AsyncManualResetEvent WaitAsync method doesn't support a cancelation token about asyncex HOT 4 CLOSED

The asynchronous methods only take a CT if the CT has a semantic meaning to the synchronization primitive (i.e., the state would change as a result of the method executing). In a MRE, the "Wait" operation does not change any state.

In other words, for a AMRE.WaitAsync(CT), the CT would only cancel the await, not have any affect on the AMRE.

You can cancel any await using ToCancellationTokenTaskSource, and adding CT support to WaitAsync would just wrap that anyway.

Contrast this with the Auto-Reset Event. For that type, the "Wait" operation does change the event state, so proper CT support is necessary.

That said, this has been a source of confusion for people, and I'm considering adding CT support even when the semantics are only to cancel the awaits, in a future .NET Core version.

from asyncex.

Thanks for this info, I took a look at ToCancellationTokenTaskSource but I didn't find any tests / examples of this. I'm guessing you were doing a continue with on the ToCancellationTokenTaskSource??

from asyncex.

You can use it like this:

async Task WaitAsync(Task operation, CancellationToken token)
{
  using (var ctSource = token.ToCancellationTokenTaskSource())
  {
    await await Task.WhenAny(operation, ctSource.Task);
  }
}

from asyncex.

Thanks! :)

from asyncex.