220 lines
7.3 KiB
Python
220 lines
7.3 KiB
Python
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"""Patch asyncio to allow nested event loops."""
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import asyncio
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import asyncio.events as events
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import os
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import sys
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import threading
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from contextlib import contextmanager, suppress
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from heapq import heappop
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def apply(loop=None):
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"""Patch asyncio to make its event loop reentrant."""
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_patch_asyncio()
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_patch_policy()
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_patch_tornado()
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loop = loop or asyncio.get_event_loop()
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_patch_loop(loop)
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def _patch_asyncio():
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"""Patch asyncio module to use pure Python tasks and futures."""
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def run(main, *, debug=False):
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loop = asyncio.get_event_loop()
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loop.set_debug(debug)
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task = asyncio.ensure_future(main)
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try:
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return loop.run_until_complete(task)
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finally:
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if not task.done():
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task.cancel()
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with suppress(asyncio.CancelledError):
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loop.run_until_complete(task)
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def _get_event_loop(stacklevel=3):
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loop = events._get_running_loop()
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if loop is None:
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loop = events.get_event_loop_policy().get_event_loop()
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return loop
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# Use module level _current_tasks, all_tasks and patch run method.
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if hasattr(asyncio, '_nest_patched'):
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return
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if sys.version_info >= (3, 6, 0):
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asyncio.Task = asyncio.tasks._CTask = asyncio.tasks.Task = \
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asyncio.tasks._PyTask
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asyncio.Future = asyncio.futures._CFuture = asyncio.futures.Future = \
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asyncio.futures._PyFuture
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if sys.version_info < (3, 7, 0):
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asyncio.tasks._current_tasks = asyncio.tasks.Task._current_tasks
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asyncio.all_tasks = asyncio.tasks.Task.all_tasks
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if sys.version_info >= (3, 9, 0):
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events._get_event_loop = events.get_event_loop = \
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asyncio.get_event_loop = _get_event_loop
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asyncio.run = run
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asyncio._nest_patched = True
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def _patch_policy():
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"""Patch the policy to always return a patched loop."""
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def get_event_loop(self):
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if self._local._loop is None:
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loop = self.new_event_loop()
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_patch_loop(loop)
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self.set_event_loop(loop)
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return self._local._loop
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policy = events.get_event_loop_policy()
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policy.__class__.get_event_loop = get_event_loop
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def _patch_loop(loop):
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"""Patch loop to make it reentrant."""
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def run_forever(self):
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with manage_run(self), manage_asyncgens(self):
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while True:
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self._run_once()
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if self._stopping:
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break
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self._stopping = False
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def run_until_complete(self, future):
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with manage_run(self):
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f = asyncio.ensure_future(future, loop=self)
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if f is not future:
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f._log_destroy_pending = False
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while not f.done():
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self._run_once()
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if self._stopping:
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break
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if not f.done():
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raise RuntimeError(
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'Event loop stopped before Future completed.')
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return f.result()
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def _run_once(self):
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"""
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Simplified re-implementation of asyncio's _run_once that
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runs handles as they become ready.
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"""
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ready = self._ready
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scheduled = self._scheduled
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while scheduled and scheduled[0]._cancelled:
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heappop(scheduled)
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timeout = (
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0 if ready or self._stopping
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else min(max(
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scheduled[0]._when - self.time(), 0), 86400) if scheduled
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else None)
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event_list = self._selector.select(timeout)
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self._process_events(event_list)
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end_time = self.time() + self._clock_resolution
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while scheduled and scheduled[0]._when < end_time:
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handle = heappop(scheduled)
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ready.append(handle)
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for _ in range(len(ready)):
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if not ready:
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break
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handle = ready.popleft()
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if not handle._cancelled:
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# preempt the current task so that that checks in
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# Task.__step do not raise
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curr_task = curr_tasks.pop(self, None)
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try:
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handle._run()
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finally:
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# restore the current task
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if curr_task is not None:
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curr_tasks[self] = curr_task
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handle = None
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@contextmanager
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def manage_run(self):
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"""Set up the loop for running."""
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self._check_closed()
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old_thread_id = self._thread_id
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old_running_loop = events._get_running_loop()
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try:
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self._thread_id = threading.get_ident()
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events._set_running_loop(self)
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self._num_runs_pending += 1
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if self._is_proactorloop:
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if self._self_reading_future is None:
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self.call_soon(self._loop_self_reading)
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yield
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finally:
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self._thread_id = old_thread_id
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events._set_running_loop(old_running_loop)
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self._num_runs_pending -= 1
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if self._is_proactorloop:
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if (self._num_runs_pending == 0
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and self._self_reading_future is not None):
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ov = self._self_reading_future._ov
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self._self_reading_future.cancel()
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if ov is not None:
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self._proactor._unregister(ov)
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self._self_reading_future = None
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@contextmanager
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def manage_asyncgens(self):
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if not hasattr(sys, 'get_asyncgen_hooks'):
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# Python version is too old.
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return
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old_agen_hooks = sys.get_asyncgen_hooks()
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try:
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self._set_coroutine_origin_tracking(self._debug)
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if self._asyncgens is not None:
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sys.set_asyncgen_hooks(
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firstiter=self._asyncgen_firstiter_hook,
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finalizer=self._asyncgen_finalizer_hook)
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yield
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finally:
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self._set_coroutine_origin_tracking(False)
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if self._asyncgens is not None:
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sys.set_asyncgen_hooks(*old_agen_hooks)
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def _check_running(self):
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"""Do not throw exception if loop is already running."""
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pass
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if hasattr(loop, '_nest_patched'):
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return
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if not isinstance(loop, asyncio.BaseEventLoop):
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raise ValueError('Can\'t patch loop of type %s' % type(loop))
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cls = loop.__class__
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cls.run_forever = run_forever
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cls.run_until_complete = run_until_complete
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cls._run_once = _run_once
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cls._check_running = _check_running
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cls._check_runnung = _check_running # typo in Python 3.7 source
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cls._num_runs_pending = 1 if loop.is_running() else 0
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cls._is_proactorloop = (
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os.name == 'nt' and issubclass(cls, asyncio.ProactorEventLoop))
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if sys.version_info < (3, 7, 0):
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cls._set_coroutine_origin_tracking = cls._set_coroutine_wrapper
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curr_tasks = asyncio.tasks._current_tasks \
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if sys.version_info >= (3, 7, 0) else asyncio.Task._current_tasks
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cls._nest_patched = True
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def _patch_tornado():
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"""
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If tornado is imported before nest_asyncio, make tornado aware of
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the pure-Python asyncio Future.
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"""
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if 'tornado' in sys.modules:
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import tornado.concurrent as tc # type: ignore
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tc.Future = asyncio.Future
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if asyncio.Future not in tc.FUTURES:
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tc.FUTURES += (asyncio.Future,)
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