poll_semaphore.rs - mozsearch

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use std::future::Future;

use std::sync::Arc;

use std::task::Poll;

use tokio::sync::{OwnedSemaphorePermit, Semaphore};

use tokio_util::sync::PollSemaphore;

type SemRet = Option<OwnedSemaphorePermit>;

fn semaphore_poll(

    sem: &mut PollSemaphore,

) -> tokio_test::task::Spawn<impl Future<Output = SemRet> + '_> {

    let fut = futures::future::poll_fn(move |cx| sem.poll_acquire(cx));

    tokio_test::task::spawn(fut)

#[tokio::test]

async fn it_works() {

    let sem = Arc::new(Semaphore::new(1));

    let mut poll_sem = PollSemaphore::new(sem.clone());

    let permit = sem.acquire().await.unwrap();

    let mut poll = semaphore_poll(&mut poll_sem);

    assert!(poll.poll().is_pending());

    drop(permit);

    assert!(matches!(poll.poll(), Poll::Ready(Some(_))));

    drop(poll);

    sem.close();

    assert!(semaphore_poll(&mut poll_sem).await.is_none());

    // Check that it is fused.

    assert!(semaphore_poll(&mut poll_sem).await.is_none());

    assert!(semaphore_poll(&mut poll_sem).await.is_none());