Refactor logging and add benchmark.

Frameworks/MQTTnet.AspnetCore/MqttHostedServer.cs

@@ -13,7 +13,7 @@ namespace MQTTnet.AspNetCore
     {
         private readonly IMqttServerOptions _options;
 
-        public MqttHostedServer(IMqttServerOptions options, IEnumerable<IMqttServerAdapter> adapters, IMqttNetLogger logger) : base(adapters, logger)
+        public MqttHostedServer(IMqttServerOptions options, IEnumerable<IMqttServerAdapter> adapters, IMqttNetLogger logger) : base(adapters, logger.CreateChildLogger(nameof(MqttHostedServer)))
         {
             _options = options ?? throw new ArgumentNullException(nameof(options));
         }

Frameworks/MQTTnet.AspnetCore/MqttWebSocketServerAdapter.cs

@@ -27,7 +27,7 @@ namespace MQTTnet.AspNetCore
         {
             if (webSocket == null) throw new ArgumentNullException(nameof(webSocket));
 
-            var clientAdapter = new MqttChannelAdapter(new MqttWebSocketChannel(webSocket), new MqttPacketSerializer(), new MqttNetLogger());
+            var clientAdapter = new MqttChannelAdapter(new MqttWebSocketChannel(webSocket), new MqttPacketSerializer(), new MqttNetLogger().CreateChildLogger(nameof(MqttWebSocketServerAdapter)));
 
             var eventArgs = new MqttServerAdapterClientAcceptedEventArgs(clientAdapter);
             ClientAccepted?.Invoke(this, eventArgs);

Frameworks/MQTTnet.NetStandard/Adapter/MqttChannelAdapter.cs

@@ -18,16 +18,19 @@ namespace MQTTnet.Adapter
         private const uint ErrorOperationAborted = 0x800703E3;
         private const int ReadBufferSize = 4096;  // TODO: Move buffer size to config
 
-        private readonly IMqttNetLogger _logger;
+        private readonly IMqttNetChildLogger _logger;
         private readonly IMqttChannel _channel;
 
         private bool _isDisposed;
 
-        public MqttChannelAdapter(IMqttChannel channel, IMqttPacketSerializer serializer, IMqttNetLogger logger)
+        public MqttChannelAdapter(IMqttChannel channel, IMqttPacketSerializer serializer, IMqttNetChildLogger logger)
         {
-            _logger = logger ?? throw new ArgumentNullException(nameof(logger));
+            if (logger == null) throw new ArgumentNullException(nameof(logger));
+
             _channel = channel ?? throw new ArgumentNullException(nameof(channel));
             PacketSerializer = serializer ?? throw new ArgumentNullException(nameof(serializer));
+
+            _logger = logger.CreateChildLogger(nameof(MqttChannelAdapter));
         }
 
         public IMqttPacketSerializer PacketSerializer { get; }
@@ -35,7 +38,7 @@ namespace MQTTnet.Adapter
         public Task ConnectAsync(TimeSpan timeout, CancellationToken cancellationToken)
         {
             ThrowIfDisposed();
-            _logger.Verbose<MqttChannelAdapter>("Connecting [Timeout={0}]", timeout);
+            _logger.Verbose("Connecting [Timeout={0}]", timeout);
 
             return ExecuteAndWrapExceptionAsync(() =>
                 Internal.TaskExtensions.TimeoutAfter(ct => _channel.ConnectAsync(ct), timeout, cancellationToken));
@@ -44,7 +47,7 @@ namespace MQTTnet.Adapter
         public Task DisconnectAsync(TimeSpan timeout, CancellationToken cancellationToken)
         {
             ThrowIfDisposed();
-            _logger.Verbose<MqttChannelAdapter>("Disconnecting [Timeout={0}]", timeout);
+            _logger.Verbose("Disconnecting [Timeout={0}]", timeout);
 
             return ExecuteAndWrapExceptionAsync(() =>
                 Internal.TaskExtensions.TimeoutAfter(ct => _channel.DisconnectAsync(), timeout, cancellationToken));
@@ -69,7 +72,7 @@ namespace MQTTnet.Adapter
         {
             return ExecuteAndWrapExceptionAsync(() =>
             {
-                _logger.Verbose<MqttChannelAdapter>("TX >>> {0} [Timeout={1}]", packet, timeout);
+                _logger.Verbose("TX >>> {0} [Timeout={1}]", packet, timeout);
 
                 var packetData = PacketSerializer.Serialize(packet);
 
@@ -111,7 +114,7 @@ namespace MQTTnet.Adapter
                         throw new MqttProtocolViolationException("Received malformed packet.");
                     }
 
-                    _logger.Verbose<MqttChannelAdapter>("RX <<< {0}", packet);
+                    _logger.Verbose("RX <<< {0}", packet);
                 }
                 finally
                 {

Frameworks/MQTTnet.NetStandard/Client/IMqttClientAdapterFactory.cs

@@ -5,6 +5,6 @@ namespace MQTTnet.Client
 {
     public interface IMqttClientAdapterFactory
     {
-        IMqttChannelAdapter CreateClientAdapter(IMqttClientOptions options, IMqttNetLogger logger);
+        IMqttChannelAdapter CreateClientAdapter(IMqttClientOptions options, IMqttNetChildLogger logger);
     }
 }

Frameworks/MQTTnet.NetStandard/Client/MqttClient.cs

@@ -21,7 +21,7 @@ namespace MQTTnet.Client
         private readonly MqttPacketDispatcher _packetDispatcher = new MqttPacketDispatcher();
 
         private readonly IMqttClientAdapterFactory _adapterFactory;
-        private readonly IMqttNetLogger _logger;
+        private readonly IMqttNetChildLogger _logger;
 
         private IMqttClientOptions _options;
         private CancellationTokenSource _cancellationTokenSource;
@@ -31,8 +31,10 @@ namespace MQTTnet.Client
 
         public MqttClient(IMqttClientAdapterFactory channelFactory, IMqttNetLogger logger)
         {
+            if (logger == null) throw new ArgumentNullException(nameof(logger));
+
             _adapterFactory = channelFactory ?? throw new ArgumentNullException(nameof(channelFactory));
-            _logger = logger ?? throw new ArgumentNullException(nameof(logger));
+            _logger = logger.CreateChildLogger(nameof(MqttClient));
         }
 
         public event EventHandler<MqttClientConnectedEventArgs> Connected;
@@ -57,14 +59,14 @@ namespace MQTTnet.Client
 
                 _adapter = _adapterFactory.CreateClientAdapter(options, _logger);
 
-                _logger.Verbose(this, "Trying to connect with server.");
+                _logger.Verbose("Trying to connect with server.");
                 await _adapter.ConnectAsync(_options.CommunicationTimeout, _cancellationTokenSource.Token).ConfigureAwait(false);
-                _logger.Verbose(this, "Connection with server established.");
+                _logger.Verbose("Connection with server established.");
 
                 StartReceivingPackets(_cancellationTokenSource.Token);
 
                 var connectResponse = await AuthenticateAsync(options.WillMessage, _cancellationTokenSource.Token).ConfigureAwait(false);
-                _logger.Verbose(this, "MQTT connection with server established.");
+                _logger.Verbose("MQTT connection with server established.");
 
                 _sendTracker.Restart();
 
@@ -76,12 +78,12 @@ namespace MQTTnet.Client
                 IsConnected = true;
                 Connected?.Invoke(this, new MqttClientConnectedEventArgs(connectResponse.IsSessionPresent));
 
-                _logger.Info(this, "Connected.");
+                _logger.Info("Connected.");
                 return new MqttClientConnectResult(connectResponse.IsSessionPresent);
             }
             catch (Exception exception)
             {
-                _logger.Error(this, exception, "Error while connecting with server.");
+                _logger.Error(exception, "Error while connecting with server.");
                 await DisconnectInternalAsync(null, exception).ConfigureAwait(false);
 
                 throw;
@@ -245,7 +247,7 @@ namespace MQTTnet.Client
             }
             catch (Exception adapterException)
             {
-                _logger.Warning(this, adapterException, "Error while disconnecting from adapter.");
+                _logger.Warning(adapterException, "Error while disconnecting from adapter.");
             }
             finally
             {
@@ -265,11 +267,11 @@ namespace MQTTnet.Client
                     await _adapter.DisconnectAsync(_options.CommunicationTimeout, CancellationToken.None).ConfigureAwait(false);
                 }
 
