Refactor logger. (#1247)

Source/MQTTnet.AspnetCore/Extensions/ServiceCollectionExtensions.cs

@@ -3,6 +3,7 @@ using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Hosting;
 using MQTTnet.Adapter;
 using MQTTnet.Diagnostics;
+using MQTTnet.Diagnostics.Logger;
 using MQTTnet.Implementations;
 using MQTTnet.Server;
 
@@ -61,7 +62,7 @@ namespace MQTTnet.AspNetCore.Extensions
 
         private static IServiceCollection AddHostedMqttServer(this IServiceCollection services)
         {
-            var logger = new MqttNetLogger();
+            var logger = new MqttNetEventLogger();
 
             services.AddSingleton<IMqttNetLogger>(logger);
             services.AddSingleton<MqttHostedServer>();

Source/MQTTnet.AspnetCore/MqttHostedServer.cs

@@ -4,14 +4,14 @@ using System.Threading;
 using System.Threading.Tasks;
 using Microsoft.Extensions.Hosting;
 using MQTTnet.Adapter;
-using MQTTnet.Diagnostics;
+using MQTTnet.Diagnostics.Logger;
 using MQTTnet.Server;
 
 namespace MQTTnet.AspNetCore
 {
-    public class MqttHostedServer : MqttServer, IHostedService
+    public sealed class MqttHostedServer : MqttServer, IHostedService
     {
-        private readonly IMqttServerOptions _options;
+        readonly IMqttServerOptions _options;
 
         public MqttHostedServer(IMqttServerOptions options, IEnumerable<IMqttServerAdapter> adapters, IMqttNetLogger logger) 
             : base(adapters, logger)

Source/MQTTnet.AspnetCore/MqttWebSocketServerAdapter.cs

@@ -1,12 +1,12 @@
 using Microsoft.AspNetCore.Http;
 using MQTTnet.Adapter;
-using MQTTnet.Diagnostics;
 using MQTTnet.Formatter;
 using MQTTnet.Implementations;
 using MQTTnet.Server;
 using System;
 using System.Net.WebSockets;
 using System.Threading.Tasks;
+using MQTTnet.Diagnostics.Logger;
 
 namespace MQTTnet.AspNetCore
 {

Source/MQTTnet.Extensions.ManagedClient/ManagedMqttClient.cs

@@ -13,6 +13,7 @@ using System.Collections.Generic;
 using System.Linq;
 using System.Threading;
 using System.Threading.Tasks;
+using MQTTnet.Diagnostics.Logger;
 
 namespace MQTTnet.Extensions.ManagedClient
 {
@@ -33,7 +34,7 @@ namespace MQTTnet.Extensions.ManagedClient
         readonly HashSet<string> _unsubscriptions = new HashSet<string>();
         readonly SemaphoreSlim _subscriptionsQueuedSignal = new SemaphoreSlim(0);
 
-        readonly IMqttNetScopedLogger _logger;
+        readonly MqttNetSourceLogger _logger;
 
         readonly AsyncLock _messageQueueLock = new AsyncLock();
 
@@ -48,7 +49,7 @@ namespace MQTTnet.Extensions.ManagedClient
             InternalClient = mqttClient ?? throw new ArgumentNullException(nameof(mqttClient));
 
             if (logger == null) throw new ArgumentNullException(nameof(logger));
-            _logger = logger.CreateScopedLogger(nameof(ManagedMqttClient));
+            _logger = logger.WithSource(nameof(ManagedMqttClient));
         }
 
         public bool IsConnected => InternalClient.IsConnected;

Source/MQTTnet.Extensions.ManagedClient/MqttFactoryExtensions.cs

@@ -1,5 +1,5 @@
-using MQTTnet.Diagnostics;
-using System;
+using System;
+using MQTTnet.Diagnostics.Logger;
 
 namespace MQTTnet.Extensions.ManagedClient
 {

Source/MQTTnet.Extensions.WebSocket4Net/WebSocket4NetMqttClientAdapterFactory.cs

@@ -4,6 +4,7 @@ using MQTTnet.Diagnostics;
 using MQTTnet.Formatter;
 using MQTTnet.Implementations;
 using System;
+using MQTTnet.Diagnostics.Logger;
 
 namespace MQTTnet.Extensions.WebSocket4Net
 {

Source/MQTTnet/Adapter/MqttChannelAdapter.cs

@@ -11,6 +11,7 @@ using System.Runtime.InteropServices;
 using System.Security.Cryptography.X509Certificates;
 using System.Threading;
 using System.Threading.Tasks;
+using MQTTnet.Diagnostics.Logger;
 using MQTTnet.Diagnostics.PacketInspection;
 
