consensus: change lock handling in reactor and handleMsg for RoundState (forward-port #7994 #7992) (#8138)

This ports the changes from #7992 and #7994 from the v0.34.x branch to v0.35.x.

internal/consensus/reactor.go

@@ -131,6 +131,7 @@ type Reactor struct {
 	mtx         sync.RWMutex
 	peers       map[types.NodeID]*PeerState
 	waitSync    bool
+	rs          *cstypes.RoundState
 	readySignal chan struct{} // closed when the node is ready to start consensus
 
 	stateCh       *p2p.Channel
@@ -161,6 +162,7 @@ func NewReactor(
 	r := &Reactor{
 		state:         cs,
 		waitSync:      waitSync,
+		rs:            cs.GetRoundState(),
 		peers:         make(map[types.NodeID]*PeerState),
 		Metrics:       NopMetrics(),
 		stateCh:       stateCh,
@@ -198,6 +200,7 @@ func (r *Reactor) OnStart() error {
 	go r.peerStatsRoutine()
 
 	r.subscribeToBroadcastEvents()
+	go r.updateRoundStateRoutine()
 
 	if !r.WaitSync() {
 		if err := r.state.Start(); err != nil {
@@ -443,7 +446,7 @@ func makeRoundStepMessage(rs *cstypes.RoundState) *tmcons.NewRoundStep {
 }
 
 func (r *Reactor) sendNewRoundStepMessage(peerID types.NodeID) {
-	rs := r.state.GetRoundState()
+	rs := r.getRoundState()
 	msg := makeRoundStepMessage(rs)
 	select {
 	case <-r.closeCh:
@@ -455,6 +458,26 @@ func (r *Reactor) sendNewRoundStepMessage(peerID types.NodeID) {
 	}
 }
 
+func (r *Reactor) updateRoundStateRoutine() {
+	t := time.NewTicker(100 * time.Microsecond)
+	defer t.Stop()
+	for range t.C {
+		if !r.IsRunning() {
+			return
+		}
+		rs := r.state.GetRoundState()
+		r.mtx.Lock()
+		r.rs = rs
+		r.mtx.Unlock()
+	}
+}
+
+func (r *Reactor) getRoundState() *cstypes.RoundState {
+	r.mtx.RLock()
+	defer r.mtx.RUnlock()
+	return r.rs
+}
+
 func (r *Reactor) gossipDataForCatchup(rs *cstypes.RoundState, prs *cstypes.PeerRoundState, ps *PeerState) {
 	logger := r.Logger.With("height", prs.Height).With("peer", ps.peerID)
 
@@ -539,7 +562,7 @@ OUTER_LOOP:
 		default:
 		}
 
-		rs := r.state.GetRoundState()
+		rs := r.getRoundState()
 		prs := ps.GetRoundState()
 
 		// Send proposal Block parts?
@@ -766,7 +789,7 @@ OUTER_LOOP:
 		default:
 		}
 
-		rs := r.state.GetRoundState()
+		rs := r.getRoundState()
 		prs := ps.GetRoundState()
 
 		switch logThrottle {
@@ -848,7 +871,7 @@ func (r *Reactor) queryMaj23Routine(ps *PeerState) {
 			return
 		}
 
-		rs := r.state.GetRoundState()
+		rs := r.getRoundState()
 		prs := ps.GetRoundState()
 		// TODO create more reliable coppies of these
 		// structures so the following go routines don't race