-                _logger.Verbose(this, "Disconnected from adapter.");
+                _logger.Verbose("Disconnected from adapter.");
             }
             catch (Exception adapterException)
             {
-                _logger.Warning(this, adapterException, "Error while disconnecting from adapter.");
+                _logger.Warning(adapterException, "Error while disconnecting from adapter.");
             }
             finally
             {
@@ -278,7 +280,7 @@ namespace MQTTnet.Client
                 _cancellationTokenSource?.Dispose();
                 _cancellationTokenSource = null;
 
-                _logger.Info(this, "Disconnected.");
+                _logger.Info("Disconnected.");
                 Disconnected?.Invoke(this, new MqttClientDisconnectedEventArgs(clientWasConnected, exception));
             }
         }
@@ -324,7 +326,7 @@ namespace MQTTnet.Client
             }
             catch (MqttCommunicationTimedOutException)
             {
-                _logger.Warning(this, null, "Timeout while waiting for packet of type '{0}'.", typeof(TResponsePacket).Namespace);
+                _logger.Warning(null, "Timeout while waiting for packet of type '{0}'.", typeof(TResponsePacket).Namespace);
                 throw;
             }
             finally
@@ -335,7 +337,7 @@ namespace MQTTnet.Client
 
         private async Task SendKeepAliveMessagesAsync(CancellationToken cancellationToken)
         {
-            _logger.Verbose(this, "Start sending keep alive packets.");
+            _logger.Verbose("Start sending keep alive packets.");
 
             try
             {
@@ -362,24 +364,24 @@ namespace MQTTnet.Client
                 }
                 else if (exception is MqttCommunicationException)
                 {
-                    _logger.Warning(this, exception, "MQTT communication exception while sending/receiving keep alive packets.");
+                    _logger.Warning(exception, "MQTT communication exception while sending/receiving keep alive packets.");
                 }
                 else
                 {
-                    _logger.Error(this, exception, "Unhandled exception while sending/receiving keep alive packets.");
+                    _logger.Error(exception, "Unhandled exception while sending/receiving keep alive packets.");
                 }
 
                 await DisconnectInternalAsync(_keepAliveMessageSenderTask, exception).ConfigureAwait(false);
             }
             finally
             {
-                _logger.Verbose(this, "Stopped sending keep alive packets.");
+                _logger.Verbose("Stopped sending keep alive packets.");
             }
         }
 
         private async Task ReceivePacketsAsync(CancellationToken cancellationToken)
         {
-            _logger.Verbose(this, "Start receiving packets.");
+            _logger.Verbose("Start receiving packets.");
 
             try
             {
@@ -414,11 +416,11 @@ namespace MQTTnet.Client
                 }
                 else if (exception is MqttCommunicationException)
                 {
-                    _logger.Warning(this, exception, "MQTT communication exception while receiving packets.");
+                    _logger.Warning(exception, "MQTT communication exception while receiving packets.");
                 }
                 else
                 {
-                    _logger.Error(this, exception, "Unhandled exception while receiving packets.");
+                    _logger.Error(exception, "Unhandled exception while receiving packets.");
                 }
 
                 await DisconnectInternalAsync(_packetReceiverTask, exception).ConfigureAwait(false);
@@ -426,7 +428,7 @@ namespace MQTTnet.Client
             }
             finally
             {
-                _logger.Verbose(this, "Stopped receiving packets.");
+                _logger.Verbose("Stopped receiving packets.");
             }
         }
 
@@ -462,7 +464,7 @@ namespace MQTTnet.Client
             }
             catch (Exception exception)
             {
-                _logger.Error(this, exception, "Unhandled exception while processing received packet.");
+                _logger.Error(exception, "Unhandled exception while processing received packet.");
             }
         }
 
@@ -534,7 +536,7 @@ namespace MQTTnet.Client
             }
             catch (Exception exception)
             {
-                _logger.Error(this, exception, "Unhandled exception while handling application message.");
+                _logger.Error(exception, "Unhandled exception while handling application message.");
             }
         }
 

Frameworks/MQTTnet.NetStandard/Diagnostics/IMqttNetChildLogger.cs

@@ -0,0 +1,17 @@
+using System;
+
+namespace MQTTnet.Diagnostics
+{
+    public interface IMqttNetChildLogger
+    {
+        IMqttNetChildLogger CreateChildLogger(string source);
+
+        void Verbose(string message, params object[] parameters);
+
+        void Info(string message, params object[] parameters);
+
+        void Warning(Exception exception, string message, params object[] parameters);
+
+        void Error(Exception exception, string message, params object[] parameters);
+    }
+}

Frameworks/MQTTnet.NetStandard/Diagnostics/IMqttNetLogger.cs

@@ -6,20 +6,8 @@ namespace MQTTnet.Diagnostics
     {
         event EventHandler<MqttNetLogMessagePublishedEventArgs> LogMessagePublished;
 
-        void Verbose<TSource>(string message, params object[] parameters);
+        IMqttNetChildLogger CreateChildLogger(string source);
 
-        void Verbose(object source, string message, params object[] parameters);
-
-        void Info<TSource>(string message, params object[] parameters);
-
-        void Info(object source, string message, params object[] parameters);
-
-        void Warning<TSource>(Exception exception, string message, params object[] parameters);
-
-        void Warning(object source, Exception exception, string message, params object[] parameters);
-
-        void Error<TSource>(Exception exception, string message, params object[] parameters);
-
-        void Error(object source, Exception exception, string message, params object[] parameters);
+        void Publish(MqttNetLogLevel logLevel, string source, string message, object[] parameters, Exception exception);
     }
 }

Frameworks/MQTTnet.NetStandard/Diagnostics/MqttNetChildLogger.cs

@@ -0,0 +1,51 @@
+using System;
+
+namespace MQTTnet.Diagnostics
+{
+    public sealed class MqttNetChildLogger : IMqttNetChildLogger
+    {
+        private readonly IMqttNetLogger _logger;
+        private readonly string _source;
+
+        public MqttNetChildLogger(IMqttNetLogger logger, string source)
+        {
+            _logger = logger;
+            _source = source;
+        }
+
+        public IMqttNetChildLogger CreateChildLogger(string source)
+        {
+            string childSource;
+            if (!string.IsNullOrEmpty(_source))
+            {
+                childSource = _source + "." + source;
+            }
+            else
+            {
+                childSource = source;
+            }
+
+            return new MqttNetChildLogger(_logger, childSource);
+        }
+
+        public void Verbose(string message, params object[] parameters)
+        {
+            _logger.Publish(MqttNetLogLevel.Verbose, _source, message, parameters, null);
+        }
+
+        public void Info(string message, params object[] parameters)
+        {
+            _logger.Publish(MqttNetLogLevel.Info, _source, message, parameters, null);
+        }
+
+        public void Warning(Exception exception, string message, params object[] parameters)
+        {
+            _logger.Publish(MqttNetLogLevel.Warning, _source, message, parameters, exception);
+        }
+
+        public void Error(Exception exception, string message, params object[] parameters)
+        {
+            _logger.Publish(MqttNetLogLevel.Error, _source, message, parameters, exception);
+        }
+    }
+}

Frameworks/MQTTnet.NetStandard/Diagnostics/MqttNetLogger.cs

@@ -2,7 +2,7 @@
 
 namespace MQTTnet.Diagnostics
 {
-    public class MqttNetLogger : IMqttNetLogger
+    public sealed class MqttNetLogger : IMqttNetLogger
     {
         private readonly string _logId;
 
@@ -13,47 +13,12 @@ namespace MQTTnet.Diagnostics
 
         public event EventHandler<MqttNetLogMessagePublishedEventArgs> LogMessagePublished;
 
-        public void Verbose<TSource>(string message, params object[] parameters)
+        public IMqttNetChildLogger CreateChildLogger(string source)
         {
-            Publish(MqttNetLogLevel.Verbose, typeof(TSource), message, parameters, null);
+            return new MqttNetChildLogger(this, source);
         }
 
