Add some message types from subsystem definitions (#1265)

* introduce polkadot-node-primitives

* guide: change statement distribution message types

* guide: remove variant from `CandidateSelectionMessage`

* add a few more message types

* add TODOs

* Almost all messages

* NewBackedCandidate notification

* Formatting

* Use AttestedCandidate as BackedCandidate

* Update node/primitives/src/lib.rs

Co-authored-by: Peter Goodspeed-Niklaus <coriolinus@users.noreply.github.com>

* Fix the tests

* Bring in types from #1242

* Adds network bridge messages

* More message types from doc

* use fn pointer type

* Fixes from the review

* Add missing Runtime subsystem message

* rename to CandidateValidationMessage and fix tests

Co-authored-by: Fedor Sakharov <fedor.sakharov@gmail.com>
Co-authored-by: Peter Goodspeed-Niklaus <coriolinus@users.noreply.github.com>

polkadot/node/messages/src/lib.rs

@@ -22,7 +22,17 @@
 //!
 //! Subsystems' APIs are defined separately from their implementation, leading to easier mocking.
 
-use polkadot_primitives::Hash;
+use futures::channel::{mpsc, oneshot};
+
+use sc_network::{ObservedRole, ReputationChange, PeerId, config::ProtocolId};
+use polkadot_primitives::{BlockNumber, Hash, Signature};
+use polkadot_primitives::parachain::{
+	AbridgedCandidateReceipt, PoVBlock, ErasureChunk, BackedCandidate, Id as ParaId,
+	SignedAvailabilityBitfield, SigningContext, ValidatorId, ValidationCode, ValidatorIndex,
+};
+use polkadot_node_primitives::{
+	MisbehaviorReport, SignedStatement,
+};
 
 /// Signals sent by an overseer to a subsystem.
 #[derive(PartialEq, Clone, Debug)]
@@ -35,24 +45,174 @@ pub enum OverseerSignal {
 	Conclude,
 }
 
-/// A message type used by the Validation Subsystem.
+/// A notification of a new backed candidate.
 #[derive(Debug)]
-pub enum ValidationSubsystemMessage {
-	ValidityAttestation,
+pub struct NewBackedCandidate(pub BackedCandidate);
+
+/// Messages received by the Candidate Selection subsystem.
+#[derive(Debug)]
+pub enum CandidateSelectionMessage {
+	/// We recommended a particular candidate to be seconded, but it was invalid; penalize the collator.
+	/// The hash is the relay parent.
+	Invalid(Hash, AbridgedCandidateReceipt),
 }
 
