Improve logger performance.

Build/MQTTnet.nuspec

@@ -14,12 +14,14 @@
     <releaseNotes>
 * [Core] Renamed some topic filter relevant classes (BREAKING CHANGE!).
 * [Core] Improved task management for UWP connections (thanks to @xgstation).
+* [Core] Fixed broken logger which decreases overall performance.
 * [Client] Added method to trigger PING/PONG manually (connection check etc.).
 * [Client] Added support for certificate validation callback when using Web Sockets (requires netstandard2.1+).
 * [Client] Fixed a memory leak when web socket based connections trying to reconnect with an offline server.
 * [Client] Fixed a memory leak when TCP based connections trying to reconnect with an offline server.
 * [Client] Fixed an issue when connecting to an invalid host (format).
 * [Client] Added support for user properties in CONNECT packet.
+* [Client] Removed _KeepAliveSendInterval_ and improved keep alive handling (BREAKING CHANGE!).
 * [ManagedClient] Added method to trigger PING/PONG manually (connection check etc.).
 * [MQTTnet.AspNetCore] improved compatibility with AspNetCore 3.1.
 * [MQTTnet.AspNetCore] Fixed several packaging issues with the Nuget package.

Source/MQTTnet.AspnetCore/Client/MqttClientConnectionContextFactory.cs

@@ -1,7 +1,6 @@
 using MQTTnet.Adapter;
 using MQTTnet.AspNetCore.Client.Tcp;
 using MQTTnet.Client.Options;
-using MQTTnet.Diagnostics;
 using MQTTnet.Formatter;
 using System;
 using System.Net;
@@ -10,7 +9,7 @@ namespace MQTTnet.AspNetCore.Client
 {
     public class MqttClientConnectionContextFactory : IMqttClientAdapterFactory
     {
-        public IMqttChannelAdapter CreateClientAdapter(IMqttClientOptions options, IMqttNetLogger logger)
+        public IMqttChannelAdapter CreateClientAdapter(IMqttClientOptions options)
         {
             if (options == null) throw new ArgumentNullException(nameof(options));
 

Source/MQTTnet.AspnetCore/MqttConnectionContext.cs

@@ -160,19 +160,19 @@ namespace MQTTnet.AspNetCore
         public async Task SendPacketAsync(MqttBasePacket packet, TimeSpan timeout, CancellationToken cancellationToken)
         {
             var formatter = PacketFormatterAdapter;
-
+            var buffer = formatter.Encode(packet);
+            var msg = buffer.AsMemory();
+            var output = _output;
 
             await _writerSemaphore.WaitAsync(cancellationToken).ConfigureAwait(false);
             try
             {
-                var buffer = formatter.Encode(packet);
-                var msg = buffer.AsMemory();
-                var output = _output;
                 var result = await output.WriteAsync(msg, cancellationToken).ConfigureAwait(false);
                 if (result.IsCompleted)
                 {
                     BytesSent += msg.Length;
                 }
+
                 PacketFormatterAdapter.FreeBuffer();
             }
             finally

Source/MQTTnet.AspnetCore/MqttHostedServer.cs

@@ -14,7 +14,7 @@ namespace MQTTnet.AspNetCore
         private readonly IMqttServerOptions _options;
 
         public MqttHostedServer(IMqttServerOptions options, IEnumerable<IMqttServerAdapter> adapters, IMqttNetLogger logger) 
-            : base(adapters, logger.CreateChildLogger(nameof(MqttHostedServer)))
+            : base(adapters, logger)
         {
             _options = options ?? throw new ArgumentNullException(nameof(options));
         }

Source/MQTTnet.AspnetCore/MqttWebSocketServerAdapter.cs

@@ -10,15 +10,13 @@ using System.Threading.Tasks;
 
 namespace MQTTnet.AspNetCore
 {
-    public class MqttWebSocketServerAdapter : IMqttServerAdapter
+    public sealed class MqttWebSocketServerAdapter : IMqttServerAdapter
     {
-        private readonly IMqttNetLogger _logger;
+        readonly IMqttNetLogger _rootLogger;
 
         public MqttWebSocketServerAdapter(IMqttNetLogger logger)
         {
-            if (logger == null) throw new ArgumentNullException(nameof(logger));
-
-            _logger = logger.CreateChildLogger(nameof(MqttTcpServerAdapter));
+            _rootLogger = logger ?? throw new ArgumentNullException(nameof(logger));
         }
 
         public Func<IMqttChannelAdapter, Task> ClientHandler { get; set; }
@@ -51,7 +49,7 @@ namespace MQTTnet.AspNetCore
                     var formatter = new MqttPacketFormatterAdapter(writer);
                     var channel = new MqttWebSocketChannel(webSocket, endpoint, isSecureConnection, clientCertificate);
 
-                    using (var channelAdapter = new MqttChannelAdapter(channel, formatter, _logger.CreateChildLogger(nameof(MqttWebSocketServerAdapter))))
+                    using (var channelAdapter = new MqttChannelAdapter(channel, formatter, _rootLogger))
                     {
                         await clientHandler(channelAdapter).ConfigureAwait(false);
                     }

Source/MQTTnet.Extensions.ManagedClient/ManagedMqttClient.cs

@@ -33,7 +33,7 @@ namespace MQTTnet.Extensions.ManagedClient
         private readonly SemaphoreSlim _subscriptionsQueuedSignal = new SemaphoreSlim(0);
 
         private readonly IMqttClient _mqttClient;
-        private readonly IMqttNetLogger _logger;
+        private readonly IMqttNetScopedLogger _logger;
 
         private readonly AsyncLock _messageQueueLock = new AsyncLock();
 
@@ -48,7 +48,7 @@ namespace MQTTnet.Extensions.ManagedClient
             _mqttClient = mqttClient ?? throw new ArgumentNullException(nameof(mqttClient));
 
             if (logger == null) throw new ArgumentNullException(nameof(logger));
-            _logger = logger.CreateChildLogger(nameof(ManagedMqttClient));
+            _logger = logger.CreateScopedLogger(nameof(ManagedMqttClient));
         }
 
         public bool IsConnected => _mqttClient.IsConnected;

Source/MQTTnet.Extensions.WebSocket4Net/MqttFactoryExtensions.cs

@@ -8,7 +8,7 @@ namespace MQTTnet.Extensions.WebSocket4Net
         {
             if (mqttFactory == null) throw new ArgumentNullException(nameof(mqttFactory));
 
-            return mqttFactory.UseClientAdapterFactory(new WebSocket4NetMqttClientAdapterFactory());
+            return mqttFactory.UseClientAdapterFactory(new WebSocket4NetMqttClientAdapterFactory(mqttFactory.DefaultLogger));
         }
     }
 }

Source/MQTTnet.Extensions.WebSocket4Net/WebSocket4NetMqttClientAdapterFactory.cs

@@ -9,21 +9,27 @@ namespace MQTTnet.Extensions.WebSocket4Net
 {
     public class WebSocket4NetMqttClientAdapterFactory : IMqttClientAdapterFactory
     {
-        public IMqttChannelAdapter CreateClientAdapter(IMqttClientOptions options, IMqttNetLogger logger)
+        readonly IMqttNetLogger _logger;
+
+        public WebSocket4NetMqttClientAdapterFactory(IMqttNetLogger logger)
+        {
+            _logger = logger ?? throw new ArgumentNullException(nameof(logger));
+        }
+
+        public IMqttChannelAdapter CreateClientAdapter(IMqttClientOptions options)
         {
             if (options == null) throw new ArgumentNullException(nameof(options));
-            if (logger == null) throw new ArgumentNullException(nameof(logger));
 
             switch (options.ChannelOptions)
             {
                 case MqttClientTcpOptions _:
                     {
-                        return new MqttChannelAdapter(new MqttTcpChannel(options), new MqttPacketFormatterAdapter(options.ProtocolVersion), logger);
+                        return new MqttChannelAdapter(new MqttTcpChannel(options), new MqttPacketFormatterAdapter(options.ProtocolVersion), _logger);
                     }
 
                 case MqttClientWebSocketOptions webSocketOptions:
                     {
-                        return new MqttChannelAdapter(new WebSocket4NetMqttChannel(options, webSocketOptions), new MqttPacketFormatterAdapter(options.ProtocolVersion), logger);
+                        return new MqttChannelAdapter(new WebSocket4NetMqttChannel(options, webSocketOptions), new MqttPacketFormatterAdapter(options.ProtocolVersion), _logger);
                     }
 
                 default:

Source/MQTTnet.Server/Logging/MqttNetLoggerWrapper.cs

@@ -5,7 +5,7 @@ using System.Threading;
 
 namespace MQTTnet.Server.Logging
 {
-    public class MqttNetLoggerWrapper : IMqttNetLogger
+    public sealed class MqttNetLoggerWrapper : IMqttNetLogger
     {
         readonly ILogger<MqttServer> _logger;
 
@@ -16,9 +16,9 @@ namespace MQTTnet.Server.Logging
 
         public event EventHandler<MqttNetLogMessagePublishedEventArgs> LogMessagePublished;
 