-        public void Verbose(object source, string message, params object[] parameters)
-        {
-            Publish(MqttNetLogLevel.Verbose, source, message, parameters, null);
-        }
-
-        public void Info<TSource>(string message, params object[] parameters)
-        {
-            Publish(MqttNetLogLevel.Info, typeof(TSource), message, parameters, null);
-        }
-
-        public void Info(object source, string message, params object[] parameters)
-        {
-            Publish(MqttNetLogLevel.Info, source, message, parameters, null);
-        }
-
-        public void Warning<TSource>(Exception exception, string message, params object[] parameters)
-        {
-            Publish(MqttNetLogLevel.Warning, typeof(TSource), message, parameters, null);
-        }
-
-        public void Warning(object source, Exception exception, string message, params object[] parameters)
-        {
-            Publish(MqttNetLogLevel.Warning, source, message, parameters, null);
-        }
-
-        public void Error<TSource>(Exception exception, string message, params object[] parameters)
-        {
-            Publish(MqttNetLogLevel.Error, typeof(TSource), message, parameters, null);
-        }
-
-        public void Error(object source, Exception exception, string message, params object[] parameters)
-        {
-            Publish(MqttNetLogLevel.Error, source, message, parameters, null);
-        }
-
-        private void Publish(MqttNetLogLevel logLevel, object source, string message, object[] parameters, Exception exception)
+        public void Publish(MqttNetLogLevel logLevel, string source, string message, object[] parameters, Exception exception)
         {
             var hasLocalListeners = LogMessagePublished != null;
             var hasGlobalListeners = MqttNetGlobalLogger.HasListeners;
@@ -63,18 +28,19 @@ namespace MQTTnet.Diagnostics
                 return;
             }
 
-            if (parameters.Length > 0)
-            {
-                message = string.Format(message, parameters);
-            }
-
-            string sourceName = null;
-            if (source != null)
+            if (parameters?.Length > 0)
             {
-                sourceName = source.GetType().Name;
+                try
+                {
+                    message = string.Format(message, parameters);
+                }
+                catch
+                {
+                    message = "MESSAGE FORMAT INVALID: " + message;
+                }
             }
 
-            var traceMessage = new MqttNetLogMessage(_logId, DateTime.Now, Environment.CurrentManagedThreadId, sourceName, logLevel, message, exception);
+            var traceMessage = new MqttNetLogMessage(_logId, DateTime.UtcNow, Environment.CurrentManagedThreadId, source, logLevel, message, exception);
 
             if (hasGlobalListeners)
             {

Frameworks/MQTTnet.NetStandard/Implementations/MqttClientAdapterFactory.cs

@@ -8,7 +8,7 @@ namespace MQTTnet.Implementations
 {
     public class MqttClientAdapterFactory : IMqttClientAdapterFactory
     {
-        public IMqttChannelAdapter CreateClientAdapter(IMqttClientOptions options, IMqttNetLogger logger)
+        public IMqttChannelAdapter CreateClientAdapter(IMqttClientOptions options, IMqttNetChildLogger logger)
         {
             if (options == null) throw new ArgumentNullException(nameof(options));
 

Frameworks/MQTTnet.NetStandard/Implementations/MqttTcpServerAdapter.Uwp.cs

@@ -11,12 +11,14 @@ namespace MQTTnet.Implementations
 {
     public class MqttTcpServerAdapter : IMqttServerAdapter
     {
-        private readonly IMqttNetLogger _logger;
+        private readonly IMqttNetChildLogger _logger;
         private StreamSocketListener _defaultEndpointSocket;
 
-        public MqttTcpServerAdapter(IMqttNetLogger logger)
+        public MqttTcpServerAdapter(IMqttNetChildLogger logger)
         {
-            _logger = logger ?? throw new ArgumentNullException(nameof(logger));
+            if (logger == null) throw new ArgumentNullException(nameof(logger));
+
+            _logger = logger.CreateChildLogger(nameof(MqttTcpServerAdapter));
         }
 
         public event EventHandler<MqttServerAdapterClientAcceptedEventArgs> ClientAccepted;
@@ -74,7 +76,7 @@ namespace MQTTnet.Implementations
             }
             catch (Exception exception)
             {
-                _logger.Error<MqttTcpServerAdapter>(exception, "Error while accepting connection at default endpoint.");
+                _logger.Error(exception, "Error while accepting connection at default endpoint.");
             }
         }
     }

Frameworks/MQTTnet.NetStandard/Implementations/MqttTcpServerAdapter.cs

@@ -16,16 +16,18 @@ namespace MQTTnet.Implementations
 {
     public class MqttTcpServerAdapter : IMqttServerAdapter
     {
-        private readonly IMqttNetLogger _logger;
+        private readonly IMqttNetChildLogger _logger;
 
         private CancellationTokenSource _cancellationTokenSource;
         private Socket _defaultEndpointSocket;
         private Socket _tlsEndpointSocket;
         private X509Certificate2 _tlsCertificate;
 
-        public MqttTcpServerAdapter(IMqttNetLogger logger)
+        public MqttTcpServerAdapter(IMqttNetChildLogger logger)
         {
-            _logger = logger ?? throw new ArgumentNullException(nameof(logger));
+            if (logger == null) throw new ArgumentNullException(nameof(logger));
+
+            _logger = logger.CreateChildLogger(nameof(MqttTcpServerAdapter));
         }
 
         public event EventHandler<MqttServerAdapterClientAcceptedEventArgs> ClientAccepted;
@@ -127,7 +129,7 @@ namespace MQTTnet.Implementations
                         return;
                     }
 
-                    _logger.Error<MqttTcpServerAdapter>(exception, "Error while accepting connection at default endpoint.");
+                    _logger.Error(exception, "Error while accepting connection at default endpoint.");
                     await Task.Delay(TimeSpan.FromSeconds(1), cancellationToken).ConfigureAwait(false);
                 }
             }
@@ -162,7 +164,7 @@ namespace MQTTnet.Implementations
                         return;
                     }
 
-                    _logger.Error<MqttTcpServerAdapter>(exception, "Error while accepting connection at TLS endpoint.");
+                    _logger.Error(exception, "Error while accepting connection at TLS endpoint.");
                     await Task.Delay(TimeSpan.FromSeconds(1), cancellationToken).ConfigureAwait(false);
                 }
             }

Frameworks/MQTTnet.NetStandard/ManagedClient/ManagedMqttClient.cs

@@ -19,7 +19,7 @@ namespace MQTTnet.ManagedClient
         private readonly List<string> _unsubscriptions = new List<string>();
 
         private readonly IMqttClient _mqttClient;
-        private readonly IMqttNetLogger _logger;
+        private readonly IMqttNetChildLogger _logger;
 
         private CancellationTokenSource _connectionCancellationToken;
         private CancellationTokenSource _publishingCancellationToken;
@@ -29,14 +29,17 @@ namespace MQTTnet.ManagedClient
 
         private bool _subscriptionsNotPushed;
 
-        public ManagedMqttClient(IMqttClient mqttClient, IMqttNetLogger logger)
+        public ManagedMqttClient(IMqttClient mqttClient, IMqttNetChildLogger logger)
         {
-            _logger = logger ?? throw new ArgumentNullException(nameof(logger));
+            if (logger == null) throw new ArgumentNullException(nameof(logger));
+
             _mqttClient = mqttClient ?? throw new ArgumentNullException(nameof(mqttClient));
 
             _mqttClient.Connected += OnConnected;
             _mqttClient.Disconnected += OnDisconnected;
             _mqttClient.ApplicationMessageReceived += OnApplicationMessageReceived;
+
+            _logger = logger.CreateChildLogger(nameof(ManagedMqttClient));
         }
 
         public bool IsConnected => _mqttClient.IsConnected;
@@ -74,7 +77,7 @@ namespace MQTTnet.ManagedClient
             Task.Run(() => MaintainConnectionAsync(_connectionCancellationToken.Token), _connectionCancellationToken.Token);
 #pragma warning restore CS4014 // Because this call is not awaited, execution of the current method continues before the call is completed
 
