27 lines
1.1 KiB
Python
27 lines
1.1 KiB
Python
import asyncio
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import contextvars
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import functools
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# Used as an alternative for asyncio.to_thread in python <=3.8
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# Repurposed from CPython, used under the terms of the PSL
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# Upstream source: https://github.com/python/cpython/blob/4b4227b907a262446b9d276c274feda2590a4e6e/Lib/asyncio/threads.py
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# License: https://github.com/python/cpython/blob/4b4227b907a262446b9d276c274feda2590a4e6e/LICENSE
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# Copyright (c) 2021 Python Software Foundation
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async def _to_thread(func, *args, **kwargs):
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"""Asynchronously run function *func* in a separate thread.
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Any *args and **kwargs supplied for this function are directly passed
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to *func*. Also, the current :class:`contextvars.Context` is propagated,
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allowing context variables from the main thread to be accessed in the
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separate thread.
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Return a coroutine that can be awaited to get the eventual result of *func*.
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"""
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loop = asyncio.get_running_loop()
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ctx = contextvars.copy_context()
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func_call = functools.partial(ctx.run, func, *args, **kwargs)
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return await loop.run_in_executor(None, func_call)
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to_thread = getattr(asyncio, 'to_thread', _to_thread)
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