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use core::{
mem::MaybeUninit,
ops::{BitAnd, BitOr, BitOrAssign, BitXorAssign},
sync::atomic::Ordering,
task::{Context, Poll, Waker},
};
pub mod oneshot;
pub mod pulse;
pub mod ring;
pub(self) trait SpscInner<A, I>
where
I: Copy + Eq + BitAnd<Output = I> + BitOr<Output = I> + BitOrAssign + BitXorAssign,
{
const ZERO: I;
const RX_WAKER_STORED: I;
const TX_WAKER_STORED: I;
const COMPLETE: I;
fn state_load(&self, order: Ordering) -> I;
fn compare_exchange_weak(
&self,
current: I,
new: I,
success: Ordering,
failure: Ordering,
) -> Result<I, I>;
#[allow(clippy::mut_from_ref)]
unsafe fn rx_waker_mut(&self) -> &mut MaybeUninit<Waker>;
#[allow(clippy::mut_from_ref)]
unsafe fn tx_waker_mut(&self) -> &mut MaybeUninit<Waker>;
#[inline]
fn transaction<R, E>(
&self,
mut old: I,
success: Ordering,
failure: Ordering,
f: impl Fn(&mut I) -> Result<R, E>,
) -> Result<R, E> {
loop {
let mut new = old;
let result = f(&mut new);
if result.is_err() {
break result;
}
match self.compare_exchange_weak(old, new, success, failure) {
Ok(_) => break result,
Err(x) => old = x,
}
}
}
#[inline]
fn is_canceled(&self, order: Ordering) -> bool {
let state = self.state_load(order);
self.take_cancel(state).is_ready()
}
fn take_cancel(&self, state: I) -> Poll<()> {
if state & Self::COMPLETE == Self::ZERO { Poll::Pending } else { Poll::Ready(()) }
}
fn poll_half<T>(
&self,
cx: &mut Context<'_>,
is_tx_half: bool,
read_order: Ordering,
cas_order: Ordering,
take: fn(&Self, I) -> Poll<T>,
) -> Poll<T> {
let waker_stored = if is_tx_half { Self::TX_WAKER_STORED } else { Self::RX_WAKER_STORED };
let state = self.state_load(read_order);
let value = take(self, state);
if value.is_ready() || state & waker_stored != Self::ZERO {
return value;
}
unsafe {
let waker = if is_tx_half { self.tx_waker_mut() } else { self.rx_waker_mut() };
waker.write(cx.waker().clone());
}
let Ok(state) = self.transaction(state, cas_order, read_order, |state| {
*state |= waker_stored;
Ok::<_, !>(*state)
});
take(self, state)
}
fn poll_half_with_transaction<T, U, V>(
&self,
cx: &mut Context<'_>,
is_tx_half: bool,
read_order: Ordering,
cas_order: Ordering,
take_try: fn(&Self, &mut I) -> Option<Result<U, V>>,
take_finalize: fn(&Self, Result<U, V>) -> T,
) -> Poll<T> {
let waker_stored = if is_tx_half { Self::TX_WAKER_STORED } else { Self::RX_WAKER_STORED };
let state = self.state_load(read_order);
self.transaction(state, cas_order, read_order, |state| match take_try(self, state) {
Some(value) => value.map(Ok).map_err(Ok),
None => Err(Err(if *state & waker_stored == Self::ZERO { Ok(()) } else { Err(()) })),
})
.or_else(|value| {
value.map(Err).or_else(|no_waker| {
no_waker.and_then(|()| {
unsafe {
let waker =
if is_tx_half { self.tx_waker_mut() } else { self.rx_waker_mut() };
waker.write(cx.waker().clone());
}
let Ok(value) = self.transaction(state, cas_order, read_order, |state| {
*state |= waker_stored;
Ok::<_, !>(take_try(self, state))
});
value.ok_or(())
})
})
})
.map_or_else(|()| Poll::Pending, |value| Poll::Ready(take_finalize(self, value)))
}
fn close_half(&self, is_tx_half: bool) {
let waker_stored = if is_tx_half { Self::RX_WAKER_STORED } else { Self::TX_WAKER_STORED };
let state = self.state_load(Ordering::Acquire);
if let Ok((waker, complete)) =
self.transaction(state, Ordering::Acquire, Ordering::Acquire, |state| {
let waker = if *state & waker_stored == Self::ZERO {
false
} else {
*state ^= waker_stored;
true
};
let complete = if *state & Self::COMPLETE == Self::ZERO {
*state |= Self::COMPLETE;
true
} else {
false
};
if waker || complete { Ok((waker, complete)) } else { Err(()) }
})
{
unsafe {
if waker {
let waker = if is_tx_half { self.rx_waker_mut() } else { self.tx_waker_mut() };
let waker = waker.assume_init_read();
if complete {
waker.wake();
}
}
}
}
}
}
pub(self) trait SpscInnerErr<A, I>: SpscInner<A, I>
where
I: Copy + Eq + BitAnd<Output = I> + BitOr<Output = I> + BitOrAssign + BitXorAssign,
{
type Error;
#[allow(clippy::mut_from_ref)]
unsafe fn err_mut(&self) -> &mut Option<Self::Error>;
fn send_err(&self, err: Self::Error) -> Result<(), Self::Error> {
if self.is_canceled(Ordering::Relaxed) {
Err(err)
} else {
unsafe { *self.err_mut() = Some(err) };
Ok(())
}
}
fn take_err<T>(&self) -> Option<Result<T, Self::Error>> {
unsafe { self.err_mut().take().map(Err) }
}
}