Add MQTTnet debug logging.

Source/MQTTnet.Server/Configuration/SettingsModel.cs

@@ -44,5 +44,7 @@
         /// The settings for retained messages.
         /// </summary>
         public RetainedApplicationMessagesModel RetainedApplicationMessages { get; set; } = new RetainedApplicationMessagesModel();
+
+        public bool EnableDebugLogging { get; set; } = false;
     }
 }

Source/MQTTnet.Server/Logging/MqttNetLoggerWrapper.cs

@@ -23,12 +23,6 @@ namespace MQTTnet.Server.Logging
         public void Publish(MqttNetLogLevel logLevel, string source, string message, object[] parameters, Exception exception)
         {
             var convertedLogLevel = ConvertLogLevel(logLevel);
-
-            if (!_logger.IsEnabled(convertedLogLevel))
-            {
-                return;
-            }
-
             _logger.Log(convertedLogLevel, exception, message, parameters);
         }
 
@@ -39,7 +33,7 @@ namespace MQTTnet.Server.Logging
                 case MqttNetLogLevel.Error: return LogLevel.Error;
                 case MqttNetLogLevel.Warning: return LogLevel.Warning;
                 case MqttNetLogLevel.Info: return LogLevel.Information;
-                case MqttNetLogLevel.Verbose: return LogLevel.Trace;
+                case MqttNetLogLevel.Verbose: return LogLevel.Debug;
             }
 
             return LogLevel.Debug;

Source/MQTTnet.Server/MQTTnet.Server.csproj

@@ -66,6 +66,9 @@
     <None Update="LICENSE">
       <CopyToOutputDirectory>Always</CopyToOutputDirectory>
     </None>
+    <None Update="Run.bat">
+      <CopyToOutputDirectory>Always</CopyToOutputDirectory>
+    </None>
     <None Update="Scripts\readme.md">
       <CopyToOutputDirectory>Always</CopyToOutputDirectory>
     </None>

Source/MQTTnet.Server/Mqtt/CustomMqttFactory.cs

@@ -3,6 +3,7 @@ using System.Collections.Generic;
 using Microsoft.Extensions.Logging;
 using MQTTnet.Adapter;
 using MQTTnet.Diagnostics;
+using MQTTnet.Server.Configuration;
 using MQTTnet.Server.Logging;
 
 namespace MQTTnet.Server.Mqtt
@@ -11,13 +12,28 @@ namespace MQTTnet.Server.Mqtt
     {
         private readonly MqttFactory _mqttFactory;
 
-        public CustomMqttFactory(ILogger<MqttServer> logger)
+        public CustomMqttFactory(SettingsModel settings, ILogger<MqttServer> logger)
         {
+            if (settings == null) throw new ArgumentNullException(nameof(settings));
             if (logger == null) throw new ArgumentNullException(nameof(logger));
+            
+            // It is important to avoid injecting the logger wrapper to ensure that no
+            // unused log messages are generated by the MQTTnet library. Debug logging
+            // has a huge performance impact.
+            if (settings.EnableDebugLogging)
+            {
+                var mqttNetLogger = new MqttNetLoggerWrapper(logger);
+                _mqttFactory = new MqttFactory(mqttNetLogger);
 
-            Logger = new MqttNetLoggerWrapper(logger);
+                logger.LogWarning("Debug logging is enabled. Performance of MQTTnet Server is decreased!");
+            }
+            else
+            {
+                _mqttFactory = new MqttFactory();
+            }
+
+            Logger = _mqttFactory.DefaultLogger;
 
-            _mqttFactory = new MqttFactory(Logger);
         }
         
         public IMqttNetLogger Logger { get; }

Source/MQTTnet.Server/Run.bat

@@ -0,0 +1,2 @@
+@echo off
+START "MQTTnet Server" dotnet .\MQTTnet.Server.dll

Source/MQTTnet.Server/appsettings.json

@@ -43,12 +43,15 @@
         "RetainedApplicationMessages": {
             "Persist": true,
             "Filename": "RetainedApplicationMessages.json",
-            "WriteInterval": 10 // In seconds. 
-        } 
+            "WriteInterval": 10 // In seconds.
+        },
+        "EnableDebugLogging": false
     },
     "Logging": {
         "LogLevel": {
-            "Default": "Warning"
+            "Default": "Debug",
+            "System": "Information",
+            "Microsoft": "Information"
         }
     },
     "AllowedHosts": "*"