Question

I want to use lock or a similar synchronization to protect a critical section. At the same time I want to listen to a CancellationToken.

Right now I’m using a mutex like this, but mutex doesn’t have as good performance. Can I use any of other synchronization classes (including the new .Net 4.0) instead of the mutex?

WaitHandle.WaitAny(new[] { CancelToken.WaitHandle, _mutex});
CancelToken.ThrowIfCancellationRequested();

Answer 1

Take a look at the new .NET 4.0 Framework feature SemaphoreSlim Class. It provides SemaphoreSlim.Wait(CancellationToken) method.

Blocks the current thread until it can enter the SemaphoreSlim, while
observing a CancellationToken

From some point of view using Semaphore in such simple case could be an overhead because initially it was designed to provide an access for multiple threads, but perhaps you might find it useful.

EDIT: The code snippet

CancellationToken token = new CancellationToken();            
SemaphoreSlim semaphore = new SemaphoreSlim(1,1);
bool tokenCanceled = false;

try {
   try {
      // block section entrance for other threads
      semaphore.Wait(token);
   }
   catch (OperationCanceledException) {
      // The token was canceled and the semaphore was NOT entered...
      tokenCanceled = true;
   }
   // critical section code
   // ...
   if (token.IsCancellationRequested)
   {
       // ...
   }
}
finally { 
   if (!tokenCanceled)
      semaphore.Release();
}