relax a memory order in once_box · qinheping/verify-rust-std@e35d9fe (original) (raw)
`@@ -8,7 +8,7 @@
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`use crate::mem::replace;
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`use crate::ptr::null_mut;
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`use crate::sync::atomic::AtomicPtr;
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``
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use crate::sync::atomic::Ordering::{AcqRel, Acquire, Relaxed};
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`+
use crate::sync::atomic::Ordering::{Acquire, Relaxed, Release};
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``
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`pub(crate) struct OnceBox {
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`ptr: AtomicPtr,
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`@@ -60,7 +60,7 @@ impl OnceBox {
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`#[cold]
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`fn initialize(&self, f: impl FnOnce() -> Box) -> &T {
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`let new_ptr = Box::into_raw(f());
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``
`-
match self.ptr.compare_exchange(null_mut(), new_ptr, AcqRel, Acquire) {
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`+
match self.ptr.compare_exchange(null_mut(), new_ptr, Release, Acquire) {
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`Ok(_) => unsafe { &*new_ptr },
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`Err(ptr) => {
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`// Lost the race to another thread.
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