mirror of https://github.com/python/cpython
164 lines
4.9 KiB
Python
164 lines
4.9 KiB
Python
import enum
|
|
|
|
from types import TracebackType
|
|
from typing import final, Optional, Type
|
|
|
|
from . import events
|
|
from . import exceptions
|
|
from . import tasks
|
|
|
|
|
|
__all__ = (
|
|
"Timeout",
|
|
"timeout",
|
|
"timeout_at",
|
|
)
|
|
|
|
|
|
class _State(enum.Enum):
|
|
CREATED = "created"
|
|
ENTERED = "active"
|
|
EXPIRING = "expiring"
|
|
EXPIRED = "expired"
|
|
EXITED = "finished"
|
|
|
|
|
|
@final
|
|
class Timeout:
|
|
"""Asynchronous context manager for cancelling overdue coroutines.
|
|
|
|
Use `timeout()` or `timeout_at()` rather than instantiating this class directly.
|
|
"""
|
|
|
|
def __init__(self, when: Optional[float]) -> None:
|
|
"""Schedule a timeout that will trigger at a given loop time.
|
|
|
|
- If `when` is `None`, the timeout will never trigger.
|
|
- If `when < loop.time()`, the timeout will trigger on the next
|
|
iteration of the event loop.
|
|
"""
|
|
self._state = _State.CREATED
|
|
|
|
self._timeout_handler: Optional[events.TimerHandle] = None
|
|
self._task: Optional[tasks.Task] = None
|
|
self._when = when
|
|
|
|
def when(self) -> Optional[float]:
|
|
"""Return the current deadline."""
|
|
return self._when
|
|
|
|
def reschedule(self, when: Optional[float]) -> None:
|
|
"""Reschedule the timeout."""
|
|
assert self._state is not _State.CREATED
|
|
if self._state is not _State.ENTERED:
|
|
raise RuntimeError(
|
|
f"Cannot change state of {self._state.value} Timeout",
|
|
)
|
|
|
|
self._when = when
|
|
|
|
if self._timeout_handler is not None:
|
|
self._timeout_handler.cancel()
|
|
|
|
if when is None:
|
|
self._timeout_handler = None
|
|
else:
|
|
loop = events.get_running_loop()
|
|
if when <= loop.time():
|
|
self._timeout_handler = loop.call_soon(self._on_timeout)
|
|
else:
|
|
self._timeout_handler = loop.call_at(when, self._on_timeout)
|
|
|
|
def expired(self) -> bool:
|
|
"""Is timeout expired during execution?"""
|
|
return self._state in (_State.EXPIRING, _State.EXPIRED)
|
|
|
|
def __repr__(self) -> str:
|
|
info = ['']
|
|
if self._state is _State.ENTERED:
|
|
when = round(self._when, 3) if self._when is not None else None
|
|
info.append(f"when={when}")
|
|
info_str = ' '.join(info)
|
|
return f"<Timeout [{self._state.value}]{info_str}>"
|
|
|
|
async def __aenter__(self) -> "Timeout":
|
|
self._state = _State.ENTERED
|
|
self._task = tasks.current_task()
|
|
if self._task is None:
|
|
raise RuntimeError("Timeout should be used inside a task")
|
|
self.reschedule(self._when)
|
|
return self
|
|
|
|
async def __aexit__(
|
|
self,
|
|
exc_type: Optional[Type[BaseException]],
|
|
exc_val: Optional[BaseException],
|
|
exc_tb: Optional[TracebackType],
|
|
) -> Optional[bool]:
|
|
assert self._state in (_State.ENTERED, _State.EXPIRING)
|
|
|
|
if self._timeout_handler is not None:
|
|
self._timeout_handler.cancel()
|
|
self._timeout_handler = None
|
|
|
|
if self._state is _State.EXPIRING:
|
|
self._state = _State.EXPIRED
|
|
|
|
if self._task.uncancel() == 0 and exc_type is exceptions.CancelledError:
|
|
# Since there are no outstanding cancel requests, we're
|
|
# handling this.
|
|
raise TimeoutError
|
|
elif self._state is _State.ENTERED:
|
|
self._state = _State.EXITED
|
|
|
|
return None
|
|
|
|
def _on_timeout(self) -> None:
|
|
assert self._state is _State.ENTERED
|
|
self._task.cancel()
|
|
self._state = _State.EXPIRING
|
|
# drop the reference early
|
|
self._timeout_handler = None
|
|
|
|
|
|
def timeout(delay: Optional[float]) -> Timeout:
|
|
"""Timeout async 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 asyncio.timeout(10): # 10 seconds timeout
|
|
... await long_running_task()
|
|
|
|
|
|
delay - value in seconds or None to disable timeout logic
|
|
|
|
long_running_task() is interrupted by raising asyncio.CancelledError,
|
|
the top-most affected timeout() context manager converts CancelledError
|
|
into TimeoutError.
|
|
"""
|
|
loop = events.get_running_loop()
|
|
return Timeout(loop.time() + delay if delay is not None else None)
|
|
|
|
|
|
def timeout_at(when: Optional[float]) -> Timeout:
|
|
"""Schedule the timeout at absolute time.
|
|
|
|
Like timeout() but argument gives absolute 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 asyncio.timeout_at(loop.time() + 10):
|
|
... await long_running_task()
|
|
|
|
|
|
when - a deadline when timeout occurs or None to disable timeout logic
|
|
|
|
long_running_task() is interrupted by raising asyncio.CancelledError,
|
|
the top-most affected timeout() context manager converts CancelledError
|
|
into TimeoutError.
|
|
"""
|
|
return Timeout(when)
|