sc-consensus-beefy: pump gossip engine while waiting for initialization conditions (#3435)

As part of BEEFY worker/voter initialization the task waits for certain
chain and backend conditions to be fulfilled:
- BEEFY consensus enabled on-chain & GRANDPA best finalized higher than
on-chain BEEFY genesis block,
- backend has synced headers for BEEFY mandatory blocks between best
BEEFY and best GRANDPA.

During this waiting time, any messages gossiped on the BEEFY topic for
current chain get enqueued in the gossip engine, leading to RAM bloating
and output warning/error messages when the wait time is non-negligible
(like during a clean sync).

This PR adds logic to pump the gossip engine while waiting for other
things to make sure gossiped messages get consumed (practically
discarded until worker is fully initialized).

Also raises the warning threshold for enqueued messages from 10k to
100k. This is in line with the other gossip protocols on the node.

Fixes https://github.com/paritytech/polkadot-sdk/issues/3390

---------

Signed-off-by: Adrian Catangiu <adrian@parity.io>

substrate/client/consensus/beefy/src/communication/gossip.rs

@@ -56,6 +56,8 @@ pub(super) enum Action<H> {
 	Keep(H, ReputationChange),
 	// discard, applying cost/benefit to originator.
 	Discard(ReputationChange),
+	// ignore, no cost/benefit applied to originator.
+	DiscardNoReport,
 }
 
 /// An outcome of examining a message.
@@ -68,7 +70,7 @@ enum Consider {
 	/// Message is from the future. Reject.
 	RejectFuture,
 	/// Message cannot be evaluated. Reject.
-	RejectOutOfScope,
+	CannotEvaluate,
 }
 
 /// BEEFY gossip message type that gets encoded and sent on the network.
@@ -168,18 +170,14 @@ impl<B: Block> Filter<B> {
 			.as_ref()
 			.map(|f|
 				// only from current set and only [filter.start, filter.end]
-				if set_id < f.validator_set.id() {
+				if set_id < f.validator_set.id() || round < f.start {
 					Consider::RejectPast
-				} else if set_id > f.validator_set.id() {
-					Consider::RejectFuture
-				} else if round < f.start {
-					Consider::RejectPast
-				} else if round > f.end {
+				} else if set_id > f.validator_set.id() || round > f.end {
 					Consider::RejectFuture
 				} else {
 					Consider::Accept
 				})
-			.unwrap_or(Consider::RejectOutOfScope)
+			.unwrap_or(Consider::CannotEvaluate)
 	}
 
 	/// Return true if `round` is >= than `max(session_start, best_beefy)`,
@@ -199,7 +197,7 @@ impl<B: Block> Filter<B> {
 					Consider::Accept
 				}
 			)
-			.unwrap_or(Consider::RejectOutOfScope)
+			.unwrap_or(Consider::CannotEvaluate)
 	}
 
 	/// Add new _known_ `round` to the set of seen valid justifications.
@@ -244,7 +242,7 @@ where
 	pub(crate) fn new(
 		known_peers: Arc<Mutex<KnownPeers<B>>>,
 	) -> (GossipValidator<B>, TracingUnboundedReceiver<PeerReport>) {
-		let (tx, rx) = tracing_unbounded("mpsc_beefy_gossip_validator", 10_000);
+		let (tx, rx) = tracing_unbounded("mpsc_beefy_gossip_validator", 100_000);
 		let val = GossipValidator {
 			votes_topic: votes_topic::<B>(),
 			justifs_topic: proofs_topic::<B>(),
@@ -289,7 +287,9 @@ where
 			match filter.consider_vote(round, set_id) {
 				Consider::RejectPast => return Action::Discard(cost::OUTDATED_MESSAGE),
 				Consider::RejectFuture => return Action::Discard(cost::FUTURE_MESSAGE),
-				Consider::RejectOutOfScope => return Action::Discard(cost::OUT_OF_SCOPE_MESSAGE),
+				// When we can't evaluate, it's our fault (e.g. filter not initialized yet), we
+				// discard the vote without punishing or rewarding the sending peer.
+				Consider::CannotEvaluate => return Action::DiscardNoReport,
 				Consider::Accept => {},
 			}
 
@@ -330,7 +330,9 @@ where
 			match guard.consider_finality_proof(round, set_id) {
 				Consider::RejectPast => return Action::Discard(cost::OUTDATED_MESSAGE),
 				Consider::RejectFuture => return Action::Discard(cost::FUTURE_MESSAGE),
-				Consider::RejectOutOfScope => return Action::Discard(cost::OUT_OF_SCOPE_MESSAGE),
+				// When we can't evaluate, it's our fault (e.g. filter not initialized yet), we
+				// discard the proof without punishing or rewarding the sending peer.
+				Consider::CannotEvaluate => return Action::DiscardNoReport,
 				Consider::Accept => {},
 			}
 
@@ -357,7 +359,9 @@ where
 						Action::Keep(self.justifs_topic, benefit::VALIDATED_PROOF)
 					}
 				})
-				.unwrap_or(Action::Discard(cost::OUT_OF_SCOPE_MESSAGE))
+				// When we can't evaluate, it's our fault (e.g. filter not initialized yet), we
+				// discard the proof without punishing or rewarding the sending peer.
+				.unwrap_or(Action::DiscardNoReport)
 		};
 		if matches!(action, Action::Keep(_, _)) {
 			self.gossip_filter.write().mark_round_as_proven(round);
@@ -404,6 +408,7 @@ where
 				self.report(*sender, cb);
 				ValidationResult::Discard
 			},
+			Action::DiscardNoReport => ValidationResult::Discard,
 		}
 	}
 
@@ -579,8 +584,8 @@ pub(crate) mod tests {
 		// filter not initialized
 		let res = gv.validate(&mut context, &sender, &encoded);
 		assert!(matches!(res, ValidationResult::Discard));
-		expected_report.cost_benefit = cost::OUT_OF_SCOPE_MESSAGE;
-		assert_eq!(report_stream.try_recv().unwrap(), expected_report);
+		// nothing reported
+		assert!(report_stream.try_recv().is_err());
 
 		gv.update_filter(GossipFilterCfg { start: 0, end: 10, validator_set: &validator_set });
 		// nothing in cache first time

substrate/client/consensus/beefy/src/communication/mod.rs

@@ -90,8 +90,6 @@ mod cost {
 	pub(super) const BAD_SIGNATURE: Rep = Rep::new(-100, "BEEFY: Bad signature");
 	// Message received with vote from voter not in validator set.
 	pub(super) const UNKNOWN_VOTER: Rep = Rep::new(-150, "BEEFY: Unknown voter");
-	// A message received that cannot be evaluated relative to our current state.
-	pub(super) const OUT_OF_SCOPE_MESSAGE: Rep = Rep::new(-500, "BEEFY: Out-of-scope message");
 	// Message containing invalid proof.
 	pub(super) const INVALID_PROOF: Rep = Rep::new(-5000, "BEEFY: Invalid commit");
 	// Reputation cost per signature checked for invalid proof.