WaitHandles: Possible race condition in InternalWaitOneAsync() #120

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1. madelson

   added this to the 2.3.1 milestone on Jul 6, 2022
2. madelson commented on Jul 8, 2022

   

   madelson

   on Jul 8, 2022

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   Reproduction:

   [Test]
           public async Task TestCancellationDoesNotLeadToLostSignal([Values] bool async)
           {
               var semaphore = new WaitHandleDistributedSemaphore(nameof(this.TestCancellationDoesNotLeadToLostSignal), 2);
               await using var _ = await semaphore.AcquireAsync(TimeSpan.FromSeconds(1));
   
               for (var i = 0; i < 50; ++i)
               {
                   using var barrier = new Barrier(2);
                   using var source = new CancellationTokenSource();
                   var acquireTask = Task.Run(async () =>
                   {
                       barrier.SignalAndWait();
                       try
                       { 
                           if (async) { await using var _ = await semaphore.AcquireAsync(cancellationToken: source.Token); }
                           else { using var _ = semaphore.Acquire(cancellationToken: source.Token); }
                       }
                       catch when (source.Token.IsCancellationRequested) { }
                   });
                   var cancelTask = Task.Run(() =>
                   {
                       barrier.SignalAndWait();
                       source.Cancel();
                   });
                   await Task.WhenAll(acquireTask, cancelTask);
               }
   
               await using var handle = await semaphore.TryAcquireAsync();
               Assert.IsNotNull(handle); // if we lost even a single signal due to cancellation in the loop above, this will fail
           }
3. madelson

   added 2 commits that reference this issue on Jul 8, 2022

   Resignal waitHandle if we choose to ignore its signal due to cancella…

   ...

   This issue will close once commit 4c42a79 is merged into the 'master' branch.

   4c42a79

   Further race condition handling for #120

   This issue will close once commit f4a3401 is merged into the 'master' branch.

   f4a3401
4. madelson

   closed this as completedin 4c42a79on Jul 9, 2022