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scheduling#

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Generic python scheduler.

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-class Scheduler(name)[source]#
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Bases: object

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Schedule the execution of coroutines and keep track of them.

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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.

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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.

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

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

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-__contains__(task_id)[source]#
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Return True if a task with the given task_id is currently scheduled.

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Parameters:
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task_id (Hashable) – The task to look for.

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Return type:
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bool

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Returns:
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True if the task was found.

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-__init__(name)[source]#
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Initialize a new Scheduler instance.

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

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-cancel(task_id)[source]#
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Unschedule the task identified by task_id. Log a warning if the task doesn’t exist.

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

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Return type:
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None

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-cancel_all()[source]#
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Unschedule all known tasks.

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Return type:
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None

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-schedule(task_id, coroutine)[source]#
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Schedule the execution of a coroutine.

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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.

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

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

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Return type:
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None

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-schedule_at(time, task_id, coroutine)[source]#
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Schedule coroutine to be executed at the given time.

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

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If time is in the past, schedule coroutine immediately.

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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.

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

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

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

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Return type:
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None

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-schedule_later(delay, task_id, coroutine)[source]#
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Schedule coroutine to be executed after delay seconds.

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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.

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

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

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

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Return type:
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None

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-create_task(coro, *, suppressed_exceptions=(), event_loop=None, **kwargs)[source]#
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Wrapper for creating an asyncio.Task which logs exceptions raised in the task.

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

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Parameters:
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Returns:
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The wrapped task.

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Return type:
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asyncio.Task

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