45 lines
1.0 KiB
Rust
45 lines
1.0 KiB
Rust
use std::future::Future;
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use std::pin::Pin;
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use std::task::{Context, Poll};
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use std::time::Duration;
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use tokio::sync::oneshot::{channel, Receiver};
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#[tokio::main]
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async fn main() {
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let (tx1, rx1) = channel::<i32>();
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let (_tx2, rx2) = channel::<i32>();
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tokio::spawn(async move {
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tokio::time::sleep(Duration::from_millis(200)).await;
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let _ = tx1.send(1);
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});
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println!("start select");
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MySelect { rx1, rx2 }.await;
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println!("end select");
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}
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struct MySelect {
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rx1: Receiver<i32>,
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rx2: Receiver<i32>,
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}
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impl Future for MySelect {
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type Output = ();
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fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<()> {
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if let Poll::Ready(val) = Pin::new(&mut self.rx1).poll(cx) {
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println!("rx1 completed first with {:?}", val);
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return Poll::Ready(());
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}
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if let Poll::Ready(val) = Pin::new(&mut self.rx2).poll(cx) {
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println!("rx2 completed first with {:?}", val);
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return Poll::Ready(());
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}
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Poll::Pending
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}
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}
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