forked from goodboy/tractor
56 lines
1.3 KiB
Python
56 lines
1.3 KiB
Python
'''
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Async context manager primitives with hard ``trio``-aware semantics
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'''
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from typing import AsyncContextManager, AsyncGenerator
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from typing import TypeVar, Sequence
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from contextlib import asynccontextmanager as acm
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import trio
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# A regular invariant generic type
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T = TypeVar("T")
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async def _enter_and_wait(
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mngr: AsyncContextManager[T],
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unwrapped: dict[int, T],
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all_entered: trio.Event,
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) -> None:
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'''Open the async context manager deliver it's value
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to this task's spawner and sleep until cancelled.
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'''
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async with mngr as value:
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unwrapped[id(mngr)] = value
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if all(unwrapped.values()):
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all_entered.set()
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await trio.sleep_forever()
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@acm
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async def async_enter_all(
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mngrs: Sequence[AsyncContextManager[T]],
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) -> AsyncGenerator[tuple[T, ...], None]:
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unwrapped = {}.fromkeys(id(mngr) for mngr in mngrs)
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all_entered = trio.Event()
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async with trio.open_nursery() as n:
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for mngr in mngrs:
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n.start_soon(
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_enter_and_wait,
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mngr,
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unwrapped,
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all_entered,
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)
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# deliver control once all managers have started up
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await all_entered.wait()
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yield tuple(unwrapped.values())
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n.cancel_scope.cancel() |