openharmony/third_party_rust_bytes
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use raw ptr for racy load and add comment (#289)

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Ralf Jung
2019-08-28 23:41:04 +02:00
committed by Carl Lerche
parent def58d121a
commit 25214da03f
1 changed files with 5 additions and 2 deletions
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src/bytes.rs
+5 -2
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@@ -1940,8 +1940,11 @@ impl Inner {
#[inline]
fn inline_len(&self) -> usize {
let p: &usize = unsafe { mem::transmute(&self.arc) };
(p & INLINE_LEN_MASK) >> INLINE_LEN_OFFSET
// This is undefind behavior due to a data race, but experimental
// evidence shows that it works in practice (discussion:
// https://internals.rust-lang.org/t/bit-wise-reasoning-for-atomic-accesses/8853).
let p: *const usize = unsafe { mem::transmute(&self.arc) };
(unsafe { *p } & INLINE_LEN_MASK) >> INLINE_LEN_OFFSET
}
/// Set the length of the inline buffer. This is done by writing to the