c# - Monitor.Enter and Monitor.Exit in different threads

Question

Monitor.Enter and Monitor.Exit are designed to be called from the same thread. But, what if I need to release a lock in a different thread than acquired?

For example: there are shared resource and asynchronous operation that uses this resource. The operation begins with BeginOperation and acquires the lock on the shared resource. There also the EndOperation method that releases the lock. EndOperation is typically called in another thread from a callback, thus I can't call Monitor.Exit in the EndOperation method. What is the best approach in this case? Will double-check locking with AutoResetEvent instead of Monitor be a good solution?

Answer 1

The primitive you're looking for is called a semaphore which can be safely entered on one thread and exited from another.