CodSpeed Performance Report

Merging #5396 will improve performances by 42.29%

_{Comparing jasnell/http-headers-take-2 (1e23169) with main (7fa38f9)}

Summary

⚡ 2 improvements
✅ 32 untouched
⏩ 9 skipped¹

Benchmarks breakdown

Internal tests are failing because the refactor changes the ordering of the headers in places... will need to see if we can preserve the order but first want to see if this has a positive impact on performance overall... waiting for benchmark results to be updated.

Marking as ready for review but there are still some internal test updates I'll need to do on the internal repo.

Whenever this is done I want as many reviewers as we can get on this, incl Harris, Kenton, Mike, Yagiz, etc.

Note for reviewers: while it likely is possible to get more performance gain with additional tweaks on this, the emphasis for review should be on correctness and ensuring that the revised implementation does not introduce new bugs, etc. We can tweak additional performance knobs separately in follow up PRs.

Further improved the revised implementation and added an additional benchmark.

• The additional benchmark shows a ~31% performance improvement in a set/append case.
• The common headers are now indexed and hashed at compile time to shave off additional work
• jsg::ByteString is removed since it was largely a useless shell anyway. It's warning functionality was wasted on header names since we strictly validate those anyway, and has been replaced to only warn on header values. Given that use of jsg::ByteString was incurring an additional redundant scan on all header names and values this yielded a fairly good performance improvement.
• Additional improvements are likely possible but this is already quite significant as it is.

Whenever this is done I want as many reviewers as we can get on this, incl Harris, Kenton, Mike, Yagiz, etc.

Bumping this
@harrishancock @kentonv @mikea @anonrig we need as many eyes as we can get on this, we can't get this change wrong again, important to optimise headers but we need to make sure we are right with our change

@fhanau ... any advice on the linting issues here?