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118 lines
3.6 KiB
Python
118 lines
3.6 KiB
Python
from __future__ import annotations
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import sys
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from abc import ABCMeta, abstractmethod
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from collections.abc import Awaitable, Callable
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from types import TracebackType
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from typing import TYPE_CHECKING, Any, Protocol, overload
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if sys.version_info >= (3, 13):
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from typing import TypeVar
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else:
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from typing_extensions import TypeVar
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if sys.version_info >= (3, 11):
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from typing import TypeVarTuple, Unpack
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else:
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from typing_extensions import TypeVarTuple, Unpack
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if TYPE_CHECKING:
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from .._core._tasks import CancelScope
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T_Retval = TypeVar("T_Retval")
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T_contra = TypeVar("T_contra", contravariant=True, default=None)
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PosArgsT = TypeVarTuple("PosArgsT")
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class TaskStatus(Protocol[T_contra]):
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@overload
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def started(self: TaskStatus[None]) -> None: ...
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@overload
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def started(self, value: T_contra) -> None: ...
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def started(self, value: T_contra | None = None) -> None:
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"""
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Signal that the task has started.
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:param value: object passed back to the starter of the task
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"""
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class TaskGroup(metaclass=ABCMeta):
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"""
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Groups several asynchronous tasks together.
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:ivar cancel_scope: the cancel scope inherited by all child tasks
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:vartype cancel_scope: CancelScope
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.. note:: On asyncio, support for eager task factories is considered to be
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**experimental**. In particular, they don't follow the usual semantics of new
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tasks being scheduled on the next iteration of the event loop, and may thus
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cause unexpected behavior in code that wasn't written with such semantics in
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mind.
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"""
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cancel_scope: CancelScope
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@abstractmethod
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def start_soon(
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self,
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func: Callable[[Unpack[PosArgsT]], Awaitable[Any]],
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*args: Unpack[PosArgsT],
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name: object = None,
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) -> None:
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"""
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Start a new task in this task group.
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:param func: a coroutine function
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:param args: positional arguments to call the function with
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:param name: name of the task, for the purposes of introspection and debugging
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.. versionadded:: 3.0
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"""
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@abstractmethod
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async def start(
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self,
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func: Callable[..., Awaitable[Any]],
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*args: object,
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name: object = None,
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) -> Any:
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"""
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Start a new task and wait until it signals for readiness.
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The target callable must accept a keyword argument ``task_status`` (of type
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:class:`TaskStatus`). Awaiting on this method will return whatever was passed to
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``task_status.started()`` (``None`` by default).
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.. note:: The :class:`TaskStatus` class is generic, and the type argument should
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indicate the type of the value that will be passed to
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``task_status.started()``.
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:param func: a coroutine function that accepts the ``task_status`` keyword
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argument
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:param args: positional arguments to call the function with
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:param name: an optional name for the task, for introspection and debugging
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:return: the value passed to ``task_status.started()``
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:raises RuntimeError: if the task finishes without calling
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``task_status.started()``
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.. seealso:: :ref:`start_initialize`
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.. versionadded:: 3.0
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"""
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@abstractmethod
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async def __aenter__(self) -> TaskGroup:
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"""Enter the task group context and allow starting new tasks."""
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@abstractmethod
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async def __aexit__(
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self,
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exc_type: type[BaseException] | None,
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exc_val: BaseException | None,
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exc_tb: TracebackType | None,
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) -> bool:
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"""Exit the task group context waiting for all tasks to finish."""
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