tag: input.parse::<kw::error>()?,
+				eq_token: input.parse()?,
+				value: input.parse()?,
+			})
+		} else if lookahead.peek(kw::prefix) {
+			Ok(SubsystemAttrItem::TraitPrefix {
+				tag: input.parse::<kw::prefix>()?,
+				eq_token: input.parse()?,
+				value: input.parse()?,
+			})
+		} else if lookahead.peek(kw::subsystem) {
+			Ok(SubsystemAttrItem::Subsystem {
+				tag: Some(input.parse::<kw::subsystem>()?),
+				eq_token: Some(input.parse()?),
+				value: input.parse()?,
+			})
+		} else {
+			Ok(SubsystemAttrItem::Subsystem { tag: None, eq_token: None, value: input.parse()? })
+		}
+	}
+}
+
+/// Attribute arguments `$args` in `#[subsystem( $args )]`.
+#[derive(Clone, Debug)]
+pub(crate) struct SubsystemAttrArgs {
+	span: Span,
+	pub(crate) error_path: Option<Path>,
+	pub(crate) subsystem_ident: Ident,
+	pub(crate) trait_prefix_path: Option<Path>,
+}
+
+impl Spanned for SubsystemAttrArgs {
+	fn span(&self) -> Span {
+		self.span.clone()
+	}
+}
+
+macro_rules! extract_variant {
+	($unique:expr, $variant:ident ; default = $fallback:expr) => {
+		extract_variant!($unique, $variant).unwrap_or_else(|| $fallback)
+	};
+	($unique:expr, $variant:ident ; err = $err:expr) => {
+		extract_variant!($unique, $variant).ok_or_else(|| Error::new(Span::call_site(), $err))
+	};
+	($unique:expr, $variant:ident) => {
+		$unique.values().find_map(|item| match item {
+			SubsystemAttrItem::$variant { value, .. } => Some(value.clone()),
+			_ => None,
+		})
+	};
+}
+
+impl Parse for SubsystemAttrArgs {
+	fn parse(input: &ParseBuffer) -> Result<Self> {
+		let span = input.span();
+		let items: Punctuated<SubsystemAttrItem, Token![,]> =
+			input.parse_terminated(SubsystemAttrItem::parse)?;
+
+		let mut unique = HashMap::<
+			std::mem::Discriminant<SubsystemAttrItem>,
+			SubsystemAttrItem,
+			RandomState,
+		>::default();
+		for item in items {
+			if let Some(first) = unique.insert(std::mem::discriminant(&item), item.clone()) {
+				let mut e = Error::new(
+					item.span(),
+					format!("Duplicate definition of subsystem generation type found"),
+				);
+				e.combine(Error::new(first.span(), "previously defined here."));
+				return Err(e)
+			}
+		}
+		let error_path = extract_variant!(unique, Error);
+		let subsystem_ident = extract_variant!(unique, Subsystem; err = "Must annotate the identical overseer error type via `subsystem=..` or plainly as `Subsystem` as specified in the overseer declaration.")?;
+		let trait_prefix_path = extract_variant!(unique, TraitPrefix);
+		Ok(SubsystemAttrArgs { span, error_path, subsystem_ident, trait_prefix_path })
+	}
+}

polkadot/node/overseer/overseer-gen/proc-macro/src/parse/tests.rs

@@ -0,0 +1,295 @@
+// Copyright 2022 Parity Technologies (UK) Ltd.
+// This file is part of Polkadot.
+
+// Polkadot is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Polkadot is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Polkadot.  If not, see <http://www.gnu.org/licenses/>.
+
+use super::*;
+use crate::{SubSysAttrItem, SubSystemAttrItems};
+use assert_matches::assert_matches;
+use quote::quote;
+use syn::parse_quote;
+
+mod attr {
+	use super::*;
+
+	#[test]
+	fn attr_full_works() {
+		let attr: OverseerAttrArgs = parse_quote! {
+			gen=AllMessage, event=::some::why::ExternEvent, signal=SigSigSig, signal_capacity=111, message_capacity=222,
+			error=OverseerError,
+		};
+		assert_matches!(attr, OverseerAttrArgs {
+			message_channel_capacity,
+			signal_channel_capacity,
+			..
+		} => {
+			assert_eq!(message_channel_capacity, 222);
+			assert_eq!(signal_channel_capacity, 111);
+		});
+	}
+
+	#[test]
+	fn attr_partial_works() {
+		let attr: OverseerAttrArgs = parse_quote! {
+			gen=AllMessage, event=::some::why::ExternEvent, signal=::foo::SigSigSig,
+			error=OverseerError,
+		};
+		assert_matches!(attr, OverseerAttrArgs {
+			message_channel_capacity: _,
+			signal_channel_capacity: _,
+			..
+		} => {
+		});
+	}
+}
+
+mod strukt {
+
+	use super::*;
+
+	#[test]
+	fn parse_subsystem_attr_item_works_00_wip() {
+		assert_matches!(
+		syn::parse2::<SubSysAttrItem>(quote! {
+			wip
+		}), Ok(SubSysAttrItem::Wip(_)) => {
+		});
+	}
+
+	#[test]
+	fn parse_subsystem_attr_item_works_02_sends() {
+		assert_matches!(
+		syn::parse2::<SubSysAttrItem>(quote! {
+			sends: [A, B, C]
+		}), Ok(SubSysAttrItem::Sends(sends)) => {
+			assert_eq!(sends.sends.len(), 3);
+		});
+	}
+
+	#[test]
+	fn parse_subsystem_attr_item_works_03_sends() {
+		assert_matches!(
+		syn::parse2::<SubSysAttrItem>(quote! {
+			sends: [A]
+		}), Ok(SubSysAttrItem::Sends(sends)) => {
+			assert_eq!(sends.sends.len(), 1);
+		});
+	}
+
+	#[test]
+	fn parse_subsystem_attr_item_works_04_sends() {
+		assert_matches!(
+		syn::parse2::<SubSysAttrItem>(quote! {
+			sends: [A,]
+		}), Ok(SubSysAttrItem::Sends(sends)) => {
+			assert_eq!(sends.sends.len(), 1);
+		});
+	}
+
+	#[test]
+	fn parse_subsystem_attr_item_works_05_sends() {
+		assert_matches!(
+		syn::parse2::<SubSysAttrItem>(quote! {
+			sends: []
+		}), Ok(SubSysAttrItem::Sends(sends)) => {
+			assert_eq!(sends.sends.len(), 0);
+		});
+	}
+
+	#[test]
+	fn parse_subsystem_attr_item_works_06_consumes() {
+		assert_matches!(
+		syn::parse2::<SubSysAttrItem>(quote! {
+			consumes: Foo
+		}), Ok(SubSysAttrItem::Consumes(_consumes)) => {
+		});
+	}
+
+	#[test]
+	fn parse_subsystem_attr_item_works_07_consumes() {
+		assert_matches!(
+		syn::parse2::<SubSysAttrItem>(quote! {
+			Foo
+		}), Ok(SubSysAttrItem::Consumes(_consumes)) => {
+		});
+	}
+
+	#[test]
+	fn parse_subsystem_attributes_works_00() {
+		syn::parse2::<SubSystemAttrItems>(quote! {
+			(wip, blocking, consumes: Foo, sends: [])
+		})
+		.unwrap();
+	}
+
+	#[test]
+	fn parse_subsystem_attributes_works_01() {
+		assert_matches!(
+		syn::parse2::<SubSystemAttrItems>(quote! {
+			(blocking, Foo, sends: [])
+		}), Ok(_) => {
+		});
+	}
+
+	#[test]
+	fn parse_subsystem_attributes_works_02() {
+		assert_matches!(
+		syn::parse2::<SubSystemAttrItems>(quote! {
+			(consumes: Foo, sends: [Bar])
+		}), Ok(_) => {
+		});
+	}
+
+	#[test]
+	fn parse_subsystem_attributes_works_03() {
+		assert_matches!(
+		syn::parse2::<SubSystemAttrItems>(quote! {
+			(blocking, consumes: Foo, sends: [Bar])
+		}), Ok(_) => {
+		});
+	}
+
+	#[test]
+	fn parse_subsystem_attributes_works_04() {
+		assert_matches!(
+		syn::parse2::<SubSystemAttrItems>(quote! {
+			(wip, consumes: Foo, sends: [Bar])
+		}), Ok(_) => {
+		});
+	}
+
+	#[test]
+	fn parse_subsystem_attributes_works_05() {
+		assert_matches!(
+		syn::parse2::<SubSystemAttrItems>(quote! {
+			(consumes: Foo)
+		}), Ok(_) => {
+		});
+	}
+
+	#[test]
+	fn parse_subsystem_attributes_works_06() {
+		assert_matches!(
+		syn::parse2::<SubSystemAttrItems>(quote! {
+			(sends: [Foo], consumes: Bar)
+		}), Ok(_) => {
+		});
+	}
+
+	#[test]
+	fn parse_subsystem_attributes_works_07_duplicate_send() {
+		assert_matches!(
+		syn::parse2::<SubSystemAttrItems>(quote! {
+			(sends: [Foo], Bar, Y)
+		}), Err(e) => {
+			dbg!(e)
+		});
+	}
+
+	#[test]
+	fn parse_subsystem_attributes_works_08() {
+		assert_matches!(
+		syn::parse2::<SubSystemAttrItems>(quote! {
+			(sends: [Foo], consumes: Bar)
+		}), Ok(_) => {
+		});
+	}
+
+	#[test]
+	fn parse_subsystem_attributes_works_09_neither_consumes_nor_sends() {
+		assert_matches!(
+		syn::parse2::<SubSystemAttrItems>(quote! {
+			(sends: [])
+		}), Err(e) => {
+			// must either consume smth or sends smth, neither is NOK
+			dbg!(e)
+		});
+	}
+
+	#[test]
+	fn parse_subsystem_attributes_works_10_empty_with_braces() {
+		assert_matches!(
+		syn::parse2::<SubSystemAttrItems>(quote! {
+			()
+		}), Err(e) => {
+			dbg!(e)
+		});
+	}
+
+	#[test]
+	fn parse_subsystem_attributes_works_11_empty() {
+		assert_matches!(
+		syn::parse2::<SubSystemAttrItems>(quote! {
+
+		}), Err(e) => {
+			dbg!(e)
+		});
+	}
+
+	#[test]
+	fn parse_subsystem_attributes_works_12_duplicate_consumes_different_fmt() {
+		assert_matches!(
+		syn::parse2::<SubSystemAttrItems>(quote! {
+			(Foo, consumes = Foo)
+		}), Err(e) => {
+			dbg!(e)
+		});
+	}
+
+	#[test]
+	fn struct_parse_baggage() {
+		let item: OverseerGuts = parse_quote! {
+			pub struct Ooooh<X = Pffffffft> where X: Secrit {
+				#[subsystem(consumes: Foo, sends: [])]
+				sub0: FooSubsystem,
+
+				metrics: Metrics,
+			}
+		};
+		let _ = dbg!(item);
+	}
+
+	#[test]
+	fn struct_parse_full() {
+		let item: OverseerGuts = parse_quote! {
+			pub struct Ooooh<X = Pffffffft> where X: Secrit {
+				#[subsystem(consumes: Foo, sends: [])]
+				sub0: FooSubsystem,
+
+				#[subsystem(blocking, consumes: Bar, sends: [])]
+				yyy: BaersBuyBilliardBalls,
+
+				#[subsystem(blocking, consumes: Twain, sends: [])]
+				fff: Beeeeep,
+
+				#[subsystem(consumes: Rope)]
+				mc: MountainCave,
+
+				metrics: Metrics,
+			}
+		};
+		let _ = dbg!(item);
+	}
+
+	#[test]
+	fn struct_parse_basic() {
+		let item: OverseerGuts = parse_quote! {
+			pub struct Ooooh {
+				#[subsystem(consumes: Foo, sends: [])]
+				sub0: FooSubsystem,
+			}
+		};
+		let _ = dbg!(item);
+	}
+}

