Improved re-entrancy Scope Lock for Session Value Layout Render

src/Shared/Internal/RendererReEntrantManager.cs

@@ -17,19 +17,39 @@ namespace NLog.Web.Internal
     /// Since NET 35 does not support AsyncLocal or even ThreadLocal
     /// a different technique must be used for that platform
     /// </summary>
-    internal struct RendererReEntrantManager : IDisposable
+    internal readonly struct RendererReEntrantManager : IDisposable
     {
         internal RendererReEntrantManager(HttpContextBase context)
         {
             _httpContext = context;
+
+            // The line below is required, because this is a struct, otherwise we get CS0188 compiler error
+            // which is 'The 'this' object cannot be used before all of its fields have been assigned.'
             _obtainedLock = false;
-            TryGetLock();
+
+            _obtainedLock = TryGetLock();
         }
 
         private readonly HttpContextBase _httpContext;
 
+        // Need to track if we were successful in the lock
+        // If we were not, we should not unlock in the dispose code
+        private readonly bool _obtainedLock;
+
         internal bool IsLockAcquired => _obtainedLock;
 
+        private bool TryGetLock()
+        {
+            // If already locked, return false
+            if (IsLocked())
+            {
+                return false;
+            }
+            // Get the lock
+            Lock();
+            return true;
+        }
+
 #if NET35
         private static readonly object ReEntrantLock = new object();
 
@@ -66,24 +86,6 @@ private void Unlock()
         }
 #endif
 
-        // Need to track if we were successful in the lock
-        // If we were not, we should not unlock in the dispose code
-        private bool _obtainedLock;
-
-
-        private void TryGetLock()
-        {
-            // If already locked, return false
-            if (IsLocked())
-            {
-                return;
-            }
-            // Get the lock
-            Lock();
-            // Mark that we locked it, not another instance locked it
-            _obtainedLock = true;
-        }
-
         private void DisposalImpl()
         {
             // Only unlock if we were the ones who locked it

src/Shared/LayoutRenderers/AspNetSessionValueLayoutRenderer.cs

@@ -104,8 +104,8 @@ protected override void DoAppend(StringBuilder builder, LogEventInfo logEvent)
             {
                 if (!reEntry.IsLockAcquired)
                 {
-                    InternalLogger.Error(
-                        $"Reentrant log event detected. Logging when inside the scope of another log event can cause a StackOverflowException. LogEventInfo.Message:{logEvent.Message}");
+                    InternalLogger.Debug(
+                        $"Reentrant log event detected. Logging when inside the scope of another log event can cause a StackOverflowException.");
                     return;
                 }