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use core::mem::MaybeUninit;
use core::ptr;
use std::task::Waker;
const NUM_WAKERS: usize = 32;
pub(crate) struct WakeList {
inner: [MaybeUninit<Waker>; NUM_WAKERS],
curr: usize,
}
impl WakeList {
pub(crate) fn new() -> Self {
Self {
inner: unsafe {
// safety: Create an uninitialized array of `MaybeUninit`. The
// `assume_init` is safe because the type we are claiming to
// have initialized here is a bunch of `MaybeUninit`s, which do
// not require initialization.
MaybeUninit::uninit().assume_init()
},
curr: 0,
}
}
#[inline]
pub(crate) fn can_push(&self) -> bool {
self.curr < NUM_WAKERS
}
pub(crate) fn push(&mut self, val: Waker) {
debug_assert!(self.can_push());
self.inner[self.curr] = MaybeUninit::new(val);
self.curr += 1;
}
pub(crate) fn wake_all(&mut self) {
assert!(self.curr <= NUM_WAKERS);
while self.curr > 0 {
self.curr -= 1;
let waker = unsafe { ptr::read(self.inner[self.curr].as_mut_ptr()) };
waker.wake();
}
}
}
impl Drop for WakeList {
fn drop(&mut self) {
let slice = ptr::slice_from_raw_parts_mut(self.inner.as_mut_ptr() as *mut Waker, self.curr);
unsafe { ptr::drop_in_place(slice) };
}
}