-        public IMqttNetLogger CreateChildLogger(string source)
+        public IMqttNetScopedLogger CreateScopedLogger(string source)
         {
-            return new MqttNetLogger(source);
+            return new MqttNetScopedLogger(this, source);
         }
 
         public void Publish(MqttNetLogLevel level, string source, string message, object[] parameters, Exception exception)

Source/MQTTnet/Adapter/IMqttClientAdapterFactory.cs

@@ -1,10 +1,9 @@
 using MQTTnet.Client.Options;
-using MQTTnet.Diagnostics;
 
 namespace MQTTnet.Adapter
 {
     public interface IMqttClientAdapterFactory
     {
-        IMqttChannelAdapter CreateClientAdapter(IMqttClientOptions options, IMqttNetLogger logger);
+        IMqttChannelAdapter CreateClientAdapter(IMqttClientOptions options);
     }
 }

Source/MQTTnet/Adapter/MqttChannelAdapter.cs

@@ -19,7 +19,7 @@ namespace MQTTnet.Adapter
         const uint ErrorOperationAborted = 0x800703E3;
         const int ReadBufferSize = 4096;  // TODO: Move buffer size to config
 
-        readonly IMqttNetLogger _logger;
+        readonly IMqttNetScopedLogger _logger;
         readonly IMqttChannel _channel;
         readonly MqttPacketReader _packetReader;
 
@@ -39,7 +39,7 @@ namespace MQTTnet.Adapter
 
             _packetReader = new MqttPacketReader(_channel);
 
-            _logger = logger.CreateChildLogger(nameof(MqttChannelAdapter));
+            _logger = logger.CreateScopedLogger(nameof(MqttChannelAdapter));
         }
 
         public string Endpoint => _channel.Endpoint;
@@ -128,8 +128,6 @@ namespace MQTTnet.Adapter
 
                 Interlocked.Add(ref _bytesReceived, packetData.Count);
 
-                PacketFormatterAdapter.FreeBuffer();
-
                 _logger.Verbose("TX ({0} bytes) >>> {1}", packetData.Count, packet);
             }
             catch (Exception exception)
@@ -143,6 +141,7 @@ namespace MQTTnet.Adapter
             }
             finally
             {
+                PacketFormatterAdapter.FreeBuffer();
                 _writerSemaphore?.Release();
             }
         }

Source/MQTTnet/Client/MqttClient.cs

@@ -29,7 +29,7 @@ namespace MQTTnet.Client
         readonly object _disconnectLock = new object();
 
         readonly IMqttClientAdapterFactory _adapterFactory;
-        readonly IMqttNetLogger _logger;
+        readonly IMqttNetScopedLogger _logger;
 
         CancellationTokenSource _backgroundCancellationTokenSource;
         Task _packetReceiverTask;
@@ -48,7 +48,7 @@ namespace MQTTnet.Client
             if (logger == null) throw new ArgumentNullException(nameof(logger));
 
             _adapterFactory = channelFactory ?? throw new ArgumentNullException(nameof(channelFactory));
-            _logger = logger.CreateChildLogger(nameof(MqttClient));
+            _logger = logger.CreateScopedLogger(nameof(MqttClient));
         }
 
         public IMqttClientConnectedHandler ConnectedHandler { get; set; }
@@ -89,7 +89,7 @@ namespace MQTTnet.Client
                 var backgroundCancellationToken = _backgroundCancellationTokenSource.Token;
 
                 _isDisconnectPending = 0;
-                var adapter = _adapterFactory.CreateClientAdapter(options, _logger);
+                var adapter = _adapterFactory.CreateClientAdapter(options);
                 _adapter = adapter;
 
                 using (var combined = CancellationTokenSource.CreateLinkedTokenSource(backgroundCancellationToken, cancellationToken))
@@ -295,7 +295,10 @@ namespace MQTTnet.Client
 
         void ThrowIfNotConnected()
         {
-            if (!IsConnected || Interlocked.Read(ref _isDisconnectPending) == 1) throw new MqttCommunicationException("The client is not connected.");
+            if (!IsConnected || Interlocked.Read(ref _isDisconnectPending) == 1)
+            {
+                throw new MqttCommunicationException("The client is not connected.");
+            }
         }
 
         void ThrowIfConnected(string message)
@@ -376,12 +379,9 @@ namespace MQTTnet.Client
             }
         }
 
-        private Task SendAsync(MqttBasePacket packet, CancellationToken cancellationToken)
+        Task SendAsync(MqttBasePacket packet, CancellationToken cancellationToken)
         {
-            if (cancellationToken.IsCancellationRequested)
-            {
-                return Task.FromResult(0);
-            }
+            cancellationToken.ThrowIfCancellationRequested();
 
             _sendTracker.Restart();
 
@@ -391,9 +391,7 @@ namespace MQTTnet.Client
         async Task<TResponsePacket> SendAndReceiveAsync<TResponsePacket>(MqttBasePacket requestPacket, CancellationToken cancellationToken) where TResponsePacket : MqttBasePacket
         {
             cancellationToken.ThrowIfCancellationRequested();
-
-            _sendTracker.Restart();
-
+            
             ushort identifier = 0;
             if (requestPacket is IMqttPacketWithIdentifier packetWithIdentifier && packetWithIdentifier.PacketIdentifier.HasValue)
             {
@@ -404,6 +402,8 @@ namespace MQTTnet.Client
             {
                 try
                 {
+                    _sendTracker.Restart();
+
                     await _adapter.SendPacketAsync(requestPacket, Options.CommunicationTimeout, cancellationToken).ConfigureAwait(false);
                 }
                 catch (Exception e)
@@ -414,9 +414,7 @@ namespace MQTTnet.Client
 
                 try
                 {
-                    var response = await packetAwaiter.WaitOneAsync(Options.CommunicationTimeout).ConfigureAwait(false);
-                    _receiveTracker.Restart();
-                    return response;
+                    return await packetAwaiter.WaitOneAsync(Options.CommunicationTimeout).ConfigureAwait(false);
                 }
                 catch (Exception exception)
                 {
@@ -436,23 +434,19 @@ namespace MQTTnet.Client
             {
                 _logger.Verbose("Start sending keep alive packets.");
 
+                var keepAlivePeriod = Options.KeepAlivePeriod;
+
                 while (!cancellationToken.IsCancellationRequested)
                 {
                     // Values described here: [MQTT-3.1.2-24].
-                    var keepAliveSendInterval = TimeSpan.FromSeconds(Options.KeepAlivePeriod.TotalSeconds * 0.75);
-                    if (Options.KeepAliveSendInterval.HasValue)
-                    {
-                        keepAliveSendInterval = Options.KeepAliveSendInterval.Value;
-                    }
-
-                    var waitTimeSend = keepAliveSendInterval - _sendTracker.Elapsed;
-                    var waitTimeReceive = keepAliveSendInterval - _receiveTracker.Elapsed;
-                    if (waitTimeSend <= TimeSpan.Zero || waitTimeReceive <= TimeSpan.Zero)
+                    var waitTime = keepAlivePeriod - _sendTracker.Elapsed;
+                    
+                    if (waitTime <= TimeSpan.Zero)
                     {
                         await SendAndReceiveAsync<MqttPingRespPacket>(new MqttPingReqPacket(), cancellationToken).ConfigureAwait(false);
                     }
 
-                    await Task.Delay(keepAliveSendInterval, cancellationToken).ConfigureAwait(false);
+                    await Task.Delay(keepAlivePeriod, cancellationToken).ConfigureAwait(false);
                 }
             }
             catch (Exception exception)

Source/MQTTnet/Client/Options/IMqttClientOptions.cs

@@ -17,8 +17,6 @@ namespace MQTTnet.Client.Options
 
         TimeSpan CommunicationTimeout { get; }
         TimeSpan KeepAlivePeriod { get; }
-        TimeSpan? KeepAliveSendInterval { get; }
-
         MqttApplicationMessage WillMessage { get; }
         uint? WillDelayInterval { get; }
 

Source/MQTTnet/Client/Options/MqttClientOptions.cs

@@ -17,7 +17,6 @@ namespace MQTTnet.Client.Options
         public IMqttClientChannelOptions ChannelOptions { get; set; }
         public TimeSpan CommunicationTimeout { get; set; } = TimeSpan.FromSeconds(10);
         public TimeSpan KeepAlivePeriod { get; set; } = TimeSpan.FromSeconds(15);
-        public TimeSpan? KeepAliveSendInterval { get; set; }
 
         public MqttApplicationMessage WillMessage { get; set; }
         public uint? WillDelayInterval { get; set; }

Source/MQTTnet/Client/Options/MqttClientOptionsBuilder.cs

@@ -45,15 +45,15 @@ namespace MQTTnet.Client.Options
             return WithKeepAlivePeriod(TimeSpan.Zero);
         }
 
-        public MqttClientOptionsBuilder WithKeepAlivePeriod(TimeSpan value)
+        public MqttClientOptionsBuilder WithoutKeepAlivePeriod()
         {
-            _options.KeepAlivePeriod = value;
+            _options.KeepAlivePeriod = TimeSpan.Zero;
             return this;
         }
 
