+
+

scheduling#

+

Generic python scheduler.

+
+
+class Scheduler(name)[source]#
+

Bases: object

+

Schedule the execution of coroutines and keep track of them.

+

When instantiating a Scheduler, a name must be provided. This name is used to distinguish the +instance’s log messages from other instances. Using the name of the class or module containing +the instance is suggested.

+

Coroutines can be scheduled immediately with schedule or in the future with schedule_at +or schedule_later. A unique ID is required to be given in order to keep track of the +resulting Tasks. Any scheduled task can be cancelled prematurely using cancel by providing +the same ID used to schedule it.

+

The in operator is supported for checking if a task with a given ID is currently scheduled.

+

Any exception raised in a scheduled task is logged when the task is done.

+
+
+__contains__(task_id)[source]#
+

Return True if a task with the given task_id is currently scheduled.

+
+
Parameters:
+

task_id (Hashable) – The task to look for.

+
+
Return type:
+

bool

+
+
Returns:
+

True if the task was found.

+
+
+
+ +
+
+__init__(name)[source]#
+

Initialize a new Scheduler instance.

+
+
Parameters:
+

name (str) – The name of the Scheduler. Used in logging, and namespacing.

+
+
+
+ +
+
+cancel(task_id)[source]#
+

Unschedule the task identified by task_id. Log a warning if the task doesn’t exist.

+
+
Parameters:
+

task_id (Hashable) – The task’s unique ID.

+
+
Return type:
+

None

+
+
+
+ +
+
+cancel_all()[source]#
+

Unschedule all known tasks.

+
+
Return type:
+

None

+
+
+
+ +
+
+schedule(task_id, coroutine)[source]#
+

Schedule the execution of a coroutine.

+

If a task with task_id already exists, close coroutine instead of scheduling it. This +prevents unawaited coroutine warnings. Don’t pass a coroutine that’ll be re-used elsewhere.

+
+
Parameters:
+
    +

  • task_id (Hashable) – A unique ID to create the task with.

    • +

  • coroutine (Coroutine) – The function to be called.

    • +
+
+
Return type:
+

None

+
+
+
+ +
+
+schedule_at(time, task_id, coroutine)[source]#
+

Schedule coroutine to be executed at the given time.

+

If time is timezone aware, then use that timezone to calculate now() when subtracting. +If time is naïve, then use UTC.

+

If time is in the past, schedule coroutine immediately.

+

If a task with task_id already exists, close coroutine instead of scheduling it. This +prevents unawaited coroutine warnings. Don’t pass a coroutine that’ll be re-used elsewhere.

+
+
Parameters:
+
    +

  • time (datetime) – The time to start the task.

    • +

  • task_id (Hashable) – A unique ID to create the task with.

    • +

  • coroutine (Coroutine) – The function to be called.

    • +
+
+
Return type:
+

None

+
+
+
+ +
+
+schedule_later(delay, task_id, coroutine)[source]#
+

Schedule coroutine to be executed after delay seconds.

+

If a task with task_id already exists, close coroutine instead of scheduling it. This +prevents unawaited coroutine warnings. Don’t pass a coroutine that’ll be re-used elsewhere.

+
+
Parameters:
+
    +

  • delay (Union[int, float]) – How long to wait before starting the task.

    • +

  • task_id (Hashable) – A unique ID to create the task with.

    • +

  • coroutine (Coroutine) – The function to be called.

    • +
+
+
Return type:
+

None

+
+
+
+ +
+ +
+
+create_task(coro, *, suppressed_exceptions=(), event_loop=None, **kwargs)[source]#
+

Wrapper for creating an asyncio.Task which logs exceptions raised in the task.

+

If the event_loop kwarg is provided, the task is created from that event loop, +otherwise the running loop is used.

+
+
Parameters:
+
+
+
Returns:
+

The wrapped task.

+
+
Return type:
+

asyncio.Task

+
+
+
+ +
+ +