polkadot/node/overseer/overseer-gen/proc-macro/src/subsystem.rs

@@ -0,0 +1,310 @@
+// Copyright 2022 Parity Technologies (UK) Ltd.
+// This file is part of Polkadot.
+
+// Polkadot is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Polkadot is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Polkadot.  If not, see <http://www.gnu.org/licenses/>.
+
+//! Generates the bounds for a particular subsystem `Context` and associate `type Sender`.
+//!
+//!
+//! ## Implement `trait Subsystem<Context, Error>` via `subsystem`
+//!
+//! ```ignore
+//! # use polkadot_overseer_gen_proc_macro::subsystem;
+//! # mod somewhere {
+//! # use polkadot_overseer_gen_proc_macro::overlord;
+//! # pub use polkadot_overseer_gen::*;
+//! #
+//! # #[derive(Debug, thiserror::Error)]
+//! # #[error("Yikes!")]
+//! # pub struct Yikes;
+//! # impl From<OverseerError> for Yikes {
+//! #   fn from(_: OverseerError) -> Yikes { Yikes }
+//! # }
+//! # impl From<mpsc::SendError> for Yikes {
+//! #   fn from(_: mpsc::SendError) -> Yikes { Yikes }
+//! # }
+//! #
+//! # #[derive(Debug)]
+//! # pub struct Eve;
+//! #
+//! # #[derive(Debug, Clone)]
+//! # pub struct Sig;
+//! #
+//! # #[derive(Debug, Clone, Copy)]
+//! # pub struct A;
+//! # #[derive(Debug, Clone, Copy)]
+//! # pub struct B;
+//! #
+//! # #[overlord(signal=Sig, gen=AllOfThem, event=Eve, error=Yikes)]
+//! # pub struct Wonderland {
+//! # 	#[subsystem(A, sends: [B])]
+//! # 	foo: Foo,
+//! # 	#[subsystem(B, sends: [A])]
+//! # 	bar: Bar,
+//! # }
+//! # }
+//! # use somewhere::{Yikes, SpawnedSubsystem};
+//! #
+//! # struct FooSubsystem;
+//! #
+//! #[subsystem(Foo, error = Yikes, prefix = somewhere)]
+//! impl<Context> FooSubsystem {
+//!    fn start(self, context: Context) -> SpawnedSubsystem<Yikes> {
+//!	       // ..
+//!        # let _ = context;
+//!        # unimplemented!()
+//!    }
+//! }
+//! ```
+//!
+//! expands to
+//!
+//! ```ignore
+//! # use polkadot_overseer_gen_proc_macro::subsystem;
+//! # mod somewhere {
+//! # use polkadot_overseer_gen_proc_macro::overlord;
+//! # pub use polkadot_overseer_gen::*;
+//! #
+//! # #[derive(Debug, thiserror::Error)]
+//! # #[error("Yikes!")]
+//! # pub struct Yikes;
+//! # impl From<OverseerError> for Yikes {
+//! #   fn from(_: OverseerError) -> Yikes { Yikes }
+//! # }
+//! # impl From<mpsc::SendError> for Yikes {
+//! #   fn from(_: mpsc::SendError) -> Yikes { Yikes }
+//! # }
+//! #
+//! # #[derive(Debug)]
+//! # pub struct Eve;
+//! #
+//! # #[derive(Debug, Clone)]
+//! # pub struct Sig;
+//! #
+//! # #[derive(Debug, Clone, Copy)]
+//! # pub struct A;
+//! # #[derive(Debug, Clone, Copy)]
+//! # pub struct B;
+//! #
+//! # #[overlord(signal=Sig, gen=AllOfThem, event=Eve, error=Yikes)]
+//! # pub struct Wonderland {
+//! # 	#[subsystem(A, sends: [B])]
+//! # 	foo: Foo,
+//! # 	#[subsystem(B, sends: [A])]
+//! # 	bar: Bar,
+//! # }
+//! # }
+//! # use somewhere::{Yikes, SpawnedSubsystem};
+//! # use polkadot_overseer_gen as support_crate;
+//! #
+//! # struct FooSubsystem;
+//! #
+//! impl<Context> support_crate::Subsystem<Context, Yikes> for FooSubsystem
+//! where
+//! 	Context: somewhere::FooContextTrait,
+//!     Context: support_crate::SubsystemContext,
+//!		<Context as somewhere::FooContextTrait>::Sender: somewhere::FooSenderTrait,
+//!		<Context as support_crate::SubsystemContext>::Sender: somewhere::FooSenderTrait,
+//! {
+//!       fn start(self, context: Context) -> SpawnedSubsystem<Yikes> {
+//!        // ..
+//!        # let _ = context;
+//!        # unimplemented!()
+//!       }
+//! }
+//! ```
+//!
+//! where `support_crate` is either equivalent to `somewhere` or derived from the cargo manifest.
+//!
+//!
+//! ## Add additional trait bounds for a generic `Context` via `contextbounds`
+//!
+//! ### To an `ImplItem`
+//!
+//! ```ignore
+//! #[contextbounds(Foo, prefix = somewhere)]
+//! impl<Context> X {
+//! ..
+//! }
+//! ```
+//!
+//! expands to
+//!
+//! ```ignore
+//! impl<Context> X
+//! where
+//! 	Context: somewhere::FooSubsystemTrait,
+//!     Context: support_crate::SubsystemContext,
+//!		<Context as somewhere::FooContextTrait>::Sender: somewhere::FooSenderTrait,
+//!		<Context as support_crate::SubsystemContext>::Sender: somewhere::FooSenderTrait,
+//! {
+//! }
+//! ```
+//!
+//! ### To a free standing `Fn` (not a method, that's covered by the above)
+//!
+//! ```ignore
+//! #[contextbounds(Foo, prefix = somewhere)]
+//! fn do_smth<Context>(context: &mut Context) {
+//! ..
+//! }
+//! ```
+//!
+//! expands to
+//!
+//! ```ignore
+//! fn do_smth<Context>(context: &mut Context)
+//! where
+//! 	Context: somewhere::FooSubsystemTrait,
+//!     Context: support_crate::SubsystemContext,
+//!		<Context as somewhere::FooContextTrait>::Sender: somewhere::FooSenderTrait,
+//!		<Context as support_crate::SubsystemContext>::Sender: somewhere::FooSenderTrait,
+//! {
+//! }
+//! ```
+use proc_macro2::TokenStream;
+use quote::{format_ident, ToTokens};
+use syn::{parse2, parse_quote, punctuated::Punctuated, Result};
+
+use super::{parse::*, *};
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub(crate) enum MakeSubsystem {
+	/// Implements `trait Subsystem` and apply the trait bounds to the `Context` generic.
+	///
+	/// Relevant to `impl Item` only.
+	ImplSubsystemTrait,
+	/// Only apply the trait bounds to the context.
+	AddContextTraitBounds,
+}
+
+pub(crate) fn impl_subsystem_context_trait_bounds(
+	attr: TokenStream,
+	orig: TokenStream,
+	make_subsystem: MakeSubsystem,
+) -> Result<proc_macro2::TokenStream> {
+	let args = parse2::<SubsystemAttrArgs>(attr.clone())?;
+	let span = args.span();
+	let SubsystemAttrArgs { error_path, subsystem_ident, trait_prefix_path, .. } = args;
+
+	let mut item = parse2::<syn::Item>(orig)?;
+
+	// always prefer the direct usage, if it's not there, let's see if there is
+	// a `prefix=*` provided. Either is ok.
+
+	// Technically this is two different things:
+	// The place where the `#[overlord]` is annotated is where all `trait *SenderTrait` and
+	// `trait *ContextTrait` types exist.
+	// The other usage is the true support crate `polkadot-overseer-gen`, where the static ones
+	// are declared.
+	// Right now, if the `support_crate` is not included, it falls back silently to the `trait_prefix_path`.
+	let support_crate = support_crate()
+		.or_else(|_e| {
+			trait_prefix_path.clone().ok_or_else(|| {
+				syn::Error::new(attr.span(), "Couldn't find `polkadot-overseer-gen` in manifest, but also missing a `prefix=` to help trait bound resolution")
+			})
+		})?;
+
+	let trait_prefix_path = trait_prefix_path.unwrap_or_else(|| parse_quote! { self });
+	if trait_prefix_path.segments.trailing_punct() {
+		return Err(syn::Error::new(trait_prefix_path.span(), "Must not end with `::`"))
+	}
+
+	let subsystem_ctx_trait = format_ident!("{}ContextTrait", subsystem_ident);
+	let subsystem_sender_trait = format_ident!("{}SenderTrait", subsystem_ident);
+
+	let extra_where_predicates: Punctuated<syn::WherePredicate, syn::Token![,]> = parse_quote! {
+		Context: #trait_prefix_path::#subsystem_ctx_trait,
+		Context: #support_crate::SubsystemContext,
+		<Context as #trait_prefix_path::#subsystem_ctx_trait>::Sender: #trait_prefix_path::#subsystem_sender_trait,
+		<Context as #support_crate::SubsystemContext>::Sender: #trait_prefix_path::#subsystem_sender_trait,
+	};
+
+	let apply_ctx_bound_if_present = move |generics: &mut syn::Generics| -> bool {
+		if generics
+			.params
+			.iter()
+			.find(|generic| match generic {
+				syn::GenericParam::Type(ty) if ty.ident == "Context" => true,
+				_ => false,
+			})
+			.is_some()
+		{
+			let where_clause = generics.make_where_clause();
+			where_clause.predicates.extend(extra_where_predicates.clone());
+			true
+		} else {
+			false
+		}
+	};
+
+	match item {
+		syn::Item::Impl(ref mut struktured_impl) => {
+			if make_subsystem == MakeSubsystem::ImplSubsystemTrait {
+				let error_path = error_path.ok_or_else(|| {
+					syn::Error::new(
+						span,
+						"Must annotate the identical overseer error type via `error=..`.",
+					)
+				})?;
+				// Only replace the subsystem trait if it's desired.
+				struktured_impl.trait_.replace((
+					None,
+					parse_quote! {
+						#support_crate::Subsystem<Context, #error_path>
+					},
+					syn::token::For::default(),
+				));
+			}
+
+			apply_ctx_bound_if_present(&mut struktured_impl.generics);
+			for item in struktured_impl.items.iter_mut() {
+				match item {
+					syn::ImplItem::Method(method) => {
+						apply_ctx_bound_if_present(&mut method.sig.generics);
+					},
+					_others => {
+						// don't error, just nop
+					},
+				}
+			}
+		},
+		syn::Item::Fn(ref mut struktured_fn) => {
+			if make_subsystem == MakeSubsystem::ImplSubsystemTrait {
+				return Err(syn::Error::new(struktured_fn.span(), "Cannot make a free function a subsystem, did you mean to apply `contextbound` instead?"))
+			}
+			apply_ctx_bound_if_present(&mut struktured_fn.sig.generics);
+		},
+		other =>
+			return Err(syn::Error::new(
+				other.span(),
+				"Macro can only be annotated on functions or struct implementations",
+			)),
+	};
+
+	Ok(item.to_token_stream())
+}
+
+#[cfg(test)]
+mod tests {
+	use super::*;
+
+	#[test]
+	fn is_path() {
+		let _p: Path = parse_quote! { self };
+		let _p: Path = parse_quote! { crate };
+		let _p: Path = parse_quote! { ::foo };
+		let _p: Path = parse_quote! { bar };
+	}
+}

