c# lock and listen to CancellationToken

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 lik

Answer 1

private object _lockObject = new object();

lock (_lockObject)
{  
   // critical section  
   using (token.Register(() => token.ThrowIfCancellationRequested())
   {
       // Do something that might need cancelling. 
   }
}

Calling Cancel() on a token will result in the ThrowIfCancellationRequested() being invoked as that was what is hooked up to the Register callback. You can put whatever cancellation logic you want in here. This approach is great because you can cancel blocking calls by forcing the conditions that will cause the call to complete.

ThrowIfCancellationRequested throws a OperationCanceledException. You need to handle this on the calling thread or your whole process could be brought down. A simple way of doing this is by starting your task using the Task class which will aggregate all the exceptions up for you to handle on the calling thread.

try
{
   var t = new Task(() => LongRunningMethod());
   t.Start();
   t.Wait();
}
catch (AggregateException ex)
{
   ex.Handle(x => true); // this effectively swallows any exceptions
}

Some good stuff here covering co-operative cancellation