Make sure to not run away when acking from the middle of pending.

Also optimize loop for interest based streams to ack msgs based on actual floor of pending.

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

server/consumer.go

@@ -2748,7 +2748,7 @@ func (o *consumer) processAckMsg(sseq, dseq, dc uint64, reply string, doSample b
 		return
 	}
 
-	var sagap uint64
+	var sgap, floor uint64
 	var needSignal bool
 
 	switch o.cfg.AckPolicy {
@@ -2792,12 +2792,29 @@ func (o *consumer) processAckMsg(sseq, dseq, dc uint64, reply string, doSample b
 		if o.maxp > 0 && len(o.pending) >= o.maxp {
 			needSignal = true
 		}
-		sagap = sseq - o.asflr
+		sgap = sseq - o.asflr
+		floor = sgap // start at same and set lower as we go.
 		o.adflr, o.asflr = dseq, sseq
-		for seq := sseq; seq > sseq-sagap && len(o.pending) > 0; seq-- {
+
+		remove := func(seq uint64) {
 			delete(o.pending, seq)
 			delete(o.rdc, seq)
 			o.removeFromRedeliverQueue(seq)
+			if seq < floor {
+				floor = seq
+			}
+		}
+		// Determine if smarter to walk all of pending vs the sequence range.
+		if sgap > uint64(len(o.pending)) {
+			for seq := range o.pending {
+				if seq <= sseq {
+					remove(seq)
+				}
+			}
+		} else {
+			for seq := sseq; seq > sseq-sgap && len(o.pending) > 0; seq-- {
+				remove(seq)
+			}
 		}
 	case AckNone:
 		// FIXME(dlc) - This is error but do we care?
@@ -2808,20 +2825,19 @@ func (o *consumer) processAckMsg(sseq, dseq, dc uint64, reply string, doSample b
 	// Update underlying store.
 	o.updateAcks(dseq, sseq, reply)
 
-	clustered := o.node != nil
-
 	// In case retention changes for a stream, this ought to have been updated
 	// using the consumer lock to avoid a race.
 	retention := o.retention
+	clustered := o.node != nil
 	o.mu.Unlock()
 
 	// Let the owning stream know if we are interest or workqueue retention based.
 	// If this consumer is clustered this will be handled by processReplicatedAck
 	// after the ack has propagated.
 	if !clustered && mset != nil && retention != LimitsPolicy {
-		if sagap > 1 {
-			// FIXME(dlc) - This is very inefficient, will need to fix.
-			for seq := sseq; seq > sseq-sagap; seq-- {
+		if sgap > 1 {
+			// FIXME(dlc) - This can very inefficient, will need to fix.
+			for seq := sseq; seq >= floor; seq-- {
 				mset.ackMsg(o, seq)
 			}
 		} else {

server/filestore.go

@@ -8616,9 +8616,16 @@ func (o *consumerFileStore) UpdateAcks(dseq, sseq uint64) error {
 		sgap := sseq - o.state.AckFloor.Stream
 		o.state.AckFloor.Consumer = dseq
 		o.state.AckFloor.Stream = sseq
-		for seq := sseq; seq > sseq-sgap && len(o.state.Pending) > 0; seq-- {
-			delete(o.state.Pending, seq)
-			if len(o.state.Redelivered) > 0 {
+		if sgap > uint64(len(o.state.Pending)) {
+			for seq := range o.state.Pending {
+				if seq <= sseq {
+					delete(o.state.Pending, seq)
+					delete(o.state.Redelivered, seq)
+				}
+			}
+		} else {
+			for seq := sseq; seq > sseq-sgap && len(o.state.Pending) > 0; seq-- {
+				delete(o.state.Pending, seq)
 				delete(o.state.Redelivered, seq)
 			}
 		}

server/jetstream_test.go

@@ -22523,7 +22523,7 @@ func TestJetStreamAckAllWithLargeFirstSequenceAndNoAckFloor(t *testing.T) {
 		js.Publish("foo.bar", []byte("hello"))
 	}
 
-	ss, err := js.PullSubscribe("foo.*", "TEST", nats.AckAll())
+	ss, err := js.PullSubscribe("foo.*", "C1", nats.AckAll())
 	require_NoError(t, err)
 	msgs, err := ss.Fetch(10, nats.MaxWait(100*time.Millisecond))
 	require_NoError(t, err)
@@ -22542,4 +22542,69 @@ func TestJetStreamAckAllWithLargeFirstSequenceAndNoAckFloor(t *testing.T) {
 
 	_, err = js.StreamInfo("TEST", nats.MaxWait(250*time.Millisecond))
 	require_NoError(t, err)
+
+	// Now make sure that if we ack in the middle, meaning we still have ack pending,
+	// that we do the right thing as well.
+	ss, err = js.PullSubscribe("foo.*", "C2", nats.AckAll())
+	require_NoError(t, err)
+	msgs, err = ss.Fetch(10, nats.MaxWait(100*time.Millisecond))
+	require_NoError(t, err)
+	require_Equal(t, len(msgs), 10)
+
+	start = time.Now()
+	msgs[5].AckSync()
+	if elapsed := time.Since(start); elapsed > 250*time.Millisecond {
+		t.Fatalf("AckSync took too long %v", elapsed)
+	}
+
+	// Make sure next fetch works right away with low timeout.
+	msgs, err = ss.Fetch(10, nats.MaxWait(100*time.Millisecond))
+	require_NoError(t, err)
+	require_Equal(t, len(msgs), 10)
+
+	_, err = js.StreamInfo("TEST", nats.MaxWait(250*time.Millisecond))
+	require_NoError(t, err)
+}
+
+func TestJetStreamAckAllWithLargeFirstSequenceAndNoAckFloorWithInterestPolicy(t *testing.T) {
+	s := RunBasicJetStreamServer(t)
+	defer s.Shutdown()
+
+	// Client for API requests.
+	nc, js := jsClientConnect(t, s)
+	defer nc.Close()
+
+	_, err := js.AddStream(&nats.StreamConfig{
+		Name:      "TEST",
+		Subjects:  []string{"foo.>"},
+		Retention: nats.InterestPolicy,
+	})
+	require_NoError(t, err)
+
+	// Set first sequence to something very big here. This shows the issue with AckAll the
+	// first time it is called and existing ack floor is 0.
+	err = js.PurgeStream("TEST", &nats.StreamPurgeRequest{Sequence: 10_000_000_000})
+	require_NoError(t, err)
+
+	ss, err := js.PullSubscribe("foo.*", "C1", nats.AckAll())
+	require_NoError(t, err)
+
+	// Now add in 100 msgs
+	for i := 0; i < 100; i++ {
+		js.Publish("foo.bar", []byte("hello"))
+	}
+
+	msgs, err := ss.Fetch(10, nats.MaxWait(100*time.Millisecond))
+	require_NoError(t, err)
+	require_Equal(t, len(msgs), 10)
+
+	start := time.Now()
+	msgs[5].AckSync()
+	if elapsed := time.Since(start); elapsed > 250*time.Millisecond {
+		t.Fatalf("AckSync took too long %v", elapsed)
+	}
+
+	// We are testing for run away loops acking messages in the stream that are not there.
+	_, err = js.StreamInfo("TEST", nats.MaxWait(100*time.Millisecond))
+	require_NoError(t, err)
 }