Refactoring.

Source/MQTTnet/Adapter/MqttChannelAdapter.cs

@@ -128,11 +128,11 @@ namespace MQTTnet.Adapter
 
                 if (timeout > TimeSpan.Zero)
                 {
-                    receivedMqttPacket = await Internal.TaskExtensions.TimeoutAfterAsync(ct => ReceiveAsync(_channel, ct), timeout, cancellationToken).ConfigureAwait(false);
+                    receivedMqttPacket = await Internal.TaskExtensions.TimeoutAfterAsync(ReceiveAsync, timeout, cancellationToken).ConfigureAwait(false);
                 }
                 else
                 {
-                    receivedMqttPacket = await ReceiveAsync(_channel, cancellationToken).ConfigureAwait(false);
+                    receivedMqttPacket = await ReceiveAsync(cancellationToken).ConfigureAwait(false);
                 }
 
                 if (receivedMqttPacket == null || cancellationToken.IsCancellationRequested)
@@ -163,9 +163,9 @@ namespace MQTTnet.Adapter
             return null;
         }
 
-        private async Task<ReceivedMqttPacket> ReceiveAsync(IMqttChannel channel, CancellationToken cancellationToken)
+        private async Task<ReceivedMqttPacket> ReceiveAsync(CancellationToken cancellationToken)
         {
-            var fixedHeader = await MqttPacketReader.ReadFixedHeaderAsync(channel, _fixedHeaderBuffer, _singleByteBuffer, cancellationToken).ConfigureAwait(false);
+            var fixedHeader = await MqttPacketReader.ReadFixedHeaderAsync(_channel, _fixedHeaderBuffer, _singleByteBuffer, cancellationToken).ConfigureAwait(false);
 
             try
             {
@@ -189,19 +189,15 @@ namespace MQTTnet.Adapter
                     }
 
 #if WINDOWS_UWP
-                    var readBytes = await channel.ReadAsync(body, bodyOffset, chunkSize, cancellationToken).ConfigureAwait(false);
+                    var readBytes = await _channel.ReadAsync(body, bodyOffset, chunkSize, cancellationToken).ConfigureAwait(false);
 #else
                     // async/await is not used to avoid the overhead of context switches. We assume that the reamining data
                     // has been sent from the sender directly after the initial bytes.
-                    var readBytes = channel.ReadAsync(body, bodyOffset, chunkSize, cancellationToken).ConfigureAwait(false).GetAwaiter().GetResult();
+                    var readBytes = _channel.ReadAsync(body, bodyOffset, chunkSize, cancellationToken).ConfigureAwait(false).GetAwaiter().GetResult();
 #endif
 
                     cancellationToken.ThrowIfCancellationRequested();
-
-                    if (readBytes <= 0)
-                    {
-                        ExceptionHelper.ThrowGracefulSocketClose();
-                    }
+                    ExceptionHelper.ThrowIfGracefulSocketClose(readBytes);
 
                     bodyOffset += readBytes;
                 } while (bodyOffset < body.Length);

Source/MQTTnet/Internal/ExceptionHelper.cs

@@ -8,5 +8,13 @@ namespace MQTTnet.Internal
         {
             throw new MqttCommunicationClosedGracefullyException();
         }
+
+        public static void ThrowIfGracefulSocketClose(int readBytesCount)
+        {
+            if (readBytesCount <= 0)
+            {
+                throw new MqttCommunicationClosedGracefullyException();
+            }
+        }
     }
 }

Source/MQTTnet/Serializer/MqttPacketReader.cs

@@ -20,11 +20,9 @@ namespace MQTTnet.Serializer
             while (totalBytesRead < buffer.Length)
             {
                 var bytesRead = await channel.ReadAsync(buffer, totalBytesRead, buffer.Length - totalBytesRead, cancellationToken).ConfigureAwait(false);
-                if (bytesRead <= 0)
-                {
-                    cancellationToken.ThrowIfCancellationRequested();
-                    ExceptionHelper.ThrowGracefulSocketClose();
-                }
+
+                cancellationToken.ThrowIfCancellationRequested();
+                ExceptionHelper.ThrowIfGracefulSocketClose(bytesRead);
 
                 totalBytesRead += bytesRead;
             }