57 lines
1.8 KiB
Python
57 lines
1.8 KiB
Python
import asyncio
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import logging
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import sys
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from typing import Any, Iterable
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from black.output import err
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def maybe_install_uvloop() -> None:
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"""If our environment has uvloop installed we use it.
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This is called only from command-line entry points to avoid
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interfering with the parent process if Black is used as a library.
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"""
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try:
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import uvloop
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uvloop.install()
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except ImportError:
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pass
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def cancel(tasks: Iterable["asyncio.Task[Any]"]) -> None:
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"""asyncio signal handler that cancels all `tasks` and reports to stderr."""
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err("Aborted!")
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for task in tasks:
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task.cancel()
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def shutdown(loop: asyncio.AbstractEventLoop) -> None:
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"""Cancel all pending tasks on `loop`, wait for them, and close the loop."""
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try:
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if sys.version_info[:2] >= (3, 7):
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all_tasks = asyncio.all_tasks
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else:
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all_tasks = asyncio.Task.all_tasks
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# This part is borrowed from asyncio/runners.py in Python 3.7b2.
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to_cancel = [task for task in all_tasks(loop) if not task.done()]
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if not to_cancel:
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return
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for task in to_cancel:
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task.cancel()
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if sys.version_info >= (3, 7):
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loop.run_until_complete(asyncio.gather(*to_cancel, return_exceptions=True))
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else:
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loop.run_until_complete(
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asyncio.gather(*to_cancel, loop=loop, return_exceptions=True)
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)
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finally:
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# `concurrent.futures.Future` objects cannot be cancelled once they
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# are already running. There might be some when the `shutdown()` happened.
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# Silence their logger's spew about the event loop being closed.
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cf_logger = logging.getLogger("concurrent.futures")
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cf_logger.setLevel(logging.CRITICAL)
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loop.close()
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