Refactor connection waiters to be cancellation safe

[bdraco]

A deadlock that could occur while attempting to get a new connection slot after a timeout.

The connector was not cancellation-safe.

fixes #9670

will need to backport #9600 to 3.10 as well

[codspeed-hq]

CodSpeed Performance Report

Merging #9671 will not alter performance

_{Comparing race_safe_waiter (72c1cba) with master (5b654d5)}

Summary

✅ 13 untouched benchmarks

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 98.65%. Comparing base (5b654d5) to head (72c1cba).
Report is 1 commits behind head on master.

✅ All tests successful. No failed tests found.

Additional details and impacted files

@@           Coverage Diff            @@
##           master    #9671    +/-   ##
========================================
  Coverage   98.65%   98.65%            
========================================
  Files         116      116            
  Lines       35482    35594   +112     
  Branches     4211     4221    +10     
========================================
+ Hits        35003    35116   +113     
  Misses        321      321            
+ Partials      158      157     -1     

Flag	Coverage Δ
CI-GHA	98.54% <100.00%> (+<0.01%)	⬆️
OS-Linux	98.21% <100.00%> (+<0.01%)	⬆️
OS-Windows	96.11% <100.00%> (+0.01%)	⬆️
OS-macOS	97.42% <100.00%> (+0.02%)	⬆️
Py-3.10.11	97.28% <99.56%> (+0.01%)	⬆️
Py-3.10.15	97.70% <99.56%> (+0.01%)	⬆️
Py-3.11.10	97.76% <100.00%> (+0.01%)	⬆️
Py-3.11.9	97.35% <100.00%> (+<0.01%)	⬆️
Py-3.12.7	98.24% <100.00%> (+<0.01%)	⬆️
Py-3.13.0	98.23% <100.00%> (+<0.01%)	⬆️
Py-3.9.13	97.18% <100.00%> (+0.01%)	⬆️
Py-3.9.20	97.61% <100.00%> (+0.01%)	⬆️
Py-pypy7.3.16	97.23% <100.00%> (+0.01%)	⬆️
VM-macos	97.42% <100.00%> (+0.02%)	⬆️
VM-ubuntu	98.21% <100.00%> (+<0.01%)	⬆️
VM-windows	96.11% <100.00%> (+0.01%)	⬆️

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[bdraco]

#9670 No longer reproducible with these changes .. but now we can go over the limit.

Previously it was over-enforcing. Now its under-enforcing

[bdraco]

The core problem is we have three sources of truth for limits and there is no synchronization between them

self._acquired, self._acquired_per_host, self._waiters

[bdraco]

Any await after calling self._available_connections invalidates it because it could change after that

[bdraco]

This is turning out to be really hard to fix with the current design

[bdraco]

Still a tiny perf regression in _get from calling it more often

[bdraco]

Testing looks good, and it looks like we aren't regressing performance now

[patchback]

Backport to 3.10: 💔 cherry-picking failed — conflicts found

❌ Failed to cleanly apply 37d9fe6 on top of patchback/backports/3.10/37d9fe68387e3672604ff5b183f48538bca34f16/pr-9671

Backporting merged PR #9671 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/3.10/37d9fe68387e3672604ff5b183f48538bca34f16/pr-9671 upstream/3.10

4. Now, cherry-pick PR Refactor connection waiters to be cancellation safe #9671 contents into that branch:

   $ git cherry-pick -x 37d9fe68387e3672604ff5b183f48538bca34f16

   If it'll yell at you with something like fatal: Commit 37d9fe68387e3672604ff5b183f48538bca34f16 is a merge but no -m option was given., add -m 1 as follows instead:

   $ git cherry-pick -m1 -x 37d9fe68387e3672604ff5b183f48538bca34f16

5. At this point, you'll probably encounter some merge conflicts. You must
   resolve them in to preserve the patch from PR Refactor connection waiters to be cancellation safe #9671 as close to the
   original as possible.
6. Push this branch to your fork on GitHub:

   $ git push origin patchback/backports/3.10/37d9fe68387e3672604ff5b183f48538bca34f16/pr-9671

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 3.11: 💔 cherry-picking failed — conflicts found

❌ Failed to cleanly apply 37d9fe6 on top of patchback/backports/3.11/37d9fe68387e3672604ff5b183f48538bca34f16/pr-9671

Backporting merged PR #9671 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/3.11/37d9fe68387e3672604ff5b183f48538bca34f16/pr-9671 upstream/3.11

4. Now, cherry-pick PR Refactor connection waiters to be cancellation safe #9671 contents into that branch:

   $ git cherry-pick -x 37d9fe68387e3672604ff5b183f48538bca34f16

   If it'll yell at you with something like fatal: Commit 37d9fe68387e3672604ff5b183f48538bca34f16 is a merge but no -m option was given., add -m 1 as follows instead:

   $ git cherry-pick -m1 -x 37d9fe68387e3672604ff5b183f48538bca34f16

5. At this point, you'll probably encounter some merge conflicts. You must
   resolve them in to preserve the patch from PR Refactor connection waiters to be cancellation safe #9671 as close to the
   original as possible.
6. Push this branch to your fork on GitHub:

   $ git push origin patchback/backports/3.11/37d9fe68387e3672604ff5b183f48538bca34f16/pr-9671

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.