 namespace MQTTnet.Adapter
@@ -24,7 +25,7 @@ namespace MQTTnet.Adapter
         readonly byte[] _fixedHeaderBuffer = new byte[2];
 
         readonly MqttPacketInspectorHandler _packetInspectorHandler;
-        readonly IMqttNetScopedLogger _logger;
+        readonly MqttNetSourceLogger _logger;
         readonly IMqttChannel _channel;
 
         readonly AsyncLock _syncRoot = new AsyncLock();
@@ -40,7 +41,7 @@ namespace MQTTnet.Adapter
             _packetInspectorHandler = new MqttPacketInspectorHandler(packetInspector, logger);
 
             if (logger == null) throw new ArgumentNullException(nameof(logger));
-            _logger = logger.CreateScopedLogger(nameof(MqttChannelAdapter));
+            _logger = logger.WithSource(nameof(MqttChannelAdapter));
         }
 
         public string Endpoint => _channel.Endpoint;

Source/MQTTnet/Adapter/MqttPacketInspectorHandler.cs

@@ -2,6 +2,7 @@ using System;
 using System.IO;
 using System.Linq;
 using MQTTnet.Diagnostics;
+using MQTTnet.Diagnostics.Logger;
 using MQTTnet.Diagnostics.PacketInspection;
 
 namespace MQTTnet.Adapter
@@ -10,7 +11,7 @@ namespace MQTTnet.Adapter
     {
         readonly MemoryStream _receivedPacketBuffer;
         readonly IMqttPacketInspector _packetInspector;
-        readonly IMqttNetScopedLogger _logger;
+        readonly MqttNetSourceLogger _logger;
 
         public MqttPacketInspectorHandler(IMqttPacketInspector packetInspector, IMqttNetLogger logger)
         {
@@ -22,7 +23,7 @@ namespace MQTTnet.Adapter
             }
 
             if (logger == null) throw new ArgumentNullException(nameof(logger));
-            _logger = logger.CreateScopedLogger(nameof(MqttPacketInspectorHandler));
+            _logger = logger.WithSource(nameof(MqttPacketInspectorHandler));
         }
 
         public void BeginReceivePacket()

Source/MQTTnet/Client/IMqttClientFactory.cs

@@ -1,5 +1,6 @@
 using MQTTnet.Adapter;
 using MQTTnet.Diagnostics;
+using MQTTnet.Diagnostics.Logger;
 using MQTTnet.LowLevelClient;
 
 namespace MQTTnet.Client

Source/MQTTnet/Client/MqttClient.cs

@@ -16,6 +16,7 @@ using MQTTnet.Protocol;
 using System;
 using System.Threading;
 using System.Threading.Tasks;
+using MQTTnet.Diagnostics.Logger;
 using MQTTnet.Implementations;
 
 namespace MQTTnet.Client
@@ -27,7 +28,7 @@ namespace MQTTnet.Client
         readonly object _disconnectLock = new object();
 
         readonly IMqttClientAdapterFactory _adapterFactory;
-        readonly IMqttNetScopedLogger _logger;
+        readonly MqttNetSourceLogger _logger;
 
         CancellationTokenSource _backgroundCancellationTokenSource;
         Task _packetReceiverTask;
@@ -49,7 +50,7 @@ namespace MQTTnet.Client
             if (logger == null) throw new ArgumentNullException(nameof(logger));
 
             _adapterFactory = channelFactory ?? throw new ArgumentNullException(nameof(channelFactory));
-            _logger = logger.CreateScopedLogger(nameof(MqttClient));
+            _logger = logger.WithSource(nameof(MqttClient));
         }
 
         public IMqttClientConnectedHandler ConnectedHandler { get; set; }

Source/MQTTnet/Diagnostics/IMqttNetScopedLogger.cs

@@ -1,11 +0,0 @@
-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/Logger/IMqttNetLogger.cs

@@ -1,11 +1,9 @@
 using System;
 
-namespace MQTTnet.Diagnostics
+namespace MQTTnet.Diagnostics.Logger
 {
     public interface IMqttNetLogger
     {
-        IMqttNetScopedLogger CreateScopedLogger(string source);
-
         void Publish(MqttNetLogLevel logLevel, string source, string message, object[] parameters, Exception exception);
     }
 }