polkadot/node/overseer/overseer-gen/proc-macro/src/tests.rs

@@ -32,13 +32,13 @@ fn print() {
 
 	let item = quote! {
 		pub struct Ooooh<X = Pffffffft> where X: Secrit {
-			#[subsystem(no_dispatch, Foo)]
+			#[subsystem(Foo)]
 			sub0: FooSubsystem,
 
 			#[subsystem(blocking, Bar)]
 			yyy: BaersBuyBilliardBalls,
 
-			#[subsystem(no_dispatch, blocking, Twain)]
+			#[subsystem(blocking, Twain)]
 			fff: Beeeeep,
 
 			#[subsystem(Rope)]
@@ -57,13 +57,13 @@ fn print() {
 fn struct_parse_full() {
 	let item: OverseerGuts = parse_quote! {
 		pub struct Ooooh<X = Pffffffft> where X: Secrit {
-			#[subsystem(no_dispatch, Foo)]
+			#[subsystem(Foo)]
 			sub0: FooSubsystem,
 
 			#[subsystem(blocking, Bar)]
 			yyy: BaersBuyBilliardBalls,
 
-			#[subsystem(no_dispatch, blocking, Twain)]
+			#[subsystem(blocking, Twain)]
 			fff: Beeeeep,
 
 			#[subsystem(Rope)]
@@ -88,11 +88,11 @@ fn struct_parse_basic() {
 
 #[test]
 fn attr_full() {
-	let attr: AttrArgs = parse_quote! {
+	let attr: OverseerAttrArgs = parse_quote! {
 		gen=AllMessage, event=::some::why::ExternEvent, signal=SigSigSig, signal_capacity=111, message_capacity=222,
 		error=OverseerError,
 	};
-	assert_matches!(attr, AttrArgs {
+	assert_matches!(attr, OverseerAttrArgs {
 		message_channel_capacity,
 		signal_channel_capacity,
 		..
@@ -104,11 +104,11 @@ fn attr_full() {
 
 #[test]
 fn attr_partial() {
-	let attr: AttrArgs = parse_quote! {
+	let attr: OverseerAttrArgs = parse_quote! {
 		gen=AllMessage, event=::some::why::ExternEvent, signal=::foo::SigSigSig,
 		error=OverseerError,
 	};
-	assert_matches!(attr, AttrArgs {
+	assert_matches!(attr, OverseerAttrArgs {
 		message_channel_capacity: _,
 		signal_channel_capacity: _,
 		..

polkadot/node/overseer/overseer-gen/src/lib.rs

@@ -60,12 +60,13 @@
 #![deny(missing_docs)]
 #![deny(unused_crate_dependencies)]
 
-pub use polkadot_overseer_gen_proc_macro::overlord;
+pub use polkadot_overseer_gen_proc_macro::{contextbounds, overlord, subsystem};
 
 #[doc(hidden)]
 pub use gum;
 #[doc(hidden)]
 pub use metered;
+
 #[doc(hidden)]
 pub use polkadot_node_primitives::SpawnNamed;
 
@@ -101,7 +102,7 @@ use std::fmt;
 #[cfg(test)]
 mod tests;
 
-/// A type of messages that are sent from [`Subsystem`] to [`Overseer`].
+/// A type of messages that are sent from a [`Subsystem`] to the declared overseer.
 ///
 /// Used to launch jobs.
 pub enum ToOverseer {
@@ -312,7 +313,7 @@ pub struct SubsystemMeterReadouts {
 ///
 /// [`Subsystem`]: trait.Subsystem.html
 ///
-/// `M` here is the inner message type, and _not_ the generated `enum AllMessages`.
+/// `M` here is the inner message type, and _not_ the generated `enum AllMessages` or `#message_wrapper` type.
 pub struct SubsystemInstance<Message, Signal> {
 	/// Send sink for `Signal`s to be sent to a subsystem.
 	pub tx_signal: crate::metered::MeteredSender<Signal>,
@@ -362,20 +363,23 @@ pub trait SubsystemContext: Send + 'static {
 	/// The message type of this context. Subsystems launched with this context will expect
 	/// to receive messages of this type. Commonly uses the wrapping `enum` commonly called
 	/// `AllMessages`.
-	type Message: std::fmt::Debug + Send + 'static;
+	type Message: ::std::fmt::Debug + Send + 'static;
 	/// And the same for signals.
-	type Signal: std::fmt::Debug + Send + 'static;
-	/// The overarching all messages `enum`.
-	/// In some cases can be identical to `Self::Message`.
-	type AllMessages: From<Self::Message> + Send + 'static;
+	type Signal: ::std::fmt::Debug + Send + 'static;
+	/// The overarching messages `enum` for this particular subsystem.
+	type OutgoingMessages: ::std::fmt::Debug + Send + 'static;
+
+	// The overarching messages `enum` for this particular subsystem.
+	// type AllMessages: From<Self::OutgoingMessages> + From<Self::Message> + std::fmt::Debug + Send + 'static;
+
 	/// The sender type as provided by `sender()` and underlying.
-	type Sender: SubsystemSender<Self::AllMessages> + Send + 'static;
+	type Sender: Clone + Send + 'static + SubsystemSender<Self::OutgoingMessages>;
 	/// The error type.
 	type Error: ::std::error::Error + ::std::convert::From<OverseerError> + Sync + Send + 'static;
 
 	/// Try to asynchronously receive a message.
 	///
-	/// This has to be used with caution, if you loop over this without
+	/// Has to be used with caution, if you loop over this without
 	/// using `pending!()` macro you will end up with a busy loop!
 	async fn try_recv(&mut self) -> Result<Option<FromOverseer<Self::Message, Self::Signal>>, ()>;
 
@@ -397,34 +401,37 @@ pub trait SubsystemContext: Send + 'static {
 	) -> Result<(), Self::Error>;
 
 	/// Send a direct message to some other `Subsystem`, routed based on message type.
-	async fn send_message<X>(&mut self, msg: X)
+	// #[deprecated(note = "Use `self.sender().send_message(msg) instead, avoid passing around the full context.")]
+	async fn send_message<T>(&mut self, msg: T)
 	where
-		Self::AllMessages: From<X>,
-		X: Send,
+		Self::OutgoingMessages: From<T> + Send,
+		T: Send,
 	{
-		self.sender().send_message(<Self::AllMessages>::from(msg)).await
+		self.sender().send_message(<Self::OutgoingMessages>::from(msg)).await
 	}
 
 	/// Send multiple direct messages to other `Subsystem`s, routed based on message type.
-	async fn send_messages<X, T>(&mut self, msgs: T)
+	// #[deprecated(note = "Use `self.sender().send_message(msg) instead, avoid passing around the full context.")]
+	async fn send_messages<T, I>(&mut self, msgs: I)
 	where
-		T: IntoIterator<Item = X> + Send,
-		T::IntoIter: Send,
-		Self::AllMessages: From<X>,
-		X: Send,
+		Self::OutgoingMessages: From<T> + Send,
+		I: IntoIterator<Item = T> + Send,
+		I::IntoIter: Send,
+		T: Send,
 	{
 		self.sender()
-			.send_messages(msgs.into_iter().map(|x| <Self::AllMessages>::from(x)))
+			.send_messages(msgs.into_iter().map(<Self::OutgoingMessages>::from))
 			.await
 	}
 
 	/// Send a message using the unbounded connection.
+	// #[deprecated(note = "Use `self.sender().send_unbounded_message(msg) instead, avoid passing around the full context.")]
 	fn send_unbounded_message<X>(&mut self, msg: X)
 	where
-		Self::AllMessages: From<X>,
+		Self::OutgoingMessages: From<X> + Send,
 		X: Send,
 	{
-		self.sender().send_unbounded_message(Self::AllMessages::from(msg))
+		self.sender().send_unbounded_message(<Self::OutgoingMessages>::from(msg))
 	}
 
 	/// Obtain the sender.
@@ -450,22 +457,25 @@ where
 
 /// Sender end of a channel to interface with a subsystem.
 #[async_trait::async_trait]
-pub trait SubsystemSender<Message>: Send + Clone + 'static {
+pub trait SubsystemSender<OutgoingMessage>: Clone + Send + 'static
+where
+	OutgoingMessage: Send,
+{
 	/// Send a direct message to some other `Subsystem`, routed based on message type.
-	async fn send_message(&mut self, msg: Message);
+	async fn send_message(&mut self, msg: OutgoingMessage);
 
 	/// Send multiple direct messages to other `Subsystem`s, routed based on message type.
-	async fn send_messages<T>(&mut self, msgs: T)
+	async fn send_messages<I>(&mut self, msgs: I)
 	where
-		T: IntoIterator<Item = Message> + Send,
-		T::IntoIter: Send;
+		I: IntoIterator<Item = OutgoingMessage> + Send,
+		I::IntoIter: Send;
 
 	/// Send a message onto the unbounded queue of some other `Subsystem`, routed based on message
 	/// type.
 	///
 	/// This function should be used only when there is some other bounding factor on the messages
 	/// sent with it. Otherwise, it risks a memory leak.
-	fn send_unbounded_message(&mut self, msg: Message);
+	fn send_unbounded_message(&mut self, msg: OutgoingMessage);
 }
 
