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use std::future::Future;
use std::pin::Pin;
use std::task::{Context, Poll};
use concurrent_queue::ConcurrentQueue;
use event_listener::{Event, EventListener};
use std::fmt::Debug;
use std::sync::atomic::{AtomicUsize, Ordering};
use std::sync::Arc;
use facade::*;
mod facade;
type ReceiverQueue<T> = ConcurrentQueue<Arc<T>>;
struct Shared<T> {
receiver_queues: RwLock<Vec<Arc<ReceiverQueue<T>>>>,
on_final_receive: Event,
on_send: Event,
n_receivers: AtomicUsize,
n_senders: AtomicUsize,
len: AtomicUsize,
capacity: Option<usize>,
}
#[derive(Copy, Clone, Eq, PartialEq, Debug)]
pub struct Disconnected;
pub struct Sender<T: Clone + Unpin>(Arc<Shared<T>>);
impl<T: Clone + Unpin> Clone for Sender<T> {
fn clone(&self) -> Self {
self.0.n_senders.fetch_add(1, Ordering::Relaxed);
Sender(self.0.clone())
}
}
impl<T: Clone + Unpin> Drop for Sender<T> {
fn drop(&mut self) {
if self.0.n_senders.fetch_sub(1, Ordering::Release) != 1 {
return;
}
self.0.on_send.notify(usize::MAX);
}
}
#[derive(Copy, Clone, Debug, Eq, PartialEq)]
pub enum TrySendError<T> {
Disconnected(T),
Full(T),
}
#[derive(Copy, Clone, Debug, Eq, PartialEq)]
pub struct SendError<T>(pub T);
impl<T: Clone + Unpin> Sender<T> {
pub fn try_send(&self, item: T) -> Result<(), TrySendError<T>> {
if self.0.n_receivers.load(Ordering::Acquire) == 0 {
return Err(TrySendError::Disconnected(item));
}
let shared = &self.0;
if shared.capacity.map(|c| c == shared.len.load(Ordering::Acquire)).unwrap_or(false) {
return Err(TrySendError::Full(item));
}
let item = Arc::new(item);
for q in lock_read(&shared.receiver_queues).iter() {
assert!(q.push(item.clone()).is_ok());
}
shared.len.fetch_add(1, Ordering::Release);
shared.on_send.notify(usize::MAX);
Ok(())
}
pub fn send(&self, mut item: T) -> Result<(), SendError<T>> {
loop {
let event_listener = self.0.on_final_receive.listen();
match self.try_send(item) {
Ok(()) => break Ok(()),
Err(TrySendError::Disconnected(item)) => break Err(SendError(item)),
Err(TrySendError::Full(ret)) => {
item = ret;
event_listener.wait();
}
}
}
}
pub fn send_async(&self, item: T) -> SendFut<T> {
SendFut {
item: Some(item),
sender: self,
event_listener: None,
}
}
}
pub struct SendFut<'a, T: Clone + Unpin> {
item: Option<T>,
sender: &'a Sender<T>,
event_listener: Option<EventListener>,
}
impl<'a, T: Clone + Unpin> Future for SendFut<'a, T> {
type Output = Result<(), SendError<T>>;
fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
let poll = loop {
let item = self.item.take().expect("cannot poll completed send future");
let mut listener = self.sender.0.on_final_receive.listen();
break match self.sender.try_send(item) {
Ok(()) => Poll::Ready(Ok(())),
Err(TrySendError::Disconnected(item)) => Poll::Ready(Err(SendError(item))),
Err(TrySendError::Full(ret)) => {
self.item.replace(ret);
if let Poll::Ready(_) = Pin::new(&mut listener).poll(cx) {
continue;
}
self.event_listener = Some(listener);
Poll::Pending
}
}
};
poll
}
}
pub struct Receiver<T: Clone + Unpin>(ReceiverInner<T>);
struct ReceiverInner<T: Clone + Unpin> {
shared: Arc<Shared<T>>,
queue: Arc<ConcurrentQueue<Arc<T>>>,
}
impl<T: Clone + Unpin> Drop for ReceiverInner<T> {
fn drop(&mut self) {
if Arc::strong_count(&self.queue) > 2 {
return;
}
let mut receiver_queues = lock_write(&self.shared.receiver_queues);
receiver_queues.retain(|other| !Arc::ptr_eq(&self.queue, other));
if self.shared.n_receivers.fetch_sub(1, Ordering::Release) != 1 {
return;
}
self.shared.on_final_receive.notify(self.shared.n_senders.load(Ordering::Acquire));
}
}
impl<T: Clone + Unpin> Clone for Receiver<T> {
fn clone(&self) -> Self {
let queue = Arc::new(ConcurrentQueue::unbounded());