Source/MQTTnet/Diagnostics/Logger/MqttNetEventLogger.cs

@@ -0,0 +1,58 @@
+using System;
+
+namespace MQTTnet.Diagnostics.Logger
+{
+    /// <summary>
+    /// This logger fires an event when a new message was published.
+    /// </summary>
+    public sealed class MqttNetEventLogger : IMqttNetLogger
+    {
+        public MqttNetEventLogger(string logId = null)
+        {
+            LogId = logId;
+        }
+
+        public event EventHandler<MqttNetLogMessagePublishedEventArgs> LogMessagePublished;
+
+        public string LogId { get; }
+
+        public void Publish(MqttNetLogLevel level, string source, string message, object[] parameters, Exception exception)
+        {
+            var eventHandler = LogMessagePublished;
+            if (eventHandler == null)
+            {
+                // No listener is attached so we can step out.
+                // Keep a reference to the handler because the handler
+                // might be null after preparing the message.
+                return;
+            }
+            
+            if (parameters?.Length > 0 && message?.Length > 0)
+            {
+                try
+                {
+                    message = string.Format(message, parameters);
+                }
+                catch (FormatException)
+                {
+                    message = "MESSAGE FORMAT INVALID: " + message;
+                }
+            }
+
+            // We only use UTC here to improve performance. Using a local date time
+            // would require to load the time zone settings!
+            var logMessage = new MqttNetLogMessage
+            {
+                LogId = LogId,
+                Timestamp = DateTime.UtcNow,
+                Source = source,
+                ThreadId = Environment.CurrentManagedThreadId,
+                Level = level,
+                Message = message,
+                Exception = exception
+            };
+            
+            eventHandler.Invoke(this, new MqttNetLogMessagePublishedEventArgs(logMessage));
+        }
+    }
+}

Source/MQTTnet/Diagnostics/Logger/MqttNetLogLevel.cs

@@ -1,4 +1,4 @@
-namespace MQTTnet.Diagnostics
+namespace MQTTnet.Diagnostics.Logger
 {
     public enum MqttNetLogLevel
     {

Source/MQTTnet/Diagnostics/Logger/MqttNetLogMessage.cs

@@ -1,6 +1,6 @@
 using System;
 
-namespace MQTTnet.Diagnostics
+namespace MQTTnet.Diagnostics.Logger
 {
     public sealed class MqttNetLogMessage
     {

Source/MQTTnet/Diagnostics/Logger/MqttNetLogMessagePublishedEventArgs.cs

@@ -1,21 +1,14 @@
 using System;
 
-namespace MQTTnet.Diagnostics
+namespace MQTTnet.Diagnostics.Logger
 {
     public sealed class MqttNetLogMessagePublishedEventArgs : EventArgs
     {
         public MqttNetLogMessagePublishedEventArgs(MqttNetLogMessage logMessage)
         {
             LogMessage = logMessage ?? throw new ArgumentNullException(nameof(logMessage));
-
-#pragma warning disable CS0618 // Type or member is obsolete
-            TraceMessage = logMessage;
-#pragma warning restore CS0618 // Type or member is obsolete
         }
 
-        [Obsolete("Use new property LogMessage instead.")]
-        public MqttNetLogMessage TraceMessage { get; }
-
         public MqttNetLogMessage LogMessage { get; }
     }
 }

Source/MQTTnet/Diagnostics/Logger/MqttNetNullLogger.cs

@@ -0,0 +1,14 @@
+using System;
+
+namespace MQTTnet.Diagnostics.Logger
+{
+    /// <summary>
+    /// This logger does nothing with the messages.
+    /// </summary>
+    public sealed class MqttNetNullLogger : IMqttNetLogger
+    {
+        public void Publish(MqttNetLogLevel logLevel, string source, string message, object[] parameters, Exception exception)
+        {
+        }
+    }
+}

Source/MQTTnet/Diagnostics/Logger/MqttNetSourceLogger.cs

@@ -1,21 +1,16 @@
 using System;
 
-namespace MQTTnet.Diagnostics
+namespace MQTTnet.Diagnostics.Logger
 {
-    public sealed class MqttNetScopedLogger : IMqttNetScopedLogger
+    public sealed class MqttNetSourceLogger
     {
         readonly IMqttNetLogger _logger;
         readonly string _source;
 
-        public MqttNetScopedLogger(IMqttNetLogger logger, string source)
+        public MqttNetSourceLogger(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);
+            _source = source;
         }
 
         public void Publish(MqttNetLogLevel logLevel, string message, object[] parameters, Exception exception)

