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56 lines
2.0 KiB
56 lines
2.0 KiB
from contextlib import asynccontextmanager as asynccontextmanager
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from typing import AsyncGenerator, ContextManager, TypeVar, Optional
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import functools
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import sys
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import typing
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if sys.version_info >= (3, 10): # pragma: no cover
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from typing import ParamSpec
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else: # pragma: no cover
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from typing_extensions import ParamSpec
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import anyio
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from anyio import CapacityLimiter
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from starlette.concurrency import iterate_in_threadpool as iterate_in_threadpool # noqa
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from starlette.concurrency import ( # noqa
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run_until_first_complete as run_until_first_complete,
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)
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_P = ParamSpec("_P")
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_T = TypeVar("_T")
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async def run_in_threadpool(
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func: typing.Callable[_P, _T],
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*args: typing.Any,
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_limiter: Optional[anyio.CapacityLimiter] = None,
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**kwargs: typing.Any
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) -> _T:
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if kwargs: # pragma: no cover
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# run_sync doesn't accept 'kwargs', so bind them in here
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func = functools.partial(func, **kwargs)
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return await anyio.to_thread.run_sync(func, *args, limiter=_limiter)
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@asynccontextmanager
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async def contextmanager_in_threadpool(
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cm: ContextManager[_T], limiter: Optional[anyio.CapacityLimiter] = None,
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) -> AsyncGenerator[_T, None]:
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# blocking __exit__ from running waiting on a free thread
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# can create race conditions/deadlocks if the context manager itself
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# has its own internal pool (e.g. a database connection pool)
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# to avoid this we let __exit__ run without a capacity limit
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# since we're creating a new limiter for each call, any non-zero limit
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# works (1 is arbitrary)
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exit_limiter = CapacityLimiter(1)
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try:
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yield await run_in_threadpool(cm.__enter__, _limiter=limiter)
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except Exception as e:
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ok = bool(
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await run_in_threadpool(
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cm.__exit__, type(e), e, None, _limiter=exit_limiter
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)
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)
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if not ok:
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raise e
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else:
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await run_in_threadpool(
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cm.__exit__, None, None, None, _limiter=exit_limiter
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)
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