work around the changes in 3.11, eg asyncio.TimeoutError is an OSError, and IsolatedAsyncioTestCase calls set_event_loop differently

[graingert]

What do these changes do?

Fixes #6757

Are there changes in behavior for the user?

yeah, if someone overrides asyncSetUp/asyncTearDown in their tests it could cause confusion

Related issue number

Checklist

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[graingert]

might break it for 3.7, but probably possible to fix with a sys.version_info condition

[graingert]

@webknjaz I think this fixes the issue with TestCase, but now there's a TimeoutError problem instead

[graingert]

I think I've been a bit too liberal with my except TimeoutError clauses, it's only really needed if there's a timeout contextmanager or asyncio.wait_for in the try

[webknjaz]

Could you explain the is None check? Is it just a performance optimization? Why'd you drop the separate block idea?

[graingert]

So this is for the case when you get a real OSError with an errno that's also a TimeoutError

I thought about checking for type(TimeoutError.__cause__) is CancelledError but your timeout context manager doesn't set the cause and neither does _chain_future

Then to my dismay if you do:

a, b = socket.socketpair()
with a, b:
    a.settimeout(0.1)
    a.recv(1)

You still get a TimeoutError with a None .errno so there's no way to actually tell if you have a real operating system TimeoutError or a synthetic one from asyncio

This is why trio uses trio.TooSlowError so it's a bit more clear

[Dreamsorcerer]

Maybe worth checking if asyncio.timeout() has the same problem. We could start migrating from async-timeout to that in Python 3.11+.
https://docs.python.org/3.11/library/asyncio-task.html#timeouts

[graingert]

Would be good if we can all agree on some

class TooSlowError(asyncio.TimeoutError):
   ...

[Dreamsorcerer]

Ah, it still uses the same logic from async-timeout:
https://github.com/python/cpython/blob/main/Lib/asyncio/timeouts.py#L98

You'd have to take that up with the cpython issue tracker, or @asvetlov.

[graingert]

python/cpython#95830

[Dreamsorcerer]

So, if that gets merged, what does the code here become (assuming we've switched away from async-timeout)?

[graingert]

Fixing _chain_future needs to happen first, but we can check the __cause__ to see if it's an asyncio Timeout rather than an OS timeout

[Dreamsorcerer]

Note to self: After this is merged, we should remove .loop, asyncTearDown and asyncSetUp from master branch.

[Dreamsorcerer]

I think this looks fine as is, for a temporary fix to get 3.11 working. We can come back and update this with another PR once we can do the __cause__ check.

[patchback]

Backport to 3.8: 💔 cherry-picking failed — conflicts found

❌ Failed to cleanly apply 5bf9b4a on top of patchback/backports/3.8/5bf9b4aae7046704b418c16452c2d1ced934abfb/pr-6877

Backporting merged PR #6877 into master

1. Ensure you have a local repo clone of your fork. Unless you cloned it
   from the upstream, this would be your origin remote.
2. Make sure you have an upstream repo added as a remote too. In these
   instructions you'll refer to it by the name upstream. If you don't
   have it, here's how you can add it:

   $ git remote add upstream https://github.com/aio-libs/aiohttp.git

3. Ensure you have the latest copy of upstream and prepare a branch
   that will hold the backported code:

   $ git fetch upstream
   $ git checkout -b patchback/backports/3.8/5bf9b4aae7046704b418c16452c2d1ced934abfb/pr-6877 upstream/3.8

4. Now, cherry-pick PR work around the changes in 3.11, eg asyncio.TimeoutError is an OSError, and IsolatedAsyncioTestCase calls set_event_loop differently #6877 contents into that branch:

   $ git cherry-pick -x 5bf9b4aae7046704b418c16452c2d1ced934abfb

   If it'll yell at you with something like fatal: Commit 5bf9b4aae7046704b418c16452c2d1ced934abfb is a merge but no -m option was given., add -m 1 as follows intead:

   $ git cherry-pick -m1 -x 5bf9b4aae7046704b418c16452c2d1ced934abfb

5. At this point, you'll probably encounter some merge conflicts. You must
   resolve them in to preserve the patch from PR work around the changes in 3.11, eg asyncio.TimeoutError is an OSError, and IsolatedAsyncioTestCase calls set_event_loop differently #6877 as close to the
   original as possible.
6. Push this branch to your fork on GitHub:

   $ git push origin patchback/backports/3.8/5bf9b4aae7046704b418c16452c2d1ced934abfb/pr-6877

7. Create a PR, ensure that the CI is green. If it's not — update it so that
   the tests and any other checks pass. This is it!
   Now relax and wait for the maintainers to process your pull request
   when they have some cycles to do reviews. Don't worry — they'll tell you if
   any improvements are necessary when the time comes!

🤖 @patchback
I'm built with octomachinery and
my source is open — https://github.com/sanitizers/patchback-github-app.

[patchback]

Backport to 3.9: 💔 cherry-picking failed — conflicts found

❌ Failed to cleanly apply 5bf9b4a on top of patchback/backports/3.9/5bf9b4aae7046704b418c16452c2d1ced934abfb/pr-6877

Backporting merged PR #6877 into master

1. Ensure you have a local repo clone of your fork. Unless you cloned it
   from the upstream, this would be your origin remote.
2. Make sure you have an upstream repo added as a remote too. In these
   instructions you'll refer to it by the name upstream. If you don't
   have it, here's how you can add it:

   $ git remote add upstream https://github.com/aio-libs/aiohttp.git

3. Ensure you have the latest copy of upstream and prepare a branch
   that will hold the backported code:

   $ git fetch upstream
   $ git checkout -b patchback/backports/3.9/5bf9b4aae7046704b418c16452c2d1ced934abfb/pr-6877 upstream/3.9

4. Now, cherry-pick PR work around the changes in 3.11, eg asyncio.TimeoutError is an OSError, and IsolatedAsyncioTestCase calls set_event_loop differently #6877 contents into that branch:

   $ git cherry-pick -x 5bf9b4aae7046704b418c16452c2d1ced934abfb

   If it'll yell at you with something like fatal: Commit 5bf9b4aae7046704b418c16452c2d1ced934abfb is a merge but no -m option was given., add -m 1 as follows intead:

   $ git cherry-pick -m1 -x 5bf9b4aae7046704b418c16452c2d1ced934abfb

5. At this point, you'll probably encounter some merge conflicts. You must
   resolve them in to preserve the patch from PR work around the changes in 3.11, eg asyncio.TimeoutError is an OSError, and IsolatedAsyncioTestCase calls set_event_loop differently #6877 as close to the
   original as possible.
6. Push this branch to your fork on GitHub:

   $ git push origin patchback/backports/3.9/5bf9b4aae7046704b418c16452c2d1ced934abfb/pr-6877

7. Create a PR, ensure that the CI is green. If it's not — update it so that
   the tests and any other checks pass. This is it!
   Now relax and wait for the maintainers to process your pull request
   when they have some cycles to do reviews. Don't worry — they'll tell you if
   any improvements are necessary when the time comes!

🤖 @patchback
I'm built with octomachinery and
my source is open — https://github.com/sanitizers/patchback-github-app.

[webknjaz]

Backported as fd7a29e and ae40e98.

[webknjaz]

This bit needed to be recovered in aiohttp v3.8 to preserve the compatibility with Python 3.6: ef6a373.