-        public MqttClientOptionsBuilder WithKeepAliveSendInterval(TimeSpan value)
+        public MqttClientOptionsBuilder WithKeepAlivePeriod(TimeSpan value)
         {
-            _options.KeepAliveSendInterval = value;
+            _options.KeepAlivePeriod = value;
             return this;
         }
 

Source/MQTTnet/Diagnostics/IMqttNetLogger.cs

@@ -6,8 +6,8 @@ namespace MQTTnet.Diagnostics
     {
         event EventHandler<MqttNetLogMessagePublishedEventArgs> LogMessagePublished;
 
-        IMqttNetLogger CreateChildLogger(string source);
+        IMqttNetScopedLogger CreateScopedLogger(string source);
 
-        void Publish(MqttNetLogLevel logLevel, string message, object[] parameters, Exception exception);
+        void Publish(MqttNetLogLevel logLevel, string source, string message, object[] parameters, Exception exception);
     }
 }

Source/MQTTnet/Diagnostics/IMqttNetScopedLogger.cs

@@ -0,0 +1,11 @@
+using System;
+
+namespace MQTTnet.Diagnostics
+{
+    public interface IMqttNetScopedLogger
+    {
+        IMqttNetScopedLogger CreateScopedLogger(string source);
+
+        void Publish(MqttNetLogLevel logLevel, string message, object[] parameters, Exception exception);
+    }
+}

Source/MQTTnet/Diagnostics/MqttNetLogger.cs

@@ -7,14 +7,6 @@ namespace MQTTnet.Diagnostics
         readonly string _logId;
         readonly string _source;
 
-        readonly MqttNetLogger _parentLogger;
-
-        public MqttNetLogger(string source, string logId)
-        {
-            _source = source;
-            _logId = logId;
-        }
-
         public MqttNetLogger()
         {
         }
@@ -24,31 +16,23 @@ namespace MQTTnet.Diagnostics
             _logId = logId;
         }
 
-        MqttNetLogger(MqttNetLogger parentLogger, string logId, string source)
-        {
-            _parentLogger = parentLogger ?? throw new ArgumentNullException(nameof(parentLogger));
-            _source = source ?? throw new ArgumentNullException(nameof(source));
-
-            _logId = logId;
-        }
-
         public event EventHandler<MqttNetLogMessagePublishedEventArgs> LogMessagePublished;
 
         // TODO: Consider creating a LoggerFactory which will allow creating loggers. The logger factory will
         // be the only place which has the published event.
-        public IMqttNetLogger CreateChildLogger(string source)
+        public IMqttNetScopedLogger CreateScopedLogger(string source)
         {
             if (source is null) throw new ArgumentNullException(nameof(source));
 
-            return new MqttNetLogger(this, _logId, source);
+            return new MqttNetScopedLogger(this, source);
         }
 
-        public void Publish(MqttNetLogLevel level, string message, object[] parameters, Exception exception)
+        public void Publish(MqttNetLogLevel level, string source, string message, object[] parameters, Exception exception)
         {
             var hasLocalListeners = LogMessagePublished != null;
             var hasGlobalListeners = MqttNetGlobalLogger.HasListeners;
 
-            if (!hasLocalListeners && !hasGlobalListeners && _parentLogger == null)
+            if (!hasLocalListeners && !hasGlobalListeners)
             {
                 return;
             }
@@ -85,15 +69,6 @@ namespace MQTTnet.Diagnostics
             {
                 LogMessagePublished?.Invoke(this, new MqttNetLogMessagePublishedEventArgs(logMessage));
             }
-
-            _parentLogger?.Publish(logMessage);
-        }
-
-        void Publish(MqttNetLogMessage logMessage)
-        {
-            LogMessagePublished?.Invoke(this, new MqttNetLogMessagePublishedEventArgs(logMessage));
-
-            _parentLogger?.Publish(logMessage);
         }
     }
 }

Source/MQTTnet/Diagnostics/MqttNetLoggerExtensions.cs

@@ -1,35 +0,0 @@
-using System;
-
-namespace MQTTnet.Diagnostics
-{
-    public static class MqttNetLoggerExtensions
-    {
-        public static void Verbose(this IMqttNetLogger logger, string message, params object[] parameters)
-        {
-            if (logger is null) throw new ArgumentNullException(nameof(logger));
-
-            logger.Publish(MqttNetLogLevel.Verbose, message, parameters, null);
-        }
-
-        public static void Info(this IMqttNetLogger logger, string message, params object[] parameters)
-        {
-            if (logger is null) throw new ArgumentNullException(nameof(logger));
-
-            logger.Publish(MqttNetLogLevel.Info, message, parameters, null);
-        }
-
-        public static void Warning(this IMqttNetLogger logger, Exception exception, string message, params object[] parameters)
-        {
-            if (logger is null) throw new ArgumentNullException(nameof(logger));
-
-            logger.Publish(MqttNetLogLevel.Warning, message, parameters, exception);
-        }
-
-        public static void Error(this IMqttNetLogger logger, Exception exception, string message, params object[] parameters)
-        {
-            if (logger is null) throw new ArgumentNullException(nameof(logger));
-
-            logger.Publish(MqttNetLogLevel.Error, message, parameters, exception);
-        }
-    }
-}

Source/MQTTnet/Diagnostics/MqttNetScopedLogger.cs

@@ -0,0 +1,26 @@
+using System;
+
+namespace MQTTnet.Diagnostics
+{
+    public sealed class MqttNetScopedLogger : IMqttNetScopedLogger
+    {
+        readonly IMqttNetLogger _logger;
+        readonly string _source;
+
+        public MqttNetScopedLogger(IMqttNetLogger logger, string source)
+        {
+            _logger = logger ?? throw new ArgumentNullException(nameof(logger));
+            _source = source ?? throw new ArgumentNullException(nameof(source));
+        }
+
+        public IMqttNetScopedLogger CreateScopedLogger(string source)
+        {
+            return new MqttNetScopedLogger(_logger, source);
+        }
+
+        public void Publish(MqttNetLogLevel logLevel, string message, object[] parameters, Exception exception)
+        {
+            _logger.Publish(logLevel, _source, message, parameters, exception);
+        }
+    }
+}

Source/MQTTnet/Diagnostics/MqttNetScopedLoggerExtensions.cs

@@ -0,0 +1,27 @@
+using System;
+
+namespace MQTTnet.Diagnostics
+{
+    public static class MqttNetScopedLoggerExtensions
+    {
+        public static void Verbose(this IMqttNetScopedLogger logger, string message, params object[] parameters)
+        {
+            logger.Publish(MqttNetLogLevel.Verbose, message, parameters, null);
+        }
+
+        public static void Info(this IMqttNetScopedLogger logger, string message, params object[] parameters)
+        {
+            logger.Publish(MqttNetLogLevel.Info, message, parameters, null);
+        }
+
+        public static void Warning(this IMqttNetScopedLogger logger, Exception exception, string message, params object[] parameters)
+        {
+            logger.Publish(MqttNetLogLevel.Warning, message, parameters, exception);
+        }
+
+        public static void Error(this IMqttNetScopedLogger logger, Exception exception, string message, params object[] parameters)
+        {
+            logger.Publish(MqttNetLogLevel.Error, message, parameters, exception);
+        }
+    }
+}

Source/MQTTnet/Formatter/MqttPacketFormatterAdapter.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Runtime.CompilerServices;
 using MQTTnet.Adapter;
 using MQTTnet.Exceptions;
 using MQTTnet.Formatter.V3;
@@ -9,12 +10,7 @@ namespace MQTTnet.Formatter
 {
     public class MqttPacketFormatterAdapter
     {
-        private IMqttPacketFormatter _formatter;
-
-        public MqttPacketFormatterAdapter()
-            : this(new MqttPacketWriter())
-        {
-        }
+        IMqttPacketFormatter _formatter;
                
         public MqttPacketFormatterAdapter(MqttProtocolVersion protocolVersion)
             : this(protocolVersion, new MqttPacketWriter())
@@ -120,7 +116,7 @@ namespace MQTTnet.Formatter
             }
         }
 
-        private MqttProtocolVersion ParseProtocolVersion(ReceivedMqttPacket receivedMqttPacket)
+        MqttProtocolVersion ParseProtocolVersion(ReceivedMqttPacket receivedMqttPacket)
         {
             if (receivedMqttPacket == null) throw new ArgumentNullException(nameof(receivedMqttPacket));
 
@@ -155,7 +151,8 @@ namespace MQTTnet.Formatter
             throw new MqttProtocolViolationException($"Protocol '{protocolName}' not supported.");
         }
 
-        private void ThrowIfFormatterNotSet()
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        void ThrowIfFormatterNotSet()
         {
             if (_formatter == null)
             {

