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use futures::{Future, Async};
use futures::sync::oneshot;
use std::{thread, panic};
use void::Void;
pub struct ThreadFuture<R> {
join_handle: Option<thread::JoinHandle<()>>,
rx: oneshot::Receiver<R>,
}
pub fn thread_future<F, R>(f: F) -> ThreadFuture<R>
where
R: Send + 'static,
F: FnOnce() -> R + Send + 'static
{
let (tx, rx) = oneshot::channel();
let join_handle = Some(thread::spawn(|| {
let x = f();
let _ = tx.send(x);
}));
ThreadFuture {
rx,
join_handle,
}
}
impl<R> Future for ThreadFuture<R> {
type Item = R;
type Error = Void;
fn poll(&mut self) -> Result<Async<R>, Void> {
match self.rx.poll() {
Ok(x) => Ok(x),
Err(oneshot::Canceled) => {
match unwrap!(self.join_handle.take()).join() {
Ok(()) => unreachable!(),
Err(e) => panic::resume_unwind(e),
}
},
}
}
}