Source/MQTTnet/Diagnostics/Logger/MqttNetSourceLoggerExtensions.cs

@@ -0,0 +1,69 @@
+using System;
+
+namespace MQTTnet.Diagnostics.Logger
+{
+    public static class MqttNetSourceLoggerExtensions
+    {
+        public static MqttNetSourceLogger WithSource(this IMqttNetLogger logger, string source)
+        {
+            if (logger == null) throw new ArgumentNullException(nameof(logger));
+            
+            return new MqttNetSourceLogger(logger, source);
+        }
+        
+        public static void Verbose(this MqttNetSourceLogger logger, string message, params object[] parameters)
+        {
+            logger.Publish(MqttNetLogLevel.Verbose, message, parameters, null);
+        }
+        
+        public static void Verbose(this MqttNetSourceLogger logger, string message)
+        {
+            logger.Publish(MqttNetLogLevel.Verbose, message, null, null);
+        }
+
+        public static void Info(this MqttNetSourceLogger logger, string message, params object[] parameters)
+        {
+            logger.Publish(MqttNetLogLevel.Info, message, parameters, null);
+        }
+        
+        public static void Info(this MqttNetSourceLogger logger, string message)
+        {
+            logger.Publish(MqttNetLogLevel.Info, message, null, null);
+        }
+
+        public static void Warning(this MqttNetSourceLogger logger, Exception exception, string message, params object[] parameters)
+        {
+            logger.Publish(MqttNetLogLevel.Warning, message, parameters, exception);
+        }
+        
+        public static void Warning(this MqttNetSourceLogger logger, Exception exception, string message)
+        {
+            logger.Publish(MqttNetLogLevel.Warning, message, null, exception);
+        }
+        
+        public static void Warning(this MqttNetSourceLogger logger, string message, params object[] parameters)
+        {
+            logger.Publish(MqttNetLogLevel.Warning, message, parameters, null);
+        }
+        
+        public static void Warning(this MqttNetSourceLogger logger, string message)
+        {
+            logger.Publish(MqttNetLogLevel.Warning, message, null, null);
+        }
+
+        public static void Error(this MqttNetSourceLogger logger, Exception exception, string message, params object[] parameters)
+        {
+            logger.Publish(MqttNetLogLevel.Error, message, parameters, exception);
+        }
+        
+        public static void Error(this MqttNetSourceLogger logger, Exception exception, string message)
+        {
+            logger.Publish(MqttNetLogLevel.Error, message, null, exception);
+        }
+        
+        public static void Error(this MqttNetSourceLogger logger, string message)
+        {
+            logger.Publish(MqttNetLogLevel.Error, message, null, null);
+        }
+    }
+}

Source/MQTTnet/Diagnostics/MqttNetGlobalLogger.cs

@@ -1,17 +0,0 @@
-using System;
-
-namespace MQTTnet.Diagnostics
-{
-    [Obsolete("Please pass an instance of the IMqttNetLogger to the factory/server or client. The global logger will be deleted in the future.")]
-    public static class MqttNetGlobalLogger
-    {
-        public static event EventHandler<MqttNetLogMessagePublishedEventArgs> LogMessagePublished;
-
-        public static bool HasListeners => LogMessagePublished != null;
-
-        public static void Publish(MqttNetLogMessage logMessage)
-        {
-            LogMessagePublished?.Invoke(null, new MqttNetLogMessagePublishedEventArgs(logMessage));
-        }
-    }
-}

Source/MQTTnet/Diagnostics/MqttNetLogger.cs

@@ -1,73 +0,0 @@
-using System;
-
-namespace MQTTnet.Diagnostics
-{
-    public class MqttNetLogger : IMqttNetLogger
-    {
-        readonly string _logId;
-        
-        public MqttNetLogger()
-        {
-        }
-
-        public MqttNetLogger(string logId)
-        {
-            _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 IMqttNetScopedLogger CreateScopedLogger(string source)
-        {
-            if (source is null) throw new ArgumentNullException(nameof(source));
-
-            return new MqttNetScopedLogger(this, source);
-        }
-
-        public void Publish(MqttNetLogLevel level, string source, string message, object[] parameters, Exception exception)
-        {
-            var hasLocalListeners = LogMessagePublished != null;
-            var hasGlobalListeners = MqttNetGlobalLogger.HasListeners;
-
-            if (!hasLocalListeners && !hasGlobalListeners)
-            {
-                return;
-            }
-
-            if (parameters?.Length > 0 && message?.Length > 0)
-            {
-                try
-                {
-                    message = string.Format(message, parameters);
-                }
-                catch (FormatException)
-                {
-                    message = "MESSAGE FORMAT INVALID: " + message;
-                }
-            }
-
-            var logMessage = new MqttNetLogMessage
-            {
-                LogId = _logId,
-                Timestamp = DateTime.UtcNow,
-                Source = source,
-                ThreadId = Environment.CurrentManagedThreadId,
-                Level = level,
-                Message = message,
-                Exception = exception
-            };
-
-            if (hasGlobalListeners)
-            {
-                MqttNetGlobalLogger.Publish(logMessage);
-            }
-
-            if (hasLocalListeners)
-            {
-                LogMessagePublished?.Invoke(this, new MqttNetLogMessagePublishedEventArgs(logMessage));
-            }
-        }
-    }
-}

