Sybren A. Stüvel
d3e433b8b2
How we previously did things could cause us to miss certain calls, such as calling 'future.add_done_callback()' callbacks.
92 lines
2.5 KiB
Python
92 lines
2.5 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 len(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 %i tasks are done, fetching results and stopping.', len(all_tasks))
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for task_idx, task in enumerate(all_tasks):
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# noinspection PyBroadException
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try:
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res = task.result()
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log.debug(' task #%i: result=%r', task_idx, res)
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except asyncio.CancelledError:
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# No problem, we want to stop anyway.
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log.debug(' task #%i: cancelled', task_idx)
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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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def stop_loop(future):
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future.set_result('done')
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future = asyncio.Future()
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loop.call_later(0.005, stop_loop, future)
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loop.run_until_complete(future)
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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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