Viewing file:  async_helpers.py (2.27 KB) -rw-r--r--
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# Copyright 2019 Canonical, Ltd.
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, version 3.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
import asyncio
import concurrent.futures
import logging
log = logging.getLogger("subiquitycore.async_helpers")
def _done(fut):
try:
fut.result()
except asyncio.CancelledError:
pass
def schedule_task(coro, propagate_errors=True):
loop = asyncio.get_event_loop()
if asyncio.iscoroutine(coro):
task = asyncio.Task(coro)
else:
task = coro
if propagate_errors:
task.add_done_callback(_done)
loop.call_soon(asyncio.ensure_future, task)
return task
async def run_in_thread(func, *args):
loop = asyncio.get_event_loop()
try:
return await loop.run_in_executor(None, func, *args)
except concurrent.futures.CancelledError:
raise asyncio.CancelledError
class SingleInstanceTask:
def __init__(self, func, propagate_errors=True):
self.func = func
self.propagate_errors = propagate_errors
self.task = None
async def _start(self, old):
if old is not None:
old.cancel()
try:
await old
except BaseException:
pass
schedule_task(self.task, self.propagate_errors)
async def start(self, *args, **kw):
await self.start_sync(*args, **kw)
return self.task
def start_sync(self, *args, **kw):
old = self.task
coro = self.func(*args, **kw)
if asyncio.iscoroutine(coro):
self.task = asyncio.Task(coro)
else:
self.task = coro
return schedule_task(self._start(old))
async def wait(self):
while True:
try:
return await self.task
except asyncio.CancelledError:
pass
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