The recently-added test currently systematically deadlocks when running
it under i686 Windows 7, but not x86_64 that passes it fine. This
therefore fixes the test for the target.
Empirically, the correct value for `MAX_READERS` seems to be `2^28 - 1`:
removing the `- 1` re-introduces the deadlock, at least under our
testing environment. This fix thus uses this value. However, I have no
real justification to support that, because I find myself a bit at a
loss when comparing the implementation details, the comment added above
the test and what the current value is; some help would therefore be
nice in this aspect. Also, the value change is restricted to 32-bit Win7
as there is no evidence to support it should be done for other targets.
Signed-off-by: Paul Mabileau <paul.mabileau@harfanglab.fr>
Clarified docs in std::sync::RwLock + added test to ensure that max reader count is respected
This addresses the issue with the [`std::sync::RwLock` docs](https://doc.rust-lang.org/std/sync/struct.RwLock.html) in rust-lang/rust#115338. It centers around the following lines:
> An `RwLock` will allow any number of readers to acquire the lock as long as a writer is not holding the lock.
It's true that the `RwLock` in theory should allow any number of readers to acquire the lock when a writer is not holding it, but this may not be true in the implementation and could be os dependent. I decided to replace "any number of readers" to "multiple", so that it implies that more than 1 reader can acquire the lock, but you can't necessarily take away that this value is unbounded.
@rustbot label +A-docs
Since non-poisoning `Condvar` take non-poisoing `Mutex`es when
`wait`ing, we do not need to take by ownership since a poison error
cannot occur while we wait.
Signed-off-by: Connor Tsui <connor.tsui20@gmail.com>
Setup for writing different tests for the `nonpoison::Condvar` since it
will have a different API.
Signed-off-by: Connor Tsui <connor.tsui20@gmail.com>
Stabilize `rwlock_downgrade` library feature
Tracking Issue: https://github.com/rust-lang/rust/issues/128203
Method to be stabilized:
```rust
impl<'a, T: ?Sized> RwLockWriteGuard<'a, T> {
pub fn downgrade(s: Self) -> RwLockReadGuard<'a, T> {}
}
```
~~I would like to point out that my documentation comment is longer than ideal, but at the same time I don't really know how else to show why `downgrade` is actually necessary (instead of just unlocking and relocking). If anyone has ideas for making this more concise that would be great!~~ I have made the documentation a bit more clear.
Stabilization report: https://github.com/rust-lang/rust/issues/128203#issuecomment-3016682463
Implementation: `#[feature(nonpoison_condvar)]`
Tracking Issue: https://github.com/rust-lang/rust/issues/134645
This PR continues the effort made in https://github.com/rust-lang/rust/pull/144022 by adding the implementation of `nonpoison::condvar`.
Many of the changes here are similar to the changes made to implement `nonpoison::mutex`.
There are two other changes here. The first is that the `Barrier` implementation is migrated to use the `nonpoison::Condvar` instead of the `poison` variant. The second (which might be subject to some discussion) is that `WaitTimeoutResult` is moved up to `mod.rs`, as both `condvar` variants need that type (and I do not know if there is a better place to put it now).
### Related PRs
- `nonpoison_rwlock` implementation: https://github.com/rust-lang/rust/pull/144648
- `nonpoison_once` implementation: https://github.com/rust-lang/rust/pull/144653
Adds tests for the `nonpoison::Mutex` variant by using a macro to
duplicate the existing `poison` tests.
Note that all of the tests here are adapted from the existing `poison`
tests.
Also steals the `test_mutex_arc_condvar` test from `mutex.rs`.
Signed-off-by: Connor Tsui <connor.tsui20@gmail.com>
Fixes an issue where if the underlying `Once` panics because it is
poisoned, the panic displays the wrong message.
Signed-off-by: Connor Tsui <connor.tsui20@gmail.com>
Adds tests for the `nonpoison::RwLock` variant by using a macro to
duplicate the existing `poison` tests.
Note that all of the tests here are adapted from the existing `poison`
tests.
Adds tests for the `nonpoison::Mutex` variant by using a macro to
duplicate the existing `poison` tests.
Note that all of the tests here are adapted from the existing `poison`
tests.
This recently spuriously failed in a rollup, so I think we can afford to
increase the base timeout and the amount of time slept for to provide
a much wider margin for the timeout to be reached.
`stress_recv_timeout_two_threads`, in the mpmc and mpsc testsuites,
is a stress test of the `recv_timeout` function. This test processes and
ignores timeouts, and just ensures that every sent value gets received.
As such, the exact length of the timeouts is not critical, only that
the timeout and sleep durations ensure that at least one timeout
occurred.
The current tests have 100 iterations, half of which sleep for 200ms,
causing the test to take 10s. This represents around 2/3rds of the
*total* runtime of the `library/std` testsuite.
Reduce this to 50 iterations where half of them sleep for 10ms, causing
the test to take 0.25s.
Add a check that at least one timeout occurred.
This allows these test modules to pass on builds/targets without
unwinding support, where `panic = "abort"` - the ignored tests are for
functionality that's not supported on those targets.
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.
Jonathan Brouwer