have some lenience on outdated messages in statement distribution (#5150)

* have some lenience on outdated messages in statement distribution

* fmt

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

@@ -58,7 +58,7 @@ use indexmap::{map::Entry as IEntry, IndexMap};
 use sp_keystore::SyncCryptoStorePtr;
 use util::runtime::RuntimeInfo;
 
-use std::collections::{hash_map::Entry, HashMap, HashSet};
+use std::collections::{hash_map::Entry, HashMap, HashSet, VecDeque};
 
 use fatality::Nested;
 
@@ -153,6 +153,27 @@ impl StatementDistributionSubsystem {
 	}
 }
 
+#[derive(Default)]
+struct RecentOutdatedHeads {
+	buf: VecDeque<Hash>,
+}
+
+impl RecentOutdatedHeads {
+	fn note_outdated(&mut self, hash: Hash) {
+		const MAX_BUF_LEN: usize = 10;
+
+		self.buf.push_back(hash);
+
+		while self.buf.len() > MAX_BUF_LEN {
+			let _ = self.buf.pop_front();
+		}
+	}
+
+	fn is_recent_outdated(&self, hash: &Hash) -> bool {
+		self.buf.contains(hash)
+	}
+}
+
 /// Tracks our impression of a single peer's view of the candidates a validator has seconded
 /// for a given relay-parent.
 ///
@@ -1287,6 +1308,7 @@ async fn handle_incoming_message_and_circulate<'a>(
 	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),
 	message: protocol_v1::StatementDistributionMessage,
 	req_sender: &mpsc::Sender<RequesterMessage>,
@@ -1294,8 +1316,17 @@ async fn handle_incoming_message_and_circulate<'a>(
 ) {
 	let handled_incoming = match peers.get_mut(&peer) {
 		Some(data) =>
-			handle_incoming_message(peer, data, active_heads, ctx, message, req_sender, metrics)
+			handle_incoming_message(
-				.await,
+				peer,
+				data,
+				active_heads,
+				recent_outdated_heads,
+				ctx,
+				message,
+				req_sender,
+				metrics,
+			)
+			.await,
 		None => None,
 	};
 
@@ -1331,6 +1362,7 @@ async fn handle_incoming_message<'a>(
 	peer: PeerId,
 	peer_data: &mut PeerData,
 	active_heads: &'a mut HashMap<Hash, ActiveHeadData>,
+	recent_outdated_heads: &RecentOutdatedHeads,
 	ctx: &mut (impl SubsystemContext + overseer::SubsystemContext),
 	message: protocol_v1::StatementDistributionMessage,
 	req_sender: &mpsc::Sender<RequesterMessage>,
@@ -1347,7 +1379,11 @@ async fn handle_incoming_message<'a>(
 				%relay_parent,
 				"our view out-of-sync with active heads; head not found",
 			);
-			report_peer(ctx, peer, COST_UNEXPECTED_STATEMENT).await;
+
+			if !recent_outdated_heads.is_recent_outdated(&relay_parent) {
+				report_peer(ctx, peer, COST_UNEXPECTED_STATEMENT).await;
+			}
+
 			return None
 		},
 	};
@@ -1556,6 +1592,7 @@ async fn handle_network_update(
 	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),
 	req_sender: &mpsc::Sender<RequesterMessage>,
 	update: NetworkBridgeEvent<protocol_v1::StatementDistributionMessage>,
@@ -1612,6 +1649,7 @@ async fn handle_network_update(
 				gossip_peers,
 				peers,
 				active_heads,
+				&*recent_outdated_heads,
 				ctx,
 				message,
 				req_sender,
@@ -1653,6 +1691,7 @@ impl StatementDistributionSubsystem {
 		let mut gossip_peers: HashSet<PeerId> = HashSet::new();
 		let mut authorities: HashMap<AuthorityDiscoveryId, PeerId> = HashMap::new();
 		let mut active_heads: HashMap<Hash, ActiveHeadData> = HashMap::new();
+		let mut recent_outdated_heads = RecentOutdatedHeads::default();
 
 		let mut runtime = RuntimeInfo::new(Some(self.keystore.clone()));
 
@@ -1684,6 +1723,7 @@ impl StatementDistributionSubsystem {
 							&mut gossip_peers,
 							&mut authorities,
 							&mut active_heads,
+							&mut recent_outdated_heads,
 							&req_sender,
 							result?,
 						)
@@ -1701,6 +1741,7 @@ impl StatementDistributionSubsystem {
 							&gossip_peers,
 							&mut peers,
 							&mut active_heads,
+							&recent_outdated_heads,
 							&req_sender,
 							result.ok_or(FatalError::RequesterReceiverFinished)?,
 						)
@@ -1767,6 +1808,7 @@ impl StatementDistributionSubsystem {
 		gossip_peers: &HashSet<PeerId>,
 		peers: &mut HashMap<PeerId, PeerData>,
 		active_heads: &mut HashMap<Hash, ActiveHeadData>,
+		recent_outdated_heads: &RecentOutdatedHeads,
 		req_sender: &mpsc::Sender<RequesterMessage>,
 		message: RequesterMessage,
 	) -> JfyiErrorResult<()> {
@@ -1814,6 +1856,7 @@ impl StatementDistributionSubsystem {
 							gossip_peers,
 							peers,
 							active_heads,
+							recent_outdated_heads,
 							ctx,
 							message,
 							req_sender,
@@ -1874,6 +1917,7 @@ impl StatementDistributionSubsystem {
 		gossip_peers: &mut HashSet<PeerId>,
 		authorities: &mut HashMap<AuthorityDiscoveryId, PeerId>,
 		active_heads: &mut HashMap<Hash, ActiveHeadData>,
+		recent_outdated_heads: &mut RecentOutdatedHeads,
 		req_sender: &mpsc::Sender<RequesterMessage>,
 		message: FromOverseer<StatementDistributionMessage>,
 	) -> Result<bool> {
@@ -1893,6 +1937,8 @@ impl StatementDistributionSubsystem {
 							hash = ?deactivated,
 							"Deactivating leaf",
 						);
+
+						recent_outdated_heads.note_outdated(deactivated);
 					}
 				}
 
@@ -1985,6 +2031,7 @@ impl StatementDistributionSubsystem {
 						gossip_peers,
 						authorities,
 						active_heads,
+						&*recent_outdated_heads,
 						ctx,
 						req_sender,
 						event,