twisted.internet.task.CooperativeTask

class documentation

class CooperativeTask: (source)

A CooperativeTask is a task object inside a Cooperator, which can be paused, resumed, and stopped. It can also have its completion (or termination) monitored.

See Also
`Cooperator.cooperate`

Method	`__init__`	A private constructor: to create a new `CooperativeTask`, see `Cooperator.cooperate`.
Method	`pause`	No summary
Method	`resume`	Resume processing of a paused `CooperativeTask`.
Method	`stop`	Stop further processing of this task.
Method	`whenDone`	Get a `defer.Deferred` notification of when this task is complete.
Method	`_checkFinish`	If this task has been stopped, raise the appropriate subclass of `TaskFinished`.
Method	`_completeWith`
Method	`_oneWorkUnit`	Perform one unit of work for this task, retrieving one item from its iterator, stopping if there are no further items in the iterator, and pausing if the result was a `defer.Deferred`.
Instance Variable	`_completionResult`	Undocumented
Instance Variable	`_completionState`	The completion-state of this `CooperativeTask`. `None` if the task is not yet completed, an instance of `TaskStopped` if `stop` was called to stop this task early, of `TaskFailed` if the application code in the iterator raised an exception which caused it to terminate, and of `TaskDone` if it terminated normally via raising `StopIteration`.
Instance Variable	`_cooperator`	the `Cooperator` that this `CooperativeTask` participates in, which is used to re-insert it upon resume.
Instance Variable	`_deferreds`	the list of `defer.Deferred`s to fire when this task completes, fails, or finishes.
Instance Variable	`_iterator`	the iterator to iterate when this `CooperativeTask` is asked to do work.
Instance Variable	`_pauseCount`	the number of times that this `CooperativeTask` has been paused; if 0, it is running.

def __init__(self, iterator, cooperator): (source)

A private constructor: to create a new CooperativeTask, see Cooperator.cooperate.

def pause(self): (source)

Pause this CooperativeTask. Stop doing work until CooperativeTask.resume is called. If pause is called more than once, resume must be called an equal number of times to resume this task.

Raises
`TaskFinished`	if this task has already finished or completed.

def resume(self): (source)

Resume processing of a paused CooperativeTask.

Raises
`NotPaused`	if this `CooperativeTask` is not paused.

def stop(self): (source)

Stop further processing of this task.

Raises
`TaskFinished`	if this `CooperativeTask` has previously completed, via `stop`, completion, or failure.

def whenDone(self): (source)

Get a defer.Deferred notification of when this task is complete.

Returns
`defer.Deferred`	a `defer.Deferred` that fires with the `iterator` that this `CooperativeTask` was created with when the iterator has been exhausted (i.e. its `next` method has raised `StopIteration`), or fails with the exception raised by `next` if it raises some other exception.

def _checkFinish(self): (source)

If this task has been stopped, raise the appropriate subclass of TaskFinished.

def _completeWith(self, completionState, deferredResult): (source)

Parameters
completionState	a `TaskFinished` exception or a subclass thereof, indicating what exception should be raised when subsequent operations are performed.
deferredResult	the result to fire all the deferreds with.

def _oneWorkUnit(self): (source)

Perform one unit of work for this task, retrieving one item from its iterator, stopping if there are no further items in the iterator, and pausing if the result was a defer.Deferred.

_completionResult = (source)

Undocumented

_completionState: TaskFinished = (source)

The completion-state of this CooperativeTask. None if the task is not yet completed, an instance of TaskStopped if stop was called to stop this task early, of TaskFailed if the application code in the iterator raised an exception which caused it to terminate, and of TaskDone if it terminated normally via raising StopIteration.

_cooperator: Cooperator = (source)

the Cooperator that this CooperativeTask participates in, which is used to re-insert it upon resume.

_deferreds: list = (source)

the list of defer.Deferreds to fire when this task completes, fails, or finishes.

_iterator = (source)

the iterator to iterate when this CooperativeTask is asked to do work.

_pauseCount: int = (source)

the number of times that this CooperativeTask has been paused; if 0, it is running.