Source/MQTTnet/Diagnostics/MqttNetScopedLoggerExtensions.cs

@@ -1,62 +0,0 @@
-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 Verbose(this IMqttNetScopedLogger logger, string message)
-        {
-            logger.Publish(MqttNetLogLevel.Verbose, message, null, null);
-        }
-
-        public static void Info(this IMqttNetScopedLogger logger, string message, params object[] parameters)
-        {
-            logger.Publish(MqttNetLogLevel.Info, message, parameters, null);
-        }
-        
-        public static void Info(this IMqttNetScopedLogger logger, string message)
-        {
-            logger.Publish(MqttNetLogLevel.Info, message, null, 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 Warning(this IMqttNetScopedLogger logger, Exception exception, string message)
-        {
-            logger.Publish(MqttNetLogLevel.Warning, message, null, exception);
-        }
-        
-        public static void Warning(this IMqttNetScopedLogger logger, string message, params object[] parameters)
-        {
-            logger.Publish(MqttNetLogLevel.Warning, message, parameters, null);
-        }
-        
-        public static void Warning(this IMqttNetScopedLogger logger, string message)
-        {
-            logger.Publish(MqttNetLogLevel.Warning, message, null, null);
-        }
-
-        public static void Error(this IMqttNetScopedLogger logger, Exception exception, string message, params object[] parameters)
-        {
-            logger.Publish(MqttNetLogLevel.Error, message, parameters, exception);
-        }
-        
-        public static void Error(this IMqttNetScopedLogger logger, Exception exception, string message)
-        {
-            logger.Publish(MqttNetLogLevel.Error, message, null, exception);
-        }
-        
-        public static void Error(this IMqttNetScopedLogger logger, string message)
-        {
-            logger.Publish(MqttNetLogLevel.Error, message, null, null);
-        }
-    }
-}

Source/MQTTnet/Diagnostics/Runtime/TargetFrameworkProvider.cs

@@ -1,4 +1,4 @@
-namespace MQTTnet.Diagnostics
+namespace MQTTnet.Diagnostics.Runtime
 {
     public static class TargetFrameworkProvider
     {

Source/MQTTnet/IMqttFactory.cs

@@ -1,6 +1,7 @@
 using System.Collections.Generic;
 using MQTTnet.Client;
 using MQTTnet.Diagnostics;
+using MQTTnet.Diagnostics.Logger;
 using MQTTnet.Server;
 
 namespace MQTTnet

Source/MQTTnet/Implementations/MqttClientAdapterFactory.cs

@@ -4,6 +4,7 @@ using MQTTnet.Diagnostics;
 using MQTTnet.Formatter;
 using System;
 using MQTTnet.Channel;
+using MQTTnet.Diagnostics.Logger;
 
 namespace MQTTnet.Implementations
 {

Source/MQTTnet/Implementations/MqttTcpServerAdapter.cs

@@ -9,13 +9,14 @@ using System.Net.Sockets;
 using System.Security.Cryptography.X509Certificates;
 using System.Threading;
 using System.Threading.Tasks;
+using MQTTnet.Diagnostics.Logger;
 
 namespace MQTTnet.Implementations
 {
     public sealed class MqttTcpServerAdapter : IMqttServerAdapter
     {
         readonly List<MqttTcpServerListener> _listeners = new List<MqttTcpServerListener>();
-        readonly IMqttNetScopedLogger _logger;
+        readonly MqttNetSourceLogger _logger;
         readonly IMqttNetLogger _rootLogger;
 
         CancellationTokenSource _cancellationTokenSource;
@@ -23,7 +24,7 @@ namespace MQTTnet.Implementations
         public MqttTcpServerAdapter(IMqttNetLogger logger)
         {
             _rootLogger = logger ?? throw new ArgumentNullException(nameof(logger));
-            _logger = logger.CreateScopedLogger(nameof(MqttTcpServerAdapter));
+            _logger = logger.WithSource(nameof(MqttTcpServerAdapter));
         }
 
         public Func<IMqttChannelAdapter, Task> ClientHandler { get; set; }

Source/MQTTnet/Implementations/MqttTcpServerListener.cs

@@ -12,12 +12,13 @@ using System.Net.Sockets;
 using System.Security.Cryptography.X509Certificates;
 using System.Threading;
 using System.Threading.Tasks;
+using MQTTnet.Diagnostics.Logger;
 
 namespace MQTTnet.Implementations
 {
     public sealed class MqttTcpServerListener : IDisposable
     {
-        readonly IMqttNetScopedLogger _logger;
+        readonly MqttNetSourceLogger _logger;
         readonly IMqttNetLogger _rootLogger;
         readonly AddressFamily _addressFamily;
         readonly MqttServerTcpEndpointBaseOptions _options;
@@ -37,7 +38,7 @@ namespace MQTTnet.Implementations
             _options = options;
             _tlsCertificate = tlsCertificate;
             _rootLogger = logger;
-            _logger = logger.CreateScopedLogger(nameof(MqttTcpServerListener));
+            _logger = logger.WithSource(nameof(MqttTcpServerListener));
 
