Avoid constructing headers mulitidict twice for web.Response

[bdraco]

web.Response constructed the headers CIMultiDict, and than passed it to web.StreamResponse which would construct a new CIMultiDict from the one that was just built in web.Response and than throw away the first constructed one.

[codspeed-hq]

CodSpeed Performance Report

Merging #10043 will improve performances by 14.7%

_{Comparing avoid_double_headers_copy (21753f6) with master (6f4e961)}

Summary

⚡ 1 improvements
✅ 43 untouched benchmarks

Benchmarks breakdown

	Benchmark	master	avoid_double_headers_copy	Change
⚡	test_web_response_with_headers	1.3 ms	1.1 ms	+14.7%

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 98.73%. Comparing base (65dab0e) to head (21753f6).
Report is 2777 commits behind head on master.

✅ All tests successful. No failed tests found.

Additional details and impacted files

@@            Coverage Diff             @@
##           master   #10043      +/-   ##
==========================================
+ Coverage   98.03%   98.73%   +0.69%     
==========================================
  Files         122      121       -1     
  Lines       36930    36768     -162     
  Branches     4449     4393      -56     
==========================================
+ Hits        36205    36303      +98     
+ Misses        543      314     -229     
+ Partials      182      151      -31     

Flag	Coverage Δ
CI-GHA	98.62% <100.00%> (+0.69%)	⬆️
OS-Linux	98.31% <100.00%> (+0.67%)	⬆️
OS-Windows	96.14% <100.00%> (+1.61%)	⬆️
OS-macOS	97.41% <100.00%> (+0.65%)	⬆️
Py-3.10.11	97.25% <100.00%> (+0.65%)	⬆️
Py-3.10.15	97.85% <100.00%> (+0.70%)	⬆️
Py-3.11.10	97.89% <100.00%> (+0.68%)	⬆️
Py-3.11.9	97.31% <100.00%> (+0.64%)	⬆️
Py-3.12.7	98.37% <100.00%> (+0.66%)	⬆️
Py-3.13.0	98.35% <100.00%> (+0.67%)	⬆️
Py-3.9.13	97.18% <100.00%> (+0.63%)	⬆️
Py-3.9.20	97.72% <100.00%> (+0.64%)	⬆️
Py-pypy7.3.16	97.33% <100.00%> (+0.66%)	⬆️
VM-macos	97.41% <100.00%> (+0.65%)	⬆️
VM-ubuntu	98.31% <100.00%> (+0.67%)	⬆️
VM-windows	96.14% <100.00%> (+1.61%)	⬆️

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[patchback]

Backport to 3.11: 💔 cherry-picking failed — conflicts found

❌ Failed to cleanly apply 5255cec on top of patchback/backports/3.11/5255cecfe73c2be59e7e207449783635f4b978a2/pr-10043

Backporting merged PR #10043 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/3.11/5255cecfe73c2be59e7e207449783635f4b978a2/pr-10043 upstream/3.11

4. Now, cherry-pick PR Avoid constructing headers mulitidict twice for web.Response #10043 contents into that branch:

   $ git cherry-pick -x 5255cecfe73c2be59e7e207449783635f4b978a2

   If it'll yell at you with something like fatal: Commit 5255cecfe73c2be59e7e207449783635f4b978a2 is a merge but no -m option was given., add -m 1 as follows instead:

   $ git cherry-pick -m1 -x 5255cecfe73c2be59e7e207449783635f4b978a2

5. At this point, you'll probably encounter some merge conflicts. You must
   resolve them in to preserve the patch from PR Avoid constructing headers mulitidict twice for web.Response #10043 as close to the
   original as possible.
6. Push this branch to your fork on GitHub:

   $ git push origin patchback/backports/3.11/5255cecfe73c2be59e7e207449783635f4b978a2/pr-10043

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 3.12: 💔 cherry-picking failed — conflicts found

❌ Failed to cleanly apply 5255cec on top of patchback/backports/3.12/5255cecfe73c2be59e7e207449783635f4b978a2/pr-10043

Backporting merged PR #10043 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/3.12/5255cecfe73c2be59e7e207449783635f4b978a2/pr-10043 upstream/3.12

4. Now, cherry-pick PR Avoid constructing headers mulitidict twice for web.Response #10043 contents into that branch:

   $ git cherry-pick -x 5255cecfe73c2be59e7e207449783635f4b978a2

   If it'll yell at you with something like fatal: Commit 5255cecfe73c2be59e7e207449783635f4b978a2 is a merge but no -m option was given., add -m 1 as follows instead:

   $ git cherry-pick -m1 -x 5255cecfe73c2be59e7e207449783635f4b978a2

5. At this point, you'll probably encounter some merge conflicts. You must
   resolve them in to preserve the patch from PR Avoid constructing headers mulitidict twice for web.Response #10043 as close to the
   original as possible.
6. Push this branch to your fork on GitHub:

   $ git push origin patchback/backports/3.12/5255cecfe73c2be59e7e207449783635f4b978a2/pr-10043

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.