A lock for event driven systems.
|Method||acquire||Attempt to acquire the lock. Returns a
|Method||release||Release the lock. If there is a waiting list, then the first
|Method||_cancelAcquire||Remove a deferred d from our waiting list, as the deferred has been canceled.|
Inherited from _ConcurrencyPrimitive:
|Method||run||Acquire, run, release.|
|Method||__aenter__||We can be used as an asynchronous context manager.|
Truewhen this Lock has been acquired, false at all other times. Do not change this value, but it is useful to examine for the equivalent of a "non-blocking" acquisition.
Remove a deferred d from our waiting list, as the deferred has been canceled.
Note: We do not need to wrap this in a try/except to catch d not being in self.waiting because this canceller will not be called if d has fired. release() pops a deferred out of self.waiting and calls it, so the canceller will no longer be called.
|Parameters||d||The deferred that has been canceled.|