Prevent double reference in generic futex

This commit is contained in:
Chris Denton 2024-07-16 14:56:18 +00:00
parent a28b35eb35
commit 0585c4a23e
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GPG Key ID: 713472F2F45627DE
2 changed files with 8 additions and 5 deletions

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@ -15,6 +15,7 @@ pub type SmallAtomic = AtomicU8;
/// Must be the underlying type of SmallAtomic
pub type SmallPrimitive = u8;
pub unsafe trait Futex {}
pub unsafe trait Waitable {
type Atomic;
}
@ -24,6 +25,7 @@ macro_rules! unsafe_waitable_int {
unsafe impl Waitable for $int {
type Atomic = $atomic;
}
unsafe impl Futex for $atomic {}
)*
};
}
@ -46,6 +48,7 @@ unsafe impl<T> Waitable for *const T {
unsafe impl<T> Waitable for *mut T {
type Atomic = AtomicPtr<T>;
}
unsafe impl<T> Futex for AtomicPtr<T> {}
pub fn wait_on_address<W: Waitable>(
address: &W::Atomic,
@ -61,14 +64,14 @@ pub fn wait_on_address<W: Waitable>(
}
}
pub fn wake_by_address_single<T>(address: &T) {
pub fn wake_by_address_single<T: Futex>(address: &T) {
unsafe {
let addr = ptr::from_ref(address).cast::<c_void>();
c::WakeByAddressSingle(addr);
}
}
pub fn wake_by_address_all<T>(address: &T) {
pub fn wake_by_address_all<T: Futex>(address: &T) {
unsafe {
let addr = ptr::from_ref(address).cast::<c_void>();
c::WakeByAddressAll(addr);
@ -80,11 +83,11 @@ pub fn futex_wait<W: Waitable>(futex: &W::Atomic, expected: W, timeout: Option<D
wait_on_address(futex, expected, timeout) || api::get_last_error() != WinError::TIMEOUT
}
pub fn futex_wake<T>(futex: &T) -> bool {
pub fn futex_wake<T: Futex>(futex: &T) -> bool {
wake_by_address_single(futex);
false
}
pub fn futex_wake_all<T>(futex: &T) {
pub fn futex_wake_all<T: Futex>(futex: &T) {
wake_by_address_all(futex)
}

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@ -57,7 +57,7 @@ impl<'a> Drop for CompletionGuard<'a> {
// up on the Once. `futex_wake_all` does its own synchronization, hence
// we do not need `AcqRel`.
if self.state.swap(self.set_state_on_drop_to, Release) == QUEUED {
futex_wake_all(&self.state);
futex_wake_all(self.state);
}
}
}