-            _logger.Info<ManagedMqttClient>("Started");
+            _logger.Info("Started");
         }
 
         public Task StopAsync()
@@ -166,12 +169,12 @@ namespace MQTTnet.ManagedClient
             }
             catch (Exception exception)
             {
-                _logger.Error<ManagedMqttClient>(exception, "Unhandled exception while maintaining connection.");
+                _logger.Error(exception, "Unhandled exception while maintaining connection.");
             }
             finally
             {
                 await _mqttClient.DisconnectAsync().ConfigureAwait(false);
-                _logger.Info<ManagedMqttClient>("Stopped");
+                _logger.Info("Stopped");
             }
         }
 
@@ -204,11 +207,11 @@ namespace MQTTnet.ManagedClient
             }
             catch (MqttCommunicationException exception)
             {
-                _logger.Warning<ManagedMqttClient>(exception, "Communication exception while maintaining connection.");
+                _logger.Warning(exception, "Communication exception while maintaining connection.");
             }
             catch (Exception exception)
             {
-                _logger.Error<ManagedMqttClient>(exception, "Unhandled exception while maintaining connection.");
+                _logger.Error(exception, "Unhandled exception while maintaining connection.");
             }
         }
 
@@ -237,11 +240,11 @@ namespace MQTTnet.ManagedClient
             }
             catch (Exception exception)
             {
-                _logger.Error<ManagedMqttClient>(exception, "Unhandled exception while publishing queued application messages.");
+                _logger.Error(exception, "Unhandled exception while publishing queued application messages.");
             }
             finally
             {
-                _logger.Verbose<ManagedMqttClient>("Stopped publishing messages.");
+                _logger.Verbose("Stopped publishing messages.");
             }
         }
 
@@ -261,7 +264,7 @@ namespace MQTTnet.ManagedClient
             {
                 transmitException = exception;
 
-                _logger.Warning<ManagedMqttClient>(exception, "Publishing application message failed.");
+                _logger.Warning(exception, "Publishing application message failed.");
 
                 if (message.QualityOfServiceLevel > MqttQualityOfServiceLevel.AtMostOnce)
                 {
@@ -271,7 +274,7 @@ namespace MQTTnet.ManagedClient
             catch (Exception exception)
             {
                 transmitException = exception;
-                _logger.Error<ManagedMqttClient>(exception, "Unhandled exception while publishing queued application message.");
+                _logger.Error(exception, "Unhandled exception while publishing queued application message.");
             }
             finally
             {
@@ -281,7 +284,7 @@ namespace MQTTnet.ManagedClient
 
         private async Task SynchronizeSubscriptionsAsync()
         {
-            _logger.Info<ManagedMqttClient>(nameof(ManagedMqttClient), "Synchronizing subscriptions");
+            _logger.Info(nameof(ManagedMqttClient), "Synchronizing subscriptions");
 
             List<TopicFilter> subscriptions;
             List<string> unsubscriptions;
@@ -320,7 +323,7 @@ namespace MQTTnet.ManagedClient
             }
             catch (Exception exception)
             {
-                _logger.Warning<ManagedMqttClient>(exception, "Synchronizing subscriptions failed.");
+                _logger.Warning(exception, "Synchronizing subscriptions failed.");
                 _subscriptionsNotPushed = true;
 
                 SynchronizingSubscriptionsFailed?.Invoke(this, EventArgs.Empty);

Frameworks/MQTTnet.NetStandard/MqttFactory.cs

@@ -25,14 +25,14 @@ namespace MQTTnet
 
         public IManagedMqttClient CreateManagedMqttClient()
         {
-            return new ManagedMqttClient(CreateMqttClient(), new MqttNetLogger());
+            return new ManagedMqttClient(CreateMqttClient(), new MqttNetLogger().CreateChildLogger(string.Empty));
         }
 
         public IManagedMqttClient CreateManagedMqttClient(IMqttNetLogger logger)
         {
             if (logger == null) throw new ArgumentNullException(nameof(logger));
 
-            return new ManagedMqttClient(CreateMqttClient(), logger);
+            return new ManagedMqttClient(CreateMqttClient(), logger.CreateChildLogger(string.Empty));
         }
 
         public IMqttServer CreateMqttServer()
@@ -45,7 +45,7 @@ namespace MQTTnet
         {
             if (logger == null) throw new ArgumentNullException(nameof(logger));
 
-            return CreateMqttServer(new List<IMqttServerAdapter> { new MqttTcpServerAdapter(logger) }, logger);
+            return CreateMqttServer(new List<IMqttServerAdapter> { new MqttTcpServerAdapter(logger.CreateChildLogger(string.Empty)) }, logger);
         }
 
         public IMqttServer CreateMqttServer(IEnumerable<IMqttServerAdapter> adapters, IMqttNetLogger logger)
@@ -53,7 +53,7 @@ namespace MQTTnet
             if (adapters == null) throw new ArgumentNullException(nameof(adapters));
             if (logger == null) throw new ArgumentNullException(nameof(logger));
 
-            return new MqttServer(adapters, logger);
+            return new MqttServer(adapters, logger.CreateChildLogger(string.Empty));
         }
     }
 }

Frameworks/MQTTnet.NetStandard/Server/MqttClientKeepAliveMonitor.cs

@@ -14,15 +14,17 @@ namespace MQTTnet.Server
 
         private readonly string _clientId;
         private readonly Action _timeoutCallback;
-        private readonly IMqttNetLogger _logger;
+        private readonly IMqttNetChildLogger _logger;
 
         private Task _workerTask;
 
-        public MqttClientKeepAliveMonitor(string clientId, Action timeoutCallback, IMqttNetLogger logger)
+        public MqttClientKeepAliveMonitor(string clientId, Action timeoutCallback, IMqttNetChildLogger logger)
         {
+            if (logger == null) throw new ArgumentNullException(nameof(logger));
+
             _clientId = clientId;
             _timeoutCallback = timeoutCallback;
-            _logger = logger;
+            _logger = logger.CreateChildLogger(nameof(MqttClientKeepAliveMonitor));
         }
 
         public TimeSpan LastPacketReceived => _lastPacketReceivedTracker.Elapsed;
@@ -59,7 +61,7 @@ namespace MQTTnet.Server
                     // Values described here: [MQTT-3.1.2-24].
                     if (_lastPacketReceivedTracker.Elapsed.TotalSeconds > keepAlivePeriod * 1.5D)
                     {
-                        _logger.Warning(this, null, "Client '{0}': Did not receive any packet or keep alive signal.", _clientId);
+                        _logger.Warning(null, "Client '{0}': Did not receive any packet or keep alive signal.", _clientId);
 
                         _timeoutCallback?.Invoke();
 
@@ -74,11 +76,11 @@ namespace MQTTnet.Server
             }
             catch (Exception exception)
             {
-                _logger.Error(this, exception, "Client '{0}': Unhandled exception while checking keep alive timeouts.", _clientId);
+                _logger.Error(exception, "Client '{0}': Unhandled exception while checking keep alive timeouts.", _clientId);
             }
             finally
             {
-                _logger.Verbose(this, "Client {0}: Stopped checking keep alive timeout.", _clientId);
+                _logger.Verbose("Client {0}: Stopped checking keep alive timeout.", _clientId);
             }
         }
 

Frameworks/MQTTnet.NetStandard/Server/MqttClientPendingMessagesQueue.cs

@@ -17,15 +17,17 @@ namespace MQTTnet.Server
         private readonly AsyncAutoResetEvent _queueAutoResetEvent = new AsyncAutoResetEvent();
         private readonly IMqttServerOptions _options;
         private readonly MqttClientSession _clientSession;
-        private readonly IMqttNetLogger _logger;
+        private readonly IMqttNetChildLogger _logger;
 
         private Task _workerTask;
 
