lock_mutex.rs - mozsearch

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use futures::channel::mpsc;

use futures::executor::{block_on, ThreadPool};

use futures::future::{ready, FutureExt};

use futures::lock::Mutex;

use futures::stream::StreamExt;

use futures::task::{Context, SpawnExt};

use futures_test::future::FutureTestExt;

use futures_test::task::{new_count_waker, panic_context};

use std::sync::Arc;

#[test]

fn mutex_acquire_uncontested() {

    let mutex = Mutex::new(());

    for _ in 0..10 {

        assert!(mutex.lock().poll_unpin(&mut panic_context()).is_ready());

#[test]

fn mutex_wakes_waiters() {

    let mutex = Mutex::new(());

    let (waker, counter) = new_count_waker();

    let lock = mutex.lock().poll_unpin(&mut panic_context());

    assert!(lock.is_ready());

    let mut cx = Context::from_waker(&waker);

    let mut waiter = mutex.lock();

    assert!(waiter.poll_unpin(&mut cx).is_pending());

    assert_eq!(counter, 0);

    drop(lock);

    assert_eq!(counter, 1);

    assert!(waiter.poll_unpin(&mut panic_context()).is_ready());

#[test]

fn mutex_contested() {

        let (tx, mut rx) = mpsc::unbounded();

        let pool = ThreadPool::builder().pool_size(16).create().unwrap();

        let tx = Arc::new(tx);

        let mutex = Arc::new(Mutex::new(0));

        let num_tasks = 1000;

        for _ in 0..num_tasks {

            let tx = tx.clone();

            let mutex = mutex.clone();

            pool.spawn(async move {

                let mut lock = mutex.lock().await;

                ready(()).pending_once().await;

                *lock += 1;

                tx.unbounded_send(()).unwrap();

                drop(lock);

})

            .unwrap();

        block_on(async {

            for _ in 0..num_tasks {

                rx.next().await.unwrap();

            let lock = mutex.lock().await;

            assert_eq!(num_tasks, *lock);

});

    std::thread::sleep(std::time::Duration::from_millis(500)); // wait for background threads closed: https://github.com/rust-lang/miri/issues/1371