[IMPROVED] Removed calling consumer info on reconnect.

- `Consume()` and `Messages()` no longer call `ConsumerInfo()` on upon reconnect.
- Ordered consumers now reset on each reconnect event.

Signed-off-by: Piotr Piotrowski <[email protected]>

jetstream/ordered.go

@@ -42,6 +42,7 @@ type (
 		stopAfterMsgsLeft chan int
 		withStopAfter     bool
 		runningFetch      *fetchResult
+		subscription      *orderedSubscription
 		sync.Mutex
 	}
 
@@ -91,7 +92,8 @@ func (c *orderedConsumer) Consume(handler MessageHandler, opts ...PullConsumeOpt
 		return nil, fmt.Errorf("%w: %s", ErrInvalidOption, err)
 	}
 	c.userErrHandler = consumeOpts.ErrHandler
-	opts = append(opts, ConsumeErrHandler(c.errHandler(c.serial)))
+	opts = append(opts, consumeReconnectNotify(),
+		ConsumeErrHandler(c.errHandler(c.serial)))
 	if consumeOpts.StopAfter > 0 {
 		c.withStopAfter = true
 		c.stopAfter = consumeOpts.StopAfter
@@ -104,6 +106,7 @@ func (c *orderedConsumer) Consume(handler MessageHandler, opts ...PullConsumeOpt
 		consumer: c,
 		done:     make(chan struct{}, 1),
 	}
+	c.subscription = sub
 	internalHandler := func(serial int) func(msg Msg) {
 		return func(msg Msg) {
 			// handler is a noop if message was delivered for a consumer with different serial
@@ -196,13 +199,13 @@ func (c *orderedConsumer) errHandler(serial int) func(cc ConsumeContext, err err
 	return func(cc ConsumeContext, err error) {
 		c.Lock()
 		defer c.Unlock()
-		if c.userErrHandler != nil && !errors.Is(err, errOrderedSequenceMismatch) {
+		if c.userErrHandler != nil && !errors.Is(err, errOrderedSequenceMismatch) && !errors.Is(err, errConnected) {
 			c.userErrHandler(cc, err)
 		}
 		if errors.Is(err, ErrNoHeartbeat) ||
 			errors.Is(err, errOrderedSequenceMismatch) ||
 			errors.Is(err, ErrConsumerDeleted) ||
-			errors.Is(err, ErrConsumerNotFound) {
+			errors.Is(err, errConnected) {
 			// only reset if serial matches the current consumer serial and there is no reset in progress
 			if serial == c.serial && atomic.LoadUint32(&c.resetInProgress) == 0 {
 				atomic.StoreUint32(&c.resetInProgress, 1)
@@ -234,7 +237,9 @@ func (c *orderedConsumer) Messages(opts ...PullMessagesOpt) (MessagesContext, er
 	if err != nil {
 		return nil, fmt.Errorf("%w: %s", ErrInvalidOption, err)
 	}
-	opts = append(opts, WithMessagesErrOnMissingHeartbeat(true))
+	opts = append(opts,
+		WithMessagesErrOnMissingHeartbeat(true),
+		messagesReconnectNotify())
 	c.stopAfterMsgsLeft = make(chan int, 1)
 	if consumeOpts.StopAfter > 0 {
 		c.withStopAfter = true
@@ -254,6 +259,7 @@ func (c *orderedConsumer) Messages(opts ...PullMessagesOpt) (MessagesContext, er
 		opts:     opts,
 		done:     make(chan struct{}, 1),
 	}
+	c.subscription = sub
 
