add ActiveLeavesUpdate, remove StartWork, StopWork (#1458)

* add ActiveLeavesUpdate, remove StartWork, StopWork

* replace StartWork, StopWork in subsystem crate tests

* mechanically update OverseerSignal in other modules

* convert overseer to take advantage of new multi-hash update abilities

Note: this does not yet convert the tests; some of the tests now freeze:

test tests::overseer_start_stop_works ... test tests::overseer_start_stop_works has been running for over 60 seconds
test tests::overseer_finalize_works ... test tests::overseer_finalize_works has been running for over 60 seconds

* fix broken overseer tests

* manually impl PartialEq for ActiveLeavesUpdate, rm trait Equivalent

This cleans up the code a bit and makes it easier in the future to
do the right thing when comparing ALUs.

* use target in all network bridge logging

* reduce spamming of  and

polkadot/Cargo.lock

@@ -4670,6 +4670,7 @@ dependencies = [
  "polkadot-statement-table",
  "sc-keystore",
  "sc-network",
+ "smallvec 1.4.1",
  "sp-core",
  "streamunordered",
 ]

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

@@ -778,7 +778,7 @@ mod tests {
 	};
 	use polkadot_subsystem::{
 		messages::{RuntimeApiRequest, SchedulerRoster},
-		FromOverseer, OverseerSignal,
+		ActiveLeavesUpdate, FromOverseer, OverseerSignal,
 	};
 	use sp_keyring::Sr25519Keyring;
 	use std::collections::HashMap;
@@ -968,7 +968,7 @@ mod tests {
 	) {
 		// Start work on some new parent.
 		virtual_overseer.send(FromOverseer::Signal(
-			OverseerSignal::StartWork(test_state.relay_parent))
+			OverseerSignal::ActiveLeaves(ActiveLeavesUpdate::start_work(test_state.relay_parent)))
 		).await;
 
 		// Check that subsystem job issues a request for a validator set.
@@ -1084,7 +1084,7 @@ mod tests {
 			);
 
 			virtual_overseer.send(FromOverseer::Signal(
-				OverseerSignal::StopWork(test_state.relay_parent))
+				OverseerSignal::ActiveLeaves(ActiveLeavesUpdate::stop_work(test_state.relay_parent)))
 			).await;
 		});
 	}
@@ -1202,7 +1202,7 @@ mod tests {
 			assert_eq!(backed[0].0.validator_indices, bitvec::bitvec![Lsb0, u8; 1, 1, 0]);
 
 			virtual_overseer.send(FromOverseer::Signal(
-				OverseerSignal::StopWork(test_state.relay_parent))
+				OverseerSignal::ActiveLeaves(ActiveLeavesUpdate::stop_work(test_state.relay_parent)))
 			).await;
 		});
 	}
@@ -1476,7 +1476,7 @@ mod tests {
 			);
 
 			virtual_overseer.send(FromOverseer::Signal(
-				OverseerSignal::StopWork(test_state.relay_parent))
+				OverseerSignal::ActiveLeaves(ActiveLeavesUpdate::stop_work(test_state.relay_parent)))
 			).await;
 		});
 	}

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

@@ -28,7 +28,7 @@ use node_primitives::{ProtocolId, View};
 use log::{trace, warn};
 use polkadot_subsystem::messages::*;
 use polkadot_subsystem::{
-	FromOverseer, OverseerSignal, SpawnedSubsystem, Subsystem, SubsystemContext, SubsystemResult,
+	ActiveLeavesUpdate, FromOverseer, OverseerSignal, SpawnedSubsystem, Subsystem, SubsystemContext, SubsystemResult,
 };
 use polkadot_primitives::v1::{Hash, SignedAvailabilityBitfield, SigningContext, ValidatorId};
 use sc_network::ReputationChange;
@@ -157,24 +157,27 @@ impl BitfieldDistribution {
 						warn!(target: "bitd", "Failed to handle incomming network messages: {:?}", e);
 					}
 				}
-				FromOverseer::Signal(OverseerSignal::StartWork(relay_parent)) => {
-					trace!(target: "bitd", "Start {:?}", relay_parent);
-					// query basic system parameters once
-					let (validator_set, signing_context) =
-						query_basics(&mut ctx, relay_parent).await?;
+				FromOverseer::Signal(OverseerSignal::ActiveLeaves(ActiveLeavesUpdate { activated, deactivated })) => {
+					for relay_parent in activated {
+						trace!(target: "bitd", "Start {:?}", relay_parent);
+						// query basic system parameters once
+						let (validator_set, signing_context) =
+							query_basics(&mut ctx, relay_parent).await?;
 
