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mpsc.rs
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mpsc.rs
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use futures::future::poll_fn;
use tokio::sync::mpsc::{self, channel};
use tokio::sync::oneshot;
use tokio_test::task::spawn;
use tokio_test::{assert_pending, assert_ready, assert_ready_err, assert_ready_ok};
use tokio_util::sync::PollSender;
#[tokio::test]
async fn simple() {
let (send, mut recv) = channel(3);
let mut send = PollSender::new(send);
for i in 1..=3i32 {
let mut reserve = spawn(poll_fn(|cx| send.poll_reserve(cx)));
assert_ready_ok!(reserve.poll());
send.send_item(i).unwrap();
}
let mut reserve = spawn(poll_fn(|cx| send.poll_reserve(cx)));
assert_pending!(reserve.poll());
assert_eq!(recv.recv().await.unwrap(), 1);
assert!(reserve.is_woken());
assert_ready_ok!(reserve.poll());
drop(recv);
send.send_item(42).unwrap();
}
#[tokio::test]
async fn repeated_poll_reserve() {
let (send, mut recv) = channel::<i32>(1);
let mut send = PollSender::new(send);
let mut reserve = spawn(poll_fn(|cx| send.poll_reserve(cx)));
assert_ready_ok!(reserve.poll());
assert_ready_ok!(reserve.poll());
send.send_item(1).unwrap();
assert_eq!(recv.recv().await.unwrap(), 1);
}
#[tokio::test]
async fn abort_send() {
let (send, mut recv) = channel(3);
let mut send = PollSender::new(send);
let send2 = send.get_ref().cloned().unwrap();
for i in 1..=3i32 {
let mut reserve = spawn(poll_fn(|cx| send.poll_reserve(cx)));
assert_ready_ok!(reserve.poll());
send.send_item(i).unwrap();
}
let mut reserve = spawn(poll_fn(|cx| send.poll_reserve(cx)));
assert_pending!(reserve.poll());
assert_eq!(recv.recv().await.unwrap(), 1);
assert!(reserve.is_woken());
assert_ready_ok!(reserve.poll());
let mut send2_send = spawn(send2.send(5));
assert_pending!(send2_send.poll());
assert!(send.abort_send());
assert!(send2_send.is_woken());
assert_ready_ok!(send2_send.poll());
assert_eq!(recv.recv().await.unwrap(), 2);
assert_eq!(recv.recv().await.unwrap(), 3);
assert_eq!(recv.recv().await.unwrap(), 5);
}
#[tokio::test]
async fn close_sender_last() {
let (send, mut recv) = channel::<i32>(3);
let mut send = PollSender::new(send);
let mut recv_task = spawn(recv.recv());
assert_pending!(recv_task.poll());
send.close();
assert!(recv_task.is_woken());
assert!(assert_ready!(recv_task.poll()).is_none());
}
#[tokio::test]
async fn close_sender_not_last() {
let (send, mut recv) = channel::<i32>(3);
let mut send = PollSender::new(send);
let send2 = send.get_ref().cloned().unwrap();
let mut recv_task = spawn(recv.recv());
assert_pending!(recv_task.poll());
send.close();
assert!(!recv_task.is_woken());
assert_pending!(recv_task.poll());
drop(send2);
assert!(recv_task.is_woken());
assert!(assert_ready!(recv_task.poll()).is_none());
}
#[tokio::test]
async fn close_sender_before_reserve() {
let (send, mut recv) = channel::<i32>(3);
let mut send = PollSender::new(send);
let mut recv_task = spawn(recv.recv());
assert_pending!(recv_task.poll());
send.close();
assert!(recv_task.is_woken());
assert!(assert_ready!(recv_task.poll()).is_none());
let mut reserve = spawn(poll_fn(|cx| send.poll_reserve(cx)));
assert_ready_err!(reserve.poll());
}
#[tokio::test]
async fn close_sender_after_pending_reserve() {
let (send, mut recv) = channel::<i32>(1);
let mut send = PollSender::new(send);
let mut recv_task = spawn(recv.recv());
assert_pending!(recv_task.poll());
let mut reserve = spawn(poll_fn(|cx| send.poll_reserve(cx)));
assert_ready_ok!(reserve.poll());
send.send_item(1).unwrap();
assert!(recv_task.is_woken());
let mut reserve = spawn(poll_fn(|cx| send.poll_reserve(cx)));
assert_pending!(reserve.poll());
drop(reserve);
send.close();
assert!(send.is_closed());
let mut reserve = spawn(poll_fn(|cx| send.poll_reserve(cx)));
assert_ready_err!(reserve.poll());
}
#[tokio::test]
async fn close_sender_after_successful_reserve() {
let (send, mut recv) = channel::<i32>(3);
let mut send = PollSender::new(send);
let mut recv_task = spawn(recv.recv());
assert_pending!(recv_task.poll());
let mut reserve = spawn(poll_fn(|cx| send.poll_reserve(cx)));
assert_ready_ok!(reserve.poll());
drop(reserve);
send.close();
assert!(send.is_closed());
assert!(!recv_task.is_woken());
assert_pending!(recv_task.poll());
let mut reserve = spawn(poll_fn(|cx| send.poll_reserve(cx)));
assert_ready_ok!(reserve.poll());
}
#[tokio::test]
async fn abort_send_after_pending_reserve() {
let (send, mut recv) = channel::<i32>(1);
let mut send = PollSender::new(send);
let mut recv_task = spawn(recv.recv());
