simplify missed heartbeat recognition

Author: bollhals

projects/RabbitMQ.Client/client/impl/Connection.cs

@@ -87,10 +87,11 @@ internal sealed class Connection : IConnection
         private TimeSpan _heartbeat = TimeSpan.Zero;
         private TimeSpan _heartbeatTimeSpan = TimeSpan.FromSeconds(0);
         private int _missedHeartbeats = 0;
+        private int _heartbeatCounter;
+        private int _lastHeartbeat;
 
         private Timer _heartbeatWriteTimer;
         private Timer _heartbeatReadTimer;
-        private readonly AutoResetEvent _heartbeatRead = new AutoResetEvent(false);
 
         private Task _mainLoopTask;
 
@@ -617,10 +618,7 @@ public void MainLoopIteration()
 
         public void NotifyHeartbeatListener()
         {
-            if (_heartbeat != TimeSpan.Zero)
-            {
-                _heartbeatRead.Set();
-            }
+            _heartbeatCounter++;
         }
 
         public void NotifyReceivedCloseOk()
@@ -847,7 +845,7 @@ public void HeartbeatReadTimerCallback(object state)
             {
                 if (!_closed)
                 {
-                    if (!_heartbeatRead.WaitOne(0))
+                    if (_lastHeartbeat == _heartbeatCounter)
                     {
                         _missedHeartbeats++;
                     }
@@ -856,6 +854,8 @@ public void HeartbeatReadTimerCallback(object state)
                         _missedHeartbeats = 0;
                     }
 
+                    _lastHeartbeat = _heartbeatCounter;
+
                     // We check against 8 = 2 * 4 because we need to wait for at
                     // least two complete heartbeat setting intervals before
                     // complaining, and we've set the socket timeout to a quarter