-					let _ = state.per_relay_parent.insert(
-						relay_parent,
-						PerRelayParentData {
-							signing_context,
-							validator_set,
-							..Default::default()
-						},
-					);
-				}
-				FromOverseer::Signal(OverseerSignal::StopWork(relay_parent)) => {
-					trace!(target: "bitd", "Stop {:?}", relay_parent);
-					// defer the cleanup to the view change
+						let _ = state.per_relay_parent.insert(
+							relay_parent,
+							PerRelayParentData {
+								signing_context,
+								validator_set,
+								..Default::default()
+							},
+						);
+					}
+
+					for relay_parent in deactivated {
+						trace!(target: "bitd", "Stop {:?}", relay_parent);
+						// defer the cleanup to the view change
+					}
 				}
 				FromOverseer::Signal(OverseerSignal::Conclude) => {
 					trace!(target: "bitd", "Conclude");

polkadot/node/network/bridge/Cargo.toml

@@ -17,6 +17,7 @@ sp-runtime = { git = "https://github.com/paritytech/substrate", branch = "master
 polkadot-subsystem = { package = "polkadot-node-subsystem", path = "../../subsystem" }
 
 [dev-dependencies]
-parking_lot = "0.10.0"
 assert_matches = "1.3.0"
+parking_lot = "0.10.0"
+polkadot-subsystem = { package = "polkadot-node-subsystem", path = "../../subsystem", features = [ "test-helpers" ] }
 sp-core = { git = "https://github.com/paritytech/substrate", branch = "master" }

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

@@ -28,7 +28,7 @@ use sc_network::{
 use sp_runtime::ConsensusEngineId;
 
 use polkadot_subsystem::{
-	FromOverseer, OverseerSignal, Subsystem, SubsystemContext, SpawnedSubsystem, SubsystemError,
+	ActiveLeavesUpdate, FromOverseer, OverseerSignal, Subsystem, SubsystemContext, SpawnedSubsystem, SubsystemError,
 	SubsystemResult,
 };
 use polkadot_subsystem::messages::{NetworkBridgeEvent, NetworkBridgeMessage, AllMessages};
@@ -57,6 +57,9 @@ const UNKNOWN_PROTO_COST: ReputationChange
 const MALFORMED_VIEW_COST: ReputationChange
 	= ReputationChange::new(-500, "Malformed view");
 
+// network bridge log target
+const TARGET: &'static str = "network_bridge";
+
 /// Messages received on the network.
 #[derive(Debug, Encode, Decode, Clone)]
 pub enum WireMessage {
@@ -203,8 +206,7 @@ enum Action {
 	RegisterEventProducer(ProtocolId, fn(NetworkBridgeEvent) -> AllMessages),
 	SendMessage(Vec<PeerId>, ProtocolId, Vec<u8>),
 	ReportPeer(PeerId, ReputationChange),
-	StartWork(Hash),
-	StopWork(Hash),
+	ActiveLeaves(ActiveLeavesUpdate),
 