 	return sub, nil
 }
@@ -357,6 +363,11 @@ func (c *orderedConsumer) Fetch(batch int, opts ...FetchOpt) (MessageBatch, erro
 	}
 	c.currentConsumer.Unlock()
 	c.consumerType = consumerTypeFetch
+	sub := orderedSubscription{
+		consumer: c,
+		done:     make(chan struct{}),
+	}
+	c.subscription = &sub
 	err := c.reset()
 	if err != nil {
 		return nil, err
@@ -387,6 +398,11 @@ func (c *orderedConsumer) FetchBytes(maxBytes int, opts ...FetchOpt) (MessageBat
 		c.cursor.streamSeq = c.runningFetch.sseq
 	}
 	c.consumerType = consumerTypeFetch
+	sub := orderedSubscription{
+		consumer: c,
+		done:     make(chan struct{}),
+	}
+	c.subscription = &sub
 	err := c.reset()
 	if err != nil {
 		return nil, err
@@ -415,6 +431,11 @@ func (c *orderedConsumer) FetchNoWait(batch int) (MessageBatch, error) {
 		return nil, ErrOrderedConsumerConcurrentRequests
 	}
 	c.consumerType = consumerTypeFetch
+	sub := orderedSubscription{
+		consumer: c,
+		done:     make(chan struct{}),
+	}
+	c.subscription = &sub
 	err := c.reset()
 	if err != nil {
 		return nil, err
@@ -467,52 +488,42 @@ func (c *orderedConsumer) reset() error {
 		}
 		consName := c.currentConsumer.CachedInfo().Name
 		c.currentConsumer.Unlock()
-		var err error
-		for i := 0; ; i++ {
-			if c.cfg.MaxResetAttempts > 0 && i == c.cfg.MaxResetAttempts {
-				return fmt.Errorf("%w: maximum number of delete attempts reached: %s", ErrOrderedConsumerReset, err)
-			}
+		go func() {
 			ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
-			err = c.jetStream.DeleteConsumer(ctx, c.stream, consName)
+			_ = c.jetStream.DeleteConsumer(ctx, c.stream, consName)
 			cancel()
-			if err != nil {
-				if errors.Is(err, ErrConsumerNotFound) {
-					break
-				}
-				if errors.Is(err, nats.ErrTimeout) || errors.Is(err, context.DeadlineExceeded) {
-					continue
-				}
-				return err
-			}
-			break
-		}
+		}()
 	}
 
 	c.cursor.deliverSeq = 0
 	consumerConfig := c.getConsumerConfig()
 
 	var err error
 	var cons Consumer
-	for i := 0; ; i++ {
-		if c.cfg.MaxResetAttempts > 0 && i == c.cfg.MaxResetAttempts {
-			return fmt.Errorf("%w: maximum number of create consumer attempts reached: %s", ErrOrderedConsumerReset, err)
+
+	backoffOpts := backoffOpts{
+		attempts:        c.cfg.MaxResetAttempts,
+		initialInterval: time.Second,
+		factor:          2,
+		maxInterval:     10 * time.Second,
+		cancel:          c.subscription.done,
+	}
+	err = retryWithBackoff(func(attempt int) (bool, error) {
+		isClosed := atomic.LoadUint32(&c.subscription.closed) == 1
+		if isClosed {
+			return false, nil
 		}
 		ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
+		defer cancel()
 		cons, err = c.jetStream.CreateOrUpdateConsumer(ctx, c.stream, *consumerConfig)
 		if err != nil {
-			if errors.Is(err, ErrConsumerNotFound) {
-				cancel()
-				break
-			}
-			if errors.Is(err, nats.ErrTimeout) || errors.Is(err, context.DeadlineExceeded) {
-				cancel()
-				continue
-			}
-			cancel()
-			return err
+			return true, err
 		}
-		cancel()
-		break
+		c.currentConsumer = cons.(*pullConsumer)
+		return false, nil
+	}, backoffOpts)
+	if err != nil {
+		return err
 	}
 	c.currentConsumer = cons.(*pullConsumer)
 	return nil
@@ -534,6 +545,10 @@ func (c *orderedConsumer) getConsumerConfig() *ConsumerConfig {
 		// otherwise, start from the next sequence
 		nextSeq = c.cursor.streamSeq + 1
 	}
+
+	if c.cfg.MaxResetAttempts == 0 {
+		c.cfg.MaxResetAttempts = -1
+	}
 	name := fmt.Sprintf("%s_%d", c.namePrefix, c.serial)
 	cfg := &ConsumerConfig{
 		Name:              name,
@@ -550,6 +565,9 @@ func (c *orderedConsumer) getConsumerConfig() *ConsumerConfig {
 	} else {
 		cfg.FilterSubjects = c.cfg.FilterSubjects
 	}
+	if c.cfg.InactiveThreshold != 0 {
+		cfg.InactiveThreshold = c.cfg.InactiveThreshold
+	}
 
