Make internal message of server async.

Source/MQTTnet.AspnetCore/MqttConnectionContext.cs

@@ -20,12 +20,17 @@ namespace MQTTnet.AspNetCore
         }
 
         public string Endpoint => Connection.ConnectionId;
-        public bool IsSecureConnection => false; // TODO: Fix detection.
+        public bool IsSecureConnection => false; // TODO: Fix detection (WS vs. WSS).
+
         public ConnectionContext Connection { get; }
         public MqttPacketFormatterAdapter PacketFormatterAdapter { get; }
-        public event EventHandler ReadingPacketStarted;
-        public event EventHandler ReadingPacketCompleted;
 
+        public long BytesSent { get; } // TODO: Fix calculation.
+        public long BytesReceived { get; } // TODO: Fix calculation.
+
+        public Action ReadingPacketStartedCallback { get; set; }
+        public Action ReadingPacketCompletedCallback { get; set; }
+        
         private readonly SemaphoreSlim _writerSemaphore = new SemaphoreSlim(1, 1);
 
         public Task ConnectAsync(TimeSpan timeout, CancellationToken cancellationToken)
@@ -34,6 +39,7 @@ namespace MQTTnet.AspNetCore
             {
                 return tcp.StartAsync();
             }
+
             return Task.CompletedTask;
         }
 
@@ -80,7 +86,7 @@ namespace MQTTnet.AspNetCore
                             else
                             {
                                 // we did receive something but the message is not yet complete
-                                ReadingPacketStarted?.Invoke(this, EventArgs.Empty);
+                                ReadingPacketStartedCallback?.Invoke();
                             }
                         }
                         else if (readResult.IsCompleted)
@@ -99,7 +105,7 @@ namespace MQTTnet.AspNetCore
             }
             finally
             {
-                ReadingPacketCompleted?.Invoke(this, EventArgs.Empty);
+                ReadingPacketCompletedCallback?.Invoke();
             }
 
             cancellationToken.ThrowIfCancellationRequested();

Source/MQTTnet/Adapter/IMqttChannelAdapter.cs

@@ -13,10 +13,14 @@ namespace MQTTnet.Adapter
         bool IsSecureConnection { get; }
 
         MqttPacketFormatterAdapter PacketFormatterAdapter { get; }
-        
-        event EventHandler ReadingPacketStarted;
 
-        event EventHandler ReadingPacketCompleted;
+        long BytesSent { get; }
+
+        long BytesReceived { get; }
+
+        Action ReadingPacketStartedCallback { get; set; }
+
+        Action ReadingPacketCompletedCallback { get; set; }
 
         Task ConnectAsync(TimeSpan timeout, CancellationToken cancellationToken);
 

Source/MQTTnet/Adapter/MqttChannelAdapter.cs

@@ -25,16 +25,19 @@ namespace MQTTnet.Adapter
         private readonly MqttPacketReader _packetReader;
 
         private readonly byte[] _fixedHeaderBuffer = new byte[2];
-       
+
         private bool _isDisposed;
 
+        private long _bytesReceived;
+        private long _bytesSent;
+
         public MqttChannelAdapter(IMqttChannel channel, MqttPacketFormatterAdapter packetFormatterAdapter, IMqttNetChildLogger logger)
         {
             if (logger == null) throw new ArgumentNullException(nameof(logger));
 
             _channel = channel ?? throw new ArgumentNullException(nameof(channel));
             PacketFormatterAdapter = packetFormatterAdapter ?? throw new ArgumentNullException(nameof(packetFormatterAdapter));
-            
+
             _packetReader = new MqttPacketReader(_channel);
 
             _logger = logger.CreateChildLogger(nameof(MqttChannelAdapter));
@@ -46,9 +49,12 @@ namespace MQTTnet.Adapter
 
         public MqttPacketFormatterAdapter PacketFormatterAdapter { get; }
 
-        public event EventHandler ReadingPacketStarted;
-        public event EventHandler ReadingPacketCompleted;
+        public long BytesSent => Interlocked.Read(ref _bytesSent);
+        public long BytesReceived => Interlocked.Read(ref _bytesReceived);
 
