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use core::marker::PhantomData;
use core::ops::Add;
use core::ptr::{self, NonNull};
use generic_array::typenum::{Sum, Unsigned, U1};
use generic_array::ArrayLength;
use ring_buffer::{RingBuffer, Uxx};
impl<T, N, U> RingBuffer<T, N, U>
where
N: Add<U1> + Unsigned,
Sum<N, U1>: ArrayLength<T>,
U: Uxx,
{
pub fn split<'rb>(&'rb mut self) -> (Producer<'rb, T, N, U>, Consumer<'rb, T, N, U>) {
(
Producer {
rb: unsafe { NonNull::new_unchecked(self) },
_marker: PhantomData,
},
Consumer {
rb: unsafe { NonNull::new_unchecked(self) },
_marker: PhantomData,
},
)
}
}
pub struct Consumer<'a, T, N, U = usize>
where
N: Add<U1> + Unsigned,
Sum<N, U1>: ArrayLength<T>,
U: Uxx,
{
rb: NonNull<RingBuffer<T, N, U>>,
_marker: PhantomData<&'a ()>,
}
unsafe impl<'a, T, N, U> Send for Consumer<'a, T, N, U>
where
N: Add<U1> + Unsigned,
Sum<N, U1>: ArrayLength<T>,
T: Send,
U: Uxx,
{}
pub struct Producer<'a, T, N, U = usize>
where
N: Add<U1> + Unsigned,
Sum<N, U1>: ArrayLength<T>,
U: Uxx,
{
rb: NonNull<RingBuffer<T, N, U>>,
_marker: PhantomData<&'a ()>,
}
unsafe impl<'a, T, N, U> Send for Producer<'a, T, N, U>
where
N: Add<U1> + Unsigned,
Sum<N, U1>: ArrayLength<T>,
T: Send,
U: Uxx,
{}
macro_rules! impl_ {
($uxx:ident) => {
impl<'a, T, N> Consumer<'a, T, N, $uxx>
where
N: Add<U1> + Unsigned,
Sum<N, U1>: ArrayLength<T>,
{
pub fn ready(&self) -> bool {
let tail = unsafe { self.rb.as_ref().tail.load_acquire() };
let head = unsafe { self.rb.as_ref().head.load_relaxed() };
return head != tail;
}
pub fn dequeue(&mut self) -> Option<T> {
let tail = unsafe { self.rb.as_ref().tail.load_acquire() };
let head = unsafe { self.rb.as_ref().head.load_relaxed() };
if head != tail {
Some(unsafe { self._dequeue(head) })
} else {
None
}
}
pub unsafe fn dequeue_unchecked(&mut self) -> T {
let head = self.rb.as_ref().head.load_relaxed();
debug_assert_ne!(head, self.rb.as_ref().tail.load_acquire());
self._dequeue(head)
}
unsafe fn _dequeue(&mut self, head: $uxx) -> T {
let rb = self.rb.as_ref();
let n = rb.capacity() + 1;
let buffer = rb.buffer.get_ref();
let item = ptr::read(buffer.get_unchecked(usize::from(head)));
rb.head.store_release((head + 1) % n);
item
}
}
impl<'a, T, N> Producer<'a, T, N, $uxx>
where
N: Add<U1> + Unsigned,
Sum<N, U1>: ArrayLength<T>,
{
pub fn ready(&self) -> bool {
let n = unsafe { self.rb.as_ref().capacity() + 1 };
let tail = unsafe { self.rb.as_ref().tail.load_relaxed() };
let head = unsafe { self.rb.as_ref().head.load_acquire() };
let next_tail = (tail + 1) % n;
return next_tail != head;
}
pub fn enqueue(&mut self, item: T) -> Result<(), T> {
let n = unsafe { self.rb.as_ref().capacity() + 1 };
let tail = unsafe { self.rb.as_ref().tail.load_relaxed() };
let head = unsafe { self.rb.as_ref().head.load_acquire() };
let next_tail = (tail + 1) % n;
if next_tail != head {
unsafe { self._enqueue(tail, item) };
Ok(())
} else {
Err(item)
}
}
pub fn enqueue_unchecked(&mut self, item: T) {
unsafe {
let tail = self.rb.as_ref().tail.load_relaxed();
debug_assert_ne!(
(tail + 1) % (self.rb.as_ref().capacity() + 1),
self.rb.as_ref().head.load_acquire()
);
self._enqueue(tail, item);
}
}
unsafe fn _enqueue(&mut self, tail: $uxx, item: T) {
let rb = self.rb.as_mut();
let n = rb.capacity() + 1;
let buffer = rb.buffer.get_mut();
let next_tail = (tail + 1) % n;
ptr::write(buffer.get_unchecked_mut(usize::from(tail)), item);
rb.tail.store_release(next_tail);
}
}
};
}
#[cfg(feature = "smaller-atomics")]
impl_!(u8);
#[cfg(feature = "smaller-atomics")]
impl_!(u16);
impl_!(usize);
#[cfg(test)]
mod tests {
use consts::*;
use RingBuffer;
#[test]
fn sanity() {
let mut rb: RingBuffer<i32, U2> = RingBuffer::new();
let (mut p, mut c) = rb.split();
assert_eq!(c.dequeue(), None);
p.enqueue(0).unwrap();
assert_eq!(c.dequeue(), Some(0));
}
}