let mut receiver_queues = lock_write(&self.0.shared.receiver_queues);
receiver_queues.push(queue.clone());
self.0.shared.n_receivers.fetch_add(1, Ordering::Release);
let inner = ReceiverInner {
shared: self.0.shared.clone(),
queue,
};
Receiver(inner)
}
}
impl<T: Clone + Unpin> ReceiverInner<T> {
fn recv(&self) -> Result<T, Disconnected> {
loop {
let listener = self.shared.on_send.listen();
match self.try_recv() {
Ok(Some(item)) => break Ok(item),
Ok(None) => listener.wait(),
Err(_) => break Err(Disconnected),
}
}
}
fn try_recv(&self) -> Result<Option<T>, Disconnected> {
match self.queue.pop() {
Ok(item) => {
let old_len = self.shared.len.load(Ordering::SeqCst);
let weak = Arc::downgrade(&item);
let inner = (&*item).clone();
drop(item);
if weak.strong_count() == 0 &&
self.shared.len.compare_exchange(
old_len,
old_len - 1,
Ordering::Release,
Ordering::Relaxed
).is_ok()
{
self.shared.on_final_receive.notify_additional(1);
}
Ok(Some(inner))
},
Err(_) if self.shared.n_senders.load(Ordering::Acquire) > 0 => Ok(None),
Err(_) => Err(Disconnected),
}
}
fn recv_async(&self) -> RecvFut<T> {
RecvFut {
receiver: &self,
event_listener: None,
}
}
}
impl<T: Clone + Unpin> Receiver<T> {
pub fn recv(&self) -> Result<T, Disconnected> {
self.0.recv()
}
pub fn try_recv(&self) -> Result<Option<T>, Disconnected> {
self.0.try_recv()
}
pub fn recv_async(&self) -> RecvFut<T> {
self.0.recv_async()
}
pub fn into_shared(self) -> SharedReceiver<T> {
SharedReceiver(self.0)
}
}
pub struct SharedReceiver<T: Clone + Unpin>(ReceiverInner<T>);
impl<T: Clone + Unpin> Clone for SharedReceiver<T> {
fn clone(&self) -> Self {
let inner = ReceiverInner {
shared: self.0.shared.clone(),
queue: self.0.queue.clone(),
};
SharedReceiver(inner)
}
}
impl<T: Clone + Unpin> SharedReceiver<T> {
pub fn upgrade(mut self) -> Receiver<T> {
let queue = Arc::new(ConcurrentQueue::unbounded());
{
let mut receiver_queues = lock_write(&self.0.shared.receiver_queues);
receiver_queues.push(queue.clone());
}
self.0.shared.n_receivers.fetch_add(1, Ordering::Release);
self.0.queue = queue;
Receiver(self.0)
}
pub fn same_mailbox(&self, other: &SharedReceiver<T>) -> bool {
Arc::ptr_eq(&self.0.queue, &other.0.queue)
}
pub fn recv(&self) -> Result<T, Disconnected> {
self.0.recv()
}
pub fn try_recv(&self) -> Result<Option<T>, Disconnected> {
self.0.try_recv()
}
pub fn recv_async(&self) -> RecvFut<T> {
self.0.recv_async()
}
}
pub struct RecvFut<'a, T: Clone + Unpin> {
receiver: &'a ReceiverInner<T>,
event_listener: Option<EventListener>,
}
impl<'a, T: Clone + Unpin> Future for RecvFut<'a, T> {
type Output = Result<T, Disconnected>;
fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
loop {
let mut listener = self.receiver.shared.on_send.listen();
break match self.receiver.try_recv() {
Ok(Some(item)) => Poll::Ready(Ok(item)),
Ok(None) => {
if let Poll::Ready(_) = Pin::new(&mut listener).poll(cx) {
continue;
}
self.event_listener = Some(listener);
Poll::Pending
},
Err(_) => Poll::Ready(Err(Disconnected)),
}
}
}
}
pub fn new<T: Clone + Unpin>(capacity: Option<usize>) -> (Sender<T>, Receiver<T>) {
let receiver_queue = Arc::new(ConcurrentQueue::unbounded());
let shared = Shared {
receiver_queues: RwLock::new(vec![receiver_queue.clone()]),
on_final_receive: Event::new(),
on_send: Event::new(),
n_receivers: AtomicUsize::new(1),
n_senders: AtomicUsize::new(1),
len: AtomicUsize::new(0),
capacity,
};
let shared = Arc::new(shared);
let receiver_inner = ReceiverInner {
shared: shared.clone(),
queue: receiver_queue
};
(Sender(shared), Receiver(receiver_inner))
}
pub fn bounded<T: Clone + Unpin>(capacity: usize) -> (Sender<T>, Receiver<T>) {
new(Some(capacity))
}
pub fn unbounded<T: Clone + Unpin>() -> (Sender<T>, Receiver<T>) {
new(None)
}