EG
210 lines
6.5 KiB
Python
210 lines
6.5 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 Callable, Coroutine
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from contextvars import Context
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from types import TracebackType
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from typing import TYPE_CHECKING, Any, Literal, Protocol, final, 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, TaskHandle
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T_co = TypeVar("T_co", covariant=True)
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T_contra = TypeVar("T_contra", contravariant=True, default=None)
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PosArgsT = TypeVarTuple("PosArgsT")
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def get_callable_name(func: Callable, override: object = None) -> str:
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if override is not None:
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return str(override)
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module = getattr(func, "__module__", None)
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qualname = getattr(func, "__qualname__", None)
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return ".".join([x for x in (module, qualname) if x])
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def call_for_coroutine(
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func: Callable[[Unpack[PosArgsT]], Coroutine[Any, Any, T_co]],
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args: tuple[Unpack[PosArgsT]],
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**kwargs: Any,
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) -> Coroutine[Any, Any, T_co]:
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"""
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Call the given function with the given positional and keyword arguments.
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:return: the resulting coroutine
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:raises TypeError: if the return value was not a coroutine object
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"""
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coro = func(*args, **kwargs)
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if not isinstance(coro, Coroutine):
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prefix = f"{func.__module__}." if hasattr(func, "__module__") else ""
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raise TypeError(
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f"Expected {prefix}{func.__qualname__}() to return a coroutine, but "
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f"the return value ({coro!r}) is not a coroutine object"
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)
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return coro
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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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def cancel(self, reason: str | None = None) -> None:
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"""
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Cancel this task group's cancel scope immediately.
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This is a shortcut for calling ``.cancel_scope.cancel()`` on the task group.
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:param reason: a message describing the reason for the cancellation
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.. versionadded:: 4.14.0
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"""
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self.cancel_scope.cancel(reason)
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@abstractmethod
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def create_task(
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self,
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coro: Coroutine[Any, Any, T_co],
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*,
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name: object = None,
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context: Context | None = None,
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) -> TaskHandle[T_co]:
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"""
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Create a new task from a coroutine object and schedule it to run.
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:param coro: a coroutine object
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:param name: optional name to give the task
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:param context: optional context to run the task in
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:return: a task handle
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.. versionadded:: 4.14.0
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"""
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@final
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def start_soon(
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self,
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func: Callable[[Unpack[PosArgsT]], Coroutine[Any, Any, T_co]],
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*args: Unpack[PosArgsT],
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name: object = None,
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) -> TaskHandle[T_co]:
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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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:return: a task handle
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.. versionadded:: 3.0
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.. versionchanged:: 4.14.0
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This method now returns a task handle.
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"""
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final_name = get_callable_name(func, name)
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return self.create_task(call_for_coroutine(func, args), name=final_name)
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@overload
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async def start(
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self,
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func: Callable[..., Coroutine[Any, Any, T_co]],
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*args: object,
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name: object = None,
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return_handle: Literal[False] = ...,
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) -> Any: ...
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@overload
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async def start(
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self,
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func: Callable[..., Coroutine[Any, Any, T_co]],
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*args: object,
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name: object = None,
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return_handle: Literal[True],
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) -> TaskHandle[T_co, Any]: ...
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@abstractmethod
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async def start(
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self,
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func: Callable[..., Coroutine[Any, Any, T_co]],
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*args: object,
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name: object = None,
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return_handle: Literal[False] | Literal[True] = False,
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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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:param return_handle: if ``True``, return a :class:`TaskHandle` which also
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contains the start value in ``start_value``
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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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