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use core::sync::atomic::{fence, AtomicI32, Ordering};
#[repr(transparent)]
#[derive(Default)]
pub struct RefCount(pub(crate) AtomicI32);
impl RefCount {
/// Creates a new `RefCount` with an initial value of `1`.
pub fn new(count: u32) -> Self {
Self(AtomicI32::new(count as i32))
}
/// Increments the reference count, returning the new value.
pub fn add_ref(&self) -> u32 {
(self.0.fetch_add(1, Ordering::Relaxed) + 1) as u32
}
/// Decrements the reference count, returning the new value.
///
/// This operation inserts an `Acquire` fence when the reference count reaches zero.
/// This prevents reordering before the object is destroyed.
pub fn release(&self) -> u32 {
let remaining = self.0.fetch_sub(1, Ordering::Release) - 1;
match remaining.cmp(&0) {
core::cmp::Ordering::Equal => fence(Ordering::Acquire),
core::cmp::Ordering::Less => panic!("Object has been over-released."),
core::cmp::Ordering::Greater => {}
}
remaining as u32
}
}