Merge pull request #1869 from nats-io/dupe-delivery

[FIXED] Bug on single replica restore would deliver duplicate messages.

server/stream.go

@@ -122,6 +122,7 @@ type Stream struct {
 	ddindex   int
 	ddtmr     *time.Timer
 	qch       chan struct{}
+	active    bool
 
 	// Clustered mode.
 	sa      *streamAssignment
@@ -266,7 +267,8 @@ func (a *Account) addStream(config *StreamConfig, fsConfig *FileStoreConfig, sa
 	}
 
 	// Call directly to set leader if not in clustered mode.
-	if !s.JetStreamIsClustered() {
+	// This can be called though before we actually setup clustering, so check both.
+	if !s.JetStreamIsClustered() && s.standAloneMode() {
 		if err := mset.setLeader(true); err != nil {
 			mset.Delete()
 			return nil, err
@@ -309,6 +311,9 @@ func (mset *Stream) setLeader(isLeader bool) error {
 	mset.mu.Lock()
 	// If we are here we have a change in leader status.
 	if isLeader {
+		// Make sure we are listening for sync requests.
+		// TODO(dlc) - Original design was that all in sync members of the group would do DQ.
+		mset.startClusterSubs()
 		// Setup subscriptions
 		if err := mset.subscribeToStream(); err != nil {
 			mset.mu.Unlock()
@@ -316,9 +321,6 @@ func (mset *Stream) setLeader(isLeader bool) error {
 			mset.Delete()
 			return err
 		}
-		// Make sure we are listening for sync requests.
-		// TODO(dlc) - Original design was that all in sync members of the group would do DQ.
-		mset.startClusterSubs()
 	} else {
 		// Stop responding to sync requests.
 		mset.stopClusterSubs()
@@ -840,11 +842,15 @@ func (mset *Stream) removeMsg(seq uint64, secure bool) (bool, error) {
 // Will create internal subscriptions for the stream.
 // Lock should be held.
 func (mset *Stream) subscribeToStream() error {
+	if mset.active {
+		return nil
+	}
 	for _, subject := range mset.config.Subjects {
 		if _, err := mset.subscribeInternal(subject, mset.processInboundJetStreamMsg); err != nil {
 			return err
 		}
 	}
+	mset.active = true
 	return nil
 }
 
@@ -854,6 +860,7 @@ func (mset *Stream) unsubscribeToStream() error {
 	for _, subject := range mset.config.Subjects {
 		mset.unsubscribeInternal(subject)
 	}
+	mset.active = false
 	return nil
 }
 

test/jetstream_cluster_test.go

@@ -2612,6 +2612,56 @@ func TestJetStreamRestartAdvisories(t *testing.T) {
 	checkSubsPending(t, usub, 0)
 }
 
+func TestJetStreamClusterNoDuplicateOnNodeRestart(t *testing.T) {
+	c := createJetStreamClusterExplicit(t, "ND", 2)
+	defer c.shutdown()
+	// Client based API
+	s := c.randomServer()
+	nc, js := jsClientConnect(t, s)
+	defer nc.Close()
+	_, err := js.AddStream(&nats.StreamConfig{
+		Name:     "TEST",
+		Subjects: []string{"foo"},
+	})
+	if err != nil {
+		t.Fatalf("Unexpected error: %v", err)
+	}
+
+	sub, err := js.SubscribeSync("foo", nats.Durable("dlc"))
+	if err != nil {
+		t.Fatalf("Unexpected error: %v", err)
+	}
+
+	js.Publish("foo", []byte("msg1"))
+	if m, err := sub.NextMsg(time.Second); err != nil {
+		t.Fatalf("Unexpected error: %v", err)
+	} else {
+		m.Ack()
+	}
+
+	sl := c.streamLeader("$G", "TEST")
+	sl.Shutdown()
+	c.restartServer(sl)
+	c.waitOnStreamLeader("$G", "TEST")
+
+	// Send second msg
+	js.Publish("foo", []byte("msg2"))
+	msg, err := sub.NextMsg(time.Second)
+	if err != nil {
+		t.Fatalf("Error getting message: %v", err)
+	}
+	if string(msg.Data) != "msg2" {
+		t.Fatalf("Unexpected message: %s", msg.Data)
+	}
+	msg.Ack()
+
+	// Make sure we don't get a duplicate.
+	msg, err = sub.NextMsg(250 * time.Millisecond)
+	if err == nil {
+		t.Fatalf("Should have gotten an error, got %s", msg.Data)
+	}
+}
+
 func TestJetStreamClusterStreamPerf(t *testing.T) {
 	// Comment out to run, holding place for now.
 	skip(t)