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152 lines
4.4 KiB
Python
152 lines
4.4 KiB
Python
import enum
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from types import TracebackType
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from typing import final, Optional, Type
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from . import events
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from . import exceptions
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from . import tasks
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__all__ = (
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"Timeout",
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"timeout",
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"timeout_at",
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)
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class _State(enum.Enum):
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CREATED = "created"
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ENTERED = "active"
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EXPIRING = "expiring"
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EXPIRED = "expired"
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EXITED = "finished"
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@final
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class Timeout:
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def __init__(self, when: Optional[float]) -> None:
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self._state = _State.CREATED
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self._timeout_handler: Optional[events.TimerHandle] = None
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self._task: Optional[tasks.Task] = None
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self._when = when
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def when(self) -> Optional[float]:
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return self._when
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def reschedule(self, when: Optional[float]) -> None:
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assert self._state is not _State.CREATED
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if self._state is not _State.ENTERED:
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raise RuntimeError(
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f"Cannot change state of {self._state.value} Timeout",
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)
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self._when = when
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if self._timeout_handler is not None:
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self._timeout_handler.cancel()
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if when is None:
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self._timeout_handler = None
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else:
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loop = events.get_running_loop()
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if when <= loop.time():
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self._timeout_handler = loop.call_soon(self._on_timeout)
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else:
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self._timeout_handler = loop.call_at(when, self._on_timeout)
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def expired(self) -> bool:
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"""Is timeout expired during execution?"""
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return self._state in (_State.EXPIRING, _State.EXPIRED)
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def __repr__(self) -> str:
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info = ['']
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if self._state is _State.ENTERED:
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when = round(self._when, 3) if self._when is not None else None
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info.append(f"when={when}")
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info_str = ' '.join(info)
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return f"<Timeout [{self._state.value}]{info_str}>"
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async def __aenter__(self) -> "Timeout":
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self._state = _State.ENTERED
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self._task = tasks.current_task()
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if self._task is None:
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raise RuntimeError("Timeout should be used inside a task")
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self.reschedule(self._when)
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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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assert self._state in (_State.ENTERED, _State.EXPIRING)
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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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if self._state is _State.EXPIRING:
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self._state = _State.EXPIRED
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if self._task.uncancel() == 0 and exc_type is exceptions.CancelledError:
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# Since there are no outstanding cancel requests, we're
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# handling this.
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raise TimeoutError
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elif self._state is _State.ENTERED:
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self._state = _State.EXITED
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return None
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def _on_timeout(self) -> None:
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assert self._state is _State.ENTERED
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self._task.cancel()
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self._state = _State.EXPIRING
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# drop the reference early
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self._timeout_handler = None
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def timeout(delay: Optional[float]) -> Timeout:
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"""Timeout async 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 asyncio.timeout(10): # 10 seconds timeout
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... await long_running_task()
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delay - value in seconds or None to disable timeout logic
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long_running_task() is interrupted by raising asyncio.CancelledError,
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the top-most affected timeout() context manager converts CancelledError
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into TimeoutError.
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"""
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loop = events.get_running_loop()
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return Timeout(loop.time() + delay if delay is not None else None)
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def timeout_at(when: Optional[float]) -> Timeout:
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"""Schedule the timeout at absolute time.
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Like timeout() but argument gives absolute 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 asyncio.timeout_at(loop.time() + 10):
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... await long_running_task()
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when - a deadline when timeout occurs or None to disable timeout logic
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long_running_task() is interrupted by raising asyncio.CancelledError,
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the top-most affected timeout() context manager converts CancelledError
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into TimeoutError.
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"""
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return Timeout(when)
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