 	PeerConnected(PeerId, ObservedRole),
 	PeerDisconnected(PeerId),
@@ -217,10 +219,8 @@ fn action_from_overseer_message(
 	res: polkadot_subsystem::SubsystemResult<FromOverseer<NetworkBridgeMessage>>,
 ) -> Action {
 	match res {
-		Ok(FromOverseer::Signal(OverseerSignal::StartWork(relay_parent)))
-			=> Action::StartWork(relay_parent),
-		Ok(FromOverseer::Signal(OverseerSignal::StopWork(relay_parent)))
-			=> Action::StopWork(relay_parent),
+		Ok(FromOverseer::Signal(OverseerSignal::ActiveLeaves(active_leaves)))
+			=> Action::ActiveLeaves(active_leaves),
 		Ok(FromOverseer::Signal(OverseerSignal::Conclude)) => Action::Abort,
 		Ok(FromOverseer::Communication { msg }) => match msg {
 			NetworkBridgeMessage::RegisterEventProducer(protocol_id, message_producer)
@@ -230,7 +230,7 @@ fn action_from_overseer_message(
 				=> Action::SendMessage(peers, protocol, message),
 		},
 		Err(e) => {
-			log::warn!("Shutting down Network Bridge due to error {:?}", e);
+			log::warn!(target: TARGET, "Shutting down Network Bridge due to error {:?}", e);
 			Action::Abort
 		}
 	}
@@ -239,7 +239,7 @@ fn action_from_overseer_message(
 fn action_from_network_message(event: Option<NetworkEvent>) -> Option<Action> {
 	match event {
 		None => {
-			log::info!("Shutting down Network Bridge: underlying event stream concluded");
+			log::info!(target: TARGET, "Shutting down Network Bridge: underlying event stream concluded");
 			Some(Action::Abort)
 		}
 		Some(NetworkEvent::Dht(_)) => None,
@@ -392,37 +392,23 @@ async fn run_network<N: Network>(
 			Action::ReportPeer(peer, rep) => {
 				net.report_peer(peer, rep).await?;
 			}
-			Action::StartWork(relay_parent) => {
-				live_heads.push(relay_parent);
-				if let Some(view_update)
-					= update_view(&peers, &live_heads, &mut net, &mut local_view).await?
-				{
-					if let Err(e) = dispatch_update_to_all(
-						view_update,
-						event_producers.values(),
-						&mut ctx,
-					).await {
-						log::warn!("Aborting - Failure to dispatch messages to overseer");
-						return Err(e)
-					}
-				}
-			}
-			Action::StopWork(relay_parent) => {
-				live_heads.retain(|h| h != &relay_parent);
-				if let Some(view_update)
-					= update_view(&peers, &live_heads, &mut net, &mut local_view).await?
-				{
-					if let Err(e) = dispatch_update_to_all(
-						view_update,
-						event_producers.values(),
-						&mut ctx,
-					).await {
-						log::warn!("Aborting - Failure to dispatch messages to overseer");
-						return Err(e)
-					}
-				}
-			}
+			Action::ActiveLeaves(ActiveLeavesUpdate { activated, deactivated }) => {
+				live_heads.extend(activated);
+				live_heads.retain(|h| !deactivated.contains(h));
 
+				if let Some(view_update)
+					= update_view(&peers, &live_heads, &mut net, &mut local_view).await?
+				{
+					if let Err(e) = dispatch_update_to_all(
+						view_update,
+						event_producers.values(),
+						&mut ctx,
+					).await {
+						log::warn!(target: TARGET, "Aborting - Failure to dispatch messages to overseer");
+						return Err(e)
+					}
+				}
+			}
 			Action::PeerConnected(peer, role) => {
 				match peers.entry(peer.clone()) {
 					HEntry::Occupied(_) => continue,
@@ -450,7 +436,7 @@ async fn run_network<N: Network>(
 						event_producers.values(),
 						&mut ctx,
 					).await {
-						log::warn!("Aborting - Failure to dispatch messages to overseer");
+						log::warn!(target: TARGET, "Aborting - Failure to dispatch messages to overseer");
 						return Err(e)
 					}
 				}
@@ -510,7 +496,7 @@ async fn run_network<N: Network>(
 
 				let send_messages = ctx.send_messages(outgoing_messages);
 				if let Err(e) = send_messages.await {
-					log::warn!("Aborting - Failure to dispatch messages to overseer");
+					log::warn!(target: TARGET, "Aborting - Failure to dispatch messages to overseer");
 					return Err(e)
 				}
 			},
@@ -670,7 +656,7 @@ mod tests {
 
 			let hash_a = Hash::from([1; 32]);
 
-			virtual_overseer.send(FromOverseer::Signal(OverseerSignal::StartWork(hash_a))).await;
+			virtual_overseer.send(FromOverseer::Signal(OverseerSignal::ActiveLeaves(ActiveLeavesUpdate::start_work(hash_a)))).await;
 
 			let actions = network_handle.next_network_actions(2).await;
 			let wire_message = WireMessage::ViewUpdate(View(vec![hash_a])).encode();

