stomp: fix Unsubscribe race

I think this is OK because the only point that wakes the `sync.Cond` is _after_ closing the channel and updating the `status` member. There should be no way to close the channel _before_ updating the status. If there were, this code would be racy again. Signed-off-by: Hank Donnay <[email protected]>
go-stomp · Aug 26, 2024 · 9165d8a · 9165d8a
1 parent 9a13a1a
commit 9165d8a
Showing 1 changed file with 6 additions and 2 deletions.
diff --git a/subscription.go b/subscription.go
@@ -102,8 +102,12 @@ func (s *Subscription) Unsubscribe(opts ...func(*frame.Frame) error) error {
 	for atomic.LoadInt32(&s.state) != subStateClosed {
 		err = waitWithTimeout(s.closeCond, s.unsubscribeReceiptTimeout)
 		if err != nil && errors.Is(err, &ErrUnsubscribeReceiptTimeout) {
-			msg := s.subscriptionErrorMessage("channel unsubscribe receipt timeout")
-			s.C <- msg
+			// The [closeCond.Broadcast] can race with the timeout, so make sure
+			// the channel is still available.
+			if atomic.LoadInt32(&s.state) != subStateClosed {
+				msg := s.subscriptionErrorMessage("channel unsubscribe receipt timeout")
+				s.C <- msg
+			}
 			return err
 		}
 	}