+        public Action ReadingPacketStartedCallback { get; set; }
+        public Action ReadingPacketCompletedCallback { get; set; }
+            
         public async Task ConnectAsync(TimeSpan timeout, CancellationToken cancellationToken)
         {
             ThrowIfDisposed();
@@ -62,7 +68,7 @@ namespace MQTTnet.Adapter
                 else
                 {
                     await MqttTaskTimeout.WaitAsync(t => _channel.ConnectAsync(t), timeout, cancellationToken).ConfigureAwait(false);
-                }               
+                }
             }
             catch (Exception exception)
             {
@@ -101,7 +107,7 @@ namespace MQTTnet.Adapter
                 WrapException(exception);
             }
         }
-        
+
         public async Task SendPacketAsync(MqttBasePacket packet, TimeSpan timeout, CancellationToken cancellationToken)
         {
             await _writerSemaphore.WaitAsync(cancellationToken).ConfigureAwait(false);
@@ -118,7 +124,9 @@ namespace MQTTnet.Adapter
                     await MqttTaskTimeout.WaitAsync(
                         t => _channel.WriteAsync(packetData.Array, packetData.Offset, packetData.Count, t), timeout, cancellationToken).ConfigureAwait(false);
                 }
-                
+
+                Interlocked.Add(ref _bytesReceived, packetData.Count);
+
                 PacketFormatterAdapter.FreeBuffer();
 
                 _logger.Verbose("TX ({0} bytes) >>> {1}", packetData.Count, packet);
@@ -159,7 +167,9 @@ namespace MQTTnet.Adapter
                     return null;
                 }
 
-                if (!PacketFormatterAdapter.ProtocolVersion.HasValue)
+                Interlocked.Add(ref _bytesSent, receivedMqttPacket.TotalLength);
+
+                if (PacketFormatterAdapter.ProtocolVersion == MqttProtocolVersion.Unknown)
                 {
                     PacketFormatterAdapter.DetectProtocolVersion(receivedMqttPacket);
                 }
@@ -190,10 +200,21 @@ namespace MQTTnet.Adapter
             return null;
         }
 
+        public void ResetStatistics()
+        {
+            Interlocked.Exchange(ref _bytesReceived, 0L);
+            Interlocked.Exchange(ref _bytesSent, 0L);
+        }
+
         private async Task<ReceivedMqttPacket> ReceiveAsync(CancellationToken cancellationToken)
         {
             var readFixedHeaderResult = await _packetReader.ReadFixedHeaderAsync(_fixedHeaderBuffer, cancellationToken).ConfigureAwait(false);
 
+            if (cancellationToken.IsCancellationRequested)
+            {
+                return null;
+            }
+
             try
             {
                 if (readFixedHeaderResult.ConnectionClosed)
@@ -201,7 +222,7 @@ namespace MQTTnet.Adapter
                     return null;
                 }
 
-                ReadingPacketStarted?.Invoke(this, EventArgs.Empty);
+                ReadingPacketStartedCallback?.Invoke();
 
                 var fixedHeader = readFixedHeaderResult.FixedHeader;
                 if (fixedHeader.RemainingLength == 0)
@@ -221,13 +242,7 @@ namespace MQTTnet.Adapter
                         chunkSize = bytesLeft;
                     }
 
-#if WINDOWS_UWP
-                    var readBytes = await _channel.ReadAsync(body, bodyOffset, (int)chunkSize, cancellationToken).ConfigureAwait(false);
-#else
-                    // async/await is not used to avoid the overhead of context switches. We assume that the remaining data
-                    // has been sent from the sender directly after the initial bytes.
-                    var readBytes = _channel.ReadAsync(body, bodyOffset, chunkSize, cancellationToken).ConfigureAwait(false).GetAwaiter().GetResult();
-#endif
+                    var readBytes = await _channel.ReadAsync(body, bodyOffset, chunkSize, cancellationToken).ConfigureAwait(false);
 
                     if (cancellationToken.IsCancellationRequested)
                     {
@@ -238,7 +253,7 @@ namespace MQTTnet.Adapter
                     {
                         return null;
                     }
-                    
+
                     bodyOffset += readBytes;
                 } while (bodyOffset < body.Length);
 
