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