fix: re-send cancel message on coordination session re-attach

If a coordination service session re-attaches, idempotent conversations
requests are being re-sent. However, if a conversation has been canceled,
only its cancelation request must be re-send.

The previous version may re-send original requests for already canceled
conversations which may lead to inconsistency between the client and
server state.

CHANGELOG.md

@@ -1,3 +1,5 @@
+* Fixed the hanging semaphore issue on coordination session reconnect
+
 ## v3.65.3
 * Fixed data race in `internal/conn.grpcClientStream` 
 

internal/coordination/conversation/conversation.go

@@ -424,7 +424,12 @@ func (c *Controller) OnAttach() {
 				delete(c.conflicts, req.conflictKey)
 			}
 
-			req.requestSent = nil
+			// If the request has been canceled, re-send the cancellation message, otherwise re-send the original one.
+			if req.canceled {
+				req.cancelRequestSent = nil
+			} else {
+				req.requestSent = nil
+			}
 			notify = true
 		}
 	}