@@ -247,7 +262,7 @@ namespace MQTTnet.Adapter
             }
             finally
             {
-                ReadingPacketCompleted?.Invoke(this, EventArgs.Empty);
+                ReadingPacketCompletedCallback?.Invoke();
             }
         }
 

Source/MQTTnet/Formatter/MqttPacketFormatterAdapter.cs

@@ -20,7 +20,7 @@ namespace MQTTnet.Formatter
             UseProtocolVersion(protocolVersion);
         }
 
-        public MqttProtocolVersion? ProtocolVersion { get; private set; }
+        public MqttProtocolVersion ProtocolVersion { get; private set; }
 
         public IMqttDataConverter DataConverter
         {
@@ -64,6 +64,11 @@ namespace MQTTnet.Formatter
 
         private void UseProtocolVersion(MqttProtocolVersion protocolVersion)
         {
+            if (protocolVersion == MqttProtocolVersion.Unknown)
+            {
+                throw new InvalidOperationException("MQTT protocol version is invalid.");
+            }
+
             ProtocolVersion = protocolVersion;
 
             switch (protocolVersion)

Source/MQTTnet/Formatter/MqttPacketReader.cs

@@ -3,7 +3,6 @@ using System.Threading;
 using System.Threading.Tasks;
 using MQTTnet.Channel;
 using MQTTnet.Exceptions;
-using MQTTnet.Internal;
 
 namespace MQTTnet.Formatter
 {
@@ -31,8 +30,11 @@ namespace MQTTnet.Formatter
             {
                 var bytesRead = await _channel.ReadAsync(buffer, totalBytesRead, buffer.Length - totalBytesRead, cancellationToken).ConfigureAwait(false);
 
-                cancellationToken.ThrowIfCancellationRequested();
-
+                if (cancellationToken.IsCancellationRequested)
+                {
+                    return null;
+                }
+                
                 if (bytesRead == 0)
                 {
                     return new ReadFixedHeaderResult
@@ -100,13 +102,19 @@ namespace MQTTnet.Formatter
                     return null;
                 }
 
-                var buffer = ReadByte(cancellationToken);
-                if (!buffer.HasValue)
+                var readCount = _channel.ReadAsync(_singleByteBuffer, 0, 1, cancellationToken).GetAwaiter().GetResult();
+
+                if (cancellationToken.IsCancellationRequested)
                 {
                     return null;
                 }
 
-                encodedByte = buffer.Value;
+                if (readCount == 0)
+                {
+                    return null;
+                }
+
+                encodedByte = _singleByteBuffer[0];
 
                 value += (encodedByte & 127) * multiplier;
                 multiplier *= 128;
@@ -114,26 +122,8 @@ namespace MQTTnet.Formatter
 
             return value;
         }
-
-        private byte? ReadByte(CancellationToken cancellationToken)
-        {
-            var readCount = _channel.ReadAsync(_singleByteBuffer, 0, 1, cancellationToken).ConfigureAwait(false).GetAwaiter().GetResult();
-
-            if (cancellationToken.IsCancellationRequested)
-            {
-                return null;
-            }
-
-            if (readCount == 0)
-            {
-                return null;
-            }
-
-            return _singleByteBuffer[0];
-        }
-
 #else
-        
+
         private async Task<int?> ReadBodyLengthAsync(byte initialEncodedByte, CancellationToken cancellationToken)
         {
             var offset = 0;
@@ -154,13 +144,19 @@ namespace MQTTnet.Formatter
                     return null;
                 }
 
-                var buffer = await ReadByteAsync(cancellationToken).ConfigureAwait(false);
-                if (!buffer.HasValue)
+                var readCount = await _channel.ReadAsync(_singleByteBuffer, 0, 1, cancellationToken).ConfigureAwait(false);
+
+                if (cancellationToken.IsCancellationRequested)
+                {
+                    return null;
+                }
+
+                if (readCount == 0)
                 {
                     return null;
                 }
 
