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#![cfg(feature = "async")]
use core::{future, mem, pin, task};
#[cfg(loom)]
pub use loom::sync::{Arc, Mutex};
#[cfg(not(loom))]
pub use std::sync::{Arc, Mutex};
mod helpers;
use helpers::maybe_loom_model;
#[test]
fn multiple_receiver_polls_keeps_only_latest_waker() {
#[derive(Default)]
struct MockWaker {
cloned: usize,
dropped: usize,
}
fn clone_mock_waker(waker: *const ()) -> task::RawWaker {
let mock_waker = unsafe { Arc::from_raw(waker as *const Mutex<MockWaker>) };
mock_waker.lock().unwrap().cloned += 1;
let new_waker =
task::RawWaker::new(Arc::into_raw(mock_waker.clone()) as *const (), &VTABLE);
mem::forget(mock_waker);
new_waker
}
fn drop_mock_waker(waker: *const ()) {
let mock_waker = unsafe { Arc::from_raw(waker as *const Mutex<MockWaker>) };
mock_waker.lock().unwrap().dropped += 1;
}
const VTABLE: task::RawWakerVTable =
task::RawWakerVTable::new(clone_mock_waker, |_| (), |_| (), drop_mock_waker);
maybe_loom_model(|| {
let mock_waker1 = Arc::new(Mutex::new(MockWaker::default()));
let raw_waker1 =
task::RawWaker::new(Arc::into_raw(mock_waker1.clone()) as *const (), &VTABLE);
let waker1 = unsafe { task::Waker::from_raw(raw_waker1) };
let mut context1 = task::Context::from_waker(&waker1);
let (_sender, mut receiver) = oneshot::channel::<()>();
let poll_result = future::Future::poll(pin::Pin::new(&mut receiver), &mut context1);
assert_eq!(poll_result, task::Poll::Pending);
assert_eq!(mock_waker1.lock().unwrap().cloned, 1);
assert_eq!(mock_waker1.lock().unwrap().dropped, 0);
let mock_waker2 = Arc::new(Mutex::new(MockWaker::default()));
let raw_waker2 =
task::RawWaker::new(Arc::into_raw(mock_waker2.clone()) as *const (), &VTABLE);
let waker2 = unsafe { task::Waker::from_raw(raw_waker2) };
let mut context2 = task::Context::from_waker(&waker2);
let poll_result = future::Future::poll(pin::Pin::new(&mut receiver), &mut context2);
assert_eq!(poll_result, task::Poll::Pending);
assert_eq!(mock_waker2.lock().unwrap().cloned, 1);
assert_eq!(mock_waker2.lock().unwrap().dropped, 0);
assert_eq!(mock_waker1.lock().unwrap().cloned, 1);
assert_eq!(mock_waker1.lock().unwrap().dropped, 1);
});
}
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