Run raft.Step in serial order, without using goroutines.

conn/raft_server.go

@@ -167,24 +167,6 @@ func (w *RaftServer) JoinCluster(ctx context.Context,
 	return &api.Payload{}, err
 }
 
-var ()
-
-func (w *RaftServer) applyMessage(ctx context.Context, msg raftpb.Message) error {
-	node := w.GetNode()
-	if node == nil || node.Raft() == nil {
-		return ErrNoNode
-	}
-
-	c := make(chan error, 1)
-	go func() { c <- node.Raft().Step(ctx, msg) }()
-
-	select {
-	case <-ctx.Done():
-		return ctx.Err()
-	case err := <-c:
-		return err
-	}
-}
 func (w *RaftServer) RaftMessage(ctx context.Context,
 	batch *intern.RaftBatch) (*api.Payload, error) {
 	if ctx.Err() != nil {
@@ -194,7 +176,7 @@ func (w *RaftServer) RaftMessage(ctx context.Context,
 	rc := batch.GetContext()
 	if rc != nil {
 		n := w.GetNode()
-		if n == nil {
+		if n == nil || n.Raft() == nil {
 			return &api.Payload{}, ErrNoNode
 		}
 		n.Connect(rc.Id, rc.Addr)
@@ -203,6 +185,7 @@ func (w *RaftServer) RaftMessage(ctx context.Context,
 		return &api.Payload{}, nil
 	}
 	data := batch.Payload.Data
+	raft := w.GetNode().Raft()
 
 	for idx := 0; idx < len(data); {
 		x.AssertTruef(len(data[idx:]) >= 4,
@@ -219,7 +202,8 @@ func (w *RaftServer) RaftMessage(ctx context.Context,
 		if err := msg.Unmarshal(data[idx : idx+sz]); err != nil {
 			x.Check(err)
 		}
-		if err := w.applyMessage(ctx, msg); err != nil {
+		// This should be done in order, and not via a goroutine.
+		if err := raft.Step(ctx, msg); err != nil {
 			return &api.Payload{}, err
 		}
 		idx += sz