Make sure we inform statement listeners about received statements (#1999)

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

@@ -312,7 +312,9 @@ impl PeerData {
 		fingerprint: &(CompactStatement, ValidatorIndex),
 		max_message_count: usize,
 	) -> Result<bool, Rep> {
-		self.view_knowledge.get_mut(relay_parent).ok_or(COST_UNEXPECTED_STATEMENT)?
+		self.view_knowledge
+			.get_mut(relay_parent)
+			.ok_or(COST_UNEXPECTED_STATEMENT)?
 			.receive(fingerprint, max_message_count)
 	}
 }
@@ -492,13 +494,15 @@ fn check_statement_signature(
 		.and_then(|v| statement.check_signature(&signing_context, v))
 }
 
+type StatementListeners = Vec<mpsc::Sender<SignedFullStatement>>;
+
 /// Informs all registered listeners about a newly received statement.
 ///
 /// Removes all closed listeners.
 #[tracing::instrument(level = "trace", skip(listeners), fields(subsystem = LOG_TARGET))]
 async fn inform_statement_listeners(
 	statement: &SignedFullStatement,
-	listeners: &mut Vec<mpsc::Sender<SignedFullStatement>>,
+	listeners: &mut StatementListeners,
 ) {
 	// Ignore the errors since these will be removed later.
 	stream::iter(listeners.iter_mut()).for_each_concurrent(
@@ -524,36 +528,38 @@ async fn circulate_statement_and_dependents(
 	statement: SignedFullStatement,
 	metrics: &Metrics,
 ) {
-	if let Some(active_head)= active_heads.get_mut(&relay_parent) {
+	let active_head = match active_heads.get_mut(&relay_parent) {
+		Some(res) => res,
+		None => return,
+	};
 
-		// First circulate the statement directly to all peers needing it.
-		// The borrow of `active_head` needs to encompass only this (Rust) statement.
-		let outputs: Option<(CandidateHash, Vec<PeerId>)> = {
-			match active_head.note_statement(statement) {
-				NotedStatement::Fresh(stored) => Some((
-					*stored.compact().candidate_hash(),
-					circulate_statement(peers, ctx, relay_parent, stored).await,
-				)),
-				_ => None,
-			}
-		};
+	// First circulate the statement directly to all peers needing it.
+	// The borrow of `active_head` needs to encompass only this (Rust) statement.
+	let outputs: Option<(CandidateHash, Vec<PeerId>)> = {
+		match active_head.note_statement(statement) {
+			NotedStatement::Fresh(stored) => Some((
+				*stored.compact().candidate_hash(),
+				circulate_statement(peers, ctx, relay_parent, stored).await,
+			)),
+			_ => None,
+		}
+	};
 
-		// Now send dependent statements to all peers needing them, if any.
-		if let Some((candidate_hash, peers_needing_dependents)) = outputs {
-			for peer in peers_needing_dependents {
-				if let Some(peer_data) = peers.get_mut(&peer) {
-					// defensive: the peer data should always be some because the iterator
-					// of peers is derived from the set of peers.
-					send_statements_about(
-						peer,
-						peer_data,
-						ctx,
-						relay_parent,
-						candidate_hash,
-						&*active_head,
-						metrics,
-					).await;
-				}
+	// Now send dependent statements to all peers needing them, if any.
+	if let Some((candidate_hash, peers_needing_dependents)) = outputs {
+		for peer in peers_needing_dependents {
+			if let Some(peer_data) = peers.get_mut(&peer) {
+				// defensive: the peer data should always be some because the iterator
+				// of peers is derived from the set of peers.
+				send_statements_about(
+					peer,
+					peer_data,
+					ctx,
+					relay_parent,
+					candidate_hash,
+					&*active_head,
+					metrics,
+				).await;
 			}
 		}
 	}
@@ -679,6 +685,7 @@ async fn handle_incoming_message<'a>(
 	ctx: &mut impl SubsystemContext<Message = StatementDistributionMessage>,
 	message: protocol_v1::StatementDistributionMessage,
 	metrics: &Metrics,
+	statement_listeners: &mut StatementListeners,
 ) -> Option<(Hash, &'a StoredStatement)> {
 	let (relay_parent, statement) = match message {
 		protocol_v1::StatementDistributionMessage::Statement(r, s) => (r, s),
@@ -735,6 +742,8 @@ async fn handle_incoming_message<'a>(
 		Ok(false) => {}
 	}
 
+	inform_statement_listeners(&statement, statement_listeners).await;
+
 	// Note: `peer_data.receive` already ensures that the statement is not an unbounded equivocation
 	// or unpinned to a seconded candidate. So it is safe to place it into the storage.
 	match active_head.note_statement(statement) {
@@ -794,6 +803,7 @@ async fn handle_network_update(
 	our_view: &mut View,
 	update: NetworkBridgeEvent<protocol_v1::StatementDistributionMessage>,
 	metrics: &Metrics,
+	statement_listeners: &mut StatementListeners,
 ) {
 	match update {
 		NetworkBridgeEvent::PeerConnected(peer, _role) => {
@@ -816,6 +826,7 @@ async fn handle_network_update(
 						ctx,
 						message,
 						metrics,
+						statement_listeners,
 					).await;
 
 					if let Some((relay_parent, new)) = new_stored {
@@ -875,7 +886,7 @@ impl StatementDistribution {
 		let mut peers: HashMap<PeerId, PeerData> = HashMap::new();
 		let mut our_view = View::default();
 		let mut active_heads: HashMap<Hash, ActiveHeadData> = HashMap::new();
-		let mut statement_listeners: Vec<mpsc::Sender<SignedFullStatement>> = Vec::new();
+		let mut statement_listeners = StatementListeners::new();
 		let metrics = self.metrics;
 
 		loop {
@@ -958,6 +969,7 @@ impl StatementDistribution {
 							&mut our_view,
 							event,
 							&metrics,
+							&mut statement_listeners,
 						).await;
 					}
 					StatementDistributionMessage::RegisterStatementListener(tx) => {