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Weaken needlessly restrictive orderings on Arc::*_count #115546

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bors merged 1 commit into from
Sep 30, 2023
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Weaken needlessly restrictive orderings on Arc::*_count #115546

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Weaken needlessly restrictive orderings on Arc::*_count 
Signed-off-by: Alex Saveau <[email protected]>
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@SUPERCILEX
SUPERCILEX committed Sep 4, 2023
commit 4c2f1c615b976fcd21f6cc2078b09d10c9d72507
8 changes: 4 additions & 4 deletions library/alloc/src/sync.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1616,7 +1616,7 @@ impl<T: ?Sized, A: Allocator> Arc<T, A> {
#[must_use]
#[stable(feature = "arc_counts", since = "1.15.0")]
pub fn weak_count(this: &Self) -> usize {
let cnt = this.inner().weak.load(Acquire);
let cnt = this.inner().weak.load(Relaxed);
// If the weak count is currently locked, the value of the
// count was 0 just before taking the lock.
if cnt == usize::MAX { 0 } else { cnt - 1 }
Expand Down Expand Up @@ -1646,7 +1646,7 @@ impl<T: ?Sized, A: Allocator> Arc<T, A> {
#[must_use]
#[stable(feature = "arc_counts", since = "1.15.0")]
pub fn strong_count(this: &Self) -> usize {
this.inner().strong.load(Acquire)
this.inner().strong.load(Relaxed)
}

/// Increments the strong reference count on the `Arc<T>` associated with the
Expand Down Expand Up @@ -2801,7 +2801,7 @@ impl<T: ?Sized, A: Allocator> Weak<T, A> {
#[must_use]
#[stable(feature = "weak_counts", since = "1.41.0")]
pub fn strong_count(&self) -> usize {
if let Some(inner) = self.inner() { inner.strong.load(Acquire) } else { 0 }
if let Some(inner) = self.inner() { inner.strong.load(Relaxed) } else { 0 }
}

/// Gets an approximation of the number of `Weak` pointers pointing to this
Expand All @@ -2820,7 +2820,7 @@ impl<T: ?Sized, A: Allocator> Weak<T, A> {
pub fn weak_count(&self) -> usize {
if let Some(inner) = self.inner() {
let weak = inner.weak.load(Acquire);
let strong = inner.strong.load(Acquire);
let strong = inner.strong.load(Relaxed);
if strong == 0 {
0
} else {
Expand Down