 /// A future that wraps another future with a `Delay` allowing for time-limited futures.

polkadot/node/overseer/overseer-gen/tests/ui/err-04-missing-error.rs

@@ -15,7 +15,7 @@ struct MsgStrukt(u8);
 
 #[overlord(signal=SigSigSig, event=Event, gen=AllMessages)]
 struct Overseer {
-	#[subsystem(no_dispatch, MsgStrukt)]
+	#[subsystem(MsgStrukt)]
 	sub0: AwesomeSubSys,
 
 	i_like_pie: f64,

polkadot/node/overseer/overseer-gen/tests/ui/err-05-missing-field.rs

@@ -21,7 +21,7 @@ pub struct MsgStrukt(u8);
 
 #[overlord(signal=SigSigSig, error=OverseerError, event=Event, gen=AllMessages)]
 struct Overseer {
-	#[subsystem(no_dispatch, MsgStrukt)]
+	#[subsystem(MsgStrukt)]
 	sub0: AwesomeSubSys,
 	i_like_pie: f64,
 }
@@ -58,4 +58,4 @@ fn main() {
 		.spawner(DummySpawner)
 		.build()
 		.unwrap();
-}
+}

polkadot/node/overseer/overseer-gen/tests/ui/err-06-missing-subsystem.rs

@@ -21,7 +21,7 @@ pub struct MsgStrukt(u8);
 
 #[overlord(signal=SigSigSig, error=OverseerError, event=Event, gen=AllMessages)]
 struct Overseer {
-	#[subsystem(no_dispatch, MsgStrukt)]
+	#[subsystem(MsgStrukt)]
 	sub0: AwesomeSubSys,
 	i_like_pie: f64,
 }

polkadot/node/overseer/overseer-gen/tests/ui/err-07-missing-spawner.rs

@@ -21,7 +21,7 @@ pub struct MsgStrukt(u8);
 
 #[overlord(signal=SigSigSig, error=OverseerError, event=Event, gen=AllMessages)]
 struct Overseer {
-	#[subsystem(no_dispatch, MsgStrukt)]
+	#[subsystem(MsgStrukt)]
 	sub0: AwesomeSubSys,
 	i_like_pie: f64,
 }

polkadot/node/overseer/overseer-gen/tests/ui/err-08-duplicate-subsystem.rs

@@ -21,7 +21,7 @@ pub struct MsgStrukt(u8);
 
 #[overlord(signal=SigSigSig, error=OverseerError, event=Event, gen=AllMessages)]
 struct Overseer {
-	#[subsystem(no_dispatch, MsgStrukt)]
+	#[subsystem(MsgStrukt)]
 	sub0: AwesomeSubSys,
 	i_like_pie: f64,
 }

polkadot/node/overseer/overseer-gen/tests/ui/err-09-uninit_generic_baggage.rs

@@ -21,7 +21,7 @@ pub struct MsgStrukt(u8);
 
 #[overlord(signal=SigSigSig, error=OverseerError, event=Event, gen=AllMessages)]
 struct Overseer<T> {
-	#[subsystem(no_dispatch, MsgStrukt)]
+	#[subsystem(MsgStrukt)]
 	sub0: AwesomeSubSys,
 	i_like_pie: T,
 }

polkadot/node/overseer/src/dummy.rs

@@ -15,8 +15,8 @@
 // along with Polkadot.  If not, see <http://www.gnu.org/licenses/>.
 
 use crate::{
-	prometheus::Registry, AllMessages, HeadSupportsParachains, InitializedOverseerBuilder,
-	MetricsTrait, Overseer, OverseerMetrics, OverseerSignal, OverseerSubsystemContext, SpawnNamed,
+	prometheus::Registry, HeadSupportsParachains, InitializedOverseerBuilder, MetricsTrait,
+	Overseer, OverseerMetrics, OverseerSignal, OverseerSubsystemContext, SpawnNamed,
 	KNOWN_LEAVES_CACHE_SIZE,
 };
 use lru::LruCache;
@@ -30,11 +30,7 @@ pub struct DummySubsystem;
 
 impl<Context> Subsystem<Context, SubsystemError> for DummySubsystem
 where
-	Context: SubsystemContext<
-		Signal = OverseerSignal,
-		Error = SubsystemError,
-		AllMessages = AllMessages,
-	>,
+	Context: SubsystemContext<Signal = OverseerSignal, Error = SubsystemError>,
 {
 	fn start(self, mut ctx: Context) -> SpawnedSubsystem<SubsystemError> {
 		let future = Box::pin(async move {

polkadot/node/overseer/src/lib.rs

@@ -77,15 +77,14 @@ use polkadot_primitives::{
 };
 use sp_api::{ApiExt, ProvideRuntimeApi};
 
-use polkadot_node_network_protocol::VersionedValidationProtocol;
 use polkadot_node_subsystem_types::messages::{
 	ApprovalDistributionMessage, ApprovalVotingMessage, AvailabilityDistributionMessage,
 	AvailabilityRecoveryMessage, AvailabilityStoreMessage, BitfieldDistributionMessage,
 	BitfieldSigningMessage, CandidateBackingMessage, CandidateValidationMessage, ChainApiMessage,
 	ChainSelectionMessage, CollationGenerationMessage, CollatorProtocolMessage,
 	DisputeCoordinatorMessage, DisputeDistributionMessage, GossipSupportMessage,
-	NetworkBridgeEvent, NetworkBridgeMessage, ProvisionerMessage, PvfCheckerMessage,
-	RuntimeApiMessage, StatementDistributionMessage,
+	NetworkBridgeMessage, ProvisionerMessage, PvfCheckerMessage, RuntimeApiMessage,
+	StatementDistributionMessage,
 };
 pub use polkadot_node_subsystem_types::{
 	errors::{SubsystemError, SubsystemResult},
@@ -108,9 +107,9 @@ use parity_util_mem::MemoryAllocationTracker;
 
 pub use polkadot_overseer_gen as gen;
 pub use polkadot_overseer_gen::{
-	overlord, FromOverseer, MapSubsystem, MessagePacket, SignalsReceived, SpawnNamed, Subsystem,
-	SubsystemContext, SubsystemIncomingMessages, SubsystemInstance, SubsystemMeterReadouts,
-	SubsystemMeters, SubsystemSender, TimeoutExt, ToOverseer,
+	contextbounds, overlord, subsystem, FromOverseer, MapSubsystem, MessagePacket, SignalsReceived,
+	SpawnNamed, Subsystem, SubsystemContext, SubsystemIncomingMessages, SubsystemInstance,
+	SubsystemMeterReadouts, SubsystemMeters, SubsystemSender, TimeoutExt, ToOverseer,
 };
 
 /// Store 2 days worth of blocks, not accounting for forks,
@@ -414,71 +413,155 @@ pub async fn forward_events<P: BlockchainEvents<Block>>(client: Arc<P>, mut hand
 	event=Event,
 	signal=OverseerSignal,
 	error=SubsystemError,
-	network=NetworkBridgeEvent<VersionedValidationProtocol>,
 	message_capacity=2048,
 )]
 pub struct Overseer<SupportsParachains> {
-	#[subsystem(no_dispatch, CandidateValidationMessage)]
+	#[subsystem(CandidateValidationMessage, sends: [
+		RuntimeApiMessage,
+	])]
 	candidate_validation: CandidateValidation,
 
-	#[subsystem(no_dispatch, PvfCheckerMessage)]
+	#[subsystem(PvfCheckerMessage, sends: [
+		CandidateValidationMessage,
+		RuntimeApiMessage,
+	])]
 	pvf_checker: PvfChecker,
 
-	#[subsystem(no_dispatch, CandidateBackingMessage)]
+	#[subsystem(CandidateBackingMessage, sends: [
+		CandidateValidationMessage,
+		CollatorProtocolMessage,
+		AvailabilityDistributionMessage,
+		AvailabilityStoreMessage,
+		StatementDistributionMessage,
+		ProvisionerMessage,
+		RuntimeApiMessage,
+		DisputeCoordinatorMessage,
+	])]
 	candidate_backing: CandidateBacking,
 
-	#[subsystem(StatementDistributionMessage)]
+	#[subsystem(StatementDistributionMessage, sends: [
+		NetworkBridgeMessage,
+		CandidateBackingMessage,
+		RuntimeApiMessage,
+	])]
 	statement_distribution: StatementDistribution,
 
-	#[subsystem(no_dispatch, AvailabilityDistributionMessage)]
+	#[subsystem(AvailabilityDistributionMessage, sends: [
+		AvailabilityStoreMessage,
+		AvailabilityRecoveryMessage,
+		ChainApiMessage,
+		RuntimeApiMessage,
+		NetworkBridgeMessage,
+	])]
 	availability_distribution: AvailabilityDistribution,
 
-	#[subsystem(no_dispatch, AvailabilityRecoveryMessage)]
+	#[subsystem(AvailabilityRecoveryMessage, sends: [
+		NetworkBridgeMessage,
+		RuntimeApiMessage,
+		AvailabilityStoreMessage,
+	])]
 	availability_recovery: AvailabilityRecovery,
 
-	#[subsystem(blocking, no_dispatch, BitfieldSigningMessage)]
+	#[subsystem(blocking, BitfieldSigningMessage, sends: [
+		AvailabilityStoreMessage,
+		RuntimeApiMessage,
+		BitfieldDistributionMessage,
+	])]
 	bitfield_signing: BitfieldSigning,
 
-	#[subsystem(BitfieldDistributionMessage)]
+	#[subsystem(BitfieldDistributionMessage, sends: [
+		RuntimeApiMessage,
+		NetworkBridgeMessage,
+		ProvisionerMessage,
+	])]
 	bitfield_distribution: BitfieldDistribution,
 
-	#[subsystem(no_dispatch, ProvisionerMessage)]
+	#[subsystem(ProvisionerMessage, sends: [
+		RuntimeApiMessage,
+		CandidateBackingMessage,
+		ChainApiMessage,
+		DisputeCoordinatorMessage,
+	])]
 	provisioner: Provisioner,
 
-	#[subsystem(no_dispatch, blocking, RuntimeApiMessage)]
+	#[subsystem(blocking, RuntimeApiMessage, sends: [])]
 	runtime_api: RuntimeApi,
 
-	#[subsystem(no_dispatch, blocking, AvailabilityStoreMessage)]
+	#[subsystem(blocking, AvailabilityStoreMessage, sends: [
+		ChainApiMessage,
+		RuntimeApiMessage,
+	])]
 	availability_store: AvailabilityStore,
 
