Document guarantees of poisoning
This mostly documents the current behavior of `Mutex` and `RwLock` (rust-lang/rust#143471) as imperfect. It's unlikely that the situation improves significantly in the future, and even if it does, the rules will probably be more complicated than "poisoning is completely reliable", so this is a conservative guarantee.
We also explicitly specify that `OnceLock` never poisons, even though it has an API similar to mutexes.
Fixesrust-lang/rust#143471 by improving documentation.
r? ``@Amanieu``
Adds the equivalent `nonpoison` types to the `poison::mutex` module.
These types and implementations are gated under the `nonpoison_mutex`
feature gate.
Also blesses the ui tests that now have a name conflicts (because these
types no longer have unique names). The full path distinguishes the
different types.
Co-authored-by: Aandreba <aandreba@gmail.com>
Co-authored-by: Trevor Gross <tmgross@umich.edu>
This mostly documents the current behavior of `Mutex` and `RwLock` as
imperfect. It's unlikely that the situation improves significantly in
the future, and even if it does, the rules will probably be more
complicated than "poisoning is completely reliable", so this is a
conservative guarantee.
We also explicitly specify that `OnceLock` never poisons, even though it
has an API similar to mutexes.
Clarify &mut-methods' docs on sync::OnceLock
Three small changes to the docs of `sync::OnceLock`:
* The docs for `OnceLock::take()` used to [say](https://doc.rust-lang.org/std/sync/struct.OnceLock.html#method.take) "**Safety** is guaranteed by requiring a mutable reference." (emphasis mine). While technically correct, imho its not necessary to even mention safety - as opposed to unsafety - here: Safety never comes up wrt `OnceLock`, as there is (currently) no way to interact with a `OnceLock` in an unsafe way; there are no unsafe methods on `OnceLock`, so there is "safety" guarantee required anywhere. What we simply meant to say is "**Synchronization** is guaranteed...".
* I've add that phrase to the other methods of `OnceLock` which take a `&mut self`, to highlight the fact that having a `&mut OnceLock` guarantees that synchronization with other threads is not required. This is the same as with [`Mutex::get_mut()`](https://doc.rust-lang.org/std/sync/struct.Mutex.html#method.get_mut), [`Cell::get_mut()`](https://doc.rust-lang.org/std/cell/struct.Cell.html#method.get_mut), and others.
* In that spirit, the half-sentence "or being initialized" was removed from `get_mut()`, as there is no way that the `OnceLock` is being initialized while we are holding `&mut` to it. Probably a copy&paste from `.get()`
Add data_ptr method to Mutex and RwLock
Implementation of https://github.com/rust-lang/rust/issues/140368 / https://github.com/rust-lang/libs-team/issues/531.
I tried to write a useful safety section about when it is safe to read or write through the returned pointers, but couldn't come up with something nice. Hoping this PR is still useful without that. I'm happy to add any doc strings other people come up with if needed before merge, of course.
Unresolved questions:
- Return a `LockResult` or not?
- Return `*mut T` like existing APIs (`Cell::as_ptr` / `MaybeUninit::as[_mut]_ptr` / `Vec::as_ptr` / ...) or be more precise and return `NonNull<T>`?
Implement (part of) ACP 429: add `DerefMut` to `Lazy[Cell/Lock]`
`DerefMut` is instantly stable, as a trait impl. That means this needs an FCP.
``@rustbot`` label +needs-fcp
https://github.com/rust-lang/libs-team/issues/429
sync::mpsc: prevent double free on `Drop`
This PR is fixing a regression introduced by #121646 that can lead to a double free when dropping the channel.
The details of the bug can be found in the corresponding crossbeam PR https://github.com/crossbeam-rs/crossbeam/pull/1187
Move some std tests to integration tests
Unit tests directly inside of standard library crates require a very fragile way of building that is hard to reproduce outside of bootstrap.
Follow up to https://github.com/rust-lang/rust/pull/133859
docs: Documented Send and Sync requirements for Mutex + MutexGuard
This an attempt to continue where #123225 left off.
I did some light clean up from the work done in that PR.
I also documented the `!Send` + `Sync` implementations for `MutexGuard` to the best of my knowledge.
Let me know if I got anything wrong 😄fixes#122856
cc: ``@IoaNNUwU``
r? ``@joboet``
This removes two minor OnceLock tests which test private methods. The
rest of the tests should be more than enough to catch mistakes in those
private methods. Also makes ReentrantLock::try_lock public. And finally
it makes the mpmc tests actually run.
