Merge pull request #2834 from nats-io/fix_backoff

[FIXED] JetStream: BackOff redeliveries would always use first in list

server/consumer.go

@@ -3130,7 +3130,7 @@ func (o *consumer) checkPending() {
 		}
 		elapsed, deadline := now-p.Timestamp, ttl
 		if len(o.cfg.BackOff) > 0 && o.rdc != nil {
-			dc := int(o.rdc[p.Sequence])
+			dc := int(o.rdc[seq])
 			if dc >= len(o.cfg.BackOff) {
 				dc = len(o.cfg.BackOff) - 1
 			}

server/jetstream_cluster_test.go

@@ -10345,16 +10345,23 @@ func TestJetStreamClusterRedeliverBackoffs(t *testing.T) {
 	_, err := js.AddStream(&nats.StreamConfig{
 		Name:     "TEST",
 		Replicas: 2,
-		Subjects: []string{"foo"},
+		Subjects: []string{"foo", "bar"},
 	})
 	require_NoError(t, err)
 
+	// Produce some messages on bar so that when we create the consumer
+	// on "foo", we don't have a 1:1 between consumer/stream sequence.
+	for i := 0; i < 10; i++ {
+		js.Publish("bar", []byte("msg"))
+	}
+
 	// Test when BackOff is configured and AckWait and MaxDeliver are as well.
 	// Currently the BackOff will override AckWait, but we want MaxDeliver to be set to be at least len(BackOff)+1.
 	ccReq := &CreateConsumerRequest{
 		Stream: "TEST",
 		Config: ConsumerConfig{
 			Durable:        "dlc",
+			FilterSubject:  "foo",
 			DeliverSubject: "x",
 			AckPolicy:      AckExplicit,
 			AckWait:        30 * time.Second,