Check value of AutoResetEvent without affecting event

Question

I'm creating some "instrumentation" inside a multi-threaded server in .NET (C#).

It's fairly easy to check the value of a .NET ManualResetEvent without concern for changing the value:

aManualResetEvent.WaitOne( 0 );

returns a boolean without waiting on the event.

However, I seem to be at a loss for getting the same information from an AutoResetEvent; if you call anAutoResetEvent.WaitOne( 0 ) on a set event, it will reset the event while returning (by definition).

The best option I can determine at this point is to change the AutoResetEvent to a ManualResetEvent and manually reset when actually testing the event:

ManualResetEvent theEventFormerlyKnownAsAutoResetEvent;
...


// Using the event:
if ( theEventFormerlyKnownAsAutoResetEvent.WaitOne( timeout )
{
    theEventFormerlyKnownAsAutoResetEvent.Reset();
    ...
}
...

// Instrumentation to get event state (shouldn't change anything):
bool eventIsSet = theEventFormerlyKnownAsAutoResetEvent.WaitOne( 0 );
// Update instrumentation

Is there a better way of checking the state of an AutoResetEvent? I would prefer the intrinsic atomicity of the AutoResetEvent if possible.

Answer 1

The point of AutoResetEvent is to release one and only one waiting thread when the event transitions to a signalled state. If you used the signalled state to do something specific in one thread, you risk getting into a race condition or a deadlock between threads if another thread can still wait on the event's signal--one of the reasons for using AutoResetEvent.

If you provide more detail about what you're trying to accomplish, maybe someone can provide an alternative that would help.