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

@@ -21,7 +21,7 @@
 
 use polkadot_primitives::v1::{Hash, PoV, CandidateDescriptor};
 use polkadot_subsystem::{
-	OverseerSignal, SubsystemContext, Subsystem, SubsystemResult, FromOverseer, SpawnedSubsystem,
+	ActiveLeavesUpdate, OverseerSignal, SubsystemContext, Subsystem, SubsystemResult, FromOverseer, SpawnedSubsystem,
 };
 use polkadot_subsystem::messages::{
 	PoVDistributionMessage, NetworkBridgeEvent, ReputationChange as Rep, PeerId,
@@ -107,23 +107,24 @@ async fn handle_signal(
 ) -> SubsystemResult<bool> {
 	match signal {
 		OverseerSignal::Conclude => Ok(true),
-		OverseerSignal::StartWork(relay_parent) => {
-			let (vals_tx, vals_rx) = oneshot::channel();
-			ctx.send_message(AllMessages::RuntimeApi(RuntimeApiMessage::Request(
-				relay_parent,
-				RuntimeApiRequest::Validators(vals_tx),
-			))).await?;
+		OverseerSignal::ActiveLeaves(ActiveLeavesUpdate { activated, deactivated }) => {
+			for relay_parent in activated {
+				let (vals_tx, vals_rx) = oneshot::channel();
+				ctx.send_message(AllMessages::RuntimeApi(RuntimeApiMessage::Request(
+					relay_parent,
+					RuntimeApiRequest::Validators(vals_tx),
+				))).await?;
 
-			state.relay_parent_state.insert(relay_parent, BlockBasedState {
-				known: HashMap::new(),
-				fetching: HashMap::new(),
-				n_validators: vals_rx.await?.len(),
-			});
+				state.relay_parent_state.insert(relay_parent, BlockBasedState {
+					known: HashMap::new(),
+					fetching: HashMap::new(),
+					n_validators: vals_rx.await?.len(),
+				});
+			}
 
-			Ok(false)
-		}
-		OverseerSignal::StopWork(relay_parent) => {
-			state.relay_parent_state.remove(&relay_parent);
+			for relay_parent in deactivated {
+				state.relay_parent_state.remove(&relay_parent);
+			}
 
 			Ok(false)
 		}

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

@@ -21,7 +21,7 @@
 
 use polkadot_subsystem::{
 	Subsystem, SubsystemResult, SubsystemContext, SpawnedSubsystem,
-	FromOverseer, OverseerSignal,
+	ActiveLeavesUpdate, FromOverseer, OverseerSignal,
 };
 use polkadot_subsystem::messages::{
 	AllMessages, NetworkBridgeMessage, NetworkBridgeEvent, StatementDistributionMessage,
@@ -840,30 +840,29 @@ async fn run(
 	loop {
 		let message = ctx.recv().await?;
 		match message {
-			FromOverseer::Signal(OverseerSignal::StartWork(relay_parent)) => {
-				let (validators, session_index) = {
-					let (val_tx, val_rx) = oneshot::channel();
-					let (session_tx, session_rx) = oneshot::channel();
+			FromOverseer::Signal(OverseerSignal::ActiveLeaves(ActiveLeavesUpdate { activated, .. })) => {
+				for relay_parent in activated {
+					let (validators, session_index) = {
+						let (val_tx, val_rx) = oneshot::channel();
+						let (session_tx, session_rx) = oneshot::channel();
 
-					let val_message = AllMessages::RuntimeApi(
-						RuntimeApiMessage::Request(relay_parent, RuntimeApiRequest::Validators(val_tx)),
-					);
-					let session_message = AllMessages::RuntimeApi(
-						RuntimeApiMessage::Request(relay_parent, RuntimeApiRequest::SigningContext(session_tx)),
-					);
+						let val_message = AllMessages::RuntimeApi(
+							RuntimeApiMessage::Request(relay_parent, RuntimeApiRequest::Validators(val_tx)),
+						);
+						let session_message = AllMessages::RuntimeApi(
+							RuntimeApiMessage::Request(relay_parent, RuntimeApiRequest::SigningContext(session_tx)),
+						);
 
