Restrict WAL usage to node.go (backport #4201)

orderer/consensus/etcdraft/chain.go

@@ -1149,10 +1149,8 @@ func (c *Chain) apply(ents []raftpb.Entry) {
 				continue
 			}
 
-			// persist the WAL entries into disk
-			c.Node.storage.WALSyncC <- struct{}{}
-
 			c.confState = *c.Node.ApplyConfChange(cc)
+
 			switch cc.Type {
 			case raftpb.ConfChangeAddNode:
 				c.logger.Infof("Applied config change to add node %d, current nodes in channel: %+v", cc.NodeID, c.confState.Voters)

orderer/consensus/etcdraft/node.go

@@ -153,6 +153,7 @@ func (n *node) run(campaign bool) {
 
 			// skip empty apply
 			if len(rd.CommittedEntries) != 0 || rd.SoftState != nil {
+				n.maybeSyncWAL(rd.CommittedEntries)
 				n.chain.applyC <- apply{rd.CommittedEntries, rd.SoftState}
 			}
 
@@ -171,11 +172,6 @@ func (n *node) run(campaign bool) {
 			// to the followers and them writing to their disks. Check 10.2.1 in thesis
 			n.send(rd.Messages)
 
-		case <-n.storage.WALSyncC:
-			if err := n.storage.Sync(); err != nil {
-				n.logger.Warnf("Failed to sync raft log, error: %s", err)
-			}
-
 		case <-n.chain.haltC:
 			raftTicker.Stop()
 			n.Stop()
@@ -224,6 +220,24 @@ func (n *node) send(msgs []raftpb.Message) {
 	}
 }
 
+func (n *node) maybeSyncWAL(entries []raftpb.Entry) {
+	allNormal := true
+	for _, entry := range entries {
+		if entry.Type == raftpb.EntryNormal {
+			continue
+		}
+		allNormal = false
+	}
+
+	if allNormal {
+		return
+	}
+
+	if err := n.storage.Sync(); err != nil {
+		n.logger.Errorf("Failed to sync raft log, error: %s", err)
+	}
+}
+
 // abdicateLeadership picks a node that is recently active, and attempts to transfer leadership to it.
 // Blocks until leadership transfer happens or when a timeout expires.
 // Returns error upon failure.

orderer/consensus/etcdraft/storage.go

@@ -59,7 +59,6 @@ type RaftStorage struct {
 
 	// a queue that keeps track of indices of snapshots on disk
 	snapshotIndex []uint64
-	WALSyncC      chan struct{}
 }
 
 // CreateStorage attempts to create a storage to persist etcd/raft data.
@@ -114,7 +113,6 @@ func CreateStorage(
 		walDir:        walDir,
 		snapDir:       snapDir,
 		snapshotIndex: ListSnapshots(lg, snapDir),
-		WALSyncC:      make(chan struct{}),
 	}, nil
 }