weaken needlessly restrictive orderings on Arc::*_count

This commit is contained in:
Ibraheem Ahmed 2022-03-21 17:32:00 -04:00
parent 4b043faba3
commit 7e93032726

View File

@ -25,7 +25,7 @@
#[cfg(not(no_global_oom_handling))]
use core::slice::from_raw_parts_mut;
use core::sync::atomic;
use core::sync::atomic::Ordering::{Acquire, Relaxed, Release, SeqCst};
use core::sync::atomic::Ordering::{Acquire, Relaxed, Release};
#[cfg(not(no_global_oom_handling))]
use crate::alloc::handle_alloc_error;
@ -970,7 +970,7 @@ pub fn downgrade(this: &Self) -> Weak<T> {
#[must_use]
#[stable(feature = "arc_counts", since = "1.15.0")]
pub fn weak_count(this: &Self) -> usize {
let cnt = this.inner().weak.load(SeqCst);
let cnt = this.inner().weak.load(Acquire);
// 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 }
@ -1000,7 +1000,7 @@ pub fn weak_count(this: &Self) -> usize {
#[must_use]
#[stable(feature = "arc_counts", since = "1.15.0")]
pub fn strong_count(this: &Self) -> usize {
this.inner().strong.load(SeqCst)
this.inner().strong.load(Acquire)
}
/// Increments the strong reference count on the `Arc<T>` associated with the
@ -1961,7 +1961,7 @@ pub fn upgrade(&self) -> Option<Arc<T>> {
#[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(SeqCst) } else { 0 }
if let Some(inner) = self.inner() { inner.strong.load(Acquire) } else { 0 }
}
/// Gets an approximation of the number of `Weak` pointers pointing to this
@ -1980,8 +1980,8 @@ pub fn strong_count(&self) -> usize {
pub fn weak_count(&self) -> usize {
self.inner()
.map(|inner| {
let weak = inner.weak.load(SeqCst);
let strong = inner.strong.load(SeqCst);
let weak = inner.weak.load(Acquire);
let strong = inner.strong.load(Acquire);
if strong == 0 {
0
} else {