 	if c.serial != 1 {
 		return cfg
@@ -575,9 +593,6 @@ func (c *orderedConsumer) getConsumerConfig() *ConsumerConfig {
 		cfg.DeliverPolicy = DeliverByStartTimePolicy
 		cfg.OptStartTime = c.cfg.OptStartTime
 	}
-	if c.cfg.InactiveThreshold != 0 {
-		cfg.InactiveThreshold = c.cfg.InactiveThreshold
-	}
 
 	return cfg
 }
@@ -598,6 +613,20 @@ func messagesStopAfterNotify(numMsgs int, msgsLeftAfterStop chan int) PullMessag
 	})
 }
 
+func consumeReconnectNotify() PullConsumeOpt {
+	return pullOptFunc(func(opts *consumeOpts) error {
+		opts.notifyOnReconnect = true
+		return nil
+	})
+}
+
+func messagesReconnectNotify() PullMessagesOpt {
+	return pullOptFunc(func(opts *consumeOpts) error {
+		opts.notifyOnReconnect = true
+		return nil
+	})
+}
+
 // Info returns information about the ordered consumer.
 // Note that this method will fetch the latest instance of the
 // consumer from the server, which can be deleted by the library at any time.
@@ -638,3 +667,91 @@ func (c *orderedConsumer) CachedInfo() *ConsumerInfo {
 	}
 	return c.currentConsumer.info
 }
+
+type backoffOpts struct {
+	// total retry attempts
+	// -1 for unlimited
+	attempts int
+	// initial interval after which first retry will be performed
+	// defaults to 1s
+	initialInterval time.Duration
+	// determines whether first function execution should be performed immediately
+	disableInitialExecution bool
+	// multiplier on each attempt
+	// defaults to 2
+	factor float64
+	// max interval between retries
+	// after reaching this value, all subsequent
+	// retries will be performed with this interval
+	// defaults to 1 minute
+	maxInterval time.Duration
+	// custom backoff intervals
+	// if set, overrides all other options except attempts
+	// if attempts are set, then the last interval will be used
+	// for all subsequent retries after reaching the limit
+	customBackoff []time.Duration
+	// cancel channel
+	// if set, retry will be canceled when this channel is closed
+	cancel <-chan struct{}
+}
+
+func retryWithBackoff(f func(int) (bool, error), opts backoffOpts) error {
+	var err error
+	var shouldContinue bool
+	// if custom backoff is set, use it instead of other options
+	if len(opts.customBackoff) > 0 {
+		if opts.attempts != 0 {
+			return fmt.Errorf("cannot use custom backoff intervals when attempts are set")
+		}
+		for i, interval := range opts.customBackoff {
+			select {
+			case <-opts.cancel:
+				return nil
+			case <-time.After(interval):
+			}
+			shouldContinue, err = f(i)
+			if !shouldContinue {
+				return err
+			}
+		}
+		return err
+	}
+
+	// set default options
+	if opts.initialInterval == 0 {
+		opts.initialInterval = 1 * time.Second
+	}
+	if opts.factor == 0 {
+		opts.factor = 2
+	}
+	if opts.maxInterval == 0 {
+		opts.maxInterval = 1 * time.Minute
+	}
+	if opts.attempts == 0 {
+		return fmt.Errorf("retry attempts have to be set when not using custom backoff intervals")
+	}
+	interval := opts.initialInterval
+	for i := 0; ; i++ {
+		if i == 0 && opts.disableInitialExecution {
+			time.Sleep(interval)
+			continue
+		}
+		shouldContinue, err = f(i)
+		if !shouldContinue {
+			return err
+		}
+		if opts.attempts > 0 && i >= opts.attempts-1 {
+			break
+		}
+		select {
+		case <-opts.cancel:
+			return nil
+		case <-time.After(interval):
+		}
+		interval = time.Duration(float64(interval) * opts.factor)
+		if interval >= opts.maxInterval {
+			interval = opts.maxInterval
+		}
+	}
+	return err
+}