-	#[subsystem(no_dispatch, NetworkBridgeMessage)]
+	#[subsystem(NetworkBridgeMessage, sends: [
+		BitfieldDistributionMessage,
+		StatementDistributionMessage,
+		ApprovalDistributionMessage,
+		GossipSupportMessage,
+		DisputeDistributionMessage,
+		CollationGenerationMessage,
+		CollatorProtocolMessage,
+	])]
 	network_bridge: NetworkBridge,
 
-	#[subsystem(no_dispatch, blocking, ChainApiMessage)]
+	#[subsystem(blocking, ChainApiMessage, sends: [])]
 	chain_api: ChainApi,
 
-	#[subsystem(no_dispatch, CollationGenerationMessage)]
+	#[subsystem(CollationGenerationMessage, sends: [
+		RuntimeApiMessage,
+		CollatorProtocolMessage,
+	])]
 	collation_generation: CollationGeneration,
 
-	#[subsystem(no_dispatch, CollatorProtocolMessage)]
+	#[subsystem(CollatorProtocolMessage, sends: [
+		NetworkBridgeMessage,
+		RuntimeApiMessage,
+		CandidateBackingMessage,
+	])]
 	collator_protocol: CollatorProtocol,
 
-	#[subsystem(ApprovalDistributionMessage)]
+	#[subsystem(ApprovalDistributionMessage, sends: [
+		NetworkBridgeMessage,
+		ApprovalVotingMessage,
+	])]
 	approval_distribution: ApprovalDistribution,
 
-	#[subsystem(no_dispatch, blocking, ApprovalVotingMessage)]
+	#[subsystem(blocking, ApprovalVotingMessage, sends: [
+		RuntimeApiMessage,
+		ChainApiMessage,
+		ChainSelectionMessage,
+		DisputeCoordinatorMessage,
+		AvailabilityRecoveryMessage,
+		ApprovalDistributionMessage,
+		CandidateValidationMessage,
+	])]
 	approval_voting: ApprovalVoting,
 
-	#[subsystem(GossipSupportMessage)]
+	#[subsystem(GossipSupportMessage, sends: [
+		NetworkBridgeMessage,
+		RuntimeApiMessage,
+		ChainSelectionMessage,
+	])]
 	gossip_support: GossipSupport,
 
-	#[subsystem(no_dispatch, blocking, DisputeCoordinatorMessage)]
+	#[subsystem(blocking, DisputeCoordinatorMessage, sends: [
+		RuntimeApiMessage,
+		ChainApiMessage,
+		DisputeDistributionMessage,
+		CandidateValidationMessage,
+		AvailabilityStoreMessage,
+		AvailabilityRecoveryMessage,
+	])]
 	dispute_coordinator: DisputeCoordinator,
 
-	#[subsystem(no_dispatch, DisputeDistributionMessage)]
+	#[subsystem(DisputeDistributionMessage, sends: [
+		RuntimeApiMessage,
+		DisputeCoordinatorMessage,
+		NetworkBridgeMessage,
+	])]
 	dispute_distribution: DisputeDistribution,
 
-	#[subsystem(no_dispatch, blocking, ChainSelectionMessage)]
+	#[subsystem(blocking, ChainSelectionMessage, sends: [ChainApiMessage])]
 	chain_selection: ChainSelection,
 
 	/// External listeners waiting for a hash to be in the active-leave set.

polkadot/node/overseer/src/tests.rs

@@ -60,11 +60,7 @@ struct TestSubsystem1(metered::MeteredSender<usize>);
 
 impl<C> overseer::Subsystem<C, SubsystemError> for TestSubsystem1
 where
-	C: overseer::SubsystemContext<
-		Message = CandidateValidationMessage,
-		Signal = OverseerSignal,
-		AllMessages = AllMessages,
-	>,
+	C: overseer::SubsystemContext<Message = CandidateValidationMessage, Signal = OverseerSignal>,
 {
 	fn start(self, mut ctx: C) -> SpawnedSubsystem {
 		let mut sender = self.0;
@@ -95,8 +91,8 @@ impl<C> overseer::Subsystem<C, SubsystemError> for TestSubsystem2
 where
 	C: overseer::SubsystemContext<
 		Message = CandidateBackingMessage,
+		OutgoingMessages = <CandidateBackingMessage as AssociateOutgoing>::OutgoingMessages,
 		Signal = OverseerSignal,
-		AllMessages = AllMessages,
 	>,
 {
 	fn start(self, mut ctx: C) -> SpawnedSubsystem {
@@ -143,11 +139,7 @@ struct ReturnOnStart;
 
 impl<C> overseer::Subsystem<C, SubsystemError> for ReturnOnStart
 where
-	C: overseer::SubsystemContext<
-		Message = CandidateBackingMessage,
-		Signal = OverseerSignal,
-		AllMessages = AllMessages,
-	>,
+	C: overseer::SubsystemContext<Message = CandidateBackingMessage, Signal = OverseerSignal>,
 {
 	fn start(self, mut _ctx: C) -> SpawnedSubsystem {
 		SpawnedSubsystem {
@@ -316,11 +308,7 @@ struct TestSubsystem5(metered::MeteredSender<OverseerSignal>);
 
 impl<C> overseer::Subsystem<C, SubsystemError> for TestSubsystem5
 where
-	C: overseer::SubsystemContext<
-		Message = CandidateValidationMessage,
-		Signal = OverseerSignal,
-		AllMessages = AllMessages,
-	>,
+	C: overseer::SubsystemContext<Message = CandidateValidationMessage, Signal = OverseerSignal>,
 {
 	fn start(self, mut ctx: C) -> SpawnedSubsystem {
 		let mut sender = self.0.clone();
@@ -352,11 +340,7 @@ struct TestSubsystem6(metered::MeteredSender<OverseerSignal>);
 
 impl<C> Subsystem<C, SubsystemError> for TestSubsystem6
 where
-	C: overseer::SubsystemContext<
-		Message = CandidateBackingMessage,
-		Signal = OverseerSignal,
-		AllMessages = AllMessages,
-	>,
+	C: overseer::SubsystemContext<Message = CandidateBackingMessage, Signal = OverseerSignal>,
 {
 	fn start(self, mut ctx: C) -> SpawnedSubsystem {
 		let mut sender = self.0.clone();
@@ -761,7 +745,7 @@ impl CounterSubsystem {
 
 impl<C, M> Subsystem<C, SubsystemError> for CounterSubsystem
 where
-	C: overseer::SubsystemContext<Message = M, Signal = OverseerSignal, AllMessages = AllMessages>,
+	C: overseer::SubsystemContext<Message = M, Signal = OverseerSignal>,
 	M: Send,
 {
 	fn start(self, mut ctx: C) -> SpawnedSubsystem {

polkadot/node/primitives/src/lib.rs

@@ -86,7 +86,7 @@ pub const MAX_FINALITY_LAG: u32 = 500;
 /// We are not using `NonZeroU32` here because `expect` and `unwrap` are not yet const, so global
 /// constants of `SessionWindowSize` would require `lazy_static` in that case.
 ///
-/// See: https://github.com/rust-lang/rust/issues/67441
+/// See: <https://github.com/rust-lang/rust/issues/67441>
 #[derive(Copy, Clone, Eq, PartialEq, Ord, PartialOrd)]
 pub struct SessionWindowSize(SessionIndex);
 

polkadot/node/service/Cargo.toml

@@ -83,6 +83,7 @@ polkadot-node-primitives = { path = "../primitives" }
 polkadot-rpc = { path = "../../rpc" }
 polkadot-node-subsystem = {path = "../subsystem" }
 polkadot-node-subsystem-util = { path = "../subsystem-util" }
+polkadot-node-subsystem-types = { path = "../subsystem-types" }
 polkadot-runtime-parachains = { path = "../../runtime/parachains" }
 polkadot-node-network-protocol = { path = "../network/protocol" }
 

polkadot/node/service/src/overseer.rs

@@ -24,14 +24,16 @@ use polkadot_node_core_chain_selection::Config as ChainSelectionConfig;
 use polkadot_node_core_dispute_coordinator::Config as DisputeCoordinatorConfig;
 use polkadot_node_core_provisioner::ProvisionerConfig;
 use polkadot_node_network_protocol::request_response::{v1 as request_v1, IncomingRequestReceiver};
+use polkadot_node_subsystem_types::messages::{BitfieldSigningMessage, ProvisionerMessage};
 #[cfg(any(feature = "malus", test))]
 pub use polkadot_overseer::{
 	dummy::{dummy_overseer_builder, DummySubsystem},
 	HeadSupportsParachains,
 };
 use polkadot_overseer::{
-	metrics::Metrics as OverseerMetrics, BlockInfo, InitializedOverseerBuilder, MetricsTrait,
-	Overseer, OverseerConnector, OverseerHandle,
+	gen::SubsystemContext, metrics::Metrics as OverseerMetrics, BlockInfo,
+	InitializedOverseerBuilder, MetricsTrait, Overseer, OverseerConnector, OverseerHandle,
+	OverseerSubsystemContext,
 };
 
 use polkadot_primitives::runtime_api::ParachainHost;
@@ -152,9 +154,15 @@ pub fn prepared_overseer_builder<'a, Spawner, RuntimeClient>(
 		StatementDistributionSubsystem<rand::rngs::StdRng>,
 		AvailabilityDistributionSubsystem,
 		AvailabilityRecoverySubsystem,
-		BitfieldSigningSubsystem<Spawner>,
+		BitfieldSigningSubsystem<
+			Spawner,
+			<OverseerSubsystemContext<BitfieldSigningMessage> as SubsystemContext>::Sender,
+		>,
 		BitfieldDistributionSubsystem,
-		ProvisionerSubsystem<Spawner>,
+		ProvisionerSubsystem<
+			Spawner,
+			<OverseerSubsystemContext<ProvisionerMessage> as SubsystemContext>::Sender,
+		>,
 		RuntimeApiSubsystem<RuntimeClient>,
 		AvailabilityStoreSubsystem,
 		NetworkBridgeSubsystem<

polkadot/node/subsystem-test-helpers/src/lib.rs

@@ -20,7 +20,7 @@
 
 use polkadot_node_subsystem::{
 	messages::AllMessages, overseer, FromOverseer, OverseerSignal, SpawnedSubsystem,
-	SubsystemContext, SubsystemError, SubsystemResult,
+	SubsystemError, SubsystemResult,
 };
 use polkadot_node_subsystem_util::TimeoutExt;
 
@@ -150,24 +150,25 @@ pub fn sender_receiver() -> (TestSubsystemSender, mpsc::UnboundedReceiver<AllMes
 }
 
 #[async_trait::async_trait]
-impl<T> overseer::SubsystemSender<T> for TestSubsystemSender
+impl<OutgoingMessage> overseer::SubsystemSender<OutgoingMessage> for TestSubsystemSender
 where
-	T: Into<AllMessages> + Send + 'static,
+	AllMessages: From<OutgoingMessage>,
+	OutgoingMessage: Send + 'static,
 {
-	async fn send_message(&mut self, msg: T) {
+	async fn send_message(&mut self, msg: OutgoingMessage) {
 		self.tx.send(msg.into()).await.expect("test overseer no longer live");
 	}
 