-                encodedByte = buffer.Value;
+                encodedByte = _singleByteBuffer[0];
 
                 value += (encodedByte & 127) * multiplier;
                 multiplier *= 128;
@@ -168,24 +164,6 @@ namespace MQTTnet.Formatter
 
             return value;
         }
-
-        private async Task<byte?> ReadByteAsync(CancellationToken cancellationToken)
-        {
-            var readCount = await _channel.ReadAsync(_singleByteBuffer, 0, 1, cancellationToken).ConfigureAwait(false);
-
-            if (cancellationToken.IsCancellationRequested)
-            {
-                return null;
-            }
-
-            if (readCount == 0)
-            {
-                return null;
-            }
-
-            return _singleByteBuffer[0];
-        }
-
 #endif
     }
 }

Source/MQTTnet/Formatter/MqttProtocolVersion.cs

@@ -2,6 +2,8 @@
 {
     public enum MqttProtocolVersion
     {
+        Unknown = 0,
+
         V310 = 3,
         V311 = 4,
         V500 = 5

Source/MQTTnet/Internal/AsyncBlockingQueue.cs

@@ -8,7 +8,10 @@ namespace MQTTnet.Internal
     public sealed class AsyncQueue<TItem> : IDisposable
     {
         private readonly SemaphoreSlim _semaphore = new SemaphoreSlim(0);
-        private readonly ConcurrentQueue<TItem> _queue = new ConcurrentQueue<TItem>();
+
+        private ConcurrentQueue<TItem> _queue = new ConcurrentQueue<TItem>();
+
+        public int Count => _queue.Count;
 
         public void Enqueue(TItem item)
         {
@@ -16,9 +19,9 @@ namespace MQTTnet.Internal
             _semaphore.Release();
         }
 
-        public async Task<TItem> DequeueAsync(CancellationToken cancellationToken)
+        public async Task<AsyncQueueDequeueResult<TItem>> TryDequeueAsync(CancellationToken cancellationToken)
         {
-            while (true)
+            while (!cancellationToken.IsCancellationRequested)
             {
                 await _semaphore.WaitAsync(cancellationToken).ConfigureAwait(false);
 
@@ -26,9 +29,26 @@ namespace MQTTnet.Internal
 
                 if (_queue.TryDequeue(out var item))
                 {
-                    return item;
+                    return new AsyncQueueDequeueResult<TItem>(true, item);
                 }
             }
+
+            return new AsyncQueueDequeueResult<TItem>(false, default(TItem));
+        }
+
+        public AsyncQueueDequeueResult<TItem> TryDequeue()
+        {
+            if (_queue.TryDequeue(out var item))
+            {
+                return new AsyncQueueDequeueResult<TItem>(true, item);
+            }
+
+            return new AsyncQueueDequeueResult<TItem>(false, default(TItem));
+        }
+
+        public void Clear()
+        {
+            Interlocked.Exchange(ref _queue, new ConcurrentQueue<TItem>());
         }
 
         public void Dispose()

Source/MQTTnet/Internal/AsyncQueueDequeueResult.cs

@@ -0,0 +1,15 @@
+namespace MQTTnet.Internal
+{
+    public class AsyncQueueDequeueResult<TItem>
+    {
+        public AsyncQueueDequeueResult(bool isSuccess, TItem item)
+        {
+            IsSuccess = isSuccess;
+            Item = item;
+        }
+
+        public bool IsSuccess { get; }
+
+        public TItem Item { get; }
+    }
+}

Source/MQTTnet/Server/MqttClientConnection.cs

@@ -34,8 +34,10 @@ namespace MQTTnet.Server
         private readonly MqttConnectPacket _connectPacket;
 
         private DateTime _lastPacketReceivedTimestamp;
+        private DateTime _lastNonKeepAlivePacketReceivedTimestamp;
+
         private long _receivedPacketsCount;
-        private long _sentPacketsCount;
+        private long _sentPacketsCount = 1; // Start with 1 because the CONNECT packet is not counted anywhere.
         private long _receivedApplicationMessagesCount;
         private long _sentApplicationMessagesCount;
 
