fix: prevent BackgroundFileTraceListener from queuing events infinitely when failing to write to file by adding a MaxQueueSize setting defaulted to 10000

Author: cruikshj

SMLogging/BackgroundFileTraceListener.cs

@@ -4,6 +4,7 @@
 using System.Diagnostics;
 using System.Threading;
 using System.Threading.Tasks;
+using SMLogging.Properties;
 
 namespace SMLogging
 {
@@ -24,8 +25,7 @@ public BackgroundFileTraceListener(string path)
         {
             FlushInterval = 5000;
             MaxFlushSize = 1000;
-
-            _queue = new ConcurrentQueue<Event>();
+            MaxQueueSize = 10000;
         }
 
         /// <summary>
@@ -38,8 +38,7 @@ public BackgroundFileTraceListener(string path, string name)
         {
             FlushInterval = 5000;
             MaxFlushSize = 1000;
-
-            _queue = new ConcurrentQueue<Event>();
+            MaxQueueSize = 10000;
         }
 
         #endregion
@@ -67,6 +66,15 @@ public BackgroundFileTraceListener(string path, string name)
         [ConfigurationProperty("maxFlushSize")]
         public int MaxFlushSize { get; set; }
 
+        /// <summary>
+        /// Gets or sets the maximum size of the queue.
+        /// </summary>
+        /// <remarks>
+        /// This value specifies the maximum number of events to queue. The default value is 10000.
+        /// </remarks>
+        [ConfigurationProperty("maxQueueSize")]
+        public int MaxQueueSize { get; set; }
+
         #endregion
 
         #region Protected Properties
@@ -133,7 +141,7 @@ public override void Flush()
                 {
                     foreach (var evt in events)
                     {
-                        _queue.Enqueue(evt);
+                        EnqueueEvent(evt, false);
                     }
                 }
             }
@@ -181,14 +189,38 @@ private void EnqueueEvent(TraceEventCache eventCache, string source, TraceEventT
                 Message = message
             };
 
-            _queue.Enqueue(evt);
+            EnqueueEvent(evt, true);
 
             if (FlushInterval >= 0 && !Trace.AutoFlush && !IsBackgroundFlushing)
             {
                 StartBackgroundFlushing();
             }
         }
 
+        private void EnqueueEvent(Event evt, bool force)
+        {
+            if (_queue.Count >= MaxQueueSize)
+            {
+                if (force)
+                {
+                    Event oldEvt;
+                    _queue.TryDequeue(out oldEvt);
+                    _queue.Enqueue(evt);
+                }
+
+                if (!_maxQueueSizeReached)
+                {
+                    _maxQueueSizeReached = true;
+                    Fail(AssemblyResources.MaxQueueSizeReached);
+                }
+            }
+            else
+            {
+                _queue.Enqueue(evt);
+                _maxQueueSizeReached = false;
+            }
+        }
+
         private void StartBackgroundFlushing()
         {
             lock (_workerLock)
@@ -231,9 +263,10 @@ private void StopBackgroundFlushing()
 
         #region Private Fields
 
-        private readonly ConcurrentQueue<Event> _queue;
+        private readonly ConcurrentQueue<Event> _queue = new ConcurrentQueue<Event>();
         private CancellationTokenSource _workerCts;
         private static readonly object _workerLock = new object();
+        private bool _maxQueueSizeReached = false;
 
         #endregion
 

SMLogging/Properties/AssemblyResources.Designer.cs

@@ -132,6 +132,9 @@
   <data name="LogicalOperationStackTraceToken" xml:space="preserve">
     <value>LogicalOperationStack={0}</value>
   </data>
+  <data name="MaxQueueSizeReached" xml:space="preserve">
+    <value>Max queue size reached. Events are being dropped.</value>
+  </data>
   <data name="MissingRequiredAttribute" xml:space="preserve">
     <value>The required attribute '{0}' is missing.</value>
   </data>

SMLogging/Properties/AssemblyResources.resx

@@ -86,6 +86,7 @@
     <EmbeddedResource Include="Properties\AssemblyResources.resx">
       <Generator>ResXFileCodeGenerator</Generator>
       <LastGenOutput>AssemblyResources.Designer.cs</LastGenOutput>
+      <SubType>Designer</SubType>
     </EmbeddedResource>
   </ItemGroup>
   <ItemGroup>