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use std::pin::Pin;
use futures::prelude::*;
use futures::task::{Context, Poll};
pub fn spawn<F, T>(fut: F) -> JoinHandle<T>
where
F: Future<Output = T> + Send + 'static,
T: Send + 'static,
{
let (tx, rx) = futures::channel::oneshot::channel();
let fut = async move {
let t = fut.await;
let _ = tx.send(t);
};
runtime_raw::current_runtime()
.spawn_boxed(fut.boxed())
.expect("cannot spawn a future");
JoinHandle { rx }
}
#[must_use = "futures do nothing unless you `.await` or poll them"]
#[derive(Debug)]
pub struct JoinHandle<T> {
pub(crate) rx: futures::channel::oneshot::Receiver<T>,
}
impl<T> Future for JoinHandle<T> {
type Output = T;
fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
match self.rx.poll_unpin(cx) {
Poll::Pending => Poll::Pending,
Poll::Ready(Ok(t)) => Poll::Ready(t),
Poll::Ready(Err(_)) => panic!(),
}
}
}