Handle potential NullReferenceException in HeartbeatReadTimerCallback

kjnilsson · michaelklishin · commit 9674068edeb9 · 2016-11-06T19:12:30.000+03:00
diff --git a/projects/client/RabbitMQ.Client/src/client/impl/Connection.cs b/projects/client/RabbitMQ.Client/src/client/impl/Connection.cs
@@ -1057,17 +1057,21 @@ public void HeartbeatReadTimerCallback(object state)
                     TerminateMainloop();
                     FinishClose();
                 }
-                else
+                else if(_heartbeatReadTimer != null)
                 {
                     _heartbeatReadTimer.Change(Heartbeat * 1000, Timeout.Infinite);
                 }
             }
             catch (ObjectDisposedException ignored)
             {
-
                 // timer is already disposed,
                 // e.g. due to shutdown
             }
+            catch (NullReferenceException)
+            {
+                // timer has already been disposed from a different thread after null check
+                // this event should be rare
+            }
         }
 
         public void HeartbeatWriteTimerCallback(object state)

Original file line number	Diff line number	Diff line change
`@@ -1057,17 +1057,21 @@ public void HeartbeatReadTimerCallback(object state)`
`1057`	`1057`	`TerminateMainloop();`
`1058`	`1058`	`FinishClose();`
`1059`	`1059`	`}`
`1060`		`- else`
	`1060`	`+ else if(_heartbeatReadTimer != null)`
`1061`	`1061`	`{`
`1062`	`1062`	`_heartbeatReadTimer.Change(Heartbeat * 1000, Timeout.Infinite);`
`1063`	`1063`	`}`
`1064`	`1064`	`}`
`1065`	`1065`	`catch (ObjectDisposedException ignored)`
`1066`	`1066`	`{`
`1067`		`-`
`1068`	`1067`	`// timer is already disposed,`
`1069`	`1068`	`// e.g. due to shutdown`
`1070`	`1069`	`}`
	`1070`	`+ catch (NullReferenceException)`
	`1071`	`+ {`
	`1072`	`+ // timer has already been disposed from a different thread after null check`
	`1073`	`+ // this event should be rare`
	`1074`	`+ }`
`1071`	`1075`	`}`
`1072`	`1076`
`1073`	`1077`	`public void HeartbeatWriteTimerCallback(object state)`