-        public MqttClientPendingMessagesQueue(IMqttServerOptions options, MqttClientSession clientSession, IMqttNetLogger logger)
+        public MqttClientPendingMessagesQueue(IMqttServerOptions options, MqttClientSession clientSession, IMqttNetChildLogger logger)
         {
+            if (logger == null) throw new ArgumentNullException(nameof(logger));
             _options = options ?? throw new ArgumentNullException(nameof(options));
             _clientSession = clientSession ?? throw new ArgumentNullException(nameof(clientSession));
-            _logger = logger ?? throw new ArgumentNullException(nameof(logger));
+
+            _logger = logger.CreateChildLogger(nameof(MqttClientPendingMessagesQueue));
         }
 
         public int Count => _queue.Count;
@@ -70,7 +72,7 @@ namespace MQTTnet.Server
             _queue.Enqueue(packet);
             _queueAutoResetEvent.Set();
 
-            _logger.Verbose(this, "Enqueued packet (ClientId: {0}).", _clientSession.ClientId);
+            _logger.Verbose("Enqueued packet (ClientId: {0}).", _clientSession.ClientId);
         }
 
         private async Task SendQueuedPacketsAsync(IMqttChannelAdapter adapter, CancellationToken cancellationToken)
@@ -87,7 +89,7 @@ namespace MQTTnet.Server
             }
             catch (Exception exception)
             {
-                _logger.Error(this, exception, "Unhandled exception while sending enqueued packet (ClientId: {0}).", _clientSession.ClientId);
+                _logger.Error(exception, "Unhandled exception while sending enqueued packet (ClientId: {0}).", _clientSession.ClientId);
             }
         }
 
@@ -113,25 +115,24 @@ namespace MQTTnet.Server
 
                 await adapter.SendPacketsAsync(_options.DefaultCommunicationTimeout, new[] { packet }, cancellationToken).ConfigureAwait(false);
 
-                _logger.Verbose<MqttClientPendingMessagesQueue>("Enqueued packet sent (ClientId: {0}).",
-                    _clientSession.ClientId);
+                _logger.Verbose("Enqueued packet sent (ClientId: {0}).", _clientSession.ClientId);
             }
             catch (Exception exception)
             {
                 if (exception is MqttCommunicationTimedOutException)
                 {
-                    _logger.Warning(this, exception, "Sending publish packet failed: Timeout (ClientId: {0}).", _clientSession.ClientId);
+                    _logger.Warning(exception, "Sending publish packet failed: Timeout (ClientId: {0}).", _clientSession.ClientId);
                 }
                 else if (exception is MqttCommunicationException)
                 {
-                    _logger.Warning(this, exception, "Sending publish packet failed: Communication exception (ClientId: {0}).", _clientSession.ClientId);
+                    _logger.Warning(exception, "Sending publish packet failed: Communication exception (ClientId: {0}).", _clientSession.ClientId);
                 }
                 else if (exception is OperationCanceledException)
                 {
                 }
                 else
                 {
-                    _logger.Error(this, exception, "Sending publish packet failed (ClientId: {0}).", _clientSession.ClientId);
+                    _logger.Error(exception, "Sending publish packet failed (ClientId: {0}).", _clientSession.ClientId);
                 }
 
                 if (packet is MqttPublishPacket publishPacket)

Frameworks/MQTTnet.NetStandard/Server/MqttClientSession.cs

@@ -17,7 +17,7 @@ namespace MQTTnet.Server
     {
         private readonly MqttPacketIdentifierProvider _packetIdentifierProvider = new MqttPacketIdentifierProvider();
         private readonly MqttRetainedMessagesManager _retainedMessagesManager;
-        private readonly IMqttNetLogger _logger;
+        private readonly IMqttNetChildLogger _logger;
         private readonly IMqttServerOptions _options;
         private readonly MqttClientSessionsManager _sessionsManager;
 
@@ -30,15 +30,18 @@ namespace MQTTnet.Server
             IMqttServerOptions options,
             MqttClientSessionsManager sessionsManager,
             MqttRetainedMessagesManager retainedMessagesManager,
-            IMqttNetLogger logger)
+            IMqttNetChildLogger logger)
         {
+            if (logger == null) throw new ArgumentNullException(nameof(logger));
+
             _options = options ?? throw new ArgumentNullException(nameof(options));
             _sessionsManager = sessionsManager;
             _retainedMessagesManager = retainedMessagesManager ?? throw new ArgumentNullException(nameof(retainedMessagesManager));
-            _logger = logger ?? throw new ArgumentNullException(nameof(logger));
-
+            
             ClientId = clientId;
 
+            _logger = logger.CreateChildLogger(nameof(MqttClientSession));
+
             KeepAliveMonitor = new MqttClientKeepAliveMonitor(clientId, StopDueToKeepAliveTimeout, _logger);
             SubscriptionsManager = new MqttClientSubscriptionsManager(clientId, _options, sessionsManager.Server);
             PendingMessagesQueue = new MqttClientPendingMessagesQueue(_options, this, _logger);
@@ -81,13 +84,11 @@ namespace MQTTnet.Server
             }
             catch (MqttCommunicationException exception)
             {
-                _logger.Warning<MqttClientSession>(exception,
-                    "Client '{0}': Communication exception while processing client packets.", ClientId);
+                _logger.Warning(exception, "Client '{0}': Communication exception while processing client packets.", ClientId);
             }
             catch (Exception exception)
             {
-                _logger.Error<MqttClientSession>(exception,
-                    "Client '{0}': Unhandled exception while processing client packets.", ClientId);
+                _logger.Error(exception, "Client '{0}': Unhandled exception while processing client packets.", ClientId);
             }
             finally
             {
@@ -126,7 +127,7 @@ namespace MQTTnet.Server
             }
             finally
             {
-                _logger.Info<MqttClientSession>("Client '{0}': Session stopped.", ClientId);
+                _logger.Info("Client '{0}': Session stopped.", ClientId);
             }
         }
 
@@ -185,7 +186,7 @@ namespace MQTTnet.Server
 
         private void StopDueToKeepAliveTimeout()
         {
-            _logger.Info<MqttClientSession>("Client '{0}': Timeout while waiting for KeepAlive packet.", ClientId);
+            _logger.Info("Client '{0}': Timeout while waiting for KeepAlive packet.", ClientId);
             Stop(MqttClientDisconnectType.NotClean);
         }
 
@@ -207,11 +208,11 @@ namespace MQTTnet.Server
             {
                 if (exception is MqttCommunicationException)
                 {
-                    _logger.Warning<MqttClientSession>(exception, "Client '{0}': Communication exception while processing client packets.", ClientId);
+                    _logger.Warning(exception, "Client '{0}': Communication exception while processing client packets.", ClientId);
                 }
                 else
                 {
-                    _logger.Error<MqttClientSession>(exception, "Client '{0}': Unhandled exception while processing client packets.", ClientId);
+                    _logger.Error(exception, "Client '{0}': Unhandled exception while processing client packets.", ClientId);
                 }
 
                 Stop(MqttClientDisconnectType.NotClean);
@@ -273,7 +274,7 @@ namespace MQTTnet.Server
                 return Task.FromResult(0);
             }
 
-            _logger.Warning(this, null, "Client '{0}': Received not supported packet ({1}). Closing connection.", ClientId, packet);
+            _logger.Warning(null, "Client '{0}': Received not supported packet ({1}). Closing connection.", ClientId, packet);
             Stop(MqttClientDisconnectType.NotClean);
 
             return Task.FromResult(0);

Frameworks/MQTTnet.NetStandard/Server/MqttClientSessionsManager.cs

@@ -6,6 +6,7 @@ using System.Threading.Tasks;
 using MQTTnet.Adapter;
 using MQTTnet.Diagnostics;
 using MQTTnet.Exceptions;
+using MQTTnet.Internal;
 using MQTTnet.Packets;
 using MQTTnet.Protocol;
 
@@ -14,15 +15,18 @@ namespace MQTTnet.Server
     public sealed class MqttClientSessionsManager : IDisposable
     {
         private readonly Dictionary<string, MqttClientSession> _sessions = new Dictionary<string, MqttClientSession>();
-        private readonly SemaphoreSlim _sessionsLock = new SemaphoreSlim(1, 1);
+        private readonly AsyncLock _sessionsLock = new AsyncLock();
 
         private readonly MqttRetainedMessagesManager _retainedMessagesManager;
         private readonly IMqttServerOptions _options;
-        private readonly IMqttNetLogger _logger;
+        private readonly IMqttNetChildLogger _logger;
 
