Skip to content

Commit

Permalink
Rollup merge of rust-lang#80966 - KodrAus:deprecate/spin_loop_hint, r…
Browse files Browse the repository at this point in the history
…=m-ou-se

Deprecate atomic::spin_loop_hint in favour of hint::spin_loop

For rust-lang#55002

We wanted to leave `atomic::spin_loop_hint` alone when stabilizing `hint::spin_loop` so folks had some time to migrate. This now deprecates `atomic_spin_loop_hint`.
  • Loading branch information
m-ou-se authored Jan 14, 2021
2 parents c0c379a + d65cb6e commit de47f47
Show file tree
Hide file tree
Showing 4 changed files with 19 additions and 20 deletions.
2 changes: 1 addition & 1 deletion library/alloc/src/sync/tests.rs
Original file line number Diff line number Diff line change
Expand Up @@ -370,7 +370,7 @@ fn test_weak_count_locked() {
let n = Arc::weak_count(&a2);
assert!(n < 2, "bad weak count: {}", n);
#[cfg(miri)] // Miri's scheduler does not guarantee liveness, and thus needs this hint.
atomic::spin_loop_hint();
std::hint::spin_loop();
}
t.join().unwrap();
}
Expand Down
27 changes: 12 additions & 15 deletions library/core/src/sync/atomic.rs
Original file line number Diff line number Diff line change
Expand Up @@ -120,21 +120,6 @@ use crate::intrinsics;

use crate::hint::spin_loop;

/// Signals the processor that it is inside a busy-wait spin-loop ("spin lock").
///
/// This function is expected to be deprecated in favor of
/// [`hint::spin_loop`].
///
/// **Note**: On platforms that do not support receiving spin-loop hints this function does not
/// do anything at all.
///
/// [`hint::spin_loop`]: crate::hint::spin_loop
#[inline]
#[stable(feature = "spin_loop_hint", since = "1.24.0")]
pub fn spin_loop_hint() {
spin_loop()
}

/// A boolean type which can be safely shared between threads.
///
/// This type has the same in-memory representation as a [`bool`].
Expand Down Expand Up @@ -2791,3 +2776,15 @@ impl<T> fmt::Pointer for AtomicPtr<T> {
fmt::Pointer::fmt(&self.load(Ordering::SeqCst), f)
}
}

/// Signals the processor that it is inside a busy-wait spin-loop ("spin lock").
///
/// This function is deprecated in favor of [`hint::spin_loop`].
///
/// [`hint::spin_loop`]: crate::hint::spin_loop
#[inline]
#[stable(feature = "spin_loop_hint", since = "1.24.0")]
#[rustc_deprecated(since = "1.51.0", reason = "use hint::spin_loop instead")]
pub fn spin_loop_hint() {
spin_loop()
}
5 changes: 3 additions & 2 deletions library/std/src/sys/hermit/mutex.rs
Original file line number Diff line number Diff line change
@@ -1,9 +1,10 @@
use crate::cell::UnsafeCell;
use crate::collections::VecDeque;
use crate::ffi::c_void;
use crate::hint;
use crate::ops::{Deref, DerefMut, Drop};
use crate::ptr;
use crate::sync::atomic::{spin_loop_hint, AtomicUsize, Ordering};
use crate::sync::atomic::{AtomicUsize, Ordering};
use crate::sys::hermit::abi;

/// This type provides a lock based on busy waiting to realize mutual exclusion
Expand Down Expand Up @@ -46,7 +47,7 @@ impl<T> Spinlock<T> {
fn obtain_lock(&self) {
let ticket = self.queue.fetch_add(1, Ordering::SeqCst) + 1;
while self.dequeue.load(Ordering::SeqCst) != ticket {
spin_loop_hint();
hint::spin_loop();
}
}

Expand Down
5 changes: 3 additions & 2 deletions library/std/src/sys/sgx/waitqueue/spin_mutex.rs
Original file line number Diff line number Diff line change
Expand Up @@ -2,8 +2,9 @@
mod tests;

use crate::cell::UnsafeCell;
use crate::hint;
use crate::ops::{Deref, DerefMut};
use crate::sync::atomic::{spin_loop_hint, AtomicBool, Ordering};
use crate::sync::atomic::{AtomicBool, Ordering};

#[derive(Default)]
pub struct SpinMutex<T> {
Expand Down Expand Up @@ -32,7 +33,7 @@ impl<T> SpinMutex<T> {
match self.try_lock() {
None => {
while self.lock.load(Ordering::Relaxed) {
spin_loop_hint()
hint::spin_loop()
}
}
Some(guard) => return guard,
Expand Down

0 comments on commit de47f47

Please sign in to comment.