Source/MQTTnet/Formatter/MqttPacketWriter.cs

@@ -11,17 +11,17 @@ namespace MQTTnet.Formatter
     /// same as for the original MemoryStream in .net. Also this implementation allows accessing the internal
     /// buffer for all platforms and .net framework versions (which is not available at the regular MemoryStream).
     /// </summary>
-    public class MqttPacketWriter : IMqttPacketWriter
+    public sealed class MqttPacketWriter : IMqttPacketWriter
     {
-        private static readonly ArraySegment<byte> ZeroVariableLengthIntegerArray = new ArraySegment<byte>(new byte[1], 0, 1);
-        private static readonly ArraySegment<byte> ZeroTwoByteIntegerArray = new ArraySegment<byte>(new byte[2], 0, 2);
+        static readonly ArraySegment<byte> ZeroVariableLengthIntegerArray = new ArraySegment<byte>(new byte[1], 0, 1);
+        static readonly ArraySegment<byte> ZeroTwoByteIntegerArray = new ArraySegment<byte>(new byte[2], 0, 2);
 
         public static int InitialBufferSize = 128;
         public static int MaxBufferSize = 4096;
 
-        private byte[] _buffer = new byte[InitialBufferSize];
+        byte[] _buffer = new byte[InitialBufferSize];
 
-        private int _offset;
+        int _offset;
 
         public int Length { get; private set; }
 
@@ -191,13 +191,13 @@ namespace MQTTnet.Formatter
             Array.Resize(ref _buffer, MaxBufferSize);
         }
 
-        private void Write(ArraySegment<byte> buffer)
+        void Write(ArraySegment<byte> buffer)
         {
             Write(buffer.Array, buffer.Offset, buffer.Count);
         }
 
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        private void EnsureAdditionalCapacity(int additionalCapacity)
+        void EnsureAdditionalCapacity(int additionalCapacity)
         {
             var freeSpace = _buffer.Length - _offset;
             if (freeSpace >= additionalCapacity)
@@ -209,7 +209,7 @@ namespace MQTTnet.Formatter
         }
 
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        private void EnsureCapacity(int capacity)
+        void EnsureCapacity(int capacity)
         {
             var newBufferLength = _buffer.Length;
 
@@ -227,7 +227,7 @@ namespace MQTTnet.Formatter
         }
 
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        private void IncreasePosition(int length)
+        void IncreasePosition(int length)
         {
             _offset += length;
 

Source/MQTTnet/Formatter/V3/MqttV310PacketFormatter.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Linq;
+using System.Runtime.CompilerServices;
 using MQTTnet.Adapter;
 using MQTTnet.Exceptions;
 using MQTTnet.Packets;
@@ -9,26 +10,19 @@ namespace MQTTnet.Formatter.V3
 {
     public class MqttV310PacketFormatter : IMqttPacketFormatter
     {
-        private const int FixedHeaderSize = 1;
+        const int FixedHeaderSize = 1;
 
-        private static readonly MqttPingReqPacket PingReqPacket = new MqttPingReqPacket();
-        private static readonly MqttPingRespPacket PingRespPacket = new MqttPingRespPacket();
-        private static readonly MqttDisconnectPacket DisconnectPacket = new MqttDisconnectPacket();
+        static readonly MqttPingReqPacket PingReqPacket = new MqttPingReqPacket();
+        static readonly MqttPingRespPacket PingRespPacket = new MqttPingRespPacket();
+        static readonly MqttDisconnectPacket DisconnectPacket = new MqttDisconnectPacket();
 
-        private readonly IMqttPacketWriter _packetWriter;
-
-        public MqttV310PacketFormatter()
-            : this(new MqttPacketWriter())
-        {
-
-        }
+        readonly IMqttPacketWriter _packetWriter;
 
         public MqttV310PacketFormatter(IMqttPacketWriter packetWriter)
         {
             _packetWriter = packetWriter;
         }
 
-
         public IMqttDataConverter DataConverter { get; } = new MqttV310DataConverter();
 
         public ArraySegment<byte> Encode(MqttBasePacket packet)
@@ -93,7 +87,7 @@ namespace MQTTnet.Formatter.V3
             _packetWriter.FreeBuffer();
         }
 
-        private byte EncodePacket(MqttBasePacket packet, IMqttPacketWriter packetWriter)
+        byte EncodePacket(MqttBasePacket packet, IMqttPacketWriter packetWriter)
         {
             switch (packet)
             {
@@ -116,7 +110,7 @@ namespace MQTTnet.Formatter.V3
             }
         }
 
-        private static MqttBasePacket DecodeUnsubAckPacket(IMqttPacketBodyReader body)
+        static MqttBasePacket DecodeUnsubAckPacket(IMqttPacketBodyReader body)
         {
             ThrowIfBodyIsEmpty(body);
 
@@ -126,7 +120,7 @@ namespace MQTTnet.Formatter.V3
             };
         }
 
-        private static MqttBasePacket DecodePubCompPacket(IMqttPacketBodyReader body)
+        static MqttBasePacket DecodePubCompPacket(IMqttPacketBodyReader body)
         {
             ThrowIfBodyIsEmpty(body);
 
@@ -136,7 +130,7 @@ namespace MQTTnet.Formatter.V3
             };
         }
 
-        private static MqttBasePacket DecodePubRelPacket(IMqttPacketBodyReader body)
+        static MqttBasePacket DecodePubRelPacket(IMqttPacketBodyReader body)
         {
             ThrowIfBodyIsEmpty(body);
 
@@ -146,7 +140,7 @@ namespace MQTTnet.Formatter.V3
             };
         }
 
-        private static MqttBasePacket DecodePubRecPacket(IMqttPacketBodyReader body)
+        static MqttBasePacket DecodePubRecPacket(IMqttPacketBodyReader body)
         {
             ThrowIfBodyIsEmpty(body);
 
@@ -156,7 +150,7 @@ namespace MQTTnet.Formatter.V3
             };
         }
 
-        private static MqttBasePacket DecodePubAckPacket(IMqttPacketBodyReader body)
+        static MqttBasePacket DecodePubAckPacket(IMqttPacketBodyReader body)
         {
             ThrowIfBodyIsEmpty(body);
 
@@ -166,7 +160,7 @@ namespace MQTTnet.Formatter.V3
             };
         }
 
-        private static MqttBasePacket DecodeUnsubscribePacket(IMqttPacketBodyReader body)
+        static MqttBasePacket DecodeUnsubscribePacket(IMqttPacketBodyReader body)
         {
             ThrowIfBodyIsEmpty(body);
 
@@ -183,7 +177,7 @@ namespace MQTTnet.Formatter.V3
             return packet;
         }
 
-        private static MqttBasePacket DecodeSubscribePacket(IMqttPacketBodyReader body)
+        static MqttBasePacket DecodeSubscribePacket(IMqttPacketBodyReader body)
         {
             ThrowIfBodyIsEmpty(body);
 
@@ -206,7 +200,7 @@ namespace MQTTnet.Formatter.V3
             return packet;
         }
 
-        private static MqttBasePacket DecodePublishPacket(ReceivedMqttPacket receivedMqttPacket)
+        static MqttBasePacket DecodePublishPacket(ReceivedMqttPacket receivedMqttPacket)
         {
             ThrowIfBodyIsEmpty(receivedMqttPacket.Body);
 
@@ -239,7 +233,7 @@ namespace MQTTnet.Formatter.V3
             return packet;
         }
 
-        private MqttBasePacket DecodeConnectPacket(IMqttPacketBodyReader body)
+        MqttBasePacket DecodeConnectPacket(IMqttPacketBodyReader body)
         {
             ThrowIfBodyIsEmpty(body);
 
@@ -300,7 +294,7 @@ namespace MQTTnet.Formatter.V3
             return packet;
         }
 
-        private static MqttBasePacket DecodeSubAckPacket(IMqttPacketBodyReader body)
+        static MqttBasePacket DecodeSubAckPacket(IMqttPacketBodyReader body)
         {
             ThrowIfBodyIsEmpty(body);
 
@@ -340,7 +334,7 @@ namespace MQTTnet.Formatter.V3
         }
 
         // ReSharper disable once ParameterOnlyUsedForPreconditionCheck.Local
-        private static void ValidatePublishPacket(MqttPublishPacket packet)
+        static void ValidatePublishPacket(MqttPublishPacket packet)
         {
             if (packet.QualityOfServiceLevel == 0 && packet.Dup)
             {
@@ -418,7 +412,7 @@ namespace MQTTnet.Formatter.V3
             return MqttPacketWriter.BuildFixedHeader(MqttControlPacketType.ConnAck);
         }
 
-        private static byte EncodePubRelPacket(MqttPubRelPacket packet, IMqttPacketWriter packetWriter)
+        static byte EncodePubRelPacket(MqttPubRelPacket packet, IMqttPacketWriter packetWriter)
         {
             if (!packet.PacketIdentifier.HasValue)
             {
@@ -430,7 +424,7 @@ namespace MQTTnet.Formatter.V3
             return MqttPacketWriter.BuildFixedHeader(MqttControlPacketType.PubRel, 0x02);
         }
 
-        private static byte EncodePublishPacket(MqttPublishPacket packet, IMqttPacketWriter packetWriter)
+        static byte EncodePublishPacket(MqttPublishPacket packet, IMqttPacketWriter packetWriter)
         {
             ValidatePublishPacket(packet);
 
