summaryrefslogtreecommitdiffstats
path: root/tokio/tests/sync_semaphore.rs
blob: a33b878b37b4742a6deaf5f5e54448b85004fbb2 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
#![cfg(feature = "full")]

use std::sync::Arc;
use tokio::sync::Semaphore;

#[test]
fn no_permits() {
    // this should not panic
    Semaphore::new(0);
}

#[test]
fn try_acquire() {
    let sem = Semaphore::new(1);
    {
        let p1 = sem.try_acquire();
        assert!(p1.is_ok());
        let p2 = sem.try_acquire();
        assert!(p2.is_err());
    }
    let p3 = sem.try_acquire();
    assert!(p3.is_ok());
}

#[tokio::test]
async fn acquire() {
    let sem = Arc::new(Semaphore::new(1));
    let p1 = sem.try_acquire().unwrap();
    let sem_clone = sem.clone();
    let j = tokio::spawn(async move {
        let _p2 = sem_clone.acquire().await;
    });
    drop(p1);
    j.await.unwrap();
}

#[tokio::test]
async fn add_permits() {
    let sem = Arc::new(Semaphore::new(0));
    let sem_clone = sem.clone();
    let j = tokio::spawn(async move {
        let _p2 = sem_clone.acquire().await;
    });
    sem.add_permits(1);
    j.await.unwrap();
}

#[test]
fn forget() {
    let sem = Arc::new(Semaphore::new(1));
    {
        let p = sem.try_acquire().unwrap();
        assert_eq!(sem.available_permits(), 0);
        p.forget();
        assert_eq!(sem.available_permits(), 0);
    }
    assert_eq!(sem.available_permits(), 0);
    assert!(sem.try_acquire().is_err());
}

#[tokio::test]
async fn stresstest() {
    let sem = Arc::new(Semaphore::new(5));
    let mut join_handles = Vec::new();
    for _ in 0..1000 {
        let sem_clone = sem.clone();
        join_handles.push(tokio::spawn(async move {
            let _p = sem_clone.acquire().await;
        }));
    }
    for j in join_handles {
        j.await.unwrap();
    }
    // there should be exactly 5 semaphores available now
    let _p1 = sem.try_acquire().unwrap();
    let _p2 = sem.try_acquire().unwrap();
    let _p3 = sem.try_acquire().unwrap();
    let _p4 = sem.try_acquire().unwrap();
    let _p5 = sem.try_acquire().unwrap();
    assert!(sem.try_acquire().is_err());
}

#[test]
fn add_max_amount_permits() {
    let s = tokio::sync::Semaphore::new(0);
    s.add_permits(usize::MAX >> 3);
    assert_eq!(s.available_permits(), usize::MAX >> 3);
}

#[test]
#[should_panic]
fn add_more_than_max_amount_permits() {
    let s = tokio::sync::Semaphore::new(1);
    s.add_permits(usize::MAX >> 3);
}