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use futures::executor::block_on;
use futures::future::poll_fn;
use futures::task::{AtomicWaker, Poll};
use std::sync::atomic::AtomicUsize;
use std::sync::atomic::Ordering;
use std::sync::Arc;
use std::thread;
#[test]
fn basic() {
let atomic_waker = Arc::new(AtomicWaker::new());
let atomic_waker_copy = atomic_waker.clone();
let returned_pending = Arc::new(AtomicUsize::new(0));
let returned_pending_copy = returned_pending.clone();
let woken = Arc::new(AtomicUsize::new(0));
let woken_copy = woken.clone();
let t = thread::spawn(move || {
let mut pending_count = 0;
block_on(poll_fn(move |cx| {
if woken_copy.load(Ordering::Relaxed) == 1 {
Poll::Ready(())
} else {
// Assert we return pending exactly once
assert_eq!(0, pending_count);
pending_count += 1;
atomic_waker_copy.register(cx.waker());
returned_pending_copy.store(1, Ordering::Relaxed);
Poll::Pending
}
}))
});
while returned_pending.load(Ordering::Relaxed) == 0 {}
// give spawned thread some time to sleep in `block_on`
thread::yield_now();
woken.store(1, Ordering::Relaxed);
atomic_waker.wake();
t.join().unwrap();
}
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