-        public MqttClientSessionsManager(IMqttServerOptions options, MqttServer server, MqttRetainedMessagesManager retainedMessagesManager, IMqttNetLogger logger)
+        public MqttClientSessionsManager(IMqttServerOptions options, MqttServer server, MqttRetainedMessagesManager retainedMessagesManager, IMqttNetChildLogger logger)
         {
-            _logger = logger ?? throw new ArgumentNullException(nameof(logger));
+            if (logger == null) throw new ArgumentNullException(nameof(logger));
+
+            _logger = logger.CreateChildLogger(nameof(MqttClientSessionsManager));
+
             _options = options ?? throw new ArgumentNullException(nameof(options));
             Server = server ?? throw new ArgumentNullException(nameof(server));
             _retainedMessagesManager = retainedMessagesManager ?? throw new ArgumentNullException(nameof(retainedMessagesManager));
@@ -89,7 +93,7 @@ namespace MQTTnet.Server
             }
             catch (Exception exception)
             {
-                _logger.Error<MqttClientSessionsManager>(exception, exception.Message);
+                _logger.Error(exception, exception.Message);
             }
             finally
             {
@@ -100,7 +104,7 @@ namespace MQTTnet.Server
                 }
                 catch (Exception exception)
                 {
-                    _logger.Error<MqttClientSessionsManager>(exception, exception.Message);
+                    _logger.Error(exception, exception.Message);
                 }
 
                 Server.OnClientDisconnected(new ConnectedMqttClient
@@ -115,7 +119,7 @@ namespace MQTTnet.Server
 
         public async Task StopAsync()
         {
-            await _sessionsLock.WaitAsync().ConfigureAwait(false);
+            await _sessionsLock.EnterAsync(CancellationToken.None).ConfigureAwait(false);
             try
             {
                 foreach (var session in _sessions)
@@ -127,13 +131,13 @@ namespace MQTTnet.Server
             }
             finally
             {
-                _sessionsLock.Release();
+                _sessionsLock.Exit();
             }
         }
 
         public async Task<IList<ConnectedMqttClient>> GetConnectedClientsAsync()
         {
-            await _sessionsLock.WaitAsync().ConfigureAwait(false);
+            await _sessionsLock.EnterAsync(CancellationToken.None).ConfigureAwait(false);
             try
             {
                 return _sessions.Where(s => s.Value.IsConnected).Select(s => new ConnectedMqttClient
@@ -147,7 +151,7 @@ namespace MQTTnet.Server
             }
             finally
             {
-                _sessionsLock.Release();
+                _sessionsLock.Exit();
             }
         }
 
@@ -161,7 +165,7 @@ namespace MQTTnet.Server
             if (clientId == null) throw new ArgumentNullException(nameof(clientId));
             if (topicFilters == null) throw new ArgumentNullException(nameof(topicFilters));
 
-            await _sessionsLock.WaitAsync().ConfigureAwait(false);
+            await _sessionsLock.EnterAsync(CancellationToken.None).ConfigureAwait(false);
             try
             {
                 if (!_sessions.TryGetValue(clientId, out var session))
@@ -173,7 +177,7 @@ namespace MQTTnet.Server
             }
             finally
             {
-                _sessionsLock.Release();
+                _sessionsLock.Exit();
             }
         }
 
@@ -182,7 +186,7 @@ namespace MQTTnet.Server
             if (clientId == null) throw new ArgumentNullException(nameof(clientId));
             if (topicFilters == null) throw new ArgumentNullException(nameof(topicFilters));
 
-            await _sessionsLock.WaitAsync().ConfigureAwait(false);
+            await _sessionsLock.EnterAsync(CancellationToken.None).ConfigureAwait(false);
             try
             {
                 if (!_sessions.TryGetValue(clientId, out var session))
@@ -194,7 +198,7 @@ namespace MQTTnet.Server
             }
             finally
             {
-                _sessionsLock.Release();
+                _sessionsLock.Exit();
             }
         }
 
@@ -222,7 +226,7 @@ namespace MQTTnet.Server
 
         private async Task<GetOrCreateClientSessionResult> PrepareClientSessionAsync(MqttConnectPacket connectPacket)
         {
-            await _sessionsLock.WaitAsync().ConfigureAwait(false);
+            await _sessionsLock.EnterAsync(CancellationToken.None).ConfigureAwait(false);
             try
             {
                 var isSessionPresent = _sessions.TryGetValue(connectPacket.ClientId, out var clientSession);
@@ -236,11 +240,11 @@ namespace MQTTnet.Server
                         clientSession.Dispose();
                         clientSession = null;
 
-                        _logger.Verbose<MqttClientSessionsManager>("Stopped existing session of client '{0}'.", connectPacket.ClientId);
+                        _logger.Verbose("Stopped existing session of client '{0}'.", connectPacket.ClientId);
                     }
                     else
                     {
-                        _logger.Verbose<MqttClientSessionsManager>("Reusing existing session of client '{0}'.", connectPacket.ClientId);
+                        _logger.Verbose("Reusing existing session of client '{0}'.", connectPacket.ClientId);
                     }
                 }
 
@@ -252,14 +256,14 @@ namespace MQTTnet.Server
                     clientSession = new MqttClientSession(connectPacket.ClientId, _options, this, _retainedMessagesManager, _logger);
                     _sessions[connectPacket.ClientId] = clientSession;
 
-                    _logger.Verbose<MqttClientSessionsManager>("Created a new session for client '{0}'.", connectPacket.ClientId);
+                    _logger.Verbose("Created a new session for client '{0}'.", connectPacket.ClientId);
                 }
 
                 return new GetOrCreateClientSessionResult { IsExistingSession = isExistingSession, Session = clientSession };
             }
             finally
             {
-                _sessionsLock.Release();
+                _sessionsLock.Exit();
             }
         }
 
@@ -287,10 +291,10 @@ namespace MQTTnet.Server
             }
             catch (Exception exception)
             {
-                _logger.Error<MqttClientSessionsManager>(exception, "Error while processing application message");
+                _logger.Error(exception, "Error while processing application message");
             }
 
-            await _sessionsLock.WaitAsync().ConfigureAwait(false);
+            await _sessionsLock.EnterAsync(CancellationToken.None).ConfigureAwait(false);
             try
             {
                 foreach (var clientSession in _sessions.Values)
@@ -300,7 +304,7 @@ namespace MQTTnet.Server
             }
             finally
             {
-                _sessionsLock.Release();
+                _sessionsLock.Exit();
             }
         }
 

Frameworks/MQTTnet.NetStandard/Server/MqttRetainedMessagesManager.cs

@@ -4,19 +4,21 @@ using System.Linq;
 using System.Threading;
 using System.Threading.Tasks;
 using MQTTnet.Diagnostics;
+using MQTTnet.Internal;
 
 namespace MQTTnet.Server
 {
     public sealed class MqttRetainedMessagesManager : IDisposable
     {
-        private readonly Dictionary<string, MqttApplicationMessage> _retainedMessages = new Dictionary<string, MqttApplicationMessage>();
-        private readonly SemaphoreSlim _semaphore = new SemaphoreSlim(1, 1);
-        private readonly IMqttNetLogger _logger;
+        private readonly Dictionary<string, MqttApplicationMessage> _messages = new Dictionary<string, MqttApplicationMessage>();
+        private readonly AsyncLock _messagesLock = new AsyncLock();
+        private readonly IMqttNetChildLogger _logger;
         private readonly IMqttServerOptions _options;
 
-        public MqttRetainedMessagesManager(IMqttServerOptions options, IMqttNetLogger logger)
+        public MqttRetainedMessagesManager(IMqttServerOptions options, IMqttNetChildLogger logger)
         {
-            _logger = logger ?? throw new ArgumentNullException(nameof(logger));
+            if (logger == null) throw new ArgumentNullException(nameof(logger));
+            _logger = logger.CreateChildLogger(nameof(MqttRetainedMessagesManager));
             _options = options ?? throw new ArgumentNullException(nameof(options));
         }
 
@@ -27,24 +29,24 @@ namespace MQTTnet.Server
                 return;
             }
 
