This is the async-ready almost-equivalent of the the ReaderWriterLockSlim type, similar to Stephen Toub's AsyncReaderWriterLock. It's only almost equivalent because the ReaderWriterLockSlim supports upgradeable locks and can be constructed in a way which allows reentrancy, and this is not currently possible to do with an async-ready lock.
There are two types of locks that can be taken on an AsyncReaderWriterLock:
- Write locks, which are fully exclusive. They do not allow other locks of any kind.
- Read locks, which permit other read locks but exclude write locks.
Write and read locks may be asynchronously acquired by calling WriterLockAsync or ReaderLockAsync. These locks are released by disposing the result of the returned task.
The tasks returned from WriterLockAsync and ReaderLockAsync will enter the Completed state when they have acquired the AsyncReaderWriterLock. That same task will enter the Canceled state if the CancellationToken is signaled before the wait is satisfied; in that case, the AsyncReaderWriterLock is not taken by that task.
You can call WriterLockAsync and ReaderLockAsync with an already-cancelled CancellationToken to attempt to acquire the AsyncReaderWriterLock immediately without actually entering the wait queue.