only consider cancellation if it doesn't complete synchronously

StackExchange · Nov 5, 2020 · e1e7189 · e1e7189
1 parent 3d43209
commit e1e7189
Showing 1 changed file with 12 additions and 5 deletions.
diff --git a/src/StackExchange.Redis/PhysicalConnection.cs b/src/StackExchange.Redis/PhysicalConnection.cs
@@ -269,6 +269,7 @@ public void Dispose()
             }
             OnCloseEcho();
             _arena.Dispose();
+            _reusableFlushSyncTokenSource?.Dispose();
             GC.SuppressFinalize(this);
         }
 
@@ -872,15 +873,17 @@ private async ValueTask<WriteResult> FlushAsync_Awaited(PhysicalConnection conne
             }
         }
 
+        CancellationTokenSource _reusableFlushSyncTokenSource;
         [Obsolete("this is an anti-pattern; work to reduce reliance on this is in progress")]
         internal WriteResult FlushSync(bool throwOnFailure, int millisecondsTimeout)
         {
-            using (var source = new CancellationTokenSource())
-            {
-                source.CancelAfter(TimeSpan.FromMilliseconds(millisecondsTimeout));
-                var flush = FlushAsync(throwOnFailure, source.Token);
+            var cts = _reusableFlushSyncTokenSource ??= new CancellationTokenSource();
+            var flush = FlushAsync(throwOnFailure, cts.Token);
             if (!flush.IsCompletedSuccessfully)
             {
+                // only schedule cancellation if it doesn't complete synchronously; at this point, it is doomed
+                _reusableFlushSyncTokenSource = null;
+                cts.CancelAfter(TimeSpan.FromMilliseconds(millisecondsTimeout));
                 try
                 {
                     // here lies the evil
@@ -894,9 +897,13 @@ internal WriteResult FlushSync(bool throwOnFailure, int millisecondsTimeout)
                     }
                     throw;
                 }
+                finally
+                {
+                    cts.Dispose();
+                }
             }
             return flush.Result;
-            }
+
             void ThrowTimeout()
             {
 #if DEBUG