blob: eca79861b12bf98492df85700be07d4772753ff5 [file] [log] [blame]
use std::sync::atomic::{AtomicPtr, Ordering};
use std::ptr;
unsafe impl<T: Send> Send for AtomicOption<T> {}
unsafe impl<T: Send> Sync for AtomicOption<T> {}
#[derive(Debug)]
pub struct AtomicOption<T> {
inner: AtomicPtr<T>,
}
impl<T> Drop for AtomicOption<T> {
fn drop(&mut self) {
let inner = self.inner.load(Ordering::Relaxed);
if !inner.is_null() {
unsafe {
drop(Box::from_raw(inner));
}
}
}
}
impl<T> AtomicOption<T> {
pub fn new() -> AtomicOption<T> {
AtomicOption { inner: AtomicPtr::new(ptr::null_mut()) }
}
fn swap_inner(&self, ptr: *mut T, order: Ordering) -> Option<Box<T>> {
let old = self.inner.swap(ptr, order);
if old.is_null() {
None
} else {
Some(unsafe { Box::from_raw(old) })
}
}
// allows re-use of allocation
pub fn swap_box(&self, t: Box<T>, order: Ordering) -> Option<Box<T>> {
self.swap_inner(Box::into_raw(t), order)
}
pub fn swap(&self, t: T, order: Ordering) -> Option<T> {
self.swap_box(Box::new(t), order).map(|old| *old)
}
pub fn take(&self, order: Ordering) -> Option<T> {
self.swap_inner(ptr::null_mut(), order).map(|old| *old)
}
}