@@ -64,6 +66,7 @@ namespace MQTTnet.Server
             _keepAliveMonitor = new MqttClientKeepAliveMonitor(this, _logger);
 
             _lastPacketReceivedTimestamp = DateTime.UtcNow;
+            _lastNonKeepAlivePacketReceivedTimestamp = _lastPacketReceivedTimestamp;
         }
 
         public string ClientId => _connectPacket.ClientId;
@@ -85,7 +88,7 @@ namespace MQTTnet.Server
         {
             status.ClientId = ClientId;
             status.Endpoint = _endpoint;
-            status.ProtocolVersion = _channelAdapter.PacketFormatterAdapter.ProtocolVersion.Value;
+            status.ProtocolVersion = _channelAdapter.PacketFormatterAdapter.ProtocolVersion;
 
             status.ReceivedApplicationMessagesCount = Interlocked.Read(ref _receivedApplicationMessagesCount);
             status.SentApplicationMessagesCount = Interlocked.Read(ref _sentApplicationMessagesCount);
@@ -94,8 +97,10 @@ namespace MQTTnet.Server
             status.SentPacketsCount = Interlocked.Read(ref _sentPacketsCount);
 
             status.LastPacketReceivedTimestamp = _lastPacketReceivedTimestamp;
+            status.LastNonKeepAlivePacketReceivedTimestamp = _lastNonKeepAlivePacketReceivedTimestamp;
 
-            //status.LastNonKeepAlivePacketReceived = _keepAliveMonitor.LastNonKeepAlivePacketReceived;
+            status.BytesSent = _channelAdapter.BytesSent;
+            status.BytesReceived = _channelAdapter.BytesReceived;
         }
         
         //public void ClearPendingApplicationMessages()
@@ -131,10 +136,9 @@ namespace MQTTnet.Server
             try
             {
                 _logger.Info("Client '{0}': Session started.", ClientId);
-                //_eventDispatcher.OnClientConnected(ClientId);
-
-                _channelAdapter.ReadingPacketStarted += OnAdapterReadingPacketStarted;
-                _channelAdapter.ReadingPacketCompleted += OnAdapterReadingPacketCompleted;
+                
+                _channelAdapter.ReadingPacketStartedCallback = OnAdapterReadingPacketStarted;
+                _channelAdapter.ReadingPacketCompletedCallback = OnAdapterReadingPacketCompleted;
 
                 Session.WillMessage = _connectPacket.WillMessage;
 
@@ -166,7 +170,12 @@ namespace MQTTnet.Server
 
                     Interlocked.Increment(ref _sentPacketsCount);
                     _lastPacketReceivedTimestamp = DateTime.UtcNow;
-                    
+
+                    if (!(packet is MqttPingReqPacket || packet is MqttPingRespPacket))
+                    {
+                        _lastNonKeepAlivePacketReceivedTimestamp = _lastPacketReceivedTimestamp;
+                    }
+
                     _keepAliveMonitor.PacketReceived();
 
                     if (packet is MqttPublishPacket publishPacket)
@@ -243,12 +252,11 @@ namespace MQTTnet.Server
 
                 _packetDispatcher.Reset();
 
-                _channelAdapter.ReadingPacketStarted -= OnAdapterReadingPacketStarted;
-                _channelAdapter.ReadingPacketCompleted -= OnAdapterReadingPacketCompleted;
+                _channelAdapter.ReadingPacketStartedCallback = null;
+                _channelAdapter.ReadingPacketCompletedCallback = null;
 
                 _logger.Info("Client '{0}': Session stopped.", ClientId);
-                //_eventDispatcher.OnClientDisconnected(ClientId);
-
+                
                 _packageReceiverTask = null;
             }
 
@@ -376,7 +384,7 @@ namespace MQTTnet.Server
 
         private async Task SendPendingPacketsAsync(CancellationToken cancellationToken)
         {
-            MqttPendingApplicationMessage queuedApplicationMessage = null;
+            MqttQueuedApplicationMessage queuedApplicationMessage = null;
             MqttPublishPacket publishPacket = null;
 
             try
@@ -501,12 +509,12 @@ namespace MQTTnet.Server
             }
         }
 
-        private void OnAdapterReadingPacketCompleted(object sender, EventArgs e)
+        private void OnAdapterReadingPacketCompleted()
         {
             _keepAliveMonitor?.Resume();
         }
 