             if (_options is MqttServerTlsTcpEndpointOptions tlsOptions)
             {

Source/MQTTnet/Internal/TaskExtensions.cs

@@ -1,11 +1,12 @@
 using MQTTnet.Diagnostics;
 using System.Threading.Tasks;
+using MQTTnet.Diagnostics.Logger;
 
 namespace MQTTnet.Internal
 {
     public static class TaskExtensions
     {
-        public static void RunInBackground(this Task task, IMqttNetScopedLogger logger = null)
+        public static void RunInBackground(this Task task, MqttNetSourceLogger logger = null)
         {
             task?.ContinueWith(t =>
                 {

Source/MQTTnet/LowLevelClient/LowLevelMqttClient.cs

@@ -5,12 +5,13 @@ using MQTTnet.Packets;
 using System;
 using System.Threading;
 using System.Threading.Tasks;
+using MQTTnet.Diagnostics.Logger;
 
 namespace MQTTnet.LowLevelClient
 {
     public sealed class LowLevelMqttClient : ILowLevelMqttClient
     {
-        readonly IMqttNetScopedLogger _logger;
+        readonly MqttNetSourceLogger _logger;
         readonly IMqttClientAdapterFactory _clientAdapterFactory;
 
         IMqttChannelAdapter _adapter;
@@ -21,7 +22,7 @@ namespace MQTTnet.LowLevelClient
             _clientAdapterFactory = clientAdapterFactory ?? throw new ArgumentNullException(nameof(clientAdapterFactory));
 
             if (logger is null) throw new ArgumentNullException(nameof(logger));
-            _logger = logger.CreateScopedLogger(nameof(LowLevelMqttClient));
+            _logger = logger.WithSource(nameof(LowLevelMqttClient));
         }
 
         bool IsConnected => _adapter != null;

Source/MQTTnet/MqttFactory.cs

@@ -1,6 +1,5 @@
 using MQTTnet.Adapter;
 using MQTTnet.Client;
-using MQTTnet.Diagnostics;
 using MQTTnet.Implementations;
 using MQTTnet.LowLevelClient;
 using MQTTnet.Server;
@@ -10,6 +9,7 @@ using System.Linq;
 using MQTTnet.Client.Options;
 using MQTTnet.Client.Subscribing;
 using MQTTnet.Client.Unsubscribing;
+using MQTTnet.Diagnostics.Logger;
 
 namespace MQTTnet
 {
@@ -17,7 +17,7 @@ namespace MQTTnet
     {
         IMqttClientAdapterFactory _clientAdapterFactory;
 
-        public MqttFactory() : this(new MqttNetLogger())
+        public MqttFactory() : this(new MqttNetNullLogger())
         {
         }
 

Source/MQTTnet/Server/IMqttRetainedMessagesManager.cs

@@ -1,6 +1,7 @@
 using MQTTnet.Diagnostics;
 using System.Collections.Generic;
 using System.Threading.Tasks;
+using MQTTnet.Diagnostics.Logger;
 
 namespace MQTTnet.Server
 {

Source/MQTTnet/Server/IMqttServerFactory.cs

@@ -2,6 +2,7 @@
 using System.Collections.Generic;
 using MQTTnet.Adapter;
 using MQTTnet.Diagnostics;
+using MQTTnet.Diagnostics.Logger;
 
 namespace MQTTnet.Server
 {

Source/MQTTnet/Server/Internal/MqttClientConnection.cs

@@ -6,6 +6,7 @@ using MQTTnet.Adapter;
 using MQTTnet.Client;
 using MQTTnet.Client.Disconnecting;
 using MQTTnet.Diagnostics;
+using MQTTnet.Diagnostics.Logger;
 using MQTTnet.Exceptions;
 using MQTTnet.Formatter;
 using MQTTnet.Implementations;
@@ -26,7 +27,7 @@ namespace MQTTnet.Server.Internal
         readonly MqttClientSessionsManager _sessionsManager;
 
         readonly IMqttChannelAdapter _channelAdapter;
-        readonly IMqttNetScopedLogger _logger;
+        readonly MqttNetSourceLogger _logger;
         readonly IMqttServerOptions _serverOptions;
 
         readonly string _endpoint;
@@ -52,7 +53,7 @@ namespace MQTTnet.Server.Internal
             _connectPacket = connectPacket ?? throw new ArgumentNullException(nameof(connectPacket));
 
             if (logger == null) throw new ArgumentNullException(nameof(logger));
-            _logger = logger.CreateScopedLogger(nameof(MqttClientConnection));
+            _logger = logger.WithSource(nameof(MqttClientConnection));
         }
 
         public string ClientId => _connectPacket.ClientId;

