std: use sync::RwLock for internal statics

[joboet]

Since sync::RwLock is now const-constructible, it can be used for internal statics, removing the need for sys_common::StaticRwLock. This adds some extra allocations on platforms which need to box their locks (currently SGX and some UNIX), but these will become unnecessary with the lock improvements tracked in #93740.

[rust-highfive]

r? @m-ou-se

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[rustbot]

Hey! It looks like you've submitted a new PR for the library teams!

If this PR contains changes to any rust-lang/rust public library APIs then please comment with @rustbot label +T-libs-api -T-libs to tag it appropriately. If this PR contains changes to any unstable APIs please edit the PR description to add a link to the relevant API Change Proposal or create one if you haven't already. If you're unsure where your change falls no worries, just leave it as is and the reviewer will take a look and make a decision to forward on if necessary.

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[thomcc]

I'm not a fan of making this change (or the one in #100579). Can we instead change StaticMutex/StaticRwlock to use the locks internally on platforms where that impl isn't worse?

[thomcc]

It looks like we use this for the environment lock, and for the panic hook. I don't really feel like either of these are likely to be hot enough for the extra allocation to matter, so I'm not sure how much I actually care here now that I look.

r? @thomcc

[thomcc]

This looks fine. This does actually introduce a branch even on OSes with the good locks (due to the poison error handling). I doubt it matters but is probably worth preventing a rollup as a result.

@bors r+ rollup=never

[bors]

📌 Commit 25cc0ce3c3eed6278bdeed9eddca8dc43ea55002 has been approved by thomcc

It is now in the queue for this repository.

[bors]

⌛ Testing commit 25cc0ce3c3eed6278bdeed9eddca8dc43ea55002 with merge 0f66914ea522ad0920154b14127447512a361cf0...

[bors]

💔 Test failed - checks-actions

[thomcc]

@rustbot author

[joboet]

@rustbot ready

[thomcc]

@bors r+

[bors]

📌 Commit be09a4a has been approved by thomcc

It is now in the queue for this repository.

[thomcc]

And for good measure,

@bors delegate+

[bors]

✌️ @joboet can now approve this pull request

[bors]

⌛ Testing commit be09a4a with merge 4456640f3e841eacc29fc3ecd88718c03bd0fcce...

[bors]

💔 Test failed - checks-actions

[joboet]

That looks like a spurious failure...
@bors r=thomcc

[bors]

💡 This pull request was already approved, no need to approve it again.

• This pull request previously failed. You should add more commits to fix the bug, or use retry to trigger a build again.
• There's another pull request that is currently being tested, blocking this pull request: make projection bounds with const bounds satisfy const #101989

[bors]

📌 Commit be09a4a has been approved by thomcc

It is now in the queue for this repository.

[bors]

⌛ Testing commit be09a4a with merge 7743aa8...

[bors]

☀️ Test successful - checks-actions
Approved by: thomcc
Pushing 7743aa8 to master...

[rust-timer]

Finished benchmarking commit (7743aa8): comparison URL.

Overall result: no relevant changes - no action needed

@rustbot label: -perf-regression

Instruction count

This benchmark run did not return any relevant results for this metric.

Max RSS (memory usage)

Results

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

	mean1	range	count2
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-5.3%	[-5.3%, -5.3%]	1
Improvements ✅ (secondary)	-2.8%	[-3.5%, -1.5%]	3
All ❌✅ (primary)	-5.3%	[-5.3%, -5.3%]	1

Cycles

Results

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

	mean1	range	count2
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-2.3%	[-2.5%, -2.0%]	2
All ❌✅ (primary)	-	-	0

Footnotes

1. the arithmetic mean of the percent change ↩ ↩²

2. number of relevant changes ↩ ↩²

[rust-log-analyzer]

A job failed! Check out the build log: (web) (plain)

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