-/// A message type used by the CandidateBacking Subsystem.
+/// Messages received by the Candidate Backing subsystem.
 #[derive(Debug)]
-pub enum CandidateBackingSubsystemMessage {
-	RegisterBackingWatcher,
-	Second,
+pub enum CandidateBackingMessage {
+	/// Registers a stream listener for updates to the set of backable candidates that could be backed
+	/// in a child of the given relay-parent, referenced by its hash.
+	RegisterBackingWatcher(Hash, mpsc::Sender<NewBackedCandidate>),
+	/// Note that the Candidate Backing subsystem should second the given candidate in the context of the
+	/// given relay-parent (ref. by hash). This candidate must be validated.
+	Second(Hash, AbridgedCandidateReceipt),
+	/// Note a validator's statement about a particular candidate. Disagreements about validity must be escalated
+	/// to a broader check by Misbehavior Arbitration. Agreements are simply tallied until a quorum is reached.
+	Statement(Hash, SignedStatement),
+}
+
+/// Blanket error for validation failing.
+#[derive(Debug)]
+pub struct ValidationFailed;
+
+/// Messages received by the Validation subsystem
+#[derive(Debug)]
+pub enum CandidateValidationMessage {
+	/// Validate a candidate, sending a side-channel response of valid or invalid.
+	///
+	/// Provide the relay-parent in whose context this should be validated, the full candidate receipt,
+	/// and the PoV.
+	Validate(
+		Hash,
+		AbridgedCandidateReceipt,
+		PoVBlock,
+		oneshot::Sender<Result<(), ValidationFailed>>,
+	),
+}
+
+/// Chain heads.
+///
+/// Up to `N` (5?) chain heads.
+pub struct View(pub Vec<Hash>);
+
+/// Events from network.
+pub enum NetworkBridgeEvent {
+	/// A peer has connected.
+	PeerConnected(PeerId, ObservedRole),
+
+	/// A peer has disconnected.
+	PeerDisconnected(PeerId),
+
+	/// Peer has sent a message.
+	PeerMessage(PeerId, Vec<u8>),
+
+	/// Peer's `View` has changed.
+	PeerViewChange(PeerId, View),
+
+	/// Our `View` has changed.
+	OurViewChange(View),
+}
+
+/// Messages received by the network bridge subsystem.
+pub enum NetworkBridgeSubsystemMessage {
+	/// Register an event producer on startup.
+	RegisterEventProducer(ProtocolId, fn(NetworkBridgeEvent) -> AllMessages),
+
+	/// Report a peer for their actions.
+	ReportPeer(PeerId, ReputationChange),
+
+	/// Send a message to multiple peers.
+	SendMessage(Vec<PeerId>, ProtocolId, Vec<u8>),
+}
+
+/// Availability Distribution Message.
+pub enum AvailabilityDistributionMessage {
+	/// Distribute an availability chunk to other validators.
+	DistributeChunk(Hash, ErasureChunk),
+
+	/// Fetch an erasure chunk from networking by candidate hash and chunk index.
+	FetchChunk(Hash, u32),
+
+	/// Event from the network bridge.
+	NetworkBridgeUpdate(NetworkBridgeEvent),
+}
+
+/// Bitfield distribution message.
+pub enum BitfieldDistributionMessage {
+	/// Distribute a bitfield via gossip to other validators.
+	DistributeBitfield(Hash, SignedAvailabilityBitfield),
+
+	/// Event from the network bridge.
+	NetworkBridgeUpdate(NetworkBridgeEvent),
+}
+
+/// Availability store subsystem message.
+pub enum AvailabilityStoreMessage {
+	/// Query a `PoVBlock` from the AV store.
+	QueryPoV(Hash, oneshot::Sender<Option<PoVBlock>>),
+
+	/// Query an `ErasureChunk` from the AV store.
+	QueryChunk(Hash, ValidatorIndex, oneshot::Sender<ErasureChunk>),
+
+	/// Store an `ErasureChunk` in the AV store.
+	StoreChunk(Hash, ValidatorIndex, ErasureChunk),
+}
+
+/// A request to the Runtime API subsystem.
+pub enum RuntimeApiRequest {
+	/// Get the current validator set.
+	Validators(oneshot::Sender<Vec<ValidatorId>>),
+	/// Get a signing context for bitfields and statements.
+	SigningContext(oneshot::Sender<SigningContext>),
+	/// Get the validation code for a specific para, assuming execution under given block number, and
+	/// an optional block number representing an intermediate parablock executed in the context of
+	/// that block.
+	ValidationCode(ParaId, BlockNumber, Option<BlockNumber>, oneshot::Sender<ValidationCode>),
+}
+
+/// A message to the Runtime API subsystem.
+pub enum RuntimeApiMessage {
+	/// Make a request of the runtime API against the post-state of the given relay-parent.
+	Request(Hash, RuntimeApiRequest),
+}
+
+/// Statement distribution message.
+pub enum StatementDistributionMessage {
+	/// We have originated a signed statement in the context of
+	/// given relay-parent hash and it should be distributed to other validators.
+	Share(Hash, SignedStatement),
+}
+
+/// This data becomes intrinsics or extrinsics which should be included in a future relay chain block.
+pub enum ProvisionableData {
+	/// This bitfield indicates the availability of various candidate blocks.
+	Bitfield(Hash, SignedAvailabilityBitfield),
+	/// The Candidate Backing subsystem believes that this candidate is valid, pending availability.
+	BackedCandidate(BackedCandidate),
+	/// Misbehavior reports are self-contained proofs of validator misbehavior.
+	MisbehaviorReport(Hash, MisbehaviorReport),
+	/// Disputes trigger a broad dispute resolution process.
+	Dispute(Hash, Signature),
+}
+
+/// Message to the Provisioner.
+///
+/// In all cases, the Hash is that of the relay parent.
+pub enum ProvisionerMessage {
+	/// This message allows potential block authors to be kept updated with all new authorship data
+	/// as it becomes available.
+	RequestBlockAuthorshipData(Hash, mpsc::Sender<ProvisionableData>),
+	/// This data should become part of a relay chain block
+	ProvisionableData(ProvisionableData),
 }
 
 /// A message type tying together all message types that are used across Subsystems.
 #[derive(Debug)]
 pub enum AllMessages {
-	Validation(ValidationSubsystemMessage),
-	CandidateBacking(CandidateBackingSubsystemMessage),
+	/// Message for the validation subsystem.
+	CandidateValidation(CandidateValidationMessage),
+	/// Message for the candidate backing subsystem.
+	CandidateBacking(CandidateBackingMessage),
 }
 
 /// A message type that a subsystem receives from an overseer.