# Copyright (C) 2016 VIB/BEG/UGent - Tim Diels <timdiels.m@gmail.com>
#
# This file is part of Chicken Turtle Util.
#
# Chicken Turtle Util is free software: you can redistribute it and/or modify
# it under the terms of the GNU Lesser General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# Chicken Turtle Util 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 Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public License
# along with Chicken Turtle Util. If not, see <http://www.gnu.org/licenses/>.
'''
Extensions to asyncio.
Requires Python >=3.5
'''
import asyncio
import logging
import traceback
_logger = logging.getLogger(__name__)
[docs]async def stubborn_gather(*awaitables):
'''
Stubbornly wait for awaitables, despite some of them raising
Like a more stubborn version of asyncio.gather.
Continue until all awaitables have finished or have raised. If one or more
awaitables raise, a new `Exception` is raised with the traceback and message
of each exception as message. However, if all exceptions raised are
`asyncio.CancelledError`, `asyncio.CancelledError` is raised instead.
If cancelled, cancels the (futures associated with the) awaitables.
Parameters
----------
awaitables : iterable(awaitable)
Awaitables to await
Returns
-------
results :: (any, ...)
Return of each awaitable. The return of ``awaitables[i]`` is ``results[i]``.
'''
if awaitables:
futures = [asyncio.ensure_future(awaitable) for awaitable in awaitables]
results = [None] * len(futures) # return values
exceptions = [] # [(future_index, exception_raised)]
# Await all and fill `results` and `exceptions`
pending = futures
while pending:
try:
done, pending = await asyncio.wait(pending, return_when=asyncio.FIRST_EXCEPTION)
for future in done:
i = futures.index(future)
ex = future.exception()
if ex:
_logger.error('stubborn_gather: Awaitable {} raised:\n{}'.format(i, _format_exception(ex)))
exceptions.append((i, ex))
else:
results[i] = future.result()
except asyncio.CancelledError:
for future in pending:
future.cancel()
raise
# Raise cancelled if all raised cancelled
if len(exceptions) == len(results) and all(isinstance(ex, asyncio.CancelledError) for _, ex in exceptions):
raise asyncio.CancelledError()
# Raise concatenation of exception messages if any raised
if exceptions:
formatted_exceptions = []
for i, ex in exceptions:
formatted_exceptions.append('Awaitable {}:\n{}'.format(i, _format_exception(ex)))
formatted_exceptions = '\n'.join(formatted_exceptions)
raise Exception('One or more awaitables raised an exception (not necessarily in this order):\n\n{}'.format(formatted_exceptions))
# Simply return results otherwise
return tuple(results)
return ()
def _format_exception(ex):
return ''.join(traceback.format_exception(ex.__class__, ex, ex.__traceback__))