75 lines
2.1 KiB
Python
75 lines
2.1 KiB
Python
# Copyright 2019 Canonical, Ltd.
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#
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# This program is free software: you can redistribute it and/or modify
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# it under the terms of the GNU Affero General Public License as
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# published by the Free Software Foundation, either version 3 of the
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# License, or (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU Affero General Public License for more details.
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#
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# You should have received a copy of the GNU Affero General Public License
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# along with this program. If not, see <http://www.gnu.org/licenses/>.
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import asyncio
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import logging
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log = logging.getLogger("subiquitycore.async_helpers")
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def _done(fut):
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try:
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fut.result()
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except asyncio.CancelledError:
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pass
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def schedule_task(coro, propagate_errors=True):
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loop = asyncio.get_event_loop()
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if asyncio.iscoroutine(coro):
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task = asyncio.Task(coro)
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else:
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task = coro
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if propagate_errors:
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task.add_done_callback(_done)
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loop.call_soon(asyncio.ensure_future, task)
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return task
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async def run_in_thread(func, *args):
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loop = asyncio.get_event_loop()
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return await loop.run_in_executor(None, func, *args)
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class SingleInstanceTask:
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def __init__(self, func, propagate_errors=True):
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self.func = func
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self.propagate_errors = propagate_errors
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self.task = None
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async def _start(self, old):
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if old is not None:
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old.cancel()
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try:
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await old
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except BaseException:
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pass
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schedule_task(self.task, self.propagate_errors)
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async def start(self, *args, **kw):
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await self.start_sync(*args, **kw)
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return self.task
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def start_sync(self, *args, **kw):
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old = self.task
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coro = self.func(*args, **kw)
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if asyncio.iscoroutine(coro):
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self.task = asyncio.Task(coro)
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else:
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self.task = coro
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return schedule_task(self._start(old))
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