@@ -475,7 +469,7 @@ namespace MQTTnet.Formatter.V3
             return MqttPacketWriter.BuildFixedHeader(MqttControlPacketType.Publish, fixedHeader);
         }
 
-        private static byte EncodePubAckPacket(MqttPubAckPacket packet, IMqttPacketWriter packetWriter)
+        static byte EncodePubAckPacket(MqttPubAckPacket packet, IMqttPacketWriter packetWriter)
         {
             if (!packet.PacketIdentifier.HasValue)
             {
@@ -487,7 +481,7 @@ namespace MQTTnet.Formatter.V3
             return MqttPacketWriter.BuildFixedHeader(MqttControlPacketType.PubAck);
         }
 
-        private static byte EncodePubRecPacket(MqttPubRecPacket packet, IMqttPacketWriter packetWriter)
+        static byte EncodePubRecPacket(MqttPubRecPacket packet, IMqttPacketWriter packetWriter)
         {
             if (!packet.PacketIdentifier.HasValue)
             {
@@ -499,7 +493,7 @@ namespace MQTTnet.Formatter.V3
             return MqttPacketWriter.BuildFixedHeader(MqttControlPacketType.PubRec);
         }
 
-        private static byte EncodePubCompPacket(MqttPubCompPacket packet, IMqttPacketWriter packetWriter)
+        static byte EncodePubCompPacket(MqttPubCompPacket packet, IMqttPacketWriter packetWriter)
         {
             if (!packet.PacketIdentifier.HasValue)
             {
@@ -511,7 +505,7 @@ namespace MQTTnet.Formatter.V3
             return MqttPacketWriter.BuildFixedHeader(MqttControlPacketType.PubComp);
         }
 
-        private static byte EncodeSubscribePacket(MqttSubscribePacket packet, IMqttPacketWriter packetWriter)
+        static byte EncodeSubscribePacket(MqttSubscribePacket packet, IMqttPacketWriter packetWriter)
         {
             if (!packet.TopicFilters.Any()) throw new MqttProtocolViolationException("At least one topic filter must be set [MQTT-3.8.3-3].");
 
@@ -534,7 +528,7 @@ namespace MQTTnet.Formatter.V3
             return MqttPacketWriter.BuildFixedHeader(MqttControlPacketType.Subscribe, 0x02);
         }
 
-        private static byte EncodeSubAckPacket(MqttSubAckPacket packet, IMqttPacketWriter packetWriter)
+        static byte EncodeSubAckPacket(MqttSubAckPacket packet, IMqttPacketWriter packetWriter)
         {
             if (!packet.PacketIdentifier.HasValue)
             {
@@ -554,7 +548,7 @@ namespace MQTTnet.Formatter.V3
             return MqttPacketWriter.BuildFixedHeader(MqttControlPacketType.SubAck);
         }
 
-        private static byte EncodeUnsubscribePacket(MqttUnsubscribePacket packet, IMqttPacketWriter packetWriter)
+        static byte EncodeUnsubscribePacket(MqttUnsubscribePacket packet, IMqttPacketWriter packetWriter)
         {
             if (!packet.TopicFilters.Any()) throw new MqttProtocolViolationException("At least one topic filter must be set [MQTT-3.10.3-2].");
 
@@ -576,7 +570,7 @@ namespace MQTTnet.Formatter.V3
             return MqttPacketWriter.BuildFixedHeader(MqttControlPacketType.Unsubscibe, 0x02);
         }
 
-        private static byte EncodeUnsubAckPacket(MqttUnsubAckPacket packet, IMqttPacketWriter packetWriter)
+        static byte EncodeUnsubAckPacket(MqttUnsubAckPacket packet, IMqttPacketWriter packetWriter)
         {
             if (!packet.PacketIdentifier.HasValue)
             {
@@ -587,12 +581,12 @@ namespace MQTTnet.Formatter.V3
             return MqttPacketWriter.BuildFixedHeader(MqttControlPacketType.UnsubAck);
         }
 
-        private static byte EncodeEmptyPacket(MqttControlPacketType type)
+        static byte EncodeEmptyPacket(MqttControlPacketType type)
         {
             return MqttPacketWriter.BuildFixedHeader(type);
         }
 
-        // ReSharper disable once ParameterOnlyUsedForPreconditionCheck.Local
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
         protected static void ThrowIfBodyIsEmpty(IMqttPacketBodyReader body)
         {
             if (body == null || body.Length == 0)

Source/MQTTnet/Formatter/V3/MqttV311PacketFormatter.cs

@@ -6,11 +6,6 @@ namespace MQTTnet.Formatter.V3
 {
     public class MqttV311PacketFormatter : MqttV310PacketFormatter
     {
-        public MqttV311PacketFormatter()
-            : base()
-        {
-        }
-
         public MqttV311PacketFormatter(IMqttPacketWriter packetWriter)
             : base(packetWriter)
         {

Source/MQTTnet/Implementations/MqttClientAdapterFactory.cs

@@ -8,7 +8,14 @@ namespace MQTTnet.Implementations
 {
     public class MqttClientAdapterFactory : IMqttClientAdapterFactory
     {
-        public IMqttChannelAdapter CreateClientAdapter(IMqttClientOptions options, IMqttNetLogger logger)
+        readonly IMqttNetLogger _logger;
+
+        public MqttClientAdapterFactory(IMqttNetLogger logger)
+        {
+            _logger = logger ?? throw new ArgumentNullException(nameof(logger));
+        }
+
+        public IMqttChannelAdapter CreateClientAdapter(IMqttClientOptions options)
         {
             if (options == null) throw new ArgumentNullException(nameof(options));
 
@@ -16,12 +23,12 @@ namespace MQTTnet.Implementations
             {
                 case MqttClientTcpOptions _:
                     {
-                        return new MqttChannelAdapter(new MqttTcpChannel(options), new MqttPacketFormatterAdapter(options.ProtocolVersion), logger);
+                        return new MqttChannelAdapter(new MqttTcpChannel(options), new MqttPacketFormatterAdapter(options.ProtocolVersion, new MqttPacketWriter()), _logger);
                     }
 
                 case MqttClientWebSocketOptions webSocketOptions:
                     {
-                        return new MqttChannelAdapter(new MqttWebSocketChannel(webSocketOptions), new MqttPacketFormatterAdapter(options.ProtocolVersion), logger);
+                        return new MqttChannelAdapter(new MqttWebSocketChannel(webSocketOptions), new MqttPacketFormatterAdapter(options.ProtocolVersion, new MqttPacketWriter()), _logger);
                     }
 
                 default:

Source/MQTTnet/Implementations/MqttTcpChannel.cs

@@ -115,13 +115,13 @@ namespace MQTTnet.Implementations
         {
             if (buffer is null) throw new ArgumentNullException(nameof(buffer));
 
+            cancellationToken.ThrowIfCancellationRequested();
+
             try
             {
                 // Workaround for: https://github.com/dotnet/corefx/issues/24430
                 using (cancellationToken.Register(Dispose))
                 {
-                    cancellationToken.ThrowIfCancellationRequested();
-
                     return await _stream.ReadAsync(buffer, offset, count, cancellationToken).ConfigureAwait(false);
                 }
             }
@@ -144,13 +144,13 @@ namespace MQTTnet.Implementations
         {
             if (buffer is null) throw new ArgumentNullException(nameof(buffer));
 
+            cancellationToken.ThrowIfCancellationRequested();
+
             try
             {
                 // Workaround for: https://github.com/dotnet/corefx/issues/24430
                 using (cancellationToken.Register(Dispose))
                 {
-                    cancellationToken.ThrowIfCancellationRequested();
-
                     await _stream.WriteAsync(buffer, offset, count, cancellationToken).ConfigureAwait(false);
                 }
             }

Source/MQTTnet/Implementations/MqttTcpServerAdapter.Uwp.cs

@@ -13,16 +13,16 @@ namespace MQTTnet.Implementations
 {
     public sealed class MqttTcpServerAdapter : IMqttServerAdapter
     {
-        readonly IMqttNetLogger _logger;
+        readonly IMqttNetScopedLogger _logger;
+        readonly IMqttNetLogger _rootLogger;
 
         IMqttServerOptions _options;
         StreamSocketListener _listener;
 
         public MqttTcpServerAdapter(IMqttNetLogger logger)
         {
-            if (logger == null) throw new ArgumentNullException(nameof(logger));
-
-            _logger = logger.CreateChildLogger(nameof(MqttTcpServerAdapter));
+            _rootLogger = logger ?? throw new ArgumentNullException(nameof(logger));
+            _logger = logger.CreateScopedLogger(nameof(MqttTcpServerAdapter));
         }
 
         public Func<IMqttChannelAdapter, Task> ClientHandler { get; set; }
@@ -89,7 +89,7 @@ namespace MQTTnet.Implementations
                         }
                     }
                     
-                    using (var clientAdapter = new MqttChannelAdapter(new MqttTcpChannel(args.Socket, clientCertificate, _options), new MqttPacketFormatterAdapter(), _logger))
+                    using (var clientAdapter = new MqttChannelAdapter(new MqttTcpChannel(args.Socket, clientCertificate, _options), new MqttPacketFormatterAdapter(new MqttPacketWriter()), _rootLogger))
                     {
                         await clientHandler(clientAdapter).ConfigureAwait(false);
                     }