-            await _semaphore.WaitAsync().ConfigureAwait(false);
+            await _messagesLock.EnterAsync(CancellationToken.None).ConfigureAwait(false);
             try
             {
-                var retainedMessages = await _options.Storage.LoadRetainedMessagesAsync();
+                var retainedMessages = await _options.Storage.LoadRetainedMessagesAsync().ConfigureAwait(false);
 
-                _retainedMessages.Clear();
+                _messages.Clear();
                 foreach (var retainedMessage in retainedMessages)
                 {
-                    _retainedMessages[retainedMessage.Topic] = retainedMessage;
+                    _messages[retainedMessage.Topic] = retainedMessage;
                 }
             }
             catch (Exception exception)
             {
-                _logger.Error<MqttRetainedMessagesManager>(exception, "Unhandled exception while loading retained messages.");
+                _logger.Error(exception, "Unhandled exception while loading retained messages.");
             }
             finally
             {
-                _semaphore.Release();
+                _messagesLock.Exit();
             }
         }
 
@@ -52,18 +54,18 @@ namespace MQTTnet.Server
         {
             if (applicationMessage == null) throw new ArgumentNullException(nameof(applicationMessage));
 
-            await _semaphore.WaitAsync().ConfigureAwait(false);
+            await _messagesLock.EnterAsync(CancellationToken.None).ConfigureAwait(false);
             try
             {
                 await HandleMessageInternalAsync(clientId, applicationMessage);
             }
             catch (Exception exception)
             {
-                _logger.Error<MqttRetainedMessagesManager>(exception, "Unhandled exception while handling retained messages.");
+                _logger.Error(exception, "Unhandled exception while handling retained messages.");
             }
             finally
             {
-                _semaphore.Release();
+                _messagesLock.Exit();
             }
         }
 
@@ -71,10 +73,10 @@ namespace MQTTnet.Server
         {
             var retainedMessages = new List<MqttApplicationMessage>();
 
-            await _semaphore.WaitAsync().ConfigureAwait(false);
+            await _messagesLock.EnterAsync(CancellationToken.None).ConfigureAwait(false);
             try
             {
-                foreach (var retainedMessage in _retainedMessages.Values)
+                foreach (var retainedMessage in _messages.Values)
                 {
                     foreach (var topicFilter in topicFilters)
                     {
@@ -90,7 +92,7 @@ namespace MQTTnet.Server
             }
             finally
             {
-                _semaphore.Release();
+                _messagesLock.Exit();
             }
 
             return retainedMessages;
@@ -98,7 +100,7 @@ namespace MQTTnet.Server
 
         public void Dispose()
         {
-            _semaphore?.Dispose();
+            _messagesLock?.Dispose();
         }
 
         private async Task HandleMessageInternalAsync(string clientId, MqttApplicationMessage applicationMessage)
@@ -107,37 +109,37 @@ namespace MQTTnet.Server
 
             if (applicationMessage.Payload?.Any() == false)
             {
-                saveIsRequired = _retainedMessages.Remove(applicationMessage.Topic);
-                _logger.Info<MqttRetainedMessagesManager>("Client '{0}' cleared retained message for topic '{1}'.", clientId, applicationMessage.Topic);
+                saveIsRequired = _messages.Remove(applicationMessage.Topic);
+                _logger.Info("Client '{0}' cleared retained message for topic '{1}'.", clientId, applicationMessage.Topic);
             }
             else
             {
-                if (!_retainedMessages.ContainsKey(applicationMessage.Topic))
+                if (!_messages.ContainsKey(applicationMessage.Topic))
                 {
-                    _retainedMessages[applicationMessage.Topic] = applicationMessage;
+                    _messages[applicationMessage.Topic] = applicationMessage;
                     saveIsRequired = true;
                 }
                 else
                 {
-                    var existingMessage = _retainedMessages[applicationMessage.Topic];
+                    var existingMessage = _messages[applicationMessage.Topic];
                     if (existingMessage.QualityOfServiceLevel != applicationMessage.QualityOfServiceLevel || !existingMessage.Payload.SequenceEqual(applicationMessage.Payload ?? new byte[0]))
                     {
-                        _retainedMessages[applicationMessage.Topic] = applicationMessage;
+                        _messages[applicationMessage.Topic] = applicationMessage;
                         saveIsRequired = true;
                     }
                 }
 
-                _logger.Info<MqttRetainedMessagesManager>("Client '{0}' set retained message for topic '{1}'.", clientId, applicationMessage.Topic);
+                _logger.Info("Client '{0}' set retained message for topic '{1}'.", clientId, applicationMessage.Topic);
             }
 
             if (!saveIsRequired)
             {
-                _logger.Verbose<MqttRetainedMessagesManager>("Skipped saving retained messages because no changes were detected.");
+                _logger.Verbose("Skipped saving retained messages because no changes were detected.");
             }
 
             if (saveIsRequired && _options.Storage != null)
             {
-                await _options.Storage.SaveRetainedMessagesAsync(_retainedMessages.Values.ToList());
+                await _options.Storage.SaveRetainedMessagesAsync(_messages.Values.ToList()).ConfigureAwait(false);
             }
         }
     }

Frameworks/MQTTnet.NetStandard/Server/MqttServer.cs

@@ -11,16 +11,17 @@ namespace MQTTnet.Server
     public class MqttServer : IMqttServer
     {
         private readonly ICollection<IMqttServerAdapter> _adapters;
-        private readonly IMqttNetLogger _logger;
+        private readonly IMqttNetChildLogger _logger;
 
         private MqttClientSessionsManager _clientSessionsManager;
         private MqttRetainedMessagesManager _retainedMessagesManager;
         private CancellationTokenSource _cancellationTokenSource;
 
-        public MqttServer(IEnumerable<IMqttServerAdapter> adapters, IMqttNetLogger logger)
+        public MqttServer(IEnumerable<IMqttServerAdapter> adapters, IMqttNetChildLogger logger)
         {
             if (adapters == null) throw new ArgumentNullException(nameof(adapters));
-            _logger = logger ?? throw new ArgumentNullException(nameof(logger));
+            if (logger == null) throw new ArgumentNullException(nameof(logger));
+            _logger = logger.CreateChildLogger(nameof(MqttServer));
 
             _adapters = adapters.ToList();
         }
@@ -90,7 +91,7 @@ namespace MQTTnet.Server
                 await adapter.StartAsync(Options);
             }
 
-            _logger.Info<MqttServer>("Started.");
+            _logger.Info("Started.");
             Started?.Invoke(this, new MqttServerStartedEventArgs());
         }
 
@@ -114,7 +115,7 @@ namespace MQTTnet.Server
 
                 await _clientSessionsManager.StopAsync();
 
-                _logger.Info<MqttServer>("Stopped.");
+                _logger.Info("Stopped.");
             }
             finally
             {
@@ -129,13 +130,13 @@ namespace MQTTnet.Server
 
         internal void OnClientConnected(ConnectedMqttClient client)
         {
-            _logger.Info<MqttServer>("Client '{0}': Connected.", client.ClientId);
+            _logger.Info("Client '{0}': Connected.", client.ClientId);
             ClientConnected?.Invoke(this, new MqttClientConnectedEventArgs(client));
         }
 
         internal void OnClientDisconnected(ConnectedMqttClient client, bool wasCleanDisconnect)
         {
-            _logger.Info<MqttServer>("Client '{0}': Disconnected (clean={1}).", client.ClientId, wasCleanDisconnect);
+            _logger.Info("Client '{0}': Disconnected (clean={1}).", client.ClientId, wasCleanDisconnect);
             ClientDisconnected?.Invoke(this, new MqttClientDisconnectedEventArgs(client, wasCleanDisconnect));
         }
 