Source/MQTTnet/Server/Internal/MqttClientSessionsManager.cs

@@ -7,6 +7,7 @@ using System.Threading.Tasks;
 using MQTTnet.Adapter;
 using MQTTnet.Client.Disconnecting;
 using MQTTnet.Diagnostics;
+using MQTTnet.Diagnostics.Logger;
 using MQTTnet.Exceptions;
 using MQTTnet.Formatter;
 using MQTTnet.Internal;
@@ -30,7 +31,7 @@ namespace MQTTnet.Server.Internal
 
         readonly IMqttRetainedMessagesManager _retainedMessagesManager;
         readonly IMqttServerOptions _options;
-        readonly IMqttNetScopedLogger _logger;
+        readonly MqttNetSourceLogger _logger;
         readonly IMqttNetLogger _rootLogger;
 
         public MqttClientSessionsManager(
@@ -40,7 +41,7 @@ namespace MQTTnet.Server.Internal
             IMqttNetLogger logger)
         {
             if (logger == null) throw new ArgumentNullException(nameof(logger));
-            _logger = logger.CreateScopedLogger(nameof(MqttClientSessionsManager));
+            _logger = logger.WithSource(nameof(MqttClientSessionsManager));
             _rootLogger = logger;
 
             _eventDispatcher = eventDispatcher ?? throw new ArgumentNullException(nameof(eventDispatcher));
@@ -448,7 +449,10 @@ namespace MQTTnet.Server.Internal
             return context;
         }
 
-        async Task<MqttClientConnection> CreateClientConnection(MqttConnectPacket connectPacket, IMqttChannelAdapter channelAdapter, IDictionary<object, object> sessionItems)
+        async Task<MqttClientConnection> CreateClientConnection(
+            MqttConnectPacket connectPacket, 
+            IMqttChannelAdapter channelAdapter, 
+            IDictionary<object, object> sessionItems)
         {
             MqttClientConnection connection;
 
@@ -500,7 +504,9 @@ namespace MQTTnet.Server.Internal
             return connection;
         }
 
-        async Task<MqttApplicationMessageInterceptorContext> InterceptApplicationMessageAsync(IMqttServerApplicationMessageInterceptor interceptor, MqttClientConnection clientConnection,
+        async Task<MqttApplicationMessageInterceptorContext> InterceptApplicationMessageAsync(
+            IMqttServerApplicationMessageInterceptor interceptor,
+            MqttClientConnection clientConnection,
             MqttApplicationMessage applicationMessage)
         {
             string senderClientId;
@@ -522,7 +528,6 @@ namespace MQTTnet.Server.Internal
             {
                 ClientId = senderClientId,
                 SessionItems = sessionItems,
-                Logger = _logger,
                 AcceptPublish = true,
                 ApplicationMessage = applicationMessage,
                 CloseConnection = false

Source/MQTTnet/Server/Internal/MqttRetainedMessagesManager.cs

@@ -4,6 +4,7 @@ using System.Linq;
 using System.Threading;
 using System.Threading.Tasks;
 using MQTTnet.Diagnostics;
+using MQTTnet.Diagnostics.Logger;
 using MQTTnet.Implementations;
 using MQTTnet.Internal;
 
@@ -14,14 +15,14 @@ namespace MQTTnet.Server.Internal
         readonly AsyncLock _storageAccessLock = new AsyncLock();
         readonly Dictionary<string, MqttApplicationMessage> _messages = new Dictionary<string, MqttApplicationMessage>(4096);
 
-        IMqttNetScopedLogger _logger;
+        MqttNetSourceLogger _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.CreateScopedLogger(nameof(MqttRetainedMessagesManager));
+            _logger = logger.WithSource(nameof(MqttRetainedMessagesManager));
 
             _options = options ?? throw new ArgumentNullException(nameof(options));
             return PlatformAbstractionLayer.CompletedTask;

Source/MQTTnet/Server/Internal/MqttServerEventDispatcher.cs

@@ -3,19 +3,20 @@ using System.Threading.Tasks;
 using MQTTnet.Adapter;
 using MQTTnet.Client.Receiving;
 using MQTTnet.Diagnostics;
+using MQTTnet.Diagnostics.Logger;
 using MQTTnet.Packets;
 
 namespace MQTTnet.Server.Internal
 {
     public sealed class MqttServerEventDispatcher
     {
-        readonly IMqttNetScopedLogger _logger;
+        readonly MqttNetSourceLogger _logger;
 
         public MqttServerEventDispatcher(IMqttNetLogger logger)
         {
             if (logger is null) throw new ArgumentNullException(nameof(logger));
 
