Added receiveTracker to detect whether messages are received from broker.

Source/MQTTnet/Client/MqttClient.cs

@@ -1,4 +1,4 @@
-using System;
+using System;
 using System.Diagnostics;
 using System.Threading;
 using System.Threading.Tasks;
@@ -25,6 +25,7 @@ namespace MQTTnet.Client
         private readonly MqttPacketIdentifierProvider _packetIdentifierProvider = new MqttPacketIdentifierProvider();
         private readonly MqttPacketDispatcher _packetDispatcher = new MqttPacketDispatcher();
         private readonly Stopwatch _sendTracker = new Stopwatch();
+        private readonly Stopwatch _receiveTracker = new Stopwatch();
         private readonly object _disconnectLock = new object();
 
         private readonly IMqttClientAdapterFactory _adapterFactory;
@@ -88,6 +89,7 @@ namespace MQTTnet.Client
                 authenticateResult = await AuthenticateAsync(adapter, options.WillMessage, cancellationToken).ConfigureAwait(false);
 
                 _sendTracker.Restart();
+                _receiveTracker.Restart();
 
                 if (Options.KeepAlivePeriod != TimeSpan.Zero)
                 {
@@ -344,7 +346,9 @@ namespace MQTTnet.Client
                 try
                 {
                     await _adapter.SendPacketAsync(requestPacket, Options.CommunicationTimeout, cancellationToken).ConfigureAwait(false);
-                    return await packetAwaiter.WaitOneAsync(Options.CommunicationTimeout).ConfigureAwait(false);
+                    var response = await packetAwaiter.WaitOneAsync(Options.CommunicationTimeout).ConfigureAwait(false);
+                    _receiveTracker.Restart();
+                    return response;
                 }
                 catch (MqttCommunicationTimedOutException)
                 {
@@ -369,14 +373,14 @@ namespace MQTTnet.Client
                         keepAliveSendInterval = Options.KeepAliveSendInterval.Value;
                     }
 
-                    var waitTime = keepAliveSendInterval - _sendTracker.Elapsed;
-                    if (waitTime <= TimeSpan.Zero)
+                    var waitTimeSend = keepAliveSendInterval - _sendTracker.Elapsed;
+                    var waitTimeReceive = keepAliveSendInterval - _receiveTracker.Elapsed;
+                    if (waitTimeSend <= TimeSpan.Zero || waitTimeReceive <= TimeSpan.Zero)
                     {
                         await SendAndReceiveAsync<MqttPingRespPacket>(new MqttPingReqPacket(), cancellationToken).ConfigureAwait(false);
-                        waitTime = keepAliveSendInterval;
                     }
 
-                    await Task.Delay(waitTime, cancellationToken).ConfigureAwait(false);
+                    await Task.Delay(keepAliveSendInterval, cancellationToken).ConfigureAwait(false);
                 }
             }
             catch (Exception exception)
@@ -473,6 +477,8 @@ namespace MQTTnet.Client
         {
             try
             {
+                _receiveTracker.Restart();
+
                 if (packet is MqttPublishPacket publishPacket)
                 {
                     await TryProcessReceivedPublishPacketAsync(publishPacket, cancellationToken).ConfigureAwait(false);
@@ -652,4 +658,4 @@ namespace MQTTnet.Client
             return Interlocked.CompareExchange(ref _disconnectGate, 1, 0) != 0;
         }
     }
-}
+}