-        private void OnAdapterReadingPacketStarted(object sender, EventArgs e)
+        private void OnAdapterReadingPacketStarted()
         {
             _keepAliveMonitor?.Pause();
         }

Source/MQTTnet/Server/MqttClientKeepAliveMonitor.cs

@@ -3,7 +3,6 @@ using System.Diagnostics;
 using System.Threading;
 using System.Threading.Tasks;
 using MQTTnet.Diagnostics;
-using MQTTnet.Packets;
 
 namespace MQTTnet.Server
 {

Source/MQTTnet/Server/MqttClientSessionApplicationMessagesQueue.cs

@@ -1,54 +1,29 @@
 using MQTTnet.Internal;
 using MQTTnet.Protocol;
 using System;
-using System.Collections.Generic;
 using System.Threading;
 using System.Threading.Tasks;
 
 namespace MQTTnet.Server
 {
-    public class MqttPendingApplicationMessage
-    {
-        public MqttApplicationMessage ApplicationMessage { get; set; }
-
-        public string SenderClientId { get; set; }
-
-        public bool IsRetainedMessage { get; set; }
-
-        public MqttQualityOfServiceLevel QualityOfServiceLevel { get; set; }
-
-        public bool IsDuplicate { get; set; }
-    }
-
     public class MqttClientSessionApplicationMessagesQueue : IDisposable
     {
-        private readonly Queue<MqttPendingApplicationMessage> _messageQueue = new Queue<MqttPendingApplicationMessage>();
-        private readonly AsyncAutoResetEvent _messageQueueLock = new AsyncAutoResetEvent();
-
+        private readonly AsyncQueue<MqttQueuedApplicationMessage> _messageQueue = new AsyncQueue<MqttQueuedApplicationMessage>();
+        
         private readonly IMqttServerOptions _options;
 
         public MqttClientSessionApplicationMessagesQueue(IMqttServerOptions options)
         {
             _options = options ?? throw new ArgumentNullException(nameof(options));
-
         }
 
-        public int Count
-        {
-            get
-            {
-                lock (_messageQueue)
-                {
-                    return _messageQueue.Count;
-                }
-            }
-        }
+        public int Count => _messageQueue.Count;
 
         public void Enqueue(MqttApplicationMessage applicationMessage, string senderClientId, MqttQualityOfServiceLevel qualityOfServiceLevel, bool isRetainedMessage)
         {
             if (applicationMessage == null) throw new ArgumentNullException(nameof(applicationMessage));
 
-            Enqueue(new MqttPendingApplicationMessage
+            Enqueue(new MqttQueuedApplicationMessage
             {
                 ApplicationMessage = applicationMessage,
                 SenderClientId = senderClientId,
@@ -59,39 +34,23 @@ namespace MQTTnet.Server
 
         public void Clear()
         {
-            lock (_messageQueue)
-            {
-                _messageQueue.Clear();
-            }
-        }
-
-        public void Dispose()
-        {
+            _messageQueue.Clear();
         }
 
-        public async Task<MqttPendingApplicationMessage> TakeAsync(CancellationToken cancellationToken)
+        public async Task<MqttQueuedApplicationMessage> TakeAsync(CancellationToken cancellationToken)
         {
-            // TODO: Create a blocking queue from this.
-
-            while (!cancellationToken.IsCancellationRequested)
+            var dequeueResult = await _messageQueue.TryDequeueAsync(cancellationToken).ConfigureAwait(false);
+            if (!dequeueResult.IsSuccess)
             {
-                lock (_messageQueue)
-                {
-                    if (_messageQueue.Count > 0)
-                    {
-                        return _messageQueue.Dequeue();
-                    }
-                }
-
-                await _messageQueueLock.WaitOneAsync(cancellationToken).ConfigureAwait(false);
+                return null;
             }
 