-	async fn send_messages<X>(&mut self, msgs: X)
+	async fn send_messages<I>(&mut self, msgs: I)
 	where
-		X: IntoIterator<Item = T> + Send,
-		X::IntoIter: Send,
+		I: IntoIterator<Item = OutgoingMessage> + Send,
+		I::IntoIter: Send,
 	{
 		let mut iter = stream::iter(msgs.into_iter().map(|msg| Ok(msg.into())));
 		self.tx.send_all(&mut iter).await.expect("test overseer no longer live");
 	}
 
-	fn send_unbounded_message(&mut self, msg: T) {
+	fn send_unbounded_message(&mut self, msg: OutgoingMessage) {
 		self.tx.unbounded_send(msg.into()).expect("test overseer no longer live");
 	}
 }
@@ -180,16 +181,17 @@ pub struct TestSubsystemContext<M, S> {
 }
 
 #[async_trait::async_trait]
-impl<M, S> overseer::SubsystemContext for TestSubsystemContext<M, S>
+impl<M, Spawner> overseer::SubsystemContext for TestSubsystemContext<M, Spawner>
 where
-	M: std::fmt::Debug + Send + 'static,
+	M: overseer::AssociateOutgoing + std::fmt::Debug + Send + 'static,
+	AllMessages: From<<M as overseer::AssociateOutgoing>::OutgoingMessages>,
 	AllMessages: From<M>,
-	S: SpawnNamed + Send + 'static,
+	Spawner: SpawnNamed + Send + 'static,
 {
 	type Message = M;
 	type Sender = TestSubsystemSender;
 	type Signal = OverseerSignal;
-	type AllMessages = AllMessages;
+	type OutgoingMessages = <M as overseer::AssociateOutgoing>::OutgoingMessages;
 	type Error = SubsystemError;
 
 	async fn try_recv(&mut self) -> Result<Option<FromOverseer<M>>, ()> {
@@ -316,8 +318,13 @@ pub struct ForwardSubsystem<M>(pub mpsc::Sender<M>);
 
 impl<M, Context> overseer::Subsystem<Context, SubsystemError> for ForwardSubsystem<M>
 where
-	M: std::fmt::Debug + Send + 'static,
-	Context: SubsystemContext<Message = M> + overseer::SubsystemContext<Message = M>,
+	M: overseer::AssociateOutgoing + std::fmt::Debug + Send + 'static,
+	Context: overseer::SubsystemContext<
+		Message = M,
+		Signal = OverseerSignal,
+		Error = SubsystemError,
+		OutgoingMessages = <M as overseer::AssociateOutgoing>::OutgoingMessages,
+	>,
 {
 	fn start(mut self, mut ctx: Context) -> SpawnedSubsystem {
 		let future = Box::pin(async move {

polkadot/node/subsystem-util/src/determine_new_blocks.rs

@@ -39,7 +39,7 @@ pub async fn determine_new_blocks<E, Sender>(
 	lower_bound_number: BlockNumber,
 ) -> Result<Vec<(Hash, Header)>, E>
 where
-	Sender: SubsystemSender,
+	Sender: SubsystemSender<ChainApiMessage>,
 {
 	const ANCESTRY_STEP: usize = 4;
 

polkadot/node/subsystem-util/src/lib.rs

@@ -26,9 +26,7 @@
 
 use polkadot_node_subsystem::{
 	errors::{RuntimeApiError, SubsystemError},
-	messages::{
-		AllMessages, BoundToRelayParent, RuntimeApiMessage, RuntimeApiRequest, RuntimeApiSender,
-	},
+	messages::{BoundToRelayParent, RuntimeApiMessage, RuntimeApiRequest, RuntimeApiSender},
 	overseer, ActivatedLeaf, ActiveLeavesUpdate, FromOverseer, OverseerSignal, SpawnedSubsystem,
 	SubsystemContext, SubsystemSender,
 };
@@ -144,7 +142,7 @@ pub async fn request_from_runtime<RequestBuilder, Response, Sender>(
 ) -> RuntimeApiReceiver<Response>
 where
 	RequestBuilder: FnOnce(RuntimeApiSender<Response>) -> RuntimeApiRequest,
-	Sender: SubsystemSender,
+	Sender: SubsystemSender<RuntimeApiMessage>,
 {
 	let (tx, rx) = oneshot::channel();
 
@@ -176,7 +174,7 @@ macro_rules! specialize_requests {
 			$(
 				$param_name: $param_ty,
 			)*
-			sender: &mut impl SubsystemSender,
+			sender: &mut impl overseer::SubsystemSender<RuntimeApiMessage>,
 		) -> RuntimeApiReceiver<$return_ty>
 		{
 			request_from_runtime(parent, sender, |tx| RuntimeApiRequest::$request_variant(
@@ -329,11 +327,14 @@ pub struct Validator {
 
 impl Validator {
 	/// Get a struct representing this node's validator if this node is in fact a validator in the context of the given block.
-	pub async fn new(
+	pub async fn new<S>(
 		parent: Hash,
 		keystore: SyncCryptoStorePtr,
-		sender: &mut impl SubsystemSender,
-	) -> Result<Self, Error> {
+		sender: &mut S,
+	) -> Result<Self, Error>
+	where
+		S: SubsystemSender<RuntimeApiMessage>,
+	{
 		// Note: request_validators and request_session_index_for_child do not and cannot
 		// run concurrently: they both have a mutable handle to the same sender.
 		// However, each of them returns a oneshot::Receiver, and those are resolved concurrently.
@@ -397,14 +398,14 @@ impl Drop for AbortOnDrop {
 }
 
 /// A `JobHandle` manages a particular job for a subsystem.
-struct JobHandle<ToJob> {
+struct JobHandle<Consumes> {
 	_abort_handle: AbortOnDrop,
-	to_job: mpsc::Sender<ToJob>,
+	to_job: mpsc::Sender<Consumes>,
 }
 
-impl<ToJob> JobHandle<ToJob> {
+impl<Consumes> JobHandle<Consumes> {
 	/// Send a message to the job.
-	async fn send_msg(&mut self, msg: ToJob) -> Result<(), Error> {
+	async fn send_msg(&mut self, msg: Consumes) -> Result<(), Error> {
 		self.to_job.send(msg).await.map_err(Into::into)
 	}
 }
@@ -418,49 +419,25 @@ pub enum FromJobCommand {
 }
 
 /// A sender for messages from jobs, as well as commands to the overseer.
-pub struct JobSender<S: SubsystemSender> {
+pub struct JobSender<S> {
 	sender: S,
 	from_job: mpsc::Sender<FromJobCommand>,
 }
 
 // A custom clone impl, since M does not need to impl `Clone`
 // which `#[derive(Clone)]` requires.
-impl<S: SubsystemSender> Clone for JobSender<S> {
+impl<S: Clone> Clone for JobSender<S> {
 	fn clone(&self) -> Self {
 		Self { sender: self.sender.clone(), from_job: self.from_job.clone() }
 	}
 }
 
-impl<S: SubsystemSender> JobSender<S> {
+impl<S> JobSender<S> {
 	/// Get access to the underlying subsystem sender.
 	pub fn subsystem_sender(&mut self) -> &mut S {
 		&mut self.sender
 	}
 
-	/// Send a direct message to some other `Subsystem`, routed based on message type.
-	pub async fn send_message(&mut self, msg: impl Into<AllMessages>) {
-		self.sender.send_message(msg.into()).await
-	}
-
-	/// Send multiple direct messages to other `Subsystem`s, routed based on message type.
-	pub async fn send_messages<T, M>(&mut self, msgs: T)
-	where
-		T: IntoIterator<Item = M> + Send,
-		T::IntoIter: Send,
-		M: Into<AllMessages>,
-	{
-		self.sender.send_messages(msgs.into_iter().map(|m| m.into())).await
-	}
-
-	/// Send a message onto the unbounded queue of some other `Subsystem`, routed based on message
-	/// type.
-	///
-	/// This function should be used only when there is some other bounding factor on the messages
-	/// sent with it. Otherwise, it risks a memory leak.
-	pub fn send_unbounded_message(&mut self, msg: impl Into<AllMessages>) {
-		self.sender.send_unbounded_message(msg.into())
-	}
-
 	/// Send a command to the subsystem, to be relayed onwards to the overseer.
 	pub async fn send_command(&mut self, msg: FromJobCommand) -> Result<(), mpsc::SendError> {
 		self.from_job.send(msg).await
@@ -470,23 +447,23 @@ impl<S: SubsystemSender> JobSender<S> {
 #[async_trait::async_trait]
 impl<S, M> overseer::SubsystemSender<M> for JobSender<S>
 where
-	M: Send + 'static + Into<AllMessages>,
-	S: SubsystemSender + Clone,
+	M: Send + 'static,
+	S: SubsystemSender<M> + Clone,
 {
 	async fn send_message(&mut self, msg: M) {
-		self.sender.send_message(msg.into()).await
+		self.sender.send_message(msg).await
 	}
 
-	async fn send_messages<T>(&mut self, msgs: T)
+	async fn send_messages<I>(&mut self, msgs: I)
 	where
-		T: IntoIterator<Item = M> + Send,
-		T::IntoIter: Send,
+		I: IntoIterator<Item = M> + Send,
+		I::IntoIter: Send,
 	{
-		self.sender.send_messages(msgs.into_iter().map(|m| m.into())).await
+		self.sender.send_messages(msgs).await
 	}
 
 	fn send_unbounded_message(&mut self, msg: M) {
-		self.sender.send_unbounded_message(msg.into())
+		self.sender.send_unbounded_message(msg)
 	}
 }
 
@@ -506,6 +483,14 @@ impl fmt::Debug for FromJobCommand {
 pub trait JobTrait: Unpin + Sized {
 	/// Message type used to send messages to the job.
 	type ToJob: 'static + BoundToRelayParent + Send;
+
+	/// The set of outgoing messages to be accumulated into.
+	type OutgoingMessages: 'static + Send;
+
+	/// The sender to send outgoing messages.
+	// The trait bounds are rather minimal.
+	type Sender: 'static + Send + Clone;
+
 	/// Job runtime error.
 	type Error: 'static + std::error::Error + Send;
 	/// Extra arguments this job needs to run properly.
@@ -525,12 +510,12 @@ pub trait JobTrait: Unpin + Sized {
 	/// Run a job for the given relay `parent`.
 	///
 	/// The job should be ended when `receiver` returns `None`.
-	fn run<S: SubsystemSender>(
+	fn run(
 		leaf: ActivatedLeaf,
 		run_args: Self::RunArgs,
 		metrics: Self::Metrics,
 		receiver: mpsc::Receiver<Self::ToJob>,
-		sender: JobSender<S>,
+		sender: JobSender<Self::Sender>,
 	) -> Pin<Box<dyn Future<Output = Result<(), Self::Error>> + Send>>;
 }
 