-					ctx.send_messages(
-						std::iter::once(val_message).chain(std::iter::once(session_message))
-					).await?;
+						ctx.send_messages(
+							std::iter::once(val_message).chain(std::iter::once(session_message))
+						).await?;
 
-					(val_rx.await?, session_rx.await?.session_index)
-				};
+						(val_rx.await?, session_rx.await?.session_index)
+					};
 
-				active_heads.entry(relay_parent)
-					.or_insert(ActiveHeadData::new(validators, session_index));
-			}
-			FromOverseer::Signal(OverseerSignal::StopWork(_relay_parent)) => {
-				// do nothing - we will handle this when our view changes.
+					active_heads.entry(relay_parent)
+						.or_insert(ActiveHeadData::new(validators, session_index));
+				}
 			}
 			FromOverseer::Signal(OverseerSignal::Conclude) => break,
 			FromOverseer::Communication { msg } => match msg {

polkadot/node/overseer/src/lib.rs

@@ -83,7 +83,7 @@ use polkadot_subsystem::messages::{
 };
 pub use polkadot_subsystem::{
 	Subsystem, SubsystemContext, OverseerSignal, FromOverseer, SubsystemError, SubsystemResult,
-	SpawnedSubsystem,
+	SpawnedSubsystem, ActiveLeavesUpdate,
 };
 use polkadot_node_primitives::SpawnNamed;
 
@@ -726,12 +726,15 @@ where
 	/// Run the `Overseer`.
 	pub async fn run(mut self) -> SubsystemResult<()> {
 		let leaves = std::mem::take(&mut self.leaves);
+		let mut update = ActiveLeavesUpdate::default();
 
 		for leaf in leaves.into_iter() {
-			self.broadcast_signal(OverseerSignal::StartWork(leaf.0)).await?;
+			update.activated.push(leaf.0);
 			self.active_leaves.insert(leaf);
 		}
 
+		self.broadcast_signal(OverseerSignal::ActiveLeaves(update)).await?;
+
 		loop {
 			while let Poll::Ready(Some(msg)) = poll!(&mut self.events_rx.next()) {
 				match msg {
@@ -775,33 +778,35 @@ where
 	}
 
 	async fn block_imported(&mut self, block: BlockInfo) -> SubsystemResult<()> {
+		let mut update = ActiveLeavesUpdate::default();
+
 		if let Some(parent) = self.active_leaves.take(&(block.parent_hash, block.number - 1)) {
-			self.broadcast_signal(OverseerSignal::StopWork(parent.0)).await?;
+			update.deactivated.push(parent.0);
 		}
 
 		if !self.active_leaves.contains(&(block.hash, block.number)) {
-			self.broadcast_signal(OverseerSignal::StartWork(block.hash)).await?;
+			update.activated.push(block.hash);
 			self.active_leaves.insert((block.hash, block.number));
 		}
 
+		self.broadcast_signal(OverseerSignal::ActiveLeaves(update)).await?;
+
 		Ok(())
 	}
 
 	async fn block_finalized(&mut self, block: BlockInfo) -> SubsystemResult<()> {
-		let mut stop_these = Vec::new();
+		let mut update = ActiveLeavesUpdate::default();
 
 		self.active_leaves.retain(|(h, n)| {
 			if *n <= block.number {
-				stop_these.push(*h);
+				update.deactivated.push(*h);
 				false
 			} else {
 				true
 			}
 		});
 
-		for hash in stop_these.into_iter() {
-			self.broadcast_signal(OverseerSignal::StopWork(hash)).await?
-		}
+		self.broadcast_signal(OverseerSignal::ActiveLeaves(update)).await?;
 
 		Ok(())
 	}
@@ -1273,11 +1278,15 @@ mod tests {
 			handler.block_imported(third_block).await.unwrap();
 
 			let expected_heartbeats = vec![
-				OverseerSignal::StartWork(first_block_hash),
-				OverseerSignal::StopWork(first_block_hash),
-				OverseerSignal::StartWork(second_block_hash),
-				OverseerSignal::StopWork(second_block_hash),
-				OverseerSignal::StartWork(third_block_hash),
+				OverseerSignal::ActiveLeaves(ActiveLeavesUpdate::start_work(first_block_hash)),
+				OverseerSignal::ActiveLeaves(ActiveLeavesUpdate {
+					activated: [second_block_hash].as_ref().into(),
+					deactivated: [first_block_hash].as_ref().into(),
+				}),
+				OverseerSignal::ActiveLeaves(ActiveLeavesUpdate {
+					activated: [third_block_hash].as_ref().into(),
+					deactivated: [second_block_hash].as_ref().into(),
+				}),
 			];
 
