tokio 1.52.2

An event-driven, non-blocking I/O platform for writing asynchronous I/O backed applications.
Documentation 
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
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166

#![warn(rust_2018_idioms)]
#![cfg(feature = "full")]

use tokio::runtime::Runtime;
use tokio::time::*;

use std::sync::mpsc;

fn rt_combinations() -> Vec<Runtime> {
    let mut rts = vec![];

    let rt = tokio::runtime::Builder::new_current_thread()
        .enable_all()
        .build()
        .unwrap();
    rts.push(rt);

    let rt = tokio::runtime::Builder::new_multi_thread()
        .worker_threads(1)
        .enable_all()
        .build()
        .unwrap();
    rts.push(rt);

    let rt = tokio::runtime::Builder::new_multi_thread()
        .worker_threads(4)
        .enable_all()
        .build()
        .unwrap();
    rts.push(rt);

    #[cfg(tokio_unstable)]
    {
        let rt = tokio::runtime::Builder::new_multi_thread()
            .worker_threads(1)
            .enable_alt_timer()
            .enable_all()
            .build()
            .unwrap();
        rts.push(rt);

        let rt = tokio::runtime::Builder::new_multi_thread()
            .worker_threads(4)
            .enable_alt_timer()
            .enable_all()
            .build()
            .unwrap();
        rts.push(rt);
    }

    rts
}

#[cfg(all(feature = "rt-multi-thread", not(target_os = "wasi")))] // Wasi doesn't support threads
#[test]
fn timer_with_threaded_runtime() {
    use tokio::runtime::Runtime;

    {
        let rt = Runtime::new().unwrap();
        let (tx, rx) = mpsc::channel();

        rt.spawn(async move {
            let when = Instant::now() + Duration::from_millis(10);

            sleep_until(when).await;
            assert!(Instant::now() >= when);

            tx.send(()).unwrap();
        });

        rx.recv().unwrap();
    }

    #[cfg(tokio_unstable)]
    {
        let rt = tokio::runtime::Builder::new_multi_thread()
            .enable_alt_timer()
            .build()
            .unwrap();
        let (tx, rx) = mpsc::channel();

        rt.block_on(async move {
            let when = Instant::now() + Duration::from_millis(10);

            sleep_until(when).await;
            assert!(Instant::now() >= when);

            tx.send(()).unwrap();
        });

        rx.recv().unwrap();
    }
}

#[test]
fn timer_with_current_thread_scheduler() {
    use tokio::runtime::Builder;

    let rt = Builder::new_current_thread().enable_all().build().unwrap();
    let (tx, rx) = mpsc::channel();

    rt.block_on(async move {
        let when = Instant::now() + Duration::from_millis(10);

        sleep_until(when).await;
        assert!(Instant::now() >= when);

        tx.send(()).unwrap();
    });

    rx.recv().unwrap();
}

#[test]
fn starving() {
    use std::future::Future;
    use std::pin::Pin;
    use std::task::{Context, Poll};

    struct Starve<T: Future<Output = ()> + Unpin>(T, u64);

    impl<T: Future<Output = ()> + Unpin> Future for Starve<T> {
        type Output = u64;

        fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<u64> {
            if Pin::new(&mut self.0).poll(cx).is_ready() {
                return Poll::Ready(self.1);
            }

            self.1 += 1;

            cx.waker().wake_by_ref();

            Poll::Pending
        }
    }

    for rt in rt_combinations() {
        rt.block_on(async {
            let when = Instant::now() + Duration::from_millis(10);
            let starve = Starve(Box::pin(sleep_until(when)), 0);

            starve.await;
            assert!(Instant::now() >= when);
        });
    }
}

#[test]
fn timeout_value() {
    use tokio::sync::oneshot;

    for rt in rt_combinations() {
        rt.block_on(async {
            let (_tx, rx) = oneshot::channel::<()>();

            let now = Instant::now();
            let dur = Duration::from_millis(10);

            let res = timeout(dur, rx).await;
            assert!(res.is_err());
            assert!(Instant::now() >= now + dur);
        });
    }
}