@@ -572,15 +557,14 @@ where
 	}
 
 	/// Spawn a new job for this `parent_hash`, with whatever args are appropriate.
-	fn spawn_job<Job, Sender>(
+	fn spawn_job<Job>(
 		&mut self,
 		leaf: ActivatedLeaf,
 		run_args: Job::RunArgs,
 		metrics: Job::Metrics,
-		sender: Sender,
+		sender: Job::Sender,
 	) where
 		Job: JobTrait<ToJob = ToJob>,
-		Sender: SubsystemSender,
 	{
 		let hash = leaf.hash;
 		let (to_job_tx, to_job_rx) = mpsc::channel(JOB_CHANNEL_CAPACITY);
@@ -697,8 +681,12 @@ impl<Job: JobTrait, Spawner> JobSubsystem<Job, Spawner> {
 	pub async fn run<Context>(self, mut ctx: Context)
 	where
 		Spawner: SpawnNamed + Send + Clone + Unpin + 'static,
-		Context: SubsystemContext<Message = <Job as JobTrait>::ToJob, Signal = OverseerSignal>,
-		<Context as SubsystemContext>::Sender: SubsystemSender,
+		Context: SubsystemContext<
+			Message = <Job as JobTrait>::ToJob,
+			OutgoingMessages = <Job as JobTrait>::OutgoingMessages,
+			Sender = <Job as JobTrait>::Sender,
+			Signal = OverseerSignal,
+		>,
 		Job: 'static + JobTrait + Send,
 		<Job as JobTrait>::RunArgs: Clone + Sync,
 		<Job as JobTrait>::ToJob:
@@ -719,7 +707,7 @@ impl<Job: JobTrait, Spawner> JobSubsystem<Job, Spawner> {
 						}))) => {
 							for activated in activated {
 								let sender = ctx.sender().clone();
-								jobs.spawn_job::<Job, _>(
+								jobs.spawn_job::<Job>(
 									activated,
 									run_args.clone(),
 									metrics.clone(),
@@ -773,11 +761,15 @@ impl<Job: JobTrait, Spawner> JobSubsystem<Job, Spawner> {
 impl<Context, Job, Spawner> Subsystem<Context, SubsystemError> for JobSubsystem<Job, Spawner>
 where
 	Spawner: SpawnNamed + Send + Clone + Unpin + 'static,
-	Context: SubsystemContext<Message = Job::ToJob, Signal = OverseerSignal>,
+	Context: SubsystemContext<
+		Message = Job::ToJob,
+		Signal = OverseerSignal,
+		OutgoingMessages = <Job as JobTrait>::OutgoingMessages,
+		Sender = <Job as JobTrait>::Sender,
+	>,
 	Job: 'static + JobTrait + Send,
 	Job::RunArgs: Clone + Sync,
-	<Job as JobTrait>::ToJob:
-		Sync + From<<Context as polkadot_overseer::SubsystemContext>::Message>,
+	<Job as JobTrait>::ToJob: Sync + From<<Context as SubsystemContext>::Message>,
 	Job::Metrics: Sync,
 {
 	fn start(self, ctx: Context) -> SpawnedSubsystem {

polkadot/node/subsystem-util/src/rolling_session_window.rs

@@ -26,7 +26,7 @@ use futures::channel::oneshot;
 use polkadot_node_subsystem::{
 	errors::RuntimeApiError,
 	messages::{RuntimeApiMessage, RuntimeApiRequest},
-	overseer, SubsystemContext,
+	overseer,
 };
 use thiserror::Error;
 
@@ -94,16 +94,19 @@ pub struct RollingSessionWindow {
 
 impl RollingSessionWindow {
 	/// Initialize a new session info cache with the given window size.
-	pub async fn new(
-		ctx: &mut (impl SubsystemContext + overseer::SubsystemContext),
+	pub async fn new<Sender>(
+		mut sender: Sender,
 		window_size: SessionWindowSize,
 		block_hash: Hash,
-	) -> Result<Self, SessionsUnavailable> {
-		let session_index = get_session_index_for_child(ctx, block_hash).await?;
+	) -> Result<Self, SessionsUnavailable>
+	where
+		Sender: overseer::SubsystemSender<RuntimeApiMessage>,
+	{
+		let session_index = get_session_index_for_child(&mut sender, block_hash).await?;
 
 		let window_start = session_index.saturating_sub(window_size.get() - 1);
 
-		match load_all_sessions(ctx, block_hash, window_start, session_index).await {
+		match load_all_sessions(&mut sender, block_hash, window_start, session_index).await {
 			Err(kind) => Err(SessionsUnavailable {
 				kind,
 				info: Some(SessionsUnavailableInfo {
@@ -154,10 +157,10 @@ impl RollingSessionWindow {
 	/// some backwards drift in session index is acceptable.
 	pub async fn cache_session_info_for_head(
 		&mut self,
-		ctx: &mut (impl SubsystemContext + overseer::SubsystemContext),
+		sender: &mut impl overseer::SubsystemSender<RuntimeApiMessage>,
 		block_hash: Hash,
 	) -> Result<SessionWindowUpdate, SessionsUnavailable> {
-		let session_index = get_session_index_for_child(ctx, block_hash).await?;
+		let session_index = get_session_index_for_child(sender, block_hash).await?;
 
 		let old_window_start = self.earliest_session;
 
@@ -177,7 +180,7 @@ impl RollingSessionWindow {
 
 		let fresh_start = if latest < window_start { window_start } else { latest + 1 };
 
-		match load_all_sessions(ctx, block_hash, fresh_start, session_index).await {
+		match load_all_sessions(sender, block_hash, fresh_start, session_index).await {
 			Err(kind) => Err(SessionsUnavailable {
 				kind,
 				info: Some(SessionsUnavailableInfo {
@@ -215,17 +218,18 @@ impl RollingSessionWindow {
 // cleaner to just call the runtime API directly without needing to create an instance
 // of `RuntimeInfo`.
 async fn get_session_index_for_child(
-	ctx: &mut (impl SubsystemContext + overseer::SubsystemContext),
+	sender: &mut impl overseer::SubsystemSender<RuntimeApiMessage>,
 	block_hash: Hash,
 ) -> Result<SessionIndex, SessionsUnavailable> {
 	let (s_tx, s_rx) = oneshot::channel();
 
 	// We're requesting session index of a child to populate the cache in advance.
-	ctx.send_message(RuntimeApiMessage::Request(
-		block_hash,
-		RuntimeApiRequest::SessionIndexForChild(s_tx),
-	))
-	.await;
+	sender
+		.send_message(RuntimeApiMessage::Request(
+			block_hash,
+			RuntimeApiRequest::SessionIndexForChild(s_tx),
+		))
+		.await;
 
 	match s_rx.await {
 		Ok(Ok(s)) => Ok(s),
@@ -243,7 +247,7 @@ async fn get_session_index_for_child(
 }
 
 async fn load_all_sessions(
-	ctx: &mut (impl SubsystemContext + overseer::SubsystemContext),
+	sender: &mut impl overseer::SubsystemSender<RuntimeApiMessage>,
 	block_hash: Hash,
 	start: SessionIndex,
 	end_inclusive: SessionIndex,
@@ -251,11 +255,12 @@ async fn load_all_sessions(
 	let mut v = Vec::new();
 	for i in start..=end_inclusive {
 		let (tx, rx) = oneshot::channel();
-		ctx.send_message(RuntimeApiMessage::Request(
-			block_hash,
-			RuntimeApiRequest::SessionInfo(i, tx),
-		))
-		.await;
+		sender
+			.send_message(RuntimeApiMessage::Request(
+				block_hash,
+				RuntimeApiRequest::SessionInfo(i, tx),
+			))
+			.await;
 
 		let session_info = match rx.await {
 			Ok(Ok(Some(s))) => s,
@@ -274,7 +279,10 @@ async fn load_all_sessions(
 mod tests {
 	use super::*;
 	use assert_matches::assert_matches;
-	use polkadot_node_subsystem::messages::{AllMessages, AvailabilityRecoveryMessage};
+	use polkadot_node_subsystem::{
+		messages::{AllMessages, AvailabilityRecoveryMessage},
+		SubsystemContext,
+	};
 	use polkadot_node_subsystem_test_helpers::make_subsystem_context;
 	use polkadot_primitives::v2::Header;
 	use sp_core::testing::TaskExecutor;
@@ -319,13 +327,16 @@ mod tests {
 
 		let hash = header.hash();
 
+		let sender = ctx.sender();
+
 		let test_fut = {
 			Box::pin(async move {
 				let window = match window {
-					None =>
-						RollingSessionWindow::new(&mut ctx, TEST_WINDOW_SIZE, hash).await.unwrap(),
+					None => RollingSessionWindow::new(sender.clone(), TEST_WINDOW_SIZE, hash)
+						.await
+						.unwrap(),
 					Some(mut window) => {
-						window.cache_session_info_for_head(&mut ctx, hash).await.unwrap();
+						window.cache_session_info_for_head(sender, hash).await.unwrap();
 						window
 					},
 				};
@@ -495,8 +506,9 @@ mod tests {
 		let hash = header.hash();
 
 		let test_fut = {
+			let sender = ctx.sender().clone();
 			Box::pin(async move {
-				let res = RollingSessionWindow::new(&mut ctx, TEST_WINDOW_SIZE, hash).await;
+				let res = RollingSessionWindow::new(sender, TEST_WINDOW_SIZE, hash).await;
 				assert!(res.is_err());
 			})
 		};
@@ -555,8 +567,9 @@ mod tests {
 
 		let test_fut = {
 			Box::pin(async move {
+				let sender = ctx.sender().clone();
 				let window =
-					RollingSessionWindow::new(&mut ctx, TEST_WINDOW_SIZE, hash).await.unwrap();
+					RollingSessionWindow::new(sender, TEST_WINDOW_SIZE, hash).await.unwrap();
 
 				assert_eq!(window.earliest_session, session);
 				assert_eq!(window.session_info, vec![dummy_session_info(session)]);

polkadot/node/subsystem-util/src/runtime/mod.rs

@@ -25,7 +25,7 @@ use sp_application_crypto::AppKey;
 use sp_core::crypto::ByteArray;
 use sp_keystore::{CryptoStore, SyncCryptoStorePtr};
 