Source/MQTTnet/Implementations/MqttTcpServerAdapter.cs

@@ -16,15 +16,15 @@ namespace MQTTnet.Implementations
     public sealed class MqttTcpServerAdapter : Disposable, IMqttServerAdapter
     {
         readonly List<MqttTcpServerListener> _listeners = new List<MqttTcpServerListener>();
-        readonly IMqttNetLogger _logger;
+        readonly IMqttNetScopedLogger _logger;
+        readonly IMqttNetLogger _rootLogger;
 
         CancellationTokenSource _cancellationTokenSource;
 
         public MqttTcpServerAdapter(IMqttNetLogger logger)
         {
-            if (logger == null) throw new ArgumentNullException(nameof(logger));
-
-            _logger = logger.CreateChildLogger(nameof(MqttTcpServerAdapter));
+            _rootLogger = logger ?? throw new ArgumentNullException(nameof(logger));
+            _logger = logger.CreateScopedLogger(nameof(MqttTcpServerAdapter));
         }
 
         public Func<IMqttChannelAdapter, Task> ClientHandler { get; set; }
@@ -105,11 +105,7 @@ namespace MQTTnet.Implementations
         {
             if (!options.BoundInterNetworkAddress.Equals(IPAddress.None))
             {
-                var listenerV4 = new MqttTcpServerListener(
-                    AddressFamily.InterNetwork,
-                    options,
-                    tlsCertificate,
-                    _logger)
+                var listenerV4 = new MqttTcpServerListener(AddressFamily.InterNetwork, options, tlsCertificate, _rootLogger)
                 {
                     ClientHandler = OnClientAcceptedAsync
                 };
@@ -122,11 +118,7 @@ namespace MQTTnet.Implementations
 
             if (!options.BoundInterNetworkV6Address.Equals(IPAddress.None))
             {
-                var listenerV6 = new MqttTcpServerListener(
-                    AddressFamily.InterNetworkV6,
-                    options,
-                    tlsCertificate,
-                    _logger)
+                var listenerV6 = new MqttTcpServerListener(AddressFamily.InterNetworkV6, options, tlsCertificate, _rootLogger)
                 {
                     ClientHandler = OnClientAcceptedAsync
                 };

Source/MQTTnet/Implementations/MqttTcpServerListener.cs

@@ -17,7 +17,8 @@ namespace MQTTnet.Implementations
 {
     public sealed class MqttTcpServerListener : IDisposable
     {
-        readonly IMqttNetLogger _logger;
+        readonly IMqttNetScopedLogger _logger;
+        readonly IMqttNetLogger _rootLogger;
         readonly AddressFamily _addressFamily;
         readonly MqttServerTcpEndpointBaseOptions _options;
         readonly MqttServerTlsTcpEndpointOptions _tlsOptions;
@@ -35,7 +36,8 @@ namespace MQTTnet.Implementations
             _addressFamily = addressFamily;
             _options = options;
             _tlsCertificate = tlsCertificate;
-            _logger = logger.CreateChildLogger(nameof(MqttTcpServerListener));
+            _rootLogger = logger;
+            _logger = logger.CreateScopedLogger(nameof(MqttTcpServerListener));
 
             if (_options is MqttServerTlsTcpEndpointOptions tlsOptions)
             {
@@ -178,7 +180,7 @@ namespace MQTTnet.Implementations
                 var clientHandler = ClientHandler;
                 if (clientHandler != null)
                 {
-                    using (var clientAdapter = new MqttChannelAdapter(new MqttTcpChannel(stream, remoteEndPoint, clientCertificate), new MqttPacketFormatterAdapter(), _logger))
+                    using (var clientAdapter = new MqttChannelAdapter(new MqttTcpChannel(stream, remoteEndPoint, clientCertificate), new MqttPacketFormatterAdapter(new MqttPacketWriter()), _rootLogger))
                     {
                         await clientHandler(clientAdapter).ConfigureAwait(false);
                     }

Source/MQTTnet/Internal/TaskExtensions.cs

@@ -5,7 +5,7 @@ namespace MQTTnet.Internal
 {
     public static class TaskExtensions
     {
-        public static void Forget(this Task task, IMqttNetLogger logger)
+        public static void Forget(this Task task, IMqttNetScopedLogger logger)
         {
             task?.ContinueWith(t =>
                 {

Source/MQTTnet/LowLevelClient/LowLevelMqttClient.cs

@@ -10,7 +10,7 @@ namespace MQTTnet.LowLevelClient
 {
     public sealed class LowLevelMqttClient : ILowLevelMqttClient
     {
-        readonly IMqttNetLogger _logger;
+        readonly IMqttNetScopedLogger _logger;
         readonly IMqttClientAdapterFactory _clientAdapterFactory;
 
         IMqttChannelAdapter _adapter;
@@ -22,7 +22,7 @@ namespace MQTTnet.LowLevelClient
             if (logger is null) throw new ArgumentNullException(nameof(logger));
 
             _clientAdapterFactory = clientAdapterFactory;
-            _logger = logger.CreateChildLogger(nameof(LowLevelMqttClient));
+            _logger = logger.CreateScopedLogger(nameof(LowLevelMqttClient));
         }
 
         bool IsConnected => _adapter != null;
@@ -36,7 +36,7 @@ namespace MQTTnet.LowLevelClient
                 throw new InvalidOperationException("Low level MQTT client is already connected. Disconnect first before connecting again.");
             }
 
-            var newAdapter = _clientAdapterFactory.CreateClientAdapter(options, _logger);
+            var newAdapter = _clientAdapterFactory.CreateClientAdapter(options);
 
             try
             {

Source/MQTTnet/MqttFactory.cs

@@ -11,7 +11,7 @@ namespace MQTTnet
 {
     public sealed class MqttFactory : IMqttFactory
     {
-        IMqttClientAdapterFactory _clientAdapterFactory = new MqttClientAdapterFactory();
+        IMqttClientAdapterFactory _clientAdapterFactory;
 
         public MqttFactory() : this(new MqttNetLogger())
         {
@@ -20,6 +20,7 @@ namespace MQTTnet
         public MqttFactory(IMqttNetLogger logger)
         {
             DefaultLogger = logger ?? throw new ArgumentNullException(nameof(logger));
+            _clientAdapterFactory = new MqttClientAdapterFactory(logger);
         }
 
         public IMqttNetLogger DefaultLogger { get; }

Source/MQTTnet/Protocol/MqttTopicValidator.cs

@@ -11,14 +11,17 @@ namespace MQTTnet.Protocol
                 throw new MqttProtocolViolationException("Topic should not be empty.");
             }
 
-            if (topic.Contains("+"))
+            foreach(var @char in topic)
             {
-                throw new MqttProtocolViolationException("The character '+' is not allowed in topics.");
-            }
+                if (@char == '+')
+                {
+                    throw new MqttProtocolViolationException("The character '+' is not allowed in topics.");
+                }
 
-            if (topic.Contains("#"))
-            {
-                throw new MqttProtocolViolationException("The character '#' is not allowed in topics.");
+                if (@char == '#')
+                {
+                    throw new MqttProtocolViolationException("The character '#' is not allowed in topics.");
+                }
             }
         }
     }

Source/MQTTnet/Server/MqttClientConnection.cs

@@ -28,7 +28,7 @@ namespace MQTTnet.Server
         readonly MqttClientKeepAliveMonitor _keepAliveMonitor;
         readonly MqttClientSessionsManager _sessionsManager;
 
-        readonly IMqttNetLogger _logger;
+        readonly IMqttNetScopedLogger _logger;
         readonly IMqttServerOptions _serverOptions;
 
         readonly IMqttChannelAdapter _channelAdapter;
@@ -71,9 +71,9 @@ namespace MQTTnet.Server
             ConnectPacket = connectPacket ?? throw new ArgumentNullException(nameof(connectPacket));
 
             if (logger == null) throw new ArgumentNullException(nameof(logger));
-            _logger = logger.CreateChildLogger(nameof(MqttClientConnection));
+            _logger = logger.CreateScopedLogger(nameof(MqttClientConnection));
 
-            _keepAliveMonitor = new MqttClientKeepAliveMonitor(ConnectPacket.ClientId, () => StopAsync(), _logger);
+            _keepAliveMonitor = new MqttClientKeepAliveMonitor(ConnectPacket.ClientId, () => StopAsync(), logger);
 
             _connectedTimestamp = DateTime.UtcNow;
             _lastPacketReceivedTimestamp = _connectedTimestamp;

Source/MQTTnet/Server/MqttClientKeepAliveMonitor.cs

@@ -7,13 +7,13 @@ using System.Threading.Tasks;
 
 namespace MQTTnet.Server
 {
-    public class MqttClientKeepAliveMonitor
+    public sealed class MqttClientKeepAliveMonitor
     {
         readonly Stopwatch _lastPacketReceivedTracker = new Stopwatch();
 
         readonly string _clientId;
         readonly Func<Task> _keepAliveElapsedCallback;
-        readonly IMqttNetLogger _logger;
+        readonly IMqttNetScopedLogger _logger;
 
         bool _isPaused;
 
