75 lines
2.1 KiB
Python
75 lines
2.1 KiB
Python
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__all__ = 'run',
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from . import coroutines
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from . import events
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from . import tasks
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def run(main, *, debug=None):
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"""Execute the coroutine and return the result.
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This function runs the passed coroutine, taking care of
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managing the asyncio event loop and finalizing asynchronous
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generators.
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This function cannot be called when another asyncio event loop is
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running in the same thread.
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If debug is True, the event loop will be run in debug mode.
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This function always creates a new event loop and closes it at the end.
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It should be used as a main entry point for asyncio programs, and should
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ideally only be called once.
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Example:
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async def main():
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await asyncio.sleep(1)
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print('hello')
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asyncio.run(main())
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"""
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if events._get_running_loop() is not None:
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raise RuntimeError(
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"asyncio.run() cannot be called from a running event loop")
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if not coroutines.iscoroutine(main):
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raise ValueError("a coroutine was expected, got {!r}".format(main))
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loop = events.new_event_loop()
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try:
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events.set_event_loop(loop)
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if debug is not None:
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loop.set_debug(debug)
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return loop.run_until_complete(main)
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finally:
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try:
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_cancel_all_tasks(loop)
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loop.run_until_complete(loop.shutdown_asyncgens())
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loop.run_until_complete(loop.shutdown_default_executor())
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finally:
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events.set_event_loop(None)
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loop.close()
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def _cancel_all_tasks(loop):
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to_cancel = tasks.all_tasks(loop)
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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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loop.run_until_complete(
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tasks.gather(*to_cancel, loop=loop, return_exceptions=True))
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for task in to_cancel:
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if task.cancelled():
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continue
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if task.exception() is not None:
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loop.call_exception_handler({
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'message': 'unhandled exception during asyncio.run() shutdown',
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'exception': task.exception(),
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'task': task,
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})
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