Chih-Hung Hsieh | 3a785d3 | 2021-11-15 22:15:49 -0800 | [diff] [blame^] | 1 | __all__ = 'run', |
| 2 | |
| 3 | from . import coroutines |
| 4 | from . import events |
| 5 | from . import tasks |
| 6 | |
| 7 | |
| 8 | def run(main, *, debug=None): |
| 9 | """Execute the coroutine and return the result. |
| 10 | |
| 11 | This function runs the passed coroutine, taking care of |
| 12 | managing the asyncio event loop and finalizing asynchronous |
| 13 | generators. |
| 14 | |
| 15 | This function cannot be called when another asyncio event loop is |
| 16 | running in the same thread. |
| 17 | |
| 18 | If debug is True, the event loop will be run in debug mode. |
| 19 | |
| 20 | This function always creates a new event loop and closes it at the end. |
| 21 | It should be used as a main entry point for asyncio programs, and should |
| 22 | ideally only be called once. |
| 23 | |
| 24 | Example: |
| 25 | |
| 26 | async def main(): |
| 27 | await asyncio.sleep(1) |
| 28 | print('hello') |
| 29 | |
| 30 | asyncio.run(main()) |
| 31 | """ |
| 32 | if events._get_running_loop() is not None: |
| 33 | raise RuntimeError( |
| 34 | "asyncio.run() cannot be called from a running event loop") |
| 35 | |
| 36 | if not coroutines.iscoroutine(main): |
| 37 | raise ValueError("a coroutine was expected, got {!r}".format(main)) |
| 38 | |
| 39 | loop = events.new_event_loop() |
| 40 | try: |
| 41 | events.set_event_loop(loop) |
| 42 | if debug is not None: |
| 43 | loop.set_debug(debug) |
| 44 | return loop.run_until_complete(main) |
| 45 | finally: |
| 46 | try: |
| 47 | _cancel_all_tasks(loop) |
| 48 | loop.run_until_complete(loop.shutdown_asyncgens()) |
| 49 | loop.run_until_complete(loop.shutdown_default_executor()) |
| 50 | finally: |
| 51 | events.set_event_loop(None) |
| 52 | loop.close() |
| 53 | |
| 54 | |
| 55 | def _cancel_all_tasks(loop): |
| 56 | to_cancel = tasks.all_tasks(loop) |
| 57 | if not to_cancel: |
| 58 | return |
| 59 | |
| 60 | for task in to_cancel: |
| 61 | task.cancel() |
| 62 | |
| 63 | loop.run_until_complete( |
| 64 | tasks.gather(*to_cancel, loop=loop, return_exceptions=True)) |
| 65 | |
| 66 | for task in to_cancel: |
| 67 | if task.cancelled(): |
| 68 | continue |
| 69 | if task.exception() is not None: |
| 70 | loop.call_exception_handler({ |
| 71 | 'message': 'unhandled exception during asyncio.run() shutdown', |
| 72 | 'exception': task.exception(), |
| 73 | 'task': task, |
| 74 | }) |