@@ -23,7 +23,7 @@ namespace MQTTnet.Server
             _keepAliveElapsedCallback = keepAliveElapsedCallback ?? throw new ArgumentNullException(nameof(keepAliveElapsedCallback));
 
             if (logger == null) throw new ArgumentNullException(nameof(logger));
-            _logger = logger.CreateChildLogger(nameof(MqttClientKeepAliveMonitor));
+            _logger = logger.CreateScopedLogger(nameof(MqttClientKeepAliveMonitor));
         }
 
         public void Start(int keepAlivePeriod, CancellationToken cancellationToken)

Source/MQTTnet/Server/MqttClientSession.cs

@@ -8,12 +8,18 @@ namespace MQTTnet.Server
 {
     public class MqttClientSession
     {
-        readonly IMqttNetLogger _logger;
+        readonly IMqttNetScopedLogger _logger;
 
         readonly DateTime _createdTimestamp = DateTime.UtcNow;
         readonly IMqttRetainedMessagesManager _retainedMessagesManager;
 
-        public MqttClientSession(string clientId, IDictionary<object, object> items, MqttServerEventDispatcher eventDispatcher, IMqttServerOptions serverOptions, IMqttRetainedMessagesManager retainedMessagesManager, IMqttNetLogger logger)
+        public MqttClientSession(
+            string clientId,
+            IDictionary<object, object> items,
+            MqttServerEventDispatcher eventDispatcher,
+            IMqttServerOptions serverOptions, 
+            IMqttRetainedMessagesManager retainedMessagesManager,
+            IMqttNetLogger logger)
         {
             ClientId = clientId ?? throw new ArgumentNullException(nameof(clientId));
             Items = items ?? throw new ArgumentNullException(nameof(items));
@@ -22,7 +28,7 @@ namespace MQTTnet.Server
             ApplicationMessagesQueue = new MqttClientSessionApplicationMessagesQueue(serverOptions);
 
             if (logger == null) throw new ArgumentNullException(nameof(logger));
-            _logger = logger.CreateChildLogger(nameof(MqttClientSession));
+            _logger = logger.CreateScopedLogger(nameof(MqttClientSession));
         }
 
         public string ClientId { get; }

Source/MQTTnet/Server/MqttClientSessionsManager.cs

@@ -28,7 +28,8 @@ namespace MQTTnet.Server
 
         readonly IMqttRetainedMessagesManager _retainedMessagesManager;
         readonly IMqttServerOptions _options;
-        readonly IMqttNetLogger _logger;
+        readonly IMqttNetScopedLogger _logger;
+        readonly IMqttNetLogger _rootLogger;
 
         public MqttClientSessionsManager(
             IMqttServerOptions options,
@@ -40,7 +41,8 @@ namespace MQTTnet.Server
             _cancellationToken = cancellationToken;
 
             if (logger == null) throw new ArgumentNullException(nameof(logger));
-            _logger = logger.CreateChildLogger(nameof(MqttClientSessionsManager));
+            _logger = logger.CreateScopedLogger(nameof(MqttClientSessionsManager));
+            _rootLogger = logger;
 
             _eventDispatcher = eventDispatcher ?? throw new ArgumentNullException(nameof(eventDispatcher));
             _options = options ?? throw new ArgumentNullException(nameof(options));
@@ -371,11 +373,11 @@ namespace MQTTnet.Server
 
                 if (session == null)
                 {
-                    session = new MqttClientSession(connectPacket.ClientId, connectionValidatorContext.SessionItems, _eventDispatcher, _options, _retainedMessagesManager, _logger);
+                    session = new MqttClientSession(connectPacket.ClientId, connectionValidatorContext.SessionItems, _eventDispatcher, _options, _retainedMessagesManager, _rootLogger);
                     _logger.Verbose("Created a new session for client '{0}'.", connectPacket.ClientId);
                 }
 
-                var connection = new MqttClientConnection(connectPacket, channelAdapter, session, _options, this, _retainedMessagesManager, onStart, onStop, _logger);
+                var connection = new MqttClientConnection(connectPacket, channelAdapter, session, _options, this, _retainedMessagesManager, onStart, onStop, _rootLogger);
 
                 _connections[connection.ClientId] = connection;
                 _sessions[session.ClientId] = session;

Source/MQTTnet/Server/MqttRetainedMessagesManager.cs

@@ -10,17 +10,19 @@ namespace MQTTnet.Server
 {
     public class MqttRetainedMessagesManager : IMqttRetainedMessagesManager
     {
-        private readonly byte[] _emptyArray = new byte[0];
-        private readonly AsyncLock _messagesLock = new AsyncLock();
-        private readonly Dictionary<string, MqttApplicationMessage> _messages = new Dictionary<string, MqttApplicationMessage>();
+        readonly byte[] _emptyArray = new byte[0];
+        readonly AsyncLock _messagesLock = new AsyncLock();
+        readonly Dictionary<string, MqttApplicationMessage> _messages = new Dictionary<string, MqttApplicationMessage>();
 
-        private IMqttNetLogger _logger;
-        private IMqttServerOptions _options;
+        IMqttNetScopedLogger _logger;
+        IMqttServerOptions _options;
 
+        // TODO: Get rid of the logger here!
         public Task Start(IMqttServerOptions options, IMqttNetLogger logger)
         {
             if (logger == null) throw new ArgumentNullException(nameof(logger));
-            _logger = logger.CreateChildLogger(nameof(MqttRetainedMessagesManager));
+            _logger = logger.CreateScopedLogger(nameof(MqttRetainedMessagesManager));
+
             _options = options ?? throw new ArgumentNullException(nameof(options));
             return PlatformAbstractionLayer.CompletedTask;
         }

Source/MQTTnet/Server/MqttServer.cs

@@ -17,7 +17,8 @@ namespace MQTTnet.Server
     {
         readonly MqttServerEventDispatcher _eventDispatcher;
         readonly ICollection<IMqttServerAdapter> _adapters;
-        readonly IMqttNetLogger _logger;
+        readonly IMqttNetLogger _rootLogger;
+        readonly IMqttNetScopedLogger _logger;
 
         MqttClientSessionsManager _clientSessionsManager;
         IMqttRetainedMessagesManager _retainedMessagesManager;
@@ -29,9 +30,10 @@ namespace MQTTnet.Server
             _adapters = adapters.ToList();
 
             if (logger == null) throw new ArgumentNullException(nameof(logger));
-            _logger = logger.CreateChildLogger(nameof(MqttServer));
+            _logger = logger.CreateScopedLogger(nameof(MqttServer));
+            _rootLogger = logger;
 
-            _eventDispatcher = new MqttServerEventDispatcher(logger.CreateChildLogger(nameof(MqttServerEventDispatcher)));
+            _eventDispatcher = new MqttServerEventDispatcher(logger);
         }
 
         public bool IsStarted => _cancellationTokenSource != null;
@@ -127,10 +129,10 @@ namespace MQTTnet.Server
             _cancellationTokenSource = new CancellationTokenSource();
 
             _retainedMessagesManager = Options.RetainedMessagesManager;
-            await _retainedMessagesManager.Start(Options, _logger);
+            await _retainedMessagesManager.Start(Options, _rootLogger);
             await _retainedMessagesManager.LoadMessagesAsync().ConfigureAwait(false);
 
-            _clientSessionsManager = new MqttClientSessionsManager(Options, _retainedMessagesManager, _cancellationTokenSource.Token, _eventDispatcher, _logger);
+            _clientSessionsManager = new MqttClientSessionsManager(Options, _retainedMessagesManager, _cancellationTokenSource.Token, _eventDispatcher, _rootLogger);
             _clientSessionsManager.Start();
 
             foreach (var adapter in _adapters)

Source/MQTTnet/Server/MqttServerEventDispatcher.cs

@@ -5,13 +5,15 @@ using System.Threading.Tasks;
 
 namespace MQTTnet.Server
 {
-    public class MqttServerEventDispatcher
+    public sealed class MqttServerEventDispatcher
     {
-        readonly IMqttNetLogger _logger;
+        readonly IMqttNetScopedLogger _logger;
 
         public MqttServerEventDispatcher(IMqttNetLogger logger)
         {
-            _logger = logger ?? throw new ArgumentNullException(nameof(logger));
+            if (logger is null) throw new ArgumentNullException(nameof(logger));
+
+            _logger = logger.CreateScopedLogger(nameof(MqttServerEventDispatcher));
         }
 
         public IMqttServerClientConnectedHandler ClientConnectedHandler { get; set; }

Tests/MQTTnet.Benchmarks/ChannelAdapterBenchmark.cs

@@ -43,7 +43,7 @@ namespace MQTTnet.Benchmarks
 
             var channel = new TestMqttChannel(_stream);
             