-use polkadot_node_subsystem::{SubsystemContext, SubsystemSender};
+use polkadot_node_subsystem::{messages::RuntimeApiMessage, overseer, SubsystemSender};
 use polkadot_primitives::v2::{
 	CandidateEvent, CoreState, EncodeAs, GroupIndex, GroupRotationInfo, Hash, OccupiedCore,
 	ScrapedOnChainVotes, SessionIndex, SessionInfo, Signed, SigningContext, UncheckedSigned,
@@ -123,7 +123,7 @@ impl RuntimeInfo {
 		parent: Hash,
 	) -> Result<SessionIndex>
 	where
-		Sender: SubsystemSender,
+		Sender: SubsystemSender<RuntimeApiMessage>,
 	{
 		match self.session_index_cache.get(&parent) {
 			Some(index) => Ok(*index),
@@ -143,7 +143,7 @@ impl RuntimeInfo {
 		relay_parent: Hash,
 	) -> Result<&'a ExtendedSessionInfo>
 	where
-		Sender: SubsystemSender,
+		Sender: SubsystemSender<RuntimeApiMessage>,
 	{
 		let session_index = self.get_session_index_for_child(sender, relay_parent).await?;
 
@@ -161,7 +161,7 @@ impl RuntimeInfo {
 		session_index: SessionIndex,
 	) -> Result<&'a ExtendedSessionInfo>
 	where
-		Sender: SubsystemSender,
+		Sender: SubsystemSender<RuntimeApiMessage>,
 	{
 		if !self.session_info_cache.contains(&session_index) {
 			let session_info =
@@ -190,7 +190,7 @@ impl RuntimeInfo {
 		std::result::Result<Signed<Payload, RealPayload>, UncheckedSigned<Payload, RealPayload>>,
 	>
 	where
-		Sender: SubsystemSender,
+		Sender: SubsystemSender<RuntimeApiMessage>,
 		Payload: EncodeAs<RealPayload> + Clone,
 		RealPayload: Encode + Clone,
 	{
@@ -257,25 +257,25 @@ where
 }
 
 /// Request availability cores from the runtime.
-pub async fn get_availability_cores<Context>(
-	ctx: &mut Context,
+pub async fn get_availability_cores<Sender>(
+	sender: &mut Sender,
 	relay_parent: Hash,
 ) -> Result<Vec<CoreState>>
 where
-	Context: SubsystemContext,
+	Sender: overseer::SubsystemSender<RuntimeApiMessage>,
 {
-	recv_runtime(request_availability_cores(relay_parent, ctx.sender()).await).await
+	recv_runtime(request_availability_cores(relay_parent, sender).await).await
 }
 
 /// Variant of `request_availability_cores` that only returns occupied ones.
-pub async fn get_occupied_cores<Context>(
-	ctx: &mut Context,
+pub async fn get_occupied_cores<Sender>(
+	sender: &mut Sender,
 	relay_parent: Hash,
 ) -> Result<Vec<OccupiedCore>>
 where
-	Context: SubsystemContext,
+	Sender: overseer::SubsystemSender<RuntimeApiMessage>,
 {
-	let cores = get_availability_cores(ctx, relay_parent).await?;
+	let cores = get_availability_cores(sender, relay_parent).await?;
 
 	Ok(cores
 		.into_iter()
@@ -290,17 +290,16 @@ where
 }
 
 /// Get group rotation info based on the given `relay_parent`.
-pub async fn get_group_rotation_info<Context>(
-	ctx: &mut Context,
+pub async fn get_group_rotation_info<Sender>(
+	sender: &mut Sender,
 	relay_parent: Hash,
 ) -> Result<GroupRotationInfo>
 where
-	Context: SubsystemContext,
+	Sender: overseer::SubsystemSender<RuntimeApiMessage>,
 {
 	// We drop `groups` here as we don't need them, because of `RuntimeInfo`. Ideally we would not
 	// fetch them in the first place.
-	let (_, info) =
-		recv_runtime(request_validator_groups(relay_parent, ctx.sender()).await).await?;
+	let (_, info) = recv_runtime(request_validator_groups(relay_parent, sender).await).await?;
 	Ok(info)
 }
 
@@ -310,7 +309,7 @@ pub async fn get_candidate_events<Sender>(
 	relay_parent: Hash,
 ) -> Result<Vec<CandidateEvent>>
 where
-	Sender: SubsystemSender,
+	Sender: SubsystemSender<RuntimeApiMessage>,
 {
 	recv_runtime(request_candidate_events(relay_parent, sender).await).await
 }
@@ -321,7 +320,7 @@ pub async fn get_on_chain_votes<Sender>(
 	relay_parent: Hash,
 ) -> Result<Option<ScrapedOnChainVotes>>
 where
-	Sender: SubsystemSender,
+	Sender: SubsystemSender<RuntimeApiMessage>,
 {
 	recv_runtime(request_on_chain_votes(relay_parent, sender).await).await
 }
@@ -333,7 +332,7 @@ pub async fn get_validation_code_by_hash<Sender>(
 	validation_code_hash: ValidationCodeHash,
 ) -> Result<Option<ValidationCode>>
 where
-	Sender: SubsystemSender,
+	Sender: SubsystemSender<RuntimeApiMessage>,
 {
 	recv_runtime(request_validation_code_by_hash(relay_parent, validation_code_hash, sender).await)
 		.await

polkadot/node/subsystem-util/src/tests.rs

@@ -14,6 +14,8 @@
 // You should have received a copy of the GNU General Public License
 // along with Polkadot.  If not, see <http://www.gnu.org/licenses/>.
 
+#![cfg(test)]
+
 use super::*;
 use assert_matches::assert_matches;
 use executor::block_on;
@@ -44,8 +46,9 @@ use thiserror::Error;
 
 // job structs are constructed within JobTrait::run
 // most will want to retain the sender and receiver, as well as whatever other data they like
-struct FakeCollatorProtocolJob {
+struct FakeCollatorProtocolJob<Sender> {
 	receiver: mpsc::Receiver<CollatorProtocolMessage>,
+	_phantom: std::marker::PhantomData<Sender>,
 }
 
 // Error will mostly be a wrapper to make the try operator more convenient;
@@ -57,8 +60,18 @@ enum Error {
 	Sending(#[from] mpsc::SendError),
 }
 
-impl JobTrait for FakeCollatorProtocolJob {
+impl<Sender> JobTrait for FakeCollatorProtocolJob<Sender>
+where
+	Sender: overseer::CollatorProtocolSenderTrait
+		+ std::marker::Unpin
+		+ overseer::SubsystemSender<CollatorProtocolMessage>,
+	JobSender<Sender>: overseer::CollatorProtocolSenderTrait
+		+ std::marker::Unpin
+		+ overseer::SubsystemSender<CollatorProtocolMessage>,
+{
 	type ToJob = CollatorProtocolMessage;
+	type OutgoingMessages = overseer::CollatorProtocolOutgoingMessages;
+	type Sender = Sender;
 	type Error = Error;
 	type RunArgs = bool;
 	type Metrics = ();
@@ -68,20 +81,21 @@ impl JobTrait for FakeCollatorProtocolJob {
 	/// Run a job for the parent block indicated
 	//
 	// this function is in charge of creating and executing the job's main loop
-	fn run<S: SubsystemSender>(
+	fn run(
 		_: ActivatedLeaf,
 		run_args: Self::RunArgs,
 		_metrics: Self::Metrics,
 		receiver: mpsc::Receiver<CollatorProtocolMessage>,
-		mut sender: JobSender<S>,
+		mut sender: JobSender<Sender>,
 	) -> Pin<Box<dyn Future<Output = Result<(), Self::Error>> + Send>> {
 		async move {
-			let job = FakeCollatorProtocolJob { receiver };
+			let job =
+				FakeCollatorProtocolJob { receiver, _phantom: std::marker::PhantomData::<Sender> };
 
 			if run_args {
 				sender
 					.send_message(CollatorProtocolMessage::Invalid(
-						Default::default(),
+						dummy_hash(),
 						dummy_candidate_receipt(dummy_hash()),
 					))
 					.await;
@@ -95,7 +109,10 @@ impl JobTrait for FakeCollatorProtocolJob {
 	}
 }
 
-impl FakeCollatorProtocolJob {
+impl<Sender> FakeCollatorProtocolJob<Sender>
+where
+	Sender: overseer::CollatorProtocolSenderTrait,
+{
 	async fn run_loop(mut self) -> Result<(), Error> {
 		loop {
 			match self.receiver.next().await {
@@ -111,7 +128,8 @@ impl FakeCollatorProtocolJob {
 }
 
 // with the job defined, it's straightforward to get a subsystem implementation.
-type FakeCollatorProtocolSubsystem<Spawner> = JobSubsystem<FakeCollatorProtocolJob, Spawner>;
+type FakeCollatorProtocolSubsystem<Spawner> =
+	JobSubsystem<FakeCollatorProtocolJob<test_helpers::TestSubsystemSender>, Spawner>;
 
 // this type lets us pretend to be the overseer
 type OverseerHandle = test_helpers::TestSubsystemContextHandle<CollatorProtocolMessage>;

polkadot/node/subsystem/src/lib.rs

@@ -24,9 +24,7 @@
 pub use jaeger::*;
 pub use polkadot_node_jaeger as jaeger;
 
-pub use polkadot_overseer::{
-	self as overseer, ActiveLeavesUpdate, OverseerConnector, OverseerSignal,
-};
+pub use polkadot_overseer::{self as overseer, *};
 
 pub use polkadot_node_subsystem_types::{
 	errors::{self, *},
@@ -54,37 +52,5 @@ pub type FromOverseer<M> = polkadot_overseer::gen::FromOverseer<M, OverseerSigna
 pub type SubsystemInstance<Message> =
 	polkadot_overseer::gen::SubsystemInstance<Message, OverseerSignal>;
 
-/// Sender trait for the `AllMessages` wrapper.
-pub trait SubsystemSender: polkadot_overseer::gen::SubsystemSender<messages::AllMessages> {}
-
-impl<T> SubsystemSender for T where T: polkadot_overseer::gen::SubsystemSender<messages::AllMessages>
-{}
-
 /// Spawned subsystem.
 pub type SpawnedSubsystem = polkadot_overseer::gen::SpawnedSubsystem<SubsystemError>;
-
-/// Convenience trait specialization.
-pub trait SubsystemContext:
-	polkadot_overseer::gen::SubsystemContext<
-	Signal = OverseerSignal,
-	AllMessages = messages::AllMessages,
-	Error = SubsystemError,
->
-{
-	/// The message type the subsystem consumes.
-	type Message: std::fmt::Debug + Send + 'static;
-	/// Sender type to communicate with other subsystems.
-	type Sender: SubsystemSender + Send + Clone + 'static;
-}
-
-impl<T> SubsystemContext for T
-where
-	T: polkadot_overseer::gen::SubsystemContext<
-		Signal = OverseerSignal,
-		AllMessages = messages::AllMessages,
-		Error = SubsystemError,
-	>,
-{
-	type Message = <Self as polkadot_overseer::gen::SubsystemContext>::Message;
-	type Sender = <Self as polkadot_overseer::gen::SubsystemContext>::Sender;
-}