craftbeerpi4-pione/venv3/lib/python3.7/site-packages/aiohttp/locks.py
2021-03-03 23:49:41 +01:00

45 lines
1.2 KiB
Python

import asyncio
import collections
from typing import Any, Optional
try:
from typing import Deque
except ImportError:
from typing_extensions import Deque
class EventResultOrError:
"""
This class wrappers the Event asyncio lock allowing either awake the
locked Tasks without any error or raising an exception.
thanks to @vorpalsmith for the simple design.
"""
def __init__(self, loop: asyncio.AbstractEventLoop) -> None:
self._loop = loop
self._exc = None # type: Optional[BaseException]
self._event = asyncio.Event()
self._waiters = collections.deque() # type: Deque[asyncio.Future[Any]]
def set(self, exc: Optional[BaseException] = None) -> None:
self._exc = exc
self._event.set()
async def wait(self) -> Any:
waiter = self._loop.create_task(self._event.wait())
self._waiters.append(waiter)
try:
val = await waiter
finally:
self._waiters.remove(waiter)
if self._exc is not None:
raise self._exc
return val
def cancel(self) -> None:
""" Cancel all waiters """
for waiter in self._waiters:
waiter.cancel()