Tests/MQTTnet.Benchmarks/LoggerBenchmark.cs

@@ -0,0 +1,54 @@
+using BenchmarkDotNet.Attributes;
+using BenchmarkDotNet.Attributes.Exporters;
+using BenchmarkDotNet.Attributes.Jobs;
+using MQTTnet.Diagnostics;
+
+namespace MQTTnet.Benchmarks
+{
+    [ClrJob]
+    [RPlotExporter]
+    [MemoryDiagnoser]
+    public class LoggerBenchmark
+    {
+        private IMqttNetLogger _logger;
+        private IMqttNetChildLogger _childLogger;
+        private bool _useHandler;
+
+        [GlobalSetup]
+        public void Setup()
+        {
+            _logger = new MqttNetLogger("1");
+            _childLogger = _logger.CreateChildLogger("child");
+
+            MqttNetGlobalLogger.LogMessagePublished += OnLogMessagePublished;
+        }
+
+        private void OnLogMessagePublished(object sender, MqttNetLogMessagePublishedEventArgs eventArgs)
+        {
+            if (_useHandler)
+            {
+                eventArgs.TraceMessage.ToString();
+            }
+        }
+
+        [Benchmark]
+        public void Log_10000_Messages_NoHandler()
+        {
+            _useHandler = false;
+            for (var i = 0; i < 10000; i++)
+            {
+                _childLogger.Verbose("test log message {0}", "parameter");
+            }
+        }
+
+        [Benchmark]
+        public void Log_10000_Messages_WithHandler()
+        {
+            _useHandler = true;
+            for (var i = 0; i < 10000; i++)
+            {
+                _childLogger.Verbose("test log message {0}", "parameter");
+            }
+        }
+    }
+}

Tests/MQTTnet.Benchmarks/MQTTnet.Benchmarks.csproj

@@ -147,6 +147,7 @@
     </Reference>
   </ItemGroup>
   <ItemGroup>
+    <Compile Include="LoggerBenchmark.cs" />
     <Compile Include="MessageProcessingBenchmark.cs" />
     <Compile Include="Program.cs" />
     <Compile Include="Properties\AssemblyInfo.cs" />

Tests/MQTTnet.Benchmarks/Program.cs

@@ -1,5 +1,4 @@
 using System;
-using System.Threading;
 using BenchmarkDotNet.Running;
 using MQTTnet.Diagnostics;
 
@@ -12,6 +11,7 @@ namespace MQTTnet.Benchmarks
             Console.WriteLine($"MQTTnet - BenchmarkApp.{TargetFrameworkInfoProvider.TargetFramework}");
             Console.WriteLine("1 = MessageProcessingBenchmark");
             Console.WriteLine("2 = SerializerBenchmark");
+            Console.WriteLine("3 = LoggerBenchmark");
 
             var pressedKey = Console.ReadKey(true);
             switch (pressedKey.KeyChar)
@@ -22,7 +22,8 @@ namespace MQTTnet.Benchmarks
                 case '2':
                     BenchmarkRunner.Run<SerializerBenchmark>();
                     break;
-                default:
+                case '3':
+                    BenchmarkRunner.Run<LoggerBenchmark>();
                     break;
             }
 

Tests/MQTTnet.Benchmarks/SerializerBenchmark.cs

@@ -1,9 +1,7 @@
 using BenchmarkDotNet.Attributes;
-using MQTTnet.Client;
 using MQTTnet.Packets;
 using MQTTnet.Serializer;
 using MQTTnet.Internal;
-using MQTTnet.Server;
 using BenchmarkDotNet.Attributes.Jobs;
 using BenchmarkDotNet.Attributes.Exporters;
 using System;

Tests/MQTTnet.Core.Tests/MqttKeepAliveMonitorTests.cs

@@ -17,7 +17,7 @@ namespace MQTTnet.Core.Tests
             var monitor = new MqttClientKeepAliveMonitor(string.Empty, delegate
             {
                 timeoutCalledCount++;
-            }, new MqttNetLogger());
+            }, new MqttNetLogger().CreateChildLogger(""));
 
             Assert.AreEqual(0, timeoutCalledCount);
 
@@ -38,7 +38,7 @@ namespace MQTTnet.Core.Tests
             var monitor = new MqttClientKeepAliveMonitor(string.Empty, delegate
             {
                 timeoutCalledCount++;
-            }, new MqttNetLogger());
+            }, new MqttNetLogger().CreateChildLogger(""));
 
             Assert.AreEqual(0, timeoutCalledCount);
 

Tests/MQTTnet.Core.Tests/MqttSubscriptionsManagerTests.cs

@@ -13,7 +13,7 @@ namespace MQTTnet.Core.Tests
         [TestMethod]
         public void MqttSubscriptionsManager_SubscribeSingleSuccess()
         {
-            var sm = new MqttClientSubscriptionsManager("", new MqttServerOptions(), new MqttServer(new IMqttServerAdapter[0], new MqttNetLogger()));
+            var sm = new MqttClientSubscriptionsManager("", new MqttServerOptions(), new MqttServer(new IMqttServerAdapter[0], new MqttNetLogger().CreateChildLogger("")));
 
             var sp = new MqttSubscribePacket();
             sp.TopicFilters.Add(new TopicFilterBuilder().WithTopic("A/B/C").Build());
@@ -34,7 +34,7 @@ namespace MQTTnet.Core.Tests
         [TestMethod]
         public void MqttSubscriptionsManager_SubscribeDifferentQoSSuccess()
         {
-            var sm = new MqttClientSubscriptionsManager("", new MqttServerOptions(), new MqttServer(new IMqttServerAdapter[0], new MqttNetLogger()));
+            var sm = new MqttClientSubscriptionsManager("", new MqttServerOptions(), new MqttServer(new IMqttServerAdapter[0], new MqttNetLogger().CreateChildLogger("")));
 
             var sp = new MqttSubscribePacket();
             sp.TopicFilters.Add(new TopicFilter("A/B/C", MqttQualityOfServiceLevel.AtMostOnce));
@@ -55,7 +55,7 @@ namespace MQTTnet.Core.Tests
         [TestMethod]
         public void MqttSubscriptionsManager_SubscribeTwoTimesSuccess()
         {
-            var sm = new MqttClientSubscriptionsManager("", new MqttServerOptions(), new MqttServer(new IMqttServerAdapter[0], new MqttNetLogger()));
+            var sm = new MqttClientSubscriptionsManager("", new MqttServerOptions(), new MqttServer(new IMqttServerAdapter[0], new MqttNetLogger().CreateChildLogger("")));
 
             var sp = new MqttSubscribePacket();
             sp.TopicFilters.Add(new TopicFilter("#", MqttQualityOfServiceLevel.AtMostOnce));
@@ -77,7 +77,7 @@ namespace MQTTnet.Core.Tests
         [TestMethod]
         public void MqttSubscriptionsManager_SubscribeSingleNoSuccess()
         {
-            var sm = new MqttClientSubscriptionsManager("", new MqttServerOptions(), new MqttServer(new IMqttServerAdapter[0], new MqttNetLogger()));
+            var sm = new MqttClientSubscriptionsManager("", new MqttServerOptions(), new MqttServer(new IMqttServerAdapter[0], new MqttNetLogger().CreateChildLogger("")));
 
             var sp = new MqttSubscribePacket();
             sp.TopicFilters.Add(new TopicFilterBuilder().WithTopic("A/B/C").Build());
@@ -96,7 +96,7 @@ namespace MQTTnet.Core.Tests
         [TestMethod]
         public void MqttSubscriptionsManager_SubscribeAndUnsubscribeSingle()
         {
-            var sm = new MqttClientSubscriptionsManager("", new MqttServerOptions(), new MqttServer(new IMqttServerAdapter[0], new MqttNetLogger()));
+            var sm = new MqttClientSubscriptionsManager("", new MqttServerOptions(), new MqttServer(new IMqttServerAdapter[0], new MqttNetLogger().CreateChildLogger("")));
 
             var sp = new MqttSubscribePacket();
             sp.TopicFilters.Add(new TopicFilterBuilder().WithTopic("A/B/C").Build());

Tests/MQTTnet.Core.Tests/TestMqttCommunicationAdapterFactory.cs

@@ -13,7 +13,7 @@ namespace MQTTnet.Core.Tests
             _adapter = adapter;
         }
         
-        public IMqttChannelAdapter CreateClientAdapter(IMqttClientOptions options, IMqttNetLogger logger)
+        public IMqttChannelAdapter CreateClientAdapter(IMqttClientOptions options, IMqttNetChildLogger logger)
         {
             return _adapter;
         }