BufferingTargetWrapper - Avoid Timer starvation when SlidingTimeout =…

… true
NLog · May 28, 2019 · 267d29e · 267d29e
1 parent 458feb4
commit 267d29e
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Showing 2 changed files with 24 additions and 6 deletions.
diff --git a/src/NLog/Common/LogEventInfoBuffer.cs b/src/NLog/Common/LogEventInfoBuffer.cs
@@ -65,10 +65,15 @@ public LogEventInfoBuffer(int size, bool growAsNeeded, int growLimit)
         }
 
         /// <summary>
-        /// Gets the number of items in the array.
+        /// Gets the capacity of the buffer
         /// </summary>
         public int Size => _buffer.Length;
 
+        /// <summary>
+        /// Gets the number of items in the buffer
+        /// </summary>
+        internal int Count { get { lock (_lockObject) return _count; } }
+
         /// <summary>
         /// Adds the specified log event to the buffer.
         /// </summary>

diff --git a/src/NLog/Targets/Wrappers/BufferingTargetWrapper.cs b/src/NLog/Targets/Wrappers/BufferingTargetWrapper.cs
@@ -187,10 +187,7 @@ protected override void CloseTarget()
                 _flushTimer = null;
                 if (currentTimer.WaitForDispose(TimeSpan.FromSeconds(1)))
                 {
-                    lock (_lockObject)
-                    {
-                        WriteEventsInBuffer("Closing Target");
-                    }
+                    WriteEventsInBuffer("Closing Target");
                 }
             }
 
@@ -228,15 +225,24 @@ protected override void Write(AsyncLogEventInfo logEvent)
 
         private void FlushCallback(object state)
         {
+            bool lockTaken = false;
+
             try
             {
-                lock (_lockObject)
+                int timeoutMilliseconds = Math.Min(FlushTimeout / 2, 100);
+                lockTaken = Monitor.TryEnter(_lockObject, timeoutMilliseconds);
+                if (lockTaken)
                 {
                     if (_flushTimer == null)
                         return;
 
                     WriteEventsInBuffer(null);
                 }
+                else
+                {
+                    if (_buffer.Count > 0)
+                        _flushTimer?.Change(FlushTimeout, -1);   // Schedule new retry timer
+                }
             }
             catch (Exception exception)
             {
@@ -247,6 +253,13 @@ private void FlushCallback(object state)
                     throw;  // Throwing exceptions here will crash the entire application (.NET 2.0 behavior)
                 }
             }
+            finally
+            {
+                if (lockTaken)
+                {
+                    Monitor.Exit(_lockObject);
+                }
+            }
         }
 
         private void WriteEventsInBuffer(string reason)