Updates async logging to a newer format

src/Umbraco.Core/Logging/AsyncForwardingAppenderBase.cs

@@ -0,0 +1,105 @@
+using System;
+using log4net.Appender;
+using log4net.Core;
+using log4net.Util;
+
+namespace Umbraco.Core.Logging
+{
+    /// <remarks>
+    /// Based on https://github.com/cjbhaines/Log4Net.Async
+    /// </remarks>
+    public abstract class AsyncForwardingAppenderBase : ForwardingAppender
+    {
+        #region Private Members
+
+        private const FixFlags DefaultFixFlags = FixFlags.Partial;
+        private FixFlags _fixFlags = DefaultFixFlags;
+        private LoggingEventHelper _loggingEventHelper;
+
+        #endregion Private Members
+
+        #region Properties
+
+        public FixFlags Fix
+        {
+            get { return _fixFlags; }
+            set { SetFixFlags(value); }
+        }
+
+        /// <summary>
+        /// The logger name that will be used for logging internal errors.
+        /// </summary>
+        protected abstract string InternalLoggerName { get; }
+
+        public abstract int? BufferSize { get; set; }
+
+        #endregion Properties
+
+        public override void ActivateOptions()
+        {
+            base.ActivateOptions();
+            _loggingEventHelper = new LoggingEventHelper(InternalLoggerName, DefaultFixFlags);
+            InitializeAppenders();
+        }
+
+        #region Appender Management
+
+        public override void AddAppender(IAppender newAppender)
+        {
+            base.AddAppender(newAppender);
+            SetAppenderFixFlags(newAppender);
+        }
+
+        private void SetFixFlags(FixFlags newFixFlags)
+        {
+            if (newFixFlags != _fixFlags)
+            {
+                _loggingEventHelper.Fix = newFixFlags;
+                _fixFlags = newFixFlags;
+                InitializeAppenders();
+            }
+        }
+
+        private void InitializeAppenders()
+        {
+            foreach (var appender in Appenders)
+            {
+                SetAppenderFixFlags(appender);
+            }
+        }
+
+        private void SetAppenderFixFlags(IAppender appender)
+        {
+            var bufferingAppender = appender as BufferingAppenderSkeleton;
+            if (bufferingAppender != null)
+            {
+                bufferingAppender.Fix = Fix;
+            }
+        }
+
+        #endregion Appender Management
+
+        #region Forwarding
+
+        protected void ForwardInternalError(string message, Exception exception, Type thisType)
+        {
+            LogLog.Error(thisType, message, exception);
+            var loggingEvent = _loggingEventHelper.CreateLoggingEvent(Level.Error, message, exception);
+            ForwardLoggingEvent(loggingEvent, thisType);
+        }
+
+        protected void ForwardLoggingEvent(LoggingEvent loggingEvent, Type thisType)
+        {
+            try
+            {
+                base.Append(loggingEvent);
+            }
+            catch (Exception exception)
+            {
+                LogLog.Error(thisType, "Unable to forward logging event", exception);
+            }
+        }
+
+        #endregion Forwarding
+    }
+}