| Age | Commit message (Collapse) | Author | Lines |
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std: use `sync::Mutex` for internal statics
Since `sync::Mutex` is now `const`-constructible, it can be used for internal statics, removing the need for `sys_common::StaticMutex`. This adds some extra allocations on platforms which need to box their mutexes (currently SGX and some UNIX), but these will become unnecessary with the lock improvements tracked in #93740.
I changed the program argument implementation on Hermit, it does not need `Mutex` but can use atomics like some UNIX systems (ping `@mkroening` `@stlankes).`
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Use semaphores for thread parking on Apple platforms
Currently we use a mutex-condvar pair for thread parking on Apple systems. Unfortunately, `pthread_cond_timedwait` uses the real-time clock for measuring time, which causes problems when the system time changes. The parking implementation in this PR uses a semaphore instead, which measures monotonic time by default, avoiding these issues. As a further benefit, this has the potential to improve performance a bit, since `unpark` does not need to wait for a lock to be released.
Since the Mach semaphores are poorly documented (I could not find availability or stability guarantees for instance), this uses a [dispatch semaphore](https://developer.apple.com/documentation/dispatch/dispatch_semaphore?language=objc) instead. While it adds a layer of indirection (it uses Mach semaphores internally), the overhead is probably negligible.
Tested on macOS 12.5.
r? ``````@thomcc``````
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sync thread_local key conditions exactly with what the macro uses
This makes the `cfg` in `mod.rs` syntactically the same as those in `local.rs`.
I don't think this should actually change anything, but seems better to be consistent?
I looked into this due to https://github.com/rust-lang/rust/issues/102549, but this PR would make it *less* likely that `__OsLocalKeyInner` is going to get provided, so this cannot help with that issue.
r? `@thomcc`
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scoped threads: pass closure through MaybeUninit to avoid invalid dangling references
The `main` function defined here looks roughly like this, if it were written as a more explicit stand-alone function:
```rust
// Not showing all the `'lifetime` tracking, the point is that
// this closure might live shorter than `thread`.
fn thread(control: ..., closure: impl FnOnce() + 'lifetime) {
closure();
control.signal_done();
// A lot of time can pass here.
}
```
Note that `thread` continues to run even after `signal_done`! Now consider what happens if the `closure` captures a reference of lifetime `'lifetime`:
- The type of `closure` is a struct (the implicit unnameable closure type) with a `&'lifetime mut T` field. References passed to a function are marked with `dereferenceable`, which is LLVM speak for *this reference will remain live for the entire duration of this function*.
- The closure runs, `signal_done` runs. Then -- potentially -- this thread gets scheduled away and the main thread runs, seeing the signal and returning to the user. Now `'lifetime` ends and the memory the reference points to might be deallocated.
- Now we have UB! The reference that as passed to `thread` with the promise of remaining live for the entire duration of the function, actually got deallocated while the function still runs. Oops.
Long-term I think we should be able to use `ManuallyDrop` to fix this without `unsafe`, or maybe a new `MaybeDangling` type. I am working on an RFC for that. But in the mean time it'd be nice to fix this so that Miri with `-Zmiri-retag-fields` (which is needed for "full enforcement" of all the LLVM flags we generate) stops erroring on scoped threads.
Fixes https://github.com/rust-lang/rust/issues/101983
r? `@m-ou-se`
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Never panic in `thread::park` and `thread::park_timeout`
fixes #102398
`@rustbot` label +T-libs +T-libs-api
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Co-authored-by: yvt <i@yvt.jp>
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references
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Update docs so that deprecated method points to relevant method
The docs for the deprecated 'park_timeout_ms' method suggests that the user 'use park_timeout' method instead (at https://doc.rust-lang.org/std/thread/index.html).
Making a similar change so that the docs for the deprecated `sleep_ms` method suggest that the user `use sleep` method instead.
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Add cgroupv1 support to available_parallelism
Fixes #97549
My dev machine uses cgroup v2 so I was only able to test that code path. So the v1 code path is written only based on documentation. I could use some help testing that it works on a machine with cgroups v1:
```
$ x.py build --stage 1
# quota.rs
fn main() {
println!("{:?}", std::thread::available_parallelism());
}
# assuming stage1 is linked in rustup
$ rust +stage1 quota.rs
# spawn a new cgroup scope for the current user
$ sudo systemd-run -p CPUQuota="300%" --uid=$(id -u) -tdS
# should print Ok(3)
$ ./quota
```
If it doesn't work as expected an strace, the contents of `/proc/self/cgroups` and the structure of `/sys/fs/cgroups` would help.
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Co-authored-by: Josh Triplett <josh@joshtriplett.org>
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constuct -> construct
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Remove `#[rustc_deprecated]`
This removes `#[rustc_deprecated]` and introduces diagnostics to help users to the right direction (that being `#[deprecated]`). All uses of `#[rustc_deprecated]` have been converted. CI is expected to fail initially; this requires #95958, which includes converting `stdarch`.
I plan on following up in a short while (maybe a bootstrap cycle?) removing the diagnostics, as they're only intended to be short-term.
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Mutex and Condvar are being replaced by more efficient implementations, which need thread parking themselves (see #93740). Therefore use the pthread synchronization primitives directly. Also, avoid allocating because the Parker struct is being placed in an Arc anyways.
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This reverts commit 035a717ee8bf548868fb50b5c7ca562fc4a657a7, reversing
changes made to 761e8884858759b21f3374ad610494e68c087a38.
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This is now necessary because of deny(unsafe_op_in_unsafe_fn).
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This avoids 'unused unsafe' warnings when using this feature inside std.
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Fixes issue #95533
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Stabilize thread::is_finished
Closes #90470.
r? `@m-ou-se`
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Some things like the unwinders and system APIs are not fully conformant,
this only covers a lot of low-hanging fruit.
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