-            _channelAdapter = new MqttChannelAdapter(channel, serializer, new MqttNetLogger().CreateChildLogger(nameof(MqttChannelAdapter)));
+            _channelAdapter = new MqttChannelAdapter(channel, serializer, new MqttNetLogger());
         }
 
         [Benchmark]

Tests/MQTTnet.Benchmarks/LoggerBenchmark.cs

@@ -9,15 +9,15 @@ namespace MQTTnet.Benchmarks
     [MemoryDiagnoser]
     public class LoggerBenchmark
     {
-        private IMqttNetLogger _logger;
-        private IMqttNetLogger _childLogger;
-        private bool _useHandler;
+        IMqttNetLogger _logger;
+        IMqttNetScopedLogger _childLogger;
+        bool _useHandler;
 
         [GlobalSetup]
         public void Setup()
         {
             _logger = new MqttNetLogger();
-            _childLogger = _logger.CreateChildLogger("child");
+            _childLogger = _logger.CreateScopedLogger("child");
 
             MqttNetGlobalLogger.LogMessagePublished += OnLogMessagePublished;
         }

Tests/MQTTnet.Benchmarks/SerializerBenchmark.cs

@@ -29,7 +29,7 @@ namespace MQTTnet.Benchmarks
                 Topic = "A"
             };
 
-            _serializer = new MqttV311PacketFormatter();
+            _serializer = new MqttV311PacketFormatter(new MqttPacketWriter());
             _serializedPacket = _serializer.Encode(_packet);
         }
 

Tests/MQTTnet.Core.Tests/Mockups/TestLogger.cs

@@ -7,29 +7,9 @@ namespace MQTTnet.Tests.Mockups
     {
         public event EventHandler<MqttNetLogMessagePublishedEventArgs> LogMessagePublished;
 
-        public IMqttNetLogger CreateChildLogger(string source)
-        {
-            return new TestLogger();
-        }
-
-        public void Verbose(string message, params object[] parameters)
-        {
-        }
-
-        public void Info(string message, params object[] parameters)
-        {
-        }
-
-        public void Warning(Exception exception, string message, params object[] parameters)
-        {
-        }
-
-        public void Error(Exception exception, string message, params object[] parameters)
-        {
-        }
-
-        public void Publish(MqttNetLogLevel logLevel, string source, string message, object[] parameters, Exception exception)
+        public IMqttNetScopedLogger CreateScopedLogger(string source)
         {
+            return new MqttNetScopedLogger(this, source);
         }
 
         public void Publish(MqttNetLogLevel logLevel, string message, object[] parameters, Exception exception)
@@ -40,5 +20,10 @@ namespace MQTTnet.Tests.Mockups
                 Message = message
             }));
         }
+
+        public void Publish(MqttNetLogLevel logLevel, string source, string message, object[] parameters, Exception exception)
+        {
+            throw new NotImplementedException();
+        }
     }
 }

Tests/MQTTnet.Core.Tests/Mockups/TestMqttCommunicationAdapterFactory.cs

@@ -1,19 +1,18 @@
 using MQTTnet.Adapter;
 using MQTTnet.Client.Options;
-using MQTTnet.Diagnostics;
 
 namespace MQTTnet.Tests.Mockups
 {
     public class TestMqttCommunicationAdapterFactory : IMqttClientAdapterFactory
     {
-        private readonly IMqttChannelAdapter _adapter;
+        readonly IMqttChannelAdapter _adapter;
 
         public TestMqttCommunicationAdapterFactory(IMqttChannelAdapter adapter)
         {
             _adapter = adapter;
         }
 
-        public IMqttChannelAdapter CreateClientAdapter(IMqttClientOptions options, IMqttNetLogger logger)
+        public IMqttChannelAdapter CreateClientAdapter(IMqttClientOptions options)
         {
             return _adapter;
         }

Tests/MQTTnet.Core.Tests/MqttFactory_Tests.cs

@@ -24,7 +24,7 @@ namespace MQTTnet.Tests
             //var globalLogCount = 0;
             var localLogCount = 0;
 
-            var logger = new MqttNetLogger(null, logId);
+            var logger = new MqttNetLogger(logId);
 
             // TODO: This is commented out because it is affected by other tests.
             //// we have a theoretical bug here if a concurrent test is also logging

Tests/MQTTnet.Core.Tests/MqttNetLogger_Tests.cs

@@ -10,6 +10,7 @@ namespace MQTTnet.Tests
         public void Root_Log_Messages()
         {
             var logger = new MqttNetLogger();
+            var childLogger = logger.CreateScopedLogger("Source1");
 
             var logMessagesCount = 0;
 
@@ -18,10 +19,10 @@ namespace MQTTnet.Tests
                 logMessagesCount++;
             };
 
-            logger.Verbose("Verbose");
-            logger.Info("Info");
-            logger.Warning(null, "Warning");
-            logger.Error(null, "Error");
+            childLogger.Verbose("Verbose");
+            childLogger.Info("Info");
+            childLogger.Warning(null, "Warning");
+            childLogger.Error(null, "Error");
 
             Assert.AreEqual(4, logMessagesCount);
         }
@@ -30,7 +31,7 @@ namespace MQTTnet.Tests
         public void Bubbling_Log_Messages()
         {
             var logger = new MqttNetLogger();
-            var childLogger = logger.CreateChildLogger("Source1");
+            var childLogger = logger.CreateScopedLogger("Source1");
 
             var logMessagesCount = 0;
 
@@ -50,8 +51,8 @@ namespace MQTTnet.Tests
         [TestMethod]
         public void Set_Custom_Log_ID()
         {
-            var logger = new MqttNetLogger(null, "logId");
-            var childLogger = logger.CreateChildLogger("Source1");
+            var logger = new MqttNetLogger("logId");
+            var childLogger = logger.CreateScopedLogger("Source1");
 
             logger.LogMessagePublished += (s, e) =>
             {

Tests/MQTTnet.Core.Tests/MqttPacketSerializer_Tests.cs

@@ -156,7 +156,7 @@ namespace MQTTnet.Tests
         [TestMethod]
         public void Serialize_LargePacket()
         {
-            var serializer = new MqttV311PacketFormatter();
+            var serializer = new MqttV311PacketFormatter(new MqttPacketWriter());
 
             const int payloadLength = 80000;
 
@@ -560,11 +560,11 @@ namespace MQTTnet.Tests
             IMqttPacketFormatter serializer;
             if (protocolVersion == MqttProtocolVersion.V311)
             {
-                serializer = new MqttV311PacketFormatter();
+                serializer = new MqttV311PacketFormatter(new MqttPacketWriter());
             }
             else if (protocolVersion == MqttProtocolVersion.V310)
             {
-                serializer = new MqttV310PacketFormatter();
+                serializer = new MqttV310PacketFormatter(new MqttPacketWriter());
             }
             else
             {

Tests/MQTTnet.TestApp.NetCore/PerformanceTest.cs

@@ -54,12 +54,12 @@ namespace MQTTnet.TestApp.NetCore
             }
         }
 
-        public static void RunClientAndServer()
+        public static async Task RunClientAndServer()
         {
             try
             {
                 var mqttServer = new MqttFactory().CreateMqttServer();
-                mqttServer.StartAsync(new MqttServerOptions()).GetAwaiter().GetResult();
+                await mqttServer.StartAsync(new MqttServerOptions()).ConfigureAwait(false);
 
                 var options = new MqttClientOptions
                 {
@@ -67,11 +67,12 @@ namespace MQTTnet.TestApp.NetCore
                     {
                         Server = "127.0.0.1"
                     },
-                    CleanSession = true
+                    CleanSession = true,
+                    //KeepAlivePeriod = TimeSpan.FromSeconds(1)
                 };
 
                 var client = new MqttFactory().CreateMqttClient();
-                client.ConnectAsync(options).GetAwaiter().GetResult();
+                await client.ConnectAsync(options).ConfigureAwait(false);
 
                 var message = CreateMessage();
                 var stopwatch = new Stopwatch();
@@ -83,7 +84,7 @@ namespace MQTTnet.TestApp.NetCore
                     var sentMessagesCount = 0;
                     while (stopwatch.ElapsedMilliseconds < 1000)
                     {
-                        client.PublishAsync(message).GetAwaiter().GetResult();
+                        await client.PublishAsync(message, CancellationToken.None).ConfigureAwait(false);
                         sentMessagesCount++;
                     }
 

Tests/MQTTnet.TestApp.NetCore/Program.cs

@@ -15,6 +15,8 @@ namespace MQTTnet.TestApp.NetCore
     {
         public static void Main()
         {
+            //MqttNetConsoleLogger.ForwardToConsole();
+
             Console.WriteLine($"MQTTnet - TestApp.{TargetFrameworkProvider.TargetFramework}");
             Console.WriteLine("1 = Start client");
             Console.WriteLine("2 = Start server");
@@ -40,8 +42,7 @@ namespace MQTTnet.TestApp.NetCore
             }
             else if (pressedKey.KeyChar == '3')
             {
-                PerformanceTest.RunClientAndServer();
-                return;
+                Task.Run(PerformanceTest.RunClientAndServer);
             }
             else if (pressedKey.KeyChar == '4')
             {