Sybren A. Stüvel
5e237bea22
The 'cancelled' status is now tracked by a Future that's passed to different asychronous tasks. That way it is possible to cancel all running tasks before browsing another Pillar node.
89 lines
2.3 KiB
Python
89 lines
2.3 KiB
Python
"""Manages the asyncio loop."""
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import asyncio
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import traceback
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import concurrent.futures
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import logging
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import bpy
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log = logging.getLogger(__name__)
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def setup_asyncio_executor():
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"""Sets up AsyncIO to run on a single thread.
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This ensures that only one Pillar HTTP call is performed at the same time. Other
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calls that could be performed in parallel are queued, and thus we can
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reliably cancel them.
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"""
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executor = concurrent.futures.ThreadPoolExecutor(max_workers=1)
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loop = asyncio.get_event_loop()
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loop.set_default_executor(executor)
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# loop.set_debug(True)
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def kick_async_loop(*args):
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loop = asyncio.get_event_loop()
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if loop.is_closed():
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log.warning('loop closed, stopping')
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stop_async_loop()
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return
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all_tasks = asyncio.Task.all_tasks()
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if not all_tasks:
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log.debug('no more scheduled tasks, stopping')
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stop_async_loop()
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return
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if all(task.done() for task in all_tasks):
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log.info('all tasks are done, fetching results and stopping.'.format(__name__))
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for task in all_tasks:
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# noinspection PyBroadException
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try:
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task.result()
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except asyncio.CancelledError:
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# No problem, we want to stop anyway.
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pass
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except Exception:
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print('{}: resulted in exception'.format(task))
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traceback.print_exc()
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stop_async_loop()
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return
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# Perform a single async loop step
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async def do_nothing():
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pass
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loop.run_until_complete(do_nothing())
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def async_loop_handler() -> callable:
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"""Returns the asynchronous loop handler `kick_async_loop`
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Only returns the function if it is installed as scene_update_pre handler, otherwise
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it returns None.
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"""
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name = kick_async_loop.__name__
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for handler in bpy.app.handlers.scene_update_pre:
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if getattr(handler, '__name__', '') == name:
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return handler
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return None
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def ensure_async_loop():
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if async_loop_handler() is not None:
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return
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bpy.app.handlers.scene_update_pre.append(kick_async_loop)
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def stop_async_loop():
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handler = async_loop_handler()
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if handler is None:
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return
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bpy.app.handlers.scene_update_pre.remove(handler)
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log.debug('stopped async loop.')
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