Test ack metrics

Signed-off-by: Derek Collison <derek@nats.io>

server/jetstream_test.go

@@ -628,7 +628,7 @@ func TestJetStreamConsumerMaxDeliveries(t *testing.T) {
 
 			// Wait for redeliveries to pile up.
 			checkFor(t, 250*time.Millisecond, 10*time.Millisecond, func() error {
-				if nmsgs, _, _ := sub.Pending(); err != nil || nmsgs != maxDeliver {
+				if nmsgs, _, err := sub.Pending(); err != nil || nmsgs != maxDeliver {
 					return fmt.Errorf("Did not receive correct number of messages: %d vs %d", nmsgs, maxDeliver)
 				}
 				return nil
@@ -15197,6 +15197,90 @@ func TestJetStreamRestoreBadStream(t *testing.T) {
 	}
 }
 
+func TestJetStreamConsumerAckSampling(t *testing.T) {
+	s := RunBasicJetStreamServer()
+	if config := s.JetStreamConfig(); config != nil {
+		defer removeDir(t, config.StoreDir)
+	}
+	defer s.Shutdown()
+
+	nc, js := jsClientConnect(t, s)
+	defer nc.Close()
+
+	_, err := js.AddStream(&nats.StreamConfig{Name: "TEST", Subjects: []string{"foo"}})
+	require_NoError(t, err)
+
+	_, err = js.AddConsumer("TEST", &nats.ConsumerConfig{
+		Durable:         "dlc",
+		AckPolicy:       nats.AckExplicitPolicy,
+		FilterSubject:   "foo",
+		SampleFrequency: "100%",
+	})
+	require_NoError(t, err)
+
+	sub, err := js.PullSubscribe("foo", "dlc")
+	require_NoError(t, err)
+
+	_, err = js.Publish("foo", []byte("Hello"))
+	require_NoError(t, err)
+
+	msub, err := nc.SubscribeSync("$JS.EVENT.METRIC.>")
+	require_NoError(t, err)
+
+	for _, m := range fetchMsgs(t, sub, 1, time.Second) {
+		err = m.AckSync()
+		require_NoError(t, err)
+	}
+
+	m, err := msub.NextMsg(time.Second)
+	require_NoError(t, err)
+
+	var am JSConsumerAckMetric
+	err = json.Unmarshal(m.Data, &am)
+	require_NoError(t, err)
+
+	if am.Stream != "TEST" || am.Consumer != "dlc" || am.ConsumerSeq != 1 {
+		t.Fatalf("Not a proper ack metric: %+v", am)
+	}
+
+	// Do less than 100%
+	_, err = js.AddConsumer("TEST", &nats.ConsumerConfig{
+		Durable:         "alps",
+		AckPolicy:       nats.AckExplicitPolicy,
+		FilterSubject:   "foo",
+		SampleFrequency: "50%",
+	})
+	require_NoError(t, err)
+
+	asub, err := js.PullSubscribe("foo", "alps")
+	require_NoError(t, err)
+
+	for i := 0; i < 100; i++ {
+		_, err = js.Publish("foo", []byte("Hello"))
+		require_NoError(t, err)
+	}
+
+	mp := 0
+	for _, m := range fetchMsgs(t, asub, 100, time.Second) {
+		err = m.Ack()
+		require_NoError(t, err)
+		mp++
+	}
+	nc.Flush()
+
+	if mp != 100 {
+		t.Fatalf("Got only %d msgs out of %d", mp, 100)
+	}
+
+	nmsgs, _, err := msub.Pending()
+	require_NoError(t, err)
+
+	// Should be ~50
+	if nmsgs < 35 || nmsgs > 65 {
+		t.Fatalf("Expected about 50, got %d", nmsgs)
+	}
+}
+
 ///////////////////////////////////////////////////////////////////////////
 // Simple JetStream Benchmarks
 ///////////////////////////////////////////////////////////////////////////