1 use futures::channel::mpsc;
2 use futures::executor::{block_on, ThreadPool};
3 use futures::future::{ready, FutureExt};
4 use futures::lock::Mutex;
5 use futures::stream::StreamExt;
6 use futures::task::{Context, SpawnExt};
7 use futures_test::future::FutureTestExt;
8 use futures_test::task::{new_count_waker, panic_context};
9 use std::sync::Arc;
10
11 #[test]
mutex_acquire_uncontested()12 fn mutex_acquire_uncontested() {
13 let mutex = Mutex::new(());
14 for _ in 0..10 {
15 assert!(mutex.lock().poll_unpin(&mut panic_context()).is_ready());
16 }
17 }
18
19 #[test]
mutex_wakes_waiters()20 fn mutex_wakes_waiters() {
21 let mutex = Mutex::new(());
22 let (waker, counter) = new_count_waker();
23 let lock = mutex.lock().poll_unpin(&mut panic_context());
24 assert!(lock.is_ready());
25
26 let mut cx = Context::from_waker(&waker);
27 let mut waiter = mutex.lock();
28 assert!(waiter.poll_unpin(&mut cx).is_pending());
29 assert_eq!(counter, 0);
30
31 drop(lock);
32
33 assert_eq!(counter, 1);
34 assert!(waiter.poll_unpin(&mut panic_context()).is_ready());
35 }
36
37 #[cfg_attr(miri, ignore)] // https://github.com/rust-lang/miri/issues/1038
38 #[test]
mutex_contested()39 fn mutex_contested() {
40 let (tx, mut rx) = mpsc::unbounded();
41 let pool = ThreadPool::builder().pool_size(16).create().unwrap();
42
43 let tx = Arc::new(tx);
44 let mutex = Arc::new(Mutex::new(0));
45
46 let num_tasks = 1000;
47 for _ in 0..num_tasks {
48 let tx = tx.clone();
49 let mutex = mutex.clone();
50 pool.spawn(async move {
51 let mut lock = mutex.lock().await;
52 ready(()).pending_once().await;
53 *lock += 1;
54 tx.unbounded_send(()).unwrap();
55 drop(lock);
56 })
57 .unwrap();
58 }
59
60 block_on(async {
61 for _ in 0..num_tasks {
62 rx.next().await.unwrap();
63 }
64 let lock = mutex.lock().await;
65 assert_eq!(num_tasks, *lock);
66 })
67 }
68