[IMPROVED] Return more specific cons info error on ordered consumer recreation (#1931)

Signed-off-by: Piotr Piotrowski <piotr@synadia.com>

Author: piotrpio

js.go

@@ -2836,6 +2836,10 @@ func (sub *Subscription) ConsumerInfo() (*ConsumerInfo, error) {
 	sub.mu.Lock()
 	// TODO(dlc) - Better way to mark especially if we attach.
 	if sub.jsi == nil || sub.jsi.consumer == _EMPTY_ {
+		if sub.jsi.ordered {
+			sub.mu.Unlock()
+			return nil, ErrConsumerInfoOnOrderedReset
+		}
 		sub.mu.Unlock()
 		return nil, ErrTypeSubscription
 	}

jserrors.go

@@ -150,6 +150,9 @@ var (
 	// ErrConsumerLeadershipChanged is returned when pending requests are no longer valid after leadership has changed
 	ErrConsumerLeadershipChanged JetStreamError = &jsError{message: "Leadership Changed"}
 
+	// ErrConsumerInfoOnOrderedReset is returned when attempting to fetch consumer info for an ordered consumer that is currently being recreated.
+	ErrConsumerInfoOnOrderedReset JetStreamError = &jsError{message: "cannot fetch consumer info; ordered consumer is being reset"}
+
 	// ErrNoHeartbeat is returned when no heartbeat is received from server when sending requests with pull consumer.
 	ErrNoHeartbeat JetStreamError = &jsError{message: "no heartbeat received"}
 

test/js_test.go

@@ -10105,9 +10105,21 @@ func TestJetStreamOrderedConsumerRecreateAfterReconnect(t *testing.T) {
 	if err != nil {
 		t.Fatalf("Unexpected error: %v", err)
 	}
-	consInfo, err = sub.ConsumerInfo()
-	if err != nil {
-		t.Fatalf("Unexpected error: %v", err)
+	var infoErr error
+	for range 5 {
+		consInfo, infoErr = sub.ConsumerInfo()
+		if infoErr != nil {
+			if errors.Is(infoErr, nats.ErrConsumerInfoOnOrderedReset) {
+				time.Sleep(100 * time.Millisecond)
+				continue
+			}
+			t.Fatalf("Unexpected error: %v", err)
+		}
+		infoErr = nil
+		break
+	}
+	if infoErr != nil {
+		t.Fatalf("Unexpected error: %v", infoErr)
 	}
 	if consInfo.Name == consName || len(consInfo.Name) != 8 {
 		t.Fatalf("Unexpected consumer name: %q", consInfo.Name)