240 lines
7.1 KiB
Python
240 lines
7.1 KiB
Python
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import asyncio
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import enum
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import sys
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import warnings
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from types import TracebackType
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from typing import Optional, Type
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if sys.version_info >= (3, 8):
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from typing import final
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else:
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from typing_extensions import final
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if sys.version_info >= (3, 11):
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def _uncancel_task(task: "asyncio.Task[object]") -> None:
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task.uncancel()
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else:
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def _uncancel_task(task: "asyncio.Task[object]") -> None:
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pass
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__version__ = "4.0.3"
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__all__ = ("timeout", "timeout_at", "Timeout")
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def timeout(delay: Optional[float]) -> "Timeout":
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"""timeout context manager.
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Useful in cases when you want to apply timeout logic around block
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of code or in cases when asyncio.wait_for is not suitable. For example:
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>>> async with timeout(0.001):
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... async with aiohttp.get('https://github.com') as r:
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... await r.text()
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delay - value in seconds or None to disable timeout logic
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"""
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loop = asyncio.get_running_loop()
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if delay is not None:
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deadline = loop.time() + delay # type: Optional[float]
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else:
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deadline = None
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return Timeout(deadline, loop)
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def timeout_at(deadline: Optional[float]) -> "Timeout":
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"""Schedule the timeout at absolute time.
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deadline argument points on the time in the same clock system
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as loop.time().
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Please note: it is not POSIX time but a time with
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undefined starting base, e.g. the time of the system power on.
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>>> async with timeout_at(loop.time() + 10):
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... async with aiohttp.get('https://github.com') as r:
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... await r.text()
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"""
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loop = asyncio.get_running_loop()
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return Timeout(deadline, loop)
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class _State(enum.Enum):
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INIT = "INIT"
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ENTER = "ENTER"
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TIMEOUT = "TIMEOUT"
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EXIT = "EXIT"
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@final
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class Timeout:
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# Internal class, please don't instantiate it directly
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# Use timeout() and timeout_at() public factories instead.
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#
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# Implementation note: `async with timeout()` is preferred
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# over `with timeout()`.
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# While technically the Timeout class implementation
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# doesn't need to be async at all,
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# the `async with` statement explicitly points that
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# the context manager should be used from async function context.
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#
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# This design allows to avoid many silly misusages.
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#
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# TimeoutError is raised immediately when scheduled
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# if the deadline is passed.
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# The purpose is to time out as soon as possible
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# without waiting for the next await expression.
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__slots__ = ("_deadline", "_loop", "_state", "_timeout_handler", "_task")
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def __init__(
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self, deadline: Optional[float], loop: asyncio.AbstractEventLoop
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) -> None:
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self._loop = loop
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self._state = _State.INIT
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self._task: Optional["asyncio.Task[object]"] = None
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self._timeout_handler = None # type: Optional[asyncio.Handle]
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if deadline is None:
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self._deadline = None # type: Optional[float]
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else:
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self.update(deadline)
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def __enter__(self) -> "Timeout":
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warnings.warn(
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"with timeout() is deprecated, use async with timeout() instead",
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DeprecationWarning,
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stacklevel=2,
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)
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self._do_enter()
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return self
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def __exit__(
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self,
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exc_type: Optional[Type[BaseException]],
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exc_val: Optional[BaseException],
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exc_tb: Optional[TracebackType],
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) -> Optional[bool]:
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self._do_exit(exc_type)
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return None
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async def __aenter__(self) -> "Timeout":
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self._do_enter()
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return self
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async def __aexit__(
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self,
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exc_type: Optional[Type[BaseException]],
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exc_val: Optional[BaseException],
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exc_tb: Optional[TracebackType],
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) -> Optional[bool]:
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self._do_exit(exc_type)
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return None
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@property
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def expired(self) -> bool:
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"""Is timeout expired during execution?"""
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return self._state == _State.TIMEOUT
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@property
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def deadline(self) -> Optional[float]:
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return self._deadline
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def reject(self) -> None:
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"""Reject scheduled timeout if any."""
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# cancel is maybe better name but
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# task.cancel() raises CancelledError in asyncio world.
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if self._state not in (_State.INIT, _State.ENTER):
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raise RuntimeError(f"invalid state {self._state.value}")
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self._reject()
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def _reject(self) -> None:
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self._task = None
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if self._timeout_handler is not None:
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self._timeout_handler.cancel()
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self._timeout_handler = None
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def shift(self, delay: float) -> None:
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"""Advance timeout on delay seconds.
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The delay can be negative.
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Raise RuntimeError if shift is called when deadline is not scheduled
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"""
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deadline = self._deadline
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if deadline is None:
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raise RuntimeError("cannot shift timeout if deadline is not scheduled")
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self.update(deadline + delay)
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def update(self, deadline: float) -> None:
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"""Set deadline to absolute value.
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deadline argument points on the time in the same clock system
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as loop.time().
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If new deadline is in the past the timeout is raised immediately.
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Please note: it is not POSIX time but a time with
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undefined starting base, e.g. the time of the system power on.
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"""
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if self._state == _State.EXIT:
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raise RuntimeError("cannot reschedule after exit from context manager")
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if self._state == _State.TIMEOUT:
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raise RuntimeError("cannot reschedule expired timeout")
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if self._timeout_handler is not None:
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self._timeout_handler.cancel()
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self._deadline = deadline
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if self._state != _State.INIT:
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self._reschedule()
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def _reschedule(self) -> None:
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assert self._state == _State.ENTER
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deadline = self._deadline
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if deadline is None:
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return
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now = self._loop.time()
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if self._timeout_handler is not None:
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self._timeout_handler.cancel()
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self._task = asyncio.current_task()
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if deadline <= now:
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self._timeout_handler = self._loop.call_soon(self._on_timeout)
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else:
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self._timeout_handler = self._loop.call_at(deadline, self._on_timeout)
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def _do_enter(self) -> None:
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if self._state != _State.INIT:
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raise RuntimeError(f"invalid state {self._state.value}")
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self._state = _State.ENTER
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self._reschedule()
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def _do_exit(self, exc_type: Optional[Type[BaseException]]) -> None:
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if exc_type is asyncio.CancelledError and self._state == _State.TIMEOUT:
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assert self._task is not None
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_uncancel_task(self._task)
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self._timeout_handler = None
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self._task = None
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raise asyncio.TimeoutError
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# timeout has not expired
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self._state = _State.EXIT
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self._reject()
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return None
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def _on_timeout(self) -> None:
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assert self._task is not None
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self._task.cancel()
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self._state = _State.TIMEOUT
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# drop the reference early
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self._timeout_handler = None
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