twisted.internet.defer.DeferredQueue : API documentation

An event driven queue.

Objects may be added as usual to this queue. When an attempt is made to retrieve an object when the queue is empty, a Deferred is returned which will fire when an object becomes available.

Instance Variable	size	The maximum number of objects to allow into the queue at a time. When an attempt to add a new object would exceed this limit, `QueueOverflow` is raised synchronously. `None` for no limit.
Instance Variable	backlog	The maximum number of `Deferred` gets to allow at one time. When an attempt is made to get an object which would exceed this limit, `QueueUnderflow` is raised synchronously. `None` for no limit.
Method	__init__	Undocumented
Method	put	Add an object to this queue.
Method	get	Attempt to retrieve and remove an object from the queue.
Method	_cancelGet	Remove a deferred d from our waiting list, as the deferred has been canceled.

size =

The maximum number of objects to allow into the queue at a time. When an attempt to add a new object would exceed this limit, QueueOverflow is raised synchronously. None for no limit.

backlog =

The maximum number of Deferred gets to allow at one time. When an attempt is made to get an object which would exceed this limit, QueueUnderflow is raised synchronously. None for no limit.

def _cancelGet(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. put() 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 get(self): (source)

Attempt to retrieve and remove an object from the queue.

Returns	a `Deferred` which fires with the next object available in the queue.
Raises	QueueUnderflow	Too many (more than `backlog`) `Deferred`s are already waiting for an object from this queue.

t.i.d.DeferredQueue(object) : class documentation