std: use `sync::RwLock` for internal statics by joboet · Pull Request #100581 · rust-lang/rust

joboet · 2022-08-15T12:34:14Z

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 · 2022-08-15T12:34:17Z

r? @m-ou-se

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rustbot · 2022-08-15T12:34:17Z

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 · 2022-09-18T15:46:08Z

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 · 2022-09-18T16:18:25Z

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 · 2022-09-18T16:23:43Z

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 · 2022-09-18T16:23:44Z

📌 Commit 25cc0ce3c3eed6278bdeed9eddca8dc43ea55002 has been approved by thomcc

It is now in the queue for this repository.

bors · 2022-09-18T22:40:31Z

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

bors · 2022-09-18T22:57:51Z

💔 Test failed - checks-actions

thomcc · 2022-09-19T20:24:20Z

@rustbot author

joboet · 2022-09-19T21:28:08Z

@rustbot ready

thomcc · 2022-09-19T21:29:04Z

@bors r+

bors · 2022-09-19T21:29:06Z

📌 Commit be09a4a has been approved by thomcc

It is now in the queue for this repository.

thomcc · 2022-09-19T21:29:52Z

And for good measure,

@bors delegate+

bors · 2022-09-19T21:29:54Z

✌️ @joboet can now approve this pull request

bors · 2022-09-20T16:12:47Z

⌛ Testing commit be09a4a with merge 4456640f3e841eacc29fc3ecd88718c03bd0fcce...

bors · 2022-09-20T16:16:30Z

💔 Test failed - checks-actions

joboet · 2022-09-20T17:01:24Z

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

bors · 2022-09-20T17:01:26Z

💡 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 · 2022-09-20T17:01:27Z

📌 Commit be09a4a has been approved by thomcc

It is now in the queue for this repository.

bors · 2022-09-20T22:00:12Z

⌛ Testing commit be09a4a with merge 7743aa8...

bors · 2022-09-21T00:41:27Z

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

rust-timer · 2022-09-21T02:21:36Z

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

the arithmetic mean of the percent change ↩ ↩²
number of relevant changes ↩ ↩²

rust-log-analyzer · 2022-09-21T06:26:46Z

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

Click to see the possible cause of the failure (guessed by this bot)

rust-highfive assigned m-ou-se Aug 15, 2022

rustbot added the T-libs Relevant to the library team, which will review and decide on the PR/issue. label Aug 15, 2022

rust-highfive added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Aug 15, 2022

joboet mentioned this pull request Aug 15, 2022

Do not wrap platform locks in sys_common #100505

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thomcc mentioned this pull request Sep 18, 2022

std: use sync::Mutex for internal statics #100579

Merged

rust-highfive assigned thomcc and unassigned m-ou-se Sep 18, 2022

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rustbot added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Sep 19, 2022

std: use sync::RwLock for internal statics

be09a4a

joboet force-pushed the sync_rwlock_everywhere branch from 25cc0ce to be09a4a Compare September 19, 2022 21:27

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bors added the merged-by-bors This PR was explicitly merged by bors. label Sep 21, 2022

bors merged commit 7743aa8 into rust-lang:master Sep 21, 2022

rustbot added this to the 1.66.0 milestone Sep 21, 2022

bors mentioned this pull request Sep 21, 2022

Reduce CString allocations in std as much as possible #93668

Merged

joboet deleted the sync_rwlock_everywhere branch September 21, 2022 10:39

joboet mentioned this pull request Sep 29, 2022

Allow compiling the wasm32-wasi std library with atomics #102372

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Overall result: no relevant changes - no action needed

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