internal/consensus/state.go

@@ -864,7 +864,6 @@ func (cs *State) receiveRoutine(maxSteps int) {
 func (cs *State) handleMsg(mi msgInfo) {
 	cs.mtx.Lock()
 	defer cs.mtx.Unlock()
-
 	var (
 		added bool
 		err   error
@@ -881,6 +880,24 @@ func (cs *State) handleMsg(mi msgInfo) {
 	case *BlockPartMessage:
 		// if the proposal is complete, we'll enterPrevote or tryFinalizeCommit
 		added, err = cs.addProposalBlockPart(msg, peerID)
+
+		// We unlock here to yield to any routines that need to read the the RoundState.
+		// Previously, this code held the lock from the point at which the final block
+		// part was received until the block executed against the application.
+		// This prevented the reactor from being able to retrieve the most updated
+		// version of the RoundState. The reactor needs the updated RoundState to
+		// gossip the now completed block.
+		//
+		// This code can be further improved by either always operating on a copy
+		// of RoundState and only locking when switching out State's copy of
+		// RoundState with the updated copy or by emitting RoundState events in
+		// more places for routines depending on it to listen for.
+		cs.mtx.Unlock()
+
+		cs.mtx.Lock()
+		if added && cs.ProposalBlockParts.IsComplete() {
+			cs.handleCompleteProposal(msg.Height)
+		}
 		if added {
 			cs.statsMsgQueue <- mi
 		}
@@ -1941,44 +1958,43 @@ func (cs *State) addProposalBlockPart(msg *BlockPartMessage, peerID types.NodeID
 		if err := cs.eventBus.PublishEventCompleteProposal(cs.CompleteProposalEvent()); err != nil {
 			cs.Logger.Error("failed publishing event complete proposal", "err", err)
 		}
+	}
+	return added, nil
+}
 
-		// Update Valid* if we can.
-		prevotes := cs.Votes.Prevotes(cs.Round)
-		blockID, hasTwoThirds := prevotes.TwoThirdsMajority()
-		if hasTwoThirds && !blockID.IsZero() && (cs.ValidRound < cs.Round) {
-			if cs.ProposalBlock.HashesTo(blockID.Hash) {
-				cs.Logger.Debug(
-					"updating valid block to new proposal block",
-					"valid_round", cs.Round,
-					"valid_block_hash", cs.ProposalBlock.Hash(),
-				)
+func (cs *State) handleCompleteProposal(blockHeight int64) {
+	// Update Valid* if we can.
+	prevotes := cs.Votes.Prevotes(cs.Round)
+	blockID, hasTwoThirds := prevotes.TwoThirdsMajority()
+	if hasTwoThirds && !blockID.IsZero() && (cs.ValidRound < cs.Round) {
+		if cs.ProposalBlock.HashesTo(blockID.Hash) {
+			cs.Logger.Debug(
+				"updating valid block to new proposal block",
+				"valid_round", cs.Round,
+				"valid_block_hash", cs.ProposalBlock.Hash(),
+			)
 
-				cs.ValidRound = cs.Round
-				cs.ValidBlock = cs.ProposalBlock
-				cs.ValidBlockParts = cs.ProposalBlockParts
-			}
-			// TODO: In case there is +2/3 majority in Prevotes set for some
-			// block and cs.ProposalBlock contains different block, either
-			// proposer is faulty or voting power of faulty processes is more
-			// than 1/3. We should trigger in the future accountability
-			// procedure at this point.
+			cs.ValidRound = cs.Round
+			cs.ValidBlock = cs.ProposalBlock
+			cs.ValidBlockParts = cs.ProposalBlockParts
 		}
-
-		if cs.Step <= cstypes.RoundStepPropose && cs.isProposalComplete() {
-			// Move onto the next step
-			cs.enterPrevote(height, cs.Round)
-			if hasTwoThirds { // this is optimisation as this will be triggered when prevote is added
-				cs.enterPrecommit(height, cs.Round)
-			}
-		} else if cs.Step == cstypes.RoundStepCommit {
-			// If we're waiting on the proposal block...
-			cs.tryFinalizeCommit(height)
+		// TODO: In case there is +2/3 majority in Prevotes set for some
+		// block and cs.ProposalBlock contains different block, either
+		// proposer is faulty or voting power of faulty processes is more
+		// than 1/3. We should trigger in the future accountability
+		// procedure at this point.
+	}
+
+	if cs.Step <= cstypes.RoundStepPropose && cs.isProposalComplete() {
+		// Move onto the next step
+		cs.enterPrevote(blockHeight, cs.Round)
+		if hasTwoThirds { // this is optimisation as this will be triggered when prevote is added
+			cs.enterPrecommit(blockHeight, cs.Round)
 		}
-
-		return added, nil
+	} else if cs.Step == cstypes.RoundStepCommit {
+		// If we're waiting on the proposal block...
+		cs.tryFinalizeCommit(blockHeight)
 	}
-
-	return added, nil
 }
 
 // Attempt to add the vote. if its a duplicate signature, dupeout the validator