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