twisted.internet.defer.DeferredLock : API documentation

Instance Variable	locked	`True` when 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.
Method	acquire	Attempt to acquire the lock. Returns a `Deferred` that fires on lock acquisition with the `DeferredLock` as the value. If the lock is locked, then the Deferred is placed at the end of a waiting list.
Method	release	Release the lock. If there is a waiting list, then the first `Deferred` in that waiting list will be called back.
Method	_cancelAcquire	Remove a deferred d from our waiting list, as the deferred has been canceled.

Inherited from _ConcurrencyPrimitive:

Method	__init__	Undocumented
Instance Variable	waiting	Undocumented
Method	run	Acquire, run, release.
Method	__aenter__	We can be used as an asynchronous context manager.
Method	__aexit__	Undocumented
Method	_releaseAndReturn	Undocumented

locked =

True when 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.

(type: bool)

def _cancelAcquire(self, d): (source)

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.

def acquire(self): (source)

Attempt to acquire the lock. Returns a Deferred that fires on lock acquisition with the DeferredLock as the value. If the lock is locked, then the Deferred is placed at the end of a waiting list.

Returns a Deferred which fires on lock acquisition. (type: a Deferred)

def release(self): (source)

Release the lock. If there is a waiting list, then the first Deferred in that waiting list will be called back.

Should be called by whomever did the acquire() when the shared resource is free.

twisted.internet.defer.DeferredLock(_ConcurrencyPrimitive) class documentation

`twisted.internet.defer.DeferredLock(_ConcurrencyPrimitive)` class documentation