 			loop {
@@ -1371,10 +1380,14 @@ mod tests {
 			handler.block_finalized(third_block).await.unwrap();
 
 			let expected_heartbeats = vec![
-				OverseerSignal::StartWork(first_block_hash),
-				OverseerSignal::StartWork(second_block_hash),
-				OverseerSignal::StopWork(first_block_hash),
-				OverseerSignal::StopWork(second_block_hash),
+				OverseerSignal::ActiveLeaves(ActiveLeavesUpdate {
+					activated: [first_block_hash, second_block_hash].as_ref().into(),
+					..Default::default()
+				}),
+				OverseerSignal::ActiveLeaves(ActiveLeavesUpdate {
+					deactivated: [first_block_hash, second_block_hash].as_ref().into(),
+					..Default::default()
+				}),
 			];
 
 			loop {

polkadot/node/subsystem/Cargo.toml

@@ -19,6 +19,7 @@ polkadot-node-primitives = { path = "../primitives" }
 polkadot-primitives = { path = "../../primitives" }
 polkadot-statement-table = { path = "../../statement-table" }
 sc-network = { git = "https://github.com/paritytech/substrate", branch = "master" }
+smallvec = "1.4.1"
 sp-core = { git = "https://github.com/paritytech/substrate", branch = "master" }
 streamunordered = "0.5.1"
 

polkadot/node/subsystem/src/lib.rs

@@ -30,6 +30,7 @@ use futures::future::BoxFuture;
 
 use polkadot_primitives::v1::Hash;
 use async_trait::async_trait;
+use smallvec::SmallVec;
 
 use crate::messages::AllMessages;
 
@@ -38,13 +39,51 @@ pub mod util;
 #[cfg(any(test, feature = "test-helpers"))]
 pub mod test_helpers;
 
+/// How many slots are stack-reserved for active leaves updates
+///
+/// If there are fewer than this number of slots, then we've wasted some stack space.
+/// If there are greater than this number of slots, then we fall back to a heap vector.
+const ACTIVE_LEAVES_SMALLVEC_CAPACITY: usize = 8;
+
+/// Changes in the set of active leaves: the parachain heads which we care to work on.
+///
+/// Note that the activated and deactivated fields indicate deltas, not complete sets.
+#[derive(Clone, Debug, Default, Eq)]
+pub struct ActiveLeavesUpdate {
+	/// New relay chain block hashes of interest.
+	pub activated: SmallVec<[Hash; ACTIVE_LEAVES_SMALLVEC_CAPACITY]>,
+	/// Relay chain block hashes no longer of interest.
+	pub deactivated: SmallVec<[Hash; ACTIVE_LEAVES_SMALLVEC_CAPACITY]>,
+}
+
+impl ActiveLeavesUpdate {
+	/// Create a ActiveLeavesUpdate with a single activated hash
+	pub fn start_work(hash: Hash) -> Self {
+		Self { activated: [hash].as_ref().into(), ..Default::default() }
+	}
+
+	/// Create a ActiveLeavesUpdate with a single deactivated hash
+	pub fn stop_work(hash: Hash) -> Self {
+		Self { deactivated: [hash].as_ref().into(), ..Default::default() }
+	}
+}
+
+impl PartialEq for ActiveLeavesUpdate {
+	/// Equality for `ActiveLeavesUpdate` doesnt imply bitwise equality.
+	///
+	/// Instead, it means equality when `activated` and `deactivated` are considered as sets.
+	fn eq(&self, other: &Self) -> bool {
+		use std::collections::HashSet;
+		self.activated.iter().collect::<HashSet<_>>() == other.activated.iter().collect::<HashSet<_>>() &&
+			self.deactivated.iter().collect::<HashSet<_>>() == other.deactivated.iter().collect::<HashSet<_>>()
+	}
+}
+
 /// Signals sent by an overseer to a subsystem.
 #[derive(PartialEq, Clone, Debug)]
 pub enum OverseerSignal {
-	/// `Subsystem` should start working on block-based work, given by the relay-chain block hash.
-	StartWork(Hash),
-	/// `Subsystem` should stop working on block-based work specified by the relay-chain block hash.
-	StopWork(Hash),
+	/// Subsystems should adjust their jobs to start and stop work on appropriate block hashes.
+	ActiveLeaves(ActiveLeavesUpdate),
 	/// Conclude the work of the `Overseer` and all `Subsystem`s.
 	Conclude,
 }