assert_pending!(recv_task.poll());
let mut reserve = spawn(poll_fn(|cx| send.poll_reserve(cx)));
assert_ready_ok!(reserve.poll());
send.send_item(1).unwrap();
assert_eq!(send.get_ref().unwrap().capacity(), 0);
assert!(!send.abort_send());
let mut reserve = spawn(poll_fn(|cx| send.poll_reserve(cx)));
assert_pending!(reserve.poll());
assert!(send.abort_send());
assert_eq!(send.get_ref().unwrap().capacity(), 0);
}
#[tokio::test]
async fn abort_send_after_successful_reserve() {
let (send, mut recv) = channel::<i32>(1);
let mut send = PollSender::new(send);
let mut recv_task = spawn(recv.recv());
assert_pending!(recv_task.poll());
assert_eq!(send.get_ref().unwrap().capacity(), 1);
let mut reserve = spawn(poll_fn(|cx| send.poll_reserve(cx)));
assert_ready_ok!(reserve.poll());
assert_eq!(send.get_ref().unwrap().capacity(), 0);
assert!(send.abort_send());
assert_eq!(send.get_ref().unwrap().capacity(), 1);
}
#[tokio::test]
async fn closed_when_receiver_drops() {
let (send, _) = channel::<i32>(1);
let mut send = PollSender::new(send);
let mut reserve = spawn(poll_fn(|cx| send.poll_reserve(cx)));
assert_ready_err!(reserve.poll());
}
#[should_panic]
#[test]
fn start_send_panics_when_idle() {
let (send, _) = channel::<i32>(3);
let mut send = PollSender::new(send);
send.send_item(1).unwrap();
}
#[should_panic]
#[test]
fn start_send_panics_when_acquiring() {
let (send, _) = channel::<i32>(1);
let mut send = PollSender::new(send);
let mut reserve = spawn(poll_fn(|cx| send.poll_reserve(cx)));
assert_ready_ok!(reserve.poll());
send.send_item(1).unwrap();
let mut reserve = spawn(poll_fn(|cx| send.poll_reserve(cx)));
assert_pending!(reserve.poll());
send.send_item(2).unwrap();
}
#[tokio::test]
async fn weak_sender() {
let (tx, mut rx) = channel(11);
let tx_weak = tx.clone().downgrade();
let tx_weak = tokio::spawn(async move {
for i in 0..10 {
if tx.send(i).await.is_err() {
return None;
}
}
let tx2 = tx_weak
.upgrade()
.expect("expected to be able to upgrade tx_weak");
let _ = tx2.send(20).await;
let tx_weak = tx2.downgrade();
Some(tx_weak)
})
.await
.unwrap();
for i in 0..12 {
let recvd = rx.recv().await;
match recvd {
Some(msg) => {
if i == 10 {
assert_eq!(msg, 20);
}
}
None => {
assert_eq!(i, 11);
break;
}
}
}
if let Some(tx_weak) = tx_weak {
let upgraded = tx_weak.upgrade();
assert!(upgraded.is_none());
}
}
#[tokio::test]
async fn actor_weak_sender() {
pub struct MyActor {
receiver: mpsc::Receiver<ActorMessage>,
sender: mpsc::WeakSender<ActorMessage>,
next_id: u32,
pub received_self_msg: bool,
}
enum ActorMessage {
GetUniqueId { respond_to: oneshot::Sender<u32> },
SelfMessage {},
}
impl MyActor {
fn new(
receiver: mpsc::Receiver<ActorMessage>,
sender: mpsc::WeakSender<ActorMessage>,
) -> Self {
MyActor {
receiver,
sender,
next_id: 0,
received_self_msg: false,
}
}
fn handle_message(&mut self, msg: ActorMessage) {
match msg {
ActorMessage::GetUniqueId { respond_to } => {
self.next_id += 1;
// The `let _ =` ignores any errors when sending.
//
// This can happen if the `select!` macro is used
// to cancel waiting for the response.
let _ = respond_to.send(self.next_id);
}
ActorMessage::SelfMessage { .. } => {
self.received_self_msg = true;
}
}
}
async fn send_message_to_self(&mut self) {
let msg = ActorMessage::SelfMessage {};
let sender = self.sender.clone();
// cannot move self.sender here
if let Some(sender) = sender.upgrade() {
let _ = sender.send(msg).await;
self.sender = sender.downgrade();
}
}
async fn run(&mut self) {
let mut i = 0;
while let Some(msg) = self.receiver.recv().await {
self.handle_message(msg);
if i == 0 {
self.send_message_to_self().await;
}
i += 1
}
assert!(self.received_self_msg);
}
}
#[derive(Clone)]
pub struct MyActorHandle {
sender: mpsc::Sender<ActorMessage>,
}
impl MyActorHandle {
pub fn new() -> (Self, MyActor) {
let (sender, receiver) = mpsc::channel(8);
let actor = MyActor::new(receiver, sender.clone().downgrade());
(Self { sender }, actor)
}
pub async fn get_unique_id(&self) -> u32 {
let (send, recv) = oneshot::channel();
let msg = ActorMessage::GetUniqueId { respond_to: send };
// Ignore send errors. If this send fails, so does the
// recv.await below. There's no reason to check the
// failure twice.
let _ = self.sender.send(msg).await;
recv.await.expect("Actor task has been killed")
}
}
let (handle, mut actor) = MyActorHandle::new();
let actor_handle = tokio::spawn(async move { actor.run().await });
let _ = tokio::spawn(async move {
let _ = handle.get_unique_id().await;
drop(handle);
})
.await;
let _ = actor_handle.await;
}