-            return null;
+            return dequeueResult.Item;
         }
 
-        public void Enqueue(MqttPendingApplicationMessage enqueuedApplicationMessage)
+        public void Enqueue(MqttQueuedApplicationMessage queuedApplicationMessage)
         {
-            if (enqueuedApplicationMessage == null) throw new ArgumentNullException(nameof(enqueuedApplicationMessage));
+            if (queuedApplicationMessage == null) throw new ArgumentNullException(nameof(queuedApplicationMessage));
 
             lock (_messageQueue)
             {
@@ -104,14 +63,17 @@ namespace MQTTnet.Server
 
                     if (_options.PendingMessagesOverflowStrategy == MqttPendingMessagesOverflowStrategy.DropOldestQueuedMessage)
                     {
-                        _messageQueue.Dequeue();
+                        _messageQueue.TryDequeue();
                     }
                 }
 
-                _messageQueue.Enqueue(enqueuedApplicationMessage);
+                _messageQueue.Enqueue(queuedApplicationMessage);
             }
+        }
 
-            _messageQueueLock.Set();
+        public void Dispose()
+        {
+            _messageQueue.Dispose();
         }
     }
 }

Source/MQTTnet/Server/MqttClientSessionsManager.cs

@@ -68,7 +68,7 @@ namespace MQTTnet.Server
 
             foreach (var connection in _connections.Values)
             {
-                var clientStatus = new MqttClientStatus(connection, this);
+                var clientStatus = new MqttClientStatus(connection);
                 connection.FillStatus(clientStatus);
                 
                 var sessionStatus = new MqttSessionStatus(connection.Session, this);
@@ -175,7 +175,8 @@ namespace MQTTnet.Server
                     return;
                 }
 
-                var queuedApplicationMessage = await _messageQueue.DequeueAsync(cancellationToken).ConfigureAwait(false);
+                var dequeueResult = await _messageQueue.TryDequeueAsync(cancellationToken).ConfigureAwait(false);
+                var queuedApplicationMessage = dequeueResult.Item;
 
                 var sender = queuedApplicationMessage.Sender;
                 var applicationMessage = queuedApplicationMessage.ApplicationMessage;

Source/MQTTnet/Server/MqttQueuedApplicationMessage.cs

@@ -0,0 +1,17 @@
+using MQTTnet.Protocol;
+
+namespace MQTTnet.Server
+{
+    public class MqttQueuedApplicationMessage
+    {
+        public MqttApplicationMessage ApplicationMessage { get; set; }
+
+        public string SenderClientId { get; set; }
+
+        public bool IsRetainedMessage { get; set; }
+
+        public MqttQualityOfServiceLevel QualityOfServiceLevel { get; set; }
+
+        public bool IsDuplicate { get; set; }
+    }
+}

Source/MQTTnet/Server/Status/IMqttClientStatus.cs

@@ -26,6 +26,10 @@ namespace MQTTnet.Server.Status
 
         IMqttSessionStatus Session { get; }
 
+        long BytesSent { get; }
+
+        long BytesReceived { get; }
+
         Task DisconnectAsync();
     }
 }

Source/MQTTnet/Server/Status/MqttClientStatus.cs

@@ -6,13 +6,11 @@ namespace MQTTnet.Server.Status
 {
     public class MqttClientStatus : IMqttClientStatus
     {
-        private readonly MqttClientSessionsManager _sessionsManager;
         private readonly MqttClientConnection _connection;
 
-        public MqttClientStatus(MqttClientConnection connection, MqttClientSessionsManager sessionsManager)
+        public MqttClientStatus(MqttClientConnection connection)
         {
             _connection = connection;
-            _sessionsManager = sessionsManager;
         }
 
         public string ClientId { get; set; }
@@ -35,6 +33,10 @@ namespace MQTTnet.Server.Status
 
         public IMqttSessionStatus Session { get; set; }
 
+        public long BytesSent { get; set; }
+
+        public long BytesReceived { get; set; }
+
         public Task DisconnectAsync()
         {
             return _connection.StopAsync();