-            _logger = logger.CreateScopedLogger(nameof(MqttServerEventDispatcher));
+            _logger = logger.WithSource(nameof(MqttServerEventDispatcher));
         }
 
         public IMqttServerClientConnectedHandler ClientConnectedHandler { get; set; }

Source/MQTTnet/Server/Internal/MqttServerKeepAliveMonitor.cs

@@ -3,6 +3,7 @@ using System.Threading;
 using System.Threading.Tasks;
 using MQTTnet.Client.Disconnecting;
 using MQTTnet.Diagnostics;
+using MQTTnet.Diagnostics.Logger;
 using MQTTnet.Implementations;
 using MQTTnet.Internal;
 
@@ -12,7 +13,7 @@ namespace MQTTnet.Server.Internal
     {
         readonly IMqttServerOptions _options;
         readonly MqttClientSessionsManager _sessionsManager;
-        readonly IMqttNetScopedLogger _logger;
+        readonly MqttNetSourceLogger _logger;
 
         public MqttServerKeepAliveMonitor(IMqttServerOptions options, MqttClientSessionsManager sessionsManager, IMqttNetLogger logger)
         {
@@ -20,7 +21,7 @@ namespace MQTTnet.Server.Internal
             _sessionsManager = sessionsManager ?? throw new ArgumentNullException(nameof(sessionsManager));
             
             if (logger == null) throw new ArgumentNullException(nameof(logger));
-            _logger = logger.CreateScopedLogger(nameof(MqttServerKeepAliveMonitor));
+            _logger = logger.WithSource(nameof(MqttServerKeepAliveMonitor));
         }
 
         public void Start(CancellationToken cancellationToken)

Source/MQTTnet/Server/MqttApplicationMessageInterceptorContext.cs

@@ -1,15 +1,9 @@
 using System.Collections.Generic;
-using MQTTnet.Diagnostics;
 
 namespace MQTTnet.Server
 {
     public sealed class MqttApplicationMessageInterceptorContext
-    {
-        /// <summary>
-        /// Gets the currently used logger.
-        /// </summary>
-        public IMqttNetScopedLogger Logger { get; internal set; }
-
+    { 
         /// <summary>
         /// Gets the client identifier.
         /// Hint: This identifier needs to be unique over all used clients / devices on the broker to avoid connection issues.

Source/MQTTnet/Server/MqttServer.cs

@@ -10,6 +10,7 @@ using System.Collections.Generic;
 using System.Linq;
 using System.Threading;
 using System.Threading.Tasks;
+using MQTTnet.Diagnostics.Logger;
 using MQTTnet.Implementations;
 using MQTTnet.Internal;
 using MQTTnet.Server.Internal;
@@ -21,7 +22,7 @@ namespace MQTTnet.Server
         readonly MqttServerEventDispatcher _eventDispatcher;
         readonly ICollection<IMqttServerAdapter> _adapters;
         readonly IMqttNetLogger _rootLogger;
-        readonly IMqttNetScopedLogger _logger;
+        readonly MqttNetSourceLogger _logger;
 
         MqttClientSessionsManager _clientSessionsManager;
         IMqttRetainedMessagesManager _retainedMessagesManager;
@@ -34,7 +35,7 @@ namespace MQTTnet.Server
             _adapters = adapters.ToList();
 
             if (logger == null) throw new ArgumentNullException(nameof(logger));
-            _logger = logger.CreateScopedLogger(nameof(MqttServer));
+            _logger = logger.WithSource(nameof(MqttServer));
             _rootLogger = logger;
 
             _eventDispatcher = new MqttServerEventDispatcher(logger);

Source/MQTTnet/Server/MqttServerMultiThreadedApplicationMessageInterceptorDelegate.cs

@@ -1,6 +1,5 @@
 using System;
 using System.Threading.Tasks;
-using MQTTnet.Diagnostics;
 using MQTTnet.Implementations;
 using MQTTnet.Internal;
 
@@ -21,6 +20,8 @@ namespace MQTTnet.Server
             };
         }
 
+        public Func<MqttApplicationMessageInterceptorContext, Exception, Task> ExceptionHandler { get; set; }
+
         public MqttServerMultiThreadedApplicationMessageInterceptorDelegate(Func<MqttApplicationMessageInterceptorContext, Task> callback)
         {
             _callback = callback ?? throw new ArgumentNullException(nameof(callback));
@@ -36,7 +37,11 @@ namespace MQTTnet.Server
                 }
                 catch (Exception exception)
                 {
-                    context.Logger.Error(exception, "Error while intercepting application message.");
+                    var exceptionHandler = ExceptionHandler;
+                    if (exceptionHandler != null)
+                    {
+                        await exceptionHandler.Invoke(context, exception).ConfigureAwait(false);
+                    }
                 }
             }).RunInBackground();