forked from goodboy/tractor
65 lines
1.4 KiB
Python
65 lines
1.4 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
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from typing import TypeVar
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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_sleep(
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mngr: AsyncContextManager[T],
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to_yield: dict[int, T],
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all_entered: trio.Event,
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# task_status: TaskStatus[T] = trio.TASK_STATUS_IGNORED,
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) -> T:
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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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to_yield[id(mngr)] = value
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if all(to_yield.values()):
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all_entered.set()
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# sleep until cancelled
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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: list[AsyncContextManager[T]],
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) -> tuple[T]:
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to_yield = {}.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_sleep,
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mngr,
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to_yield,
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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(to_yield.values())
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# tear down all sleeper tasks thus triggering individual
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# mngr ``__aexit__()``s.
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n.cancel_scope.cancel()
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