twisted.internet.defer.DeferredList

class documentation

class DeferredList(Deferred): (source)

DeferredList is a tool for collecting the results of several Deferreds.

This tracks a list of Deferreds for their results, and makes a single callback when they have all completed. By default, the ultimate result is a list of (success, result) tuples, 'success' being a boolean. DeferredList exposes the same API that Deferred does, so callbacks and errbacks can be added to it in the same way.

DeferredList is implemented by adding callbacks and errbacks to each Deferred in the list passed to it. This means callbacks and errbacks added to the Deferreds before they are passed to DeferredList will change the result that DeferredList sees (i.e., DeferredList is not special). Callbacks and errbacks can also be added to the Deferreds after they are passed to DeferredList and DeferredList may change the result that they see.

See the documentation for the __init__ arguments for more information.

Method	`__init__`	Initialize a DeferredList.
Method	`cancel`	Cancel this `DeferredList`.
Instance Variable	`consumeErrors`	Undocumented
Instance Variable	`finishedCount`	Undocumented
Instance Variable	`fireOnOneCallback`	Undocumented
Instance Variable	`fireOnOneErrback`	Undocumented
Instance Variable	`resultList`	Undocumented
Method	`_cbDeferred`	(internal) Callback for when one of my deferreds fires.
Instance Variable	`_deferredList`	The `list` of `Deferred`s to track.

Inherited from Deferred:

Class Method	`fromCoroutine`	Schedule the execution of a coroutine that awaits on `Deferred`s, wrapping it in a `Deferred` that will fire on success/failure of the coroutine.
Class Method	`fromFuture`	Adapt an `asyncio.Future` to a `Deferred`.
Method	`__iter__`	Undocumented
Method	`__str__`	Return a string representation of this `Deferred`.
Method	`addBoth`	Convenience method for adding a single callable as both a callback and an errback.
Method	`addCallback`	Convenience method for adding just a callback.
Method	`addCallbacks`	Add a pair of callbacks (success and error) to this `Deferred`.
Method	`addErrback`	Convenience method for adding just an errback.
Method	`addTimeout`	Time out this `Deferred` by scheduling it to be cancelled after `timeout` seconds.
Method	`asFuture`	Adapt this `Deferred` into a `asyncio.Future` which is bound to `loop`.
Method	`callback`	Run all success callbacks that have been added to this `Deferred`.
Method	`chainDeferred`	Chain another `Deferred` to this `Deferred`.
Method	`errback`	Run all error callbacks that have been added to this `Deferred`.
Method	`pause`	Stop processing on a `Deferred` until `unpause`() is called.
Method	`send`	Undocumented
Method	`unpause`	Process all callbacks made since `pause`() was called.
Class Variable	`debug`	Undocumented
Instance Variable	`callbacks`	Undocumented
Instance Variable	`called`	A flag which is `False` until either `callback` or `errback` is called and afterwards always `True`.
Instance Variable	`paused`	A counter of how many unmatched `pause` calls have been made on this instance.
Instance Variable	`result`	Undocumented
Method	`_continuation`	Build a tuple of callback and errback with `_CONTINUE`.
Method	`_runCallbacks`	Run the chain of callbacks once a result is available.
Method	`_startRunCallbacks`	Undocumented
Instance Variable	`_canceller`	Undocumented
Instance Variable	`_chainedTo`	If this `Deferred` is waiting for the result of another `Deferred`, this is a reference to the other Deferred. Otherwise, `None`.
Instance Variable	`_debugInfo`	Undocumented
Instance Variable	`_runningCallbacks`	A flag which is `True` while this instance is executing its callback chain, used to stop recursive execution of `_runCallbacks`
Instance Variable	`_suppressAlreadyCalled`	A flag used by the cancellation mechanism which is `True` if the Deferred has no canceller and has been cancelled, `False` otherwise. If `True`, it can be expected that `callback` or `errback` will eventually be called and the result should be silently discarded.

def __init__(self, deferredList, fireOnOneCallback=False, fireOnOneErrback=False, consumeErrors=False): (source)

overrides twisted.internet.defer.Deferred.__init__

Initialize a DeferredList.

Parameters
deferredList:`list` of `Deferred`s	The list of deferreds to track.
fireOnOneCallback:`bool`	(keyword param) a flag indicating that this `DeferredList` will fire when the first `Deferred` in `deferredList` fires with a non-failure result without waiting for any of the other Deferreds. When this flag is set, the DeferredList will fire with a two-tuple: the first element is the result of the Deferred which fired; the second element is the index in `deferredList` of that Deferred.
fireOnOneErrback:`bool`	(keyword param) a flag indicating that this `DeferredList` will fire when the first `Deferred` in `deferredList` fires with a failure result without waiting for any of the other Deferreds. When this flag is set, if a Deferred in the list errbacks, the DeferredList will errback with a `FirstError` failure wrapping the failure of that Deferred.
consumeErrors:`bool`	(keyword param) a flag indicating that failures in any of the included `Deferred`s should not be propagated to errbacks added to the individual `Deferred`s after this `DeferredList` is constructed. After constructing the `DeferredList`, any errors in the individual `Deferred`s will be converted to a callback result of `None`. This is useful to prevent spurious 'Unhandled error in Deferred' messages from being logged. This does not prevent `fireOnOneErrback` from working.

def cancel(self): (source)

overrides twisted.internet.defer.Deferred.cancel

Cancel this DeferredList.

If the DeferredList hasn't fired yet, cancel every Deferred in the list.

If the DeferredList has fired, including the case where the fireOnOneCallback/fireOnOneErrback flag is set and the DeferredList fires because one Deferred in the list fires with a non-failure/failure result, do nothing in the cancel method.

consumeErrors = (source)

Undocumented

finishedCount: int = (source)

Undocumented

fireOnOneCallback = (source)

Undocumented

fireOnOneErrback = (source)

Undocumented

resultList = (source)

Undocumented

def _cbDeferred(self, result, index, succeeded): (source)

(internal) Callback for when one of my deferreds fires.

_deferredList = (source)

The list of Deferreds to track.