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// run-pass
// revisions: default nomiropt
//[nomiropt]compile-flags: -Z mir-opt-level=0
// edition:2018
// aux-build:arc_wake.rs
#![feature(async_closure)]
extern crate arc_wake;
use std::pin::Pin;
use std::future::Future;
use std::sync::{
Arc,
atomic::{self, AtomicUsize},
};
use std::task::{Context, Poll};
use arc_wake::ArcWake;
struct Counter {
wakes: AtomicUsize,
}
impl ArcWake for Counter {
fn wake(self: Arc<Self>) {
Self::wake_by_ref(&self)
}
fn wake_by_ref(arc_self: &Arc<Self>) {
arc_self.wakes.fetch_add(1, atomic::Ordering::SeqCst);
}
}
struct WakeOnceThenComplete(bool);
fn wake_and_yield_once() -> WakeOnceThenComplete { WakeOnceThenComplete(false) }
impl Future for WakeOnceThenComplete {
type Output = ();
fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<()> {
if self.0 {
Poll::Ready(())
} else {
cx.waker().wake_by_ref();
self.0 = true;
Poll::Pending
}
}
}
fn async_closure(x: u8) -> impl Future<Output = u8> {
(async move |x: u8| -> u8 {
wake_and_yield_once().await;
x
})(x)
}
fn async_closure_in_unsafe_block(x: u8) -> impl Future<Output = u8> {
(unsafe {
async move |x: u8| unsafe_fn(unsafe_async_fn(x).await)
})(x)
}
async unsafe fn unsafe_async_fn(x: u8) -> u8 {
wake_and_yield_once().await;
x
}
unsafe fn unsafe_fn(x: u8) -> u8 {
x
}
fn test_future_yields_once_then_returns<F, Fut>(f: F)
where
F: FnOnce(u8) -> Fut,
Fut: Future<Output = u8>,
{
let mut fut = Box::pin(f(9));
let counter = Arc::new(Counter { wakes: AtomicUsize::new(0) });
let waker = ArcWake::into_waker(counter.clone());
let mut cx = Context::from_waker(&waker);
assert_eq!(0, counter.wakes.load(atomic::Ordering::SeqCst));
assert_eq!(Poll::Pending, fut.as_mut().poll(&mut cx));
assert_eq!(1, counter.wakes.load(atomic::Ordering::SeqCst));
assert_eq!(Poll::Ready(9), fut.as_mut().poll(&mut cx));
}
fn main() {
macro_rules! test {
($($fn_name:expr,)*) => { $(
test_future_yields_once_then_returns($fn_name);
)* }
}
test! {
async_closure,
async_closure_in_unsafe_block,
}
}
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