forked from tokio-rs/tokio
/
atomic_u64.rs
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/
atomic_u64.rs
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//! Implementation of an atomic u64 cell. On 64 bit platforms, this is a
//! re-export of `AtomicU64`. On 32 bit platforms, this is implemented using a
//! `Mutex`.
pub(crate) use self::imp::AtomicU64;
// `AtomicU64` can only be used on targets with `target_has_atomic` is 64 or greater.
// Once `cfg_target_has_atomic` feature is stable, we can replace it with
// `#[cfg(target_has_atomic = "64")]`.
// Refs: https://github.com/rust-lang/rust/tree/master/src/librustc_target
#[cfg(not(any(target_arch = "arm", target_arch = "mips", target_arch = "powerpc")))]
mod imp {
pub(crate) use std::sync::atomic::AtomicU64;
}
#[cfg(any(target_arch = "arm", target_arch = "mips", target_arch = "powerpc"))]
mod imp {
use crate::loom::sync::Mutex;
use std::sync::atomic::Ordering;
#[derive(Debug)]
pub(crate) struct AtomicU64 {
inner: Mutex<u64>,
}
impl AtomicU64 {
pub(crate) fn new(val: u64) -> Self {
Self {
inner: Mutex::new(val),
}
}
pub(crate) fn load(&self, _: Ordering) -> u64 {
*self.inner.lock()
}
pub(crate) fn store(&self, val: u64, _: Ordering) {
*self.inner.lock() = val;
}
pub(crate) fn fetch_or(&self, val: u64, _: Ordering) -> u64 {
let mut lock = self.inner.lock();
let prev = *lock;
*lock = prev | val;
prev
}
pub(crate) fn compare_exchange(
&self,
current: u64,
new: u64,
_success: Ordering,
_failure: Ordering,
) -> Result<u64, u64> {
let mut lock = self.inner.lock();
if *lock == current {
*lock = new;
Ok(current)
} else {
Err(*lock)
}
}
pub(crate) fn compare_exchange_weak(
&self,
current: u64,
new: u64,
success: Ordering,
failure: Ordering,
) -> Result<u64, u64> {
self.compare_exchange(current, new, success, failure)
}
}
}