twisted.internet.task

module documentation

(source)

Scheduling utility methods and classes.

Class	`Clock`	Provide a deterministic, easily-controlled implementation of `IReactorTime.callLater`. This is commonly useful for writing deterministic unit tests for code which schedules events using this API.
Class	`CooperativeTask`	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.
Class	`Cooperator`	Cooperative task scheduler.
Class	`LoopingCall`	Call a function repeatedly.
Class	`NotPaused`	This exception is raised when a task is resumed which was not previously paused.
Class	`SchedulerError`	No summary
Class	`SchedulerStopped`	The operation could not complete because the scheduler was stopped in progress or was already stopped.
Class	`TaskDone`	The operation could not complete because the task was already completed.
Class	`TaskFailed`	The operation could not complete because the task died with an unhandled error.
Class	`TaskFinished`	The operation could not complete because the task was already completed, stopped, encountered an error or otherwise permanently stopped running.
Class	`TaskStopped`	The operation could not complete because the task was stopped.
Function	`coiterate`	Cooperatively iterate over the given iterator, dividing runtime between it and all other iterators which have been passed to this function and not yet exhausted.
Function	`cooperate`	Start running the given iterator as a long-running cooperative task, by calling next() on it as a periodic timed event.
Function	`deferLater`	Call the given function after a certain period of time has passed.
Function	`react`	Call `main` and run the reactor until the `Deferred` it returns fires or the coroutine it returns completes.
Class	`_Timer`	Undocumented
Function	`_defaultScheduler`	Undocumented
Constant	`_EPSILON`	Undocumented
Variable	`_theCooperator`	Undocumented

def coiterate(iterator): (source)

Cooperatively iterate over the given iterator, dividing runtime between it and all other iterators which have been passed to this function and not yet exhausted.

Parameters
iterator	the iterator to invoke.
Returns
a Deferred that will fire when the iterator finishes.

def cooperate(iterator): (source)

Start running the given iterator as a long-running cooperative task, by calling next() on it as a periodic timed event.

This is very useful if you have computationally expensive tasks that you want to run without blocking the reactor. Just break each task up so that it yields frequently, pass it in here and the global Cooperator will make sure work is distributed between them without blocking longer than a single iteration of a single task.

Parameters
iterator	the iterator to invoke.
Returns
a `CooperativeTask` object representing this task.

def deferLater(clock, delay, callable=None, *args, **kw): (source)

Call the given function after a certain period of time has passed.

Parameters
clock:`IReactorTime` provider	The object which will be used to schedule the delayed call.
delay:`float` or `int`	The number of seconds to wait before calling the function.
callable	The object to call after the delay.
*args	The positional arguments to pass to `callable`.
**kw	The keyword arguments to pass to `callable`.
Returns
`defer.Deferred`	A deferred that fires with the result of the callable when the specified time has elapsed.

def react(main, argv=(), _reactor=None): (source)

Call main and run the reactor until the Deferred it returns fires or the coroutine it returns completes.

This is intended as the way to start up an application with a well-defined completion condition. Use it to write clients or one-off asynchronous operations. Prefer this to calling reactor.run directly, as this function will also:

Take care to call reactor.stop once and only once, and at the right time.
Log any failures from the Deferred returned by main.
Exit the application when done, with exit code 0 in case of success and 1 in case of failure. If main fails with a SystemExit error, the code returned is used.

The following demonstrates the signature of a main function which can be used with react:

      async def main(reactor, username, password):
          return "ok"

      task.react(main, ("alice", "secret"))

Parameters
main	A callable which returns a `Deferred` or coroutine. It should take the reactor as its first parameter, followed by the elements of `argv`.
argv	A list of arguments to pass to `main`. If omitted the callable will be invoked with no additional arguments.
_reactor	An implementation detail to allow easier unit testing. Do not supply this parameter.
Present Since
12.3

def _defaultScheduler(x): (source)

Undocumented

_EPSILON: float = (source)

Undocumented

Value

1e-08

_theCooperator = (source)

Undocumented