Linkname removal (step 1)

[vmg]

Description

First step towards fixing #16015.

In this PR I've cleaned up to Atof routines, the internal strhash and the memory size calculator. The only remaining linkname usage in the hack package is to disable serialization randomness in ProtoBuf.

Related Issue(s)

• go:linkname (de)stabilization #16015

Checklist

• "Backport to:" labels have been added if this change should be back-ported to release branches
• If this change is to be back-ported to previous releases, a justification is included in the PR description
• Tests were added or are not required
• Did the new or modified tests pass consistently locally and on CI?
• Documentation was added or is not required

Deployment Notes

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[codecov]

Codecov Report

Attention: Patch coverage is 91.70984% with 16 lines in your changes are missing coverage. Please review.

Project coverage is 68.29%. Comparing base (d95ce48) to head (5098caa).
Report is 4 commits behind head on main.

Files	Patch %	Lines
go/mysql/fastparse/atof.go	94.16%	8 Missing ⚠️
go/hack/msize.go	66.66%	5 Missing ⚠️
go/mysql/fastparse/eisel_lemire.go	91.66%	3 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #16016      +/-   ##
==========================================
+ Coverage   68.27%   68.29%   +0.01%     
==========================================
  Files        1562     1564       +2     
  Lines      197319   197499     +180     
==========================================
+ Hits       134714   134876     +162     
- Misses      62605    62623      +18     

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[dbussink]

A bunch of copy paste from Go, but that seems like the right answer here!

[frouioui]

Does that mean that every time the go runtime changes for this file (and also the package strconv) we will need to re-copy the file?

[vmg]

For msize yes, that's the price of keeping our memory usage statistics accurate. FWIW, this file hasn't been changed in more than 5 years: the sizes of the GC allocations are pretty much settled at this point.

For strconv, no. We have adapted the function to parse exactly the syntax that MySQL expects, so we do not need to ever upgrade it in the future.

[frouioui]

Okay got it. I was worried these were changing often every x release, but if it has not for over 5 years that's nice