Aren't you able to catch the cancellation error and retrieve the data from the inner task's .result()?
On Wed, Jul 31, 2019, 8:00 AM Guido van Rossum <gu...@python.org> wrote: > I wonder if Nathaniel has something to add? Trio has a different approayto > cancellation. Of course it is also an entirely new library... > > On Tue, Jul 30, 2019 at 9:51 PM <aurelien.lambert...@gmail.com> wrote: > >> Oh only now it appears in the list ! I thought the post hadn't working, >> so I posted again :/. >> >> I've fixed my "library" ( >> https://github.com/aure-olli/aiokafka/blob/3acb88d6ece4502a78e230b234f47b90b9d30fd5/syncio.py), >> and the `wrapped_consumer2` function. Now no double await, so no risk of >> afterward cancellation. >> >> stop_future = asyncio.Future() >> async def wrapped_consumer2(): >> task = asyncio.ensure_future(consume_data()) >> try: >> await asyncio.wait([task, stop_future]) >> finally: >> task.cancel() >> if not task.cancelled(): >> return task.result() >> else: >> raise RuntimeError('stopped') >> >> Or >> >> import syncio >> >> async def wrapped_consumer(): >> task = syncio.ensure_sync_future(consume_data()) >> return await task >> >> stop_future = asyncio.Future() >> async def wrapped_consumer2(): >> task = syncio.ensure_sync_future(consume_data()) >> try: >> await syncio.sync_wait([task, stop_future]) >> finally: >> task.cancel() >> if not task.cancelled(): >> return task.result() >> else: >> raise RuntimeError('stopped') >> >> My only concern is that consistent cancellation state is currently almost >> impossible with futures and tasks. The only two possibilities are either to >> ignore cancellation (highly counter intuitive to use), or to directly >> manipulate the coroutine as a generator (basically rewriting asyncio). >> >> Could be another library for sure, but the current state of asyncio makes >> it really hard to reuse it. So it would mean copy-pasting the whole library >> while changing few lines here and there. >> _______________________________________________ >> Python-ideas mailing list -- python-ideas@python.org >> To unsubscribe send an email to python-ideas-le...@python.org >> https://mail.python.org/mailman3/lists/python-ideas.python.org/ >> Message archived at >> https://mail.python.org/archives/list/python-ideas@python.org/message/4GROXASMFVVRG3UDB4LVMDXOQPU3KH5V/ >> Code of Conduct: http://python.org/psf/codeofconduct/ >> > -- > --Guido (mobile) > _______________________________________________ > Python-ideas mailing list -- python-ideas@python.org > To unsubscribe send an email to python-ideas-le...@python.org > https://mail.python.org/mailman3/lists/python-ideas.python.org/ > Message archived at > https://mail.python.org/archives/list/python-ideas@python.org/message/VMRGZQT6TX5TPEB2OKLLRMREW3SZCXNF/ > Code of Conduct: http://python.org/psf/codeofconduct/ >
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