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use super::{Inner, COMPLETE, NUMBER_BITS, NUMBER_MASK, RX_WAKER_STORED};
use crate::sync::spsc::{SpscInner, SpscInnerErr};
use alloc::sync::Arc;
use core::{
fmt, ptr,
sync::atomic::Ordering,
task::{Context, Poll},
};
const IS_TX_HALF: bool = true;
pub struct Sender<T, E> {
inner: Arc<Inner<T, E>>,
}
#[derive(Debug)]
pub struct SendError<T> {
pub value: T,
pub kind: SendErrorKind,
}
#[derive(Clone, Copy, PartialEq, Eq, Debug)]
pub enum SendErrorKind {
Canceled,
Overflow,
}
impl<T, E> Sender<T, E> {
pub(super) fn new(inner: Arc<Inner<T, E>>) -> Self {
Self { inner }
}
#[inline]
pub fn send(&mut self, value: T) -> Result<(), SendError<T>> {
self.inner.send(value)
}
#[inline]
pub fn send_overwrite(&mut self, value: T) -> Result<(), T> {
self.inner.send_overwrite(value)
}
#[inline]
pub fn send_err(self, err: E) -> Result<(), E> {
self.inner.send_err(err)
}
#[inline]
pub fn poll_canceled(&mut self, cx: &mut Context<'_>) -> Poll<()> {
self.inner.poll_half(
cx,
IS_TX_HALF,
Ordering::Relaxed,
Ordering::Release,
Inner::take_cancel,
)
}
#[inline]
pub fn is_canceled(&self) -> bool {
self.inner.is_canceled(Ordering::Relaxed)
}
}
impl<T, E> Drop for Sender<T, E> {
#[inline]
fn drop(&mut self) {
self.inner.close_half(IS_TX_HALF);
}
}
impl<T, E> Inner<T, E> {
#[allow(clippy::option_if_let_else)]
fn send(&self, value: T) -> Result<(), SendError<T>> {
let state = self.state_load(Ordering::Acquire);
if let Some(index) = self.put_index_try(state) {
self.put(value, state, index)
.map_err(|value| SendError::new(value, SendErrorKind::Canceled))
} else {
Err(SendError::new(value, SendErrorKind::Overflow))
}
}
fn send_overwrite(&self, value: T) -> Result<(), T> {
let state = self.state_load(Ordering::Acquire);
if let Some(index) = self.put_index_try(state) {
return self.put(value, state, index);
}
match self.transaction(state, Ordering::Acquire, Ordering::Acquire, |state| {
if *state & COMPLETE != 0 {
return Err(None);
}
let length = Self::get_length(*state);
if length == self.buffer.capacity() {
let index = self.take_index(state, length);
Ok((*state, index))
} else {
let index = self.put_index(*state, length);
Err(Some((*state, index)))
}
}) {
Ok((state, index)) => {
unsafe { ptr::drop_in_place(self.buffer.ptr().add(index)) };
self.put(value, state, index)
}
Err(Some((state, index))) => self.put(value, state, index),
Err(None) => Err(value),
}
}
fn put(&self, value: T, state: usize, index: usize) -> Result<(), T> {
let buffer_ptr = unsafe { self.buffer.ptr().add(index) };
unsafe { ptr::write(buffer_ptr, value) };
self.transaction(state, Ordering::AcqRel, Ordering::Acquire, |state| {
if *state & COMPLETE == 0 {
*state = state.wrapping_add(1);
Ok(*state)
} else {
Err(())
}
})
.map(|state| {
if state & RX_WAKER_STORED != 0 {
unsafe { (*self.rx_waker.get()).assume_init_ref().wake_by_ref() };
}
})
.map_err(|()| unsafe { ptr::read(buffer_ptr) })
}
fn put_index_try(&self, state: usize) -> Option<usize> {
let length = Self::get_length(state);
if length == self.buffer.capacity() { None } else { Some(self.put_index(state, length)) }
}
fn put_index(&self, state: usize, length: usize) -> usize {
let cursor = state >> NUMBER_BITS & NUMBER_MASK;
cursor.wrapping_add(length).wrapping_rem(self.buffer.capacity())
}
}
impl<T> SendError<T> {
#[inline]
fn new(value: T, kind: SendErrorKind) -> Self {
Self { value, kind }
}
}
impl<T: fmt::Display> fmt::Display for SendError<T> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
self.kind.fmt(f)
}
}
impl fmt::Display for SendErrorKind {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
match self {
SendErrorKind::Canceled => write!(f, "Receiver is dropped."),
SendErrorKind::Overflow => write!(f, "Channel buffer overflow."),
}
}
}