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)); }