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use crate::{Shared, Shield, Tag};
use std::{
marker::PhantomData,
mem,
sync::atomic::{AtomicUsize, Ordering},
};
fn map_both<T, U, F>(result: Result<T, T>, f: F) -> Result<U, U>
where
F: FnOnce(T) -> U,
{
match result {
Ok(v) => Ok(f(v)),
Err(v) => Err(f(v)),
}
}
#[repr(transparent)]
pub struct Atomic<V, T>
where
T: Tag,
{
pub(crate) data: AtomicUsize,
_m0: PhantomData<V>,
_m1: PhantomData<T>,
}
impl<V, T> Atomic<V, T>
where
T: Tag,
{
pub unsafe fn from_raw(raw: usize) -> Self {
Self {
data: AtomicUsize::new(raw),
_m0: PhantomData,
_m1: PhantomData,
}
}
pub fn null() -> Self {
unsafe { Self::from_raw(0) }
}
pub fn null_vec(len: usize) -> Vec<Self> {
unsafe {
#[allow(clippy::unsound_collection_transmute)]
mem::transmute(vec![0_usize; len])
}
}
pub fn load<'shield>(
&self,
ordering: Ordering,
_shield: &'shield Shield<'_>,
) -> Shared<'shield, V, T> {
let raw = self.data.load(ordering);
unsafe { Shared::from_raw(raw) }
}
pub fn store<'shield>(
&self,
data: Shared<'_, V, T>,
ordering: Ordering,
_shield: &'shield Shield<'_>,
) {
let raw = data.into_raw();
self.data.store(raw, ordering);
}
pub fn swap<'shield>(
&self,
new: Shared<'_, V, T>,
ordering: Ordering,
_shield: &'shield Shield<'_>,
) -> Shared<'shield, V, T> {
let new_raw = new.into_raw();
let old_raw = self.data.swap(new_raw, ordering);
unsafe { Shared::from_raw(old_raw) }
}
pub fn compare_and_swap<'shield>(
&self,
current: Shared<'_, V, T>,
new: Shared<'_, V, T>,
order: Ordering,
_shield: &'shield Shield<'_>,
) -> Shared<'shield, V, T> {
let current_raw = current.into_raw();
let new_raw = new.into_raw();
let old_raw = self.data.compare_and_swap(current_raw, new_raw, order);
unsafe { Shared::from_raw(old_raw) }
}
pub fn compare_exchange_weak<'shield>(
&self,
current: Shared<'_, V, T>,
new: Shared<'_, V, T>,
success: Ordering,
failure: Ordering,
_shield: &'shield Shield<'_>,
) -> Result<Shared<'shield, V, T>, Shared<'shield, V, T>> {
let current_raw = current.into_raw();
let new_raw = new.into_raw();
let result = self
.data
.compare_exchange_weak(current_raw, new_raw, success, failure);
map_both(result, |raw| unsafe { Shared::from_raw(raw) })
}
}