113 lines
3.4 KiB
Python
113 lines
3.4 KiB
Python
# This code is originally sourced from the aio-libs project "async_timeout",
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# under the Apache 2.0 license. You may see the original project at
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# https://github.com/aio-libs/async-timeout
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# It is vendored here to reduce chain-dependencies on this library, and
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# modified slightly to remove some features we don't use.
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import asyncio
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from types import TracebackType
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from typing import Any, Optional, Type
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class 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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>>> 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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timeout - value in seconds or None to disable timeout logic
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loop - asyncio compatible event loop
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"""
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def __init__(
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self,
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timeout: Optional[float],
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*,
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loop: Optional[asyncio.AbstractEventLoop] = None,
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) -> None:
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self._timeout = timeout
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if loop is None:
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loop = asyncio.get_event_loop()
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self._loop = loop
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self._task = None # type: Optional[asyncio.Task[Any]]
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self._cancelled = False
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self._cancel_handler = None # type: Optional[asyncio.Handle]
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self._cancel_at = None # type: Optional[float]
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def __enter__(self) -> "timeout":
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return self._do_enter()
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def __exit__(
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self,
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exc_type: Type[BaseException],
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exc_val: BaseException,
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exc_tb: 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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return self._do_enter()
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async def __aexit__(
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self,
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exc_type: Type[BaseException],
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exc_val: BaseException,
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exc_tb: TracebackType,
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) -> None:
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self._do_exit(exc_type)
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@property
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def expired(self) -> bool:
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return self._cancelled
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@property
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def remaining(self) -> Optional[float]:
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if self._cancel_at is not None:
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return max(self._cancel_at - self._loop.time(), 0.0)
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else:
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return None
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def _do_enter(self) -> "timeout":
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# Support Tornado 5- without timeout
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# Details: https://github.com/python/asyncio/issues/392
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if self._timeout is None:
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return self
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self._task = asyncio.current_task(self._loop)
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if self._task is None:
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raise RuntimeError(
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"Timeout context manager should be used " "inside a task"
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)
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if self._timeout <= 0:
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self._loop.call_soon(self._cancel_task)
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return self
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self._cancel_at = self._loop.time() + self._timeout
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self._cancel_handler = self._loop.call_at(self._cancel_at, self._cancel_task)
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return self
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def _do_exit(self, exc_type: Type[BaseException]) -> None:
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if exc_type is asyncio.CancelledError and self._cancelled:
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self._cancel_handler = None
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self._task = None
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raise asyncio.TimeoutError
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if self._timeout is not None and self._cancel_handler is not None:
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self._cancel_handler.cancel()
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self._cancel_handler = None
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self._task = None
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return None
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def _cancel_task(self) -> None:
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if self._task is not None:
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self._task.cancel()
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self._cancelled = True
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