from __future__ import annotations
import contextvars
from .taskscope import TaskScope
__all__ = ("Supervisor",)
[docs]
class Supervisor(TaskScope):
"""
Supervisor is a primitive structure to provide a long-lived context manager scope
for an indefinite set of subtasks. During its lifetime, it is free to spawn new
subtasks at any time. If the supervisor itself is cancelled from outside or
:meth:`aclose()` is called, it will cancel all running tasks immediately, wait
for their completion, and then exit the context manager block.
The main difference to :class:`asyncio.TaskGroup` is that it keeps running
sibling subtasks even when there is an unhandled exception from one of the
subtasks.
To prevent memory leaks, a supervisor does not store any result or exception
from its subtasks. Instead, the callers must use additional task-done
callbacks to process subtask results and exceptions.
Supervisor provides the same analogy to Kotlin's |SupervisorScope|_ and
Javascript's |Promise.allSettled()|_, while :class:`asyncio.TaskGroup` provides
the same analogy to Kotlin's |CoroutineScope|_ and Javascript's |Promise.all()|_.
.. |SupervisorScope| replace:: ``SupervisorScope``
.. |CoroutineScope| replace:: ``CoroutineScope``
.. _SupervisorScope: https://kotlinlang.org/api/kotlinx.coroutines/kotlinx-coroutines-core/kotlinx.coroutines/supervisor-scope.html
.. _CoroutineScope: https://kotlinlang.org/api/kotlinx.coroutines/kotlinx-coroutines-core/kotlinx.coroutines/-coroutine-scope/
.. |Promise.allSettled()| replace:: ``Promise.allSettled()``
.. |Promise.all()| replace:: ``Promise.all()``
.. _Promise.allSettled(): https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise/allSettled
.. _Promise.all(): https://developer.mozilla.org/ko/docs/Web/JavaScript/Reference/Global_Objects/Promise/all
The original implementation is based on DontPanicO's pull request
(https://github.com/achimnol/cpython/pull/31) and :class:`PersistentTaskGroup`,
but it is modified *not* to store unhandled subtask exceptions.
.. versionadded:: 2.0
""" # noqa: E501
def __init__(self, context: contextvars.Context | None = None) -> None:
super().__init__(exception_handler=None, context=context)