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remove implicit .await from core::future::join

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This commit is contained in:
Ibraheem Ahmed
2021-12-08 16:44:48 -05:00
parent d07cef22b0
commit a8c9314100
2 changed files with 64 additions and 53 deletions
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100
library/core/src/future/join.rs
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@@ -22,7 +22,7 @@ use crate::task::Poll;
/// async fn two() -> usize { 2 }
///
/// # let _ = async {
/// let x = join!(one(), two());
/// let x = join!(one(), two()).await;
/// assert_eq!(x, (1, 2));
/// # };
/// ```
@@ -39,7 +39,7 @@ use crate::task::Poll;
/// async fn three() -> usize { 3 }
///
/// # let _ = async {
/// let x = join!(one(), two(), three());
/// let x = join!(one(), two(), three()).await;
/// assert_eq!(x, (1, 2, 3));
/// # };
/// ```
@@ -71,61 +71,63 @@ pub macro join {
},
@rest: ()
) => {{
// The futures and whether they have completed
let mut state = ( $( UnsafeCell::new(($fut, false)), )* );
async move {
// The futures and whether they have completed
let mut state = ( $( UnsafeCell::new(($fut, false)), )* );
// Make sure the futures don't panic
// if polled after completion, and
// store their output separately
let mut futures = ($(
({
let ( $($pos,)* state, .. ) = &state;
// Make sure the futures don't panic
// if polled after completion, and
// store their output separately
let mut futures = ($(
({
let ( $($pos,)* state, .. ) = &state;
poll_fn(move |cx| {
// SAFETY: each future borrows a distinct element
// of the tuple
let (fut, done) = unsafe { &mut *state.get() };
poll_fn(move |cx| {
// SAFETY: each future borrows a distinct element
// of the tuple
let (fut, done) = unsafe { &mut *state.get() };
if *done {
return Poll::Ready(None)
}
if *done {
return Poll::Ready(None)
}
// SAFETY: The futures are never moved
match unsafe { Pin::new_unchecked(fut).poll(cx) } {
Poll::Ready(val) => {
*done = true;
Poll::Ready(Some(val))
}
Poll::Pending => Poll::Pending
}
})
}, None),
)*);
poll_fn(move |cx| {
let mut done = true;
$(
let ( $($pos,)* (fut, out), .. ) = &mut futures;
// SAFETY: The futures are never moved
match unsafe { Pin::new_unchecked(fut).poll(cx) } {
Poll::Ready(val) => {
*done = true;
Poll::Ready(Some(val))
}
Poll::Pending => Poll::Pending
Poll::Ready(Some(val)) => *out = Some(val),
// the future was already done
Poll::Ready(None) => {},
Poll::Pending => done = false,
}
})
}, None),
)*);
)*
poll_fn(move |cx| {
let mut done = true;
$(
let ( $($pos,)* (fut, out), .. ) = &mut futures;
// SAFETY: The futures are never moved
match unsafe { Pin::new_unchecked(fut).poll(cx) } {
Poll::Ready(Some(val)) => *out = Some(val),
// the future was already done
Poll::Ready(None) => {},
Poll::Pending => done = false,
if done {
// Extract all the outputs
Poll::Ready(($({
let ( $($pos,)* (_, val), .. ) = &mut futures;
val.unwrap()
}),*))
} else {
Poll::Pending
}
)*
if done {
// Extract all the outputs
Poll::Ready(($({
let ( $($pos,)* (_, val), .. ) = &mut futures;
val.unwrap()
}),*))
} else {
Poll::Pending
}
}).await
}).await
}
}}
}