polkadot/node/subsystem/src/util.rs

@@ -602,21 +602,25 @@ where
 		err_tx: &mut Option<mpsc::Sender<(Option<Hash>, JobsError<Job::Error>)>>
 	) -> bool {
 		use crate::FromOverseer::{Communication, Signal};
-		use crate::OverseerSignal::{Conclude, StartWork, StopWork};
+		use crate::ActiveLeavesUpdate;
+		use crate::OverseerSignal::{Conclude, ActiveLeaves};
 
 		match incoming {
-			Ok(Signal(StartWork(hash))) => {
-				if let Err(e) = jobs.spawn_job(hash, run_args.clone()) {
-					log::error!("Failed to spawn a job: {:?}", e);
-					Self::fwd_err(Some(hash), e.into(), err_tx).await;
-					return true;
+			Ok(Signal(ActiveLeaves(ActiveLeavesUpdate { activated, deactivated }))) => {
+				for hash in activated {
+					if let Err(e) = jobs.spawn_job(hash, run_args.clone()) {
+						log::error!("Failed to spawn a job: {:?}", e);
+						Self::fwd_err(Some(hash), e.into(), err_tx).await;
+						return true;
+					}
 				}
-			}
-			Ok(Signal(StopWork(hash))) => {
-				if let Err(e) = jobs.stop_job(hash).await {
-					log::error!("Failed to stop a job: {:?}", e);
-					Self::fwd_err(Some(hash), e.into(), err_tx).await;
-					return true;
+
+				for hash in deactivated {
+					if let Err(e) = jobs.stop_job(hash).await {
+						log::error!("Failed to stop a job: {:?}", e);
+						Self::fwd_err(Some(hash), e.into(), err_tx).await;
+						return true;
+					}
 				}
 			}
 			Ok(Signal(Conclude)) => {
@@ -725,6 +729,7 @@ mod tests {
 			JobTrait,
 			ToJobTrait,
 		},
+		ActiveLeavesUpdate,
 		FromOverseer,
 		OverseerSignal,
 	};
@@ -920,12 +925,12 @@ mod tests {
 		run_args.insert(relay_parent.clone(), vec![FromJob::Test(test_message.clone())]);
 
 		test_harness(run_args, |mut overseer_handle, err_rx| async move {
-			overseer_handle.send(FromOverseer::Signal(OverseerSignal::StartWork(relay_parent))).await;
+			overseer_handle.send(FromOverseer::Signal(OverseerSignal::ActiveLeaves(ActiveLeavesUpdate::start_work(relay_parent)))).await;
 			assert_matches!(
 				overseer_handle.recv().await,
 				AllMessages::Test(msg) if msg == test_message
 			);
-			overseer_handle.send(FromOverseer::Signal(OverseerSignal::StopWork(relay_parent))).await;
+			overseer_handle.send(FromOverseer::Signal(OverseerSignal::ActiveLeaves(ActiveLeavesUpdate::stop_work(relay_parent)))).await;
 
 			let errs: Vec<_> = err_rx.collect().await;
 			assert_eq!(errs.len(), 0);
@@ -938,7 +943,7 @@ mod tests {
 		let run_args = HashMap::new();
 
 		test_harness(run_args, |mut overseer_handle, err_rx| async move {
-			overseer_handle.send(FromOverseer::Signal(OverseerSignal::StopWork(relay_parent))).await;
+			overseer_handle.send(FromOverseer::Signal(OverseerSignal::ActiveLeaves(ActiveLeavesUpdate::stop_work(relay_parent)))).await;
 
 			let errs: Vec<_> = err_rx.collect().await;
 			assert_eq!(errs.len(), 1);