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

use super::*;
use crate::object::*;
use alloc::boxed::Box;
use alloc::sync::Arc;
use core::time::Duration;
use lock::Mutex;

/// An object that may be signaled at some point in the future
///
/// ## SYNOPSIS
///
/// A timer is used to wait until a specified point in time has occurred
/// or the timer has been canceled.
pub struct Timer {
    base: KObjectBase,
    _counter: CountHelper,
    #[allow(dead_code)]
    slack: Slack,
    inner: Mutex<TimerInner>,
}

impl_kobject!(Timer);
define_count_helper!(Timer);

#[derive(Default)]
struct TimerInner {
    deadline: Option<Duration>,
}

/// Slack specifies how much a timer or event is allowed to deviate from its deadline.
///
/// **Not supported: Now slack has no effect on the timer.**
#[repr(u32)]
#[derive(Debug, Copy, Clone)]
pub enum Slack {
    /// slack is centered around deadline
    Center = 0,
    /// slack interval is (deadline - slack, deadline]
    Early = 1,
    /// slack interval is [deadline, deadline + slack)
    Late = 2,
}

impl Timer {
    /// Create a new `Timer`.
    pub fn new() -> Arc<Self> {
        Self::with_slack(Slack::Center)
    }

    /// Create a new `Timer` with slack.
    pub fn with_slack(slack: Slack) -> Arc<Self> {
        Arc::new(Timer {
            base: KObjectBase::default(),
            _counter: CountHelper::new(),
            slack,
            inner: Mutex::default(),
        })
    }

    /// Create a one-shot timer.
    pub fn one_shot(deadline: Duration) -> Arc<Self> {
        let timer = Timer::new();
        timer.set(deadline, Duration::default());
        timer
    }

    /// Starts a one-shot timer that will fire when `deadline` passes.
    ///
    /// If a previous call to `set` was pending, the previous timer is canceled
    /// and `Signal::SIGNALED` is de-asserted as needed.
    pub fn set(self: &Arc<Self>, deadline: Duration, _slack: Duration) {
        let mut inner = self.inner.lock();
        inner.deadline = Some(deadline);
        self.base.signal_clear(Signal::SIGNALED);
        let me = Arc::downgrade(self);
        kernel_hal::timer::timer_set(
            deadline,
            Box::new(move |now| me.upgrade().map(|timer| timer.touch(now)).unwrap_or(())),
        );
    }

    /// Cancel the pending timer started by `set`.
    pub fn cancel(&self) {
        let mut inner = self.inner.lock();
        inner.deadline = None;
    }

    /// Called by HAL timer.
    fn touch(&self, now: Duration) {
        let mut inner = self.inner.lock();
        if let Some(deadline) = inner.deadline {
            if now >= deadline {
                self.base.signal_set(Signal::SIGNALED);
                inner.deadline = None;
            }
        }
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use kernel_hal::timer::timer_now;

    #[test]
    fn one_shot() {
        let timer = Timer::one_shot(timer_now() + Duration::from_millis(15));
        std::thread::sleep(Duration::from_millis(10));
        assert_eq!(timer.signal(), Signal::empty());

        std::thread::sleep(Duration::from_millis(20));
        assert_eq!(timer.signal(), Signal::SIGNALED);
    }

    #[test]
    fn set() {
        let timer = Timer::new();
        timer.set(timer_now() + Duration::from_millis(10), Duration::default());
        timer.set(timer_now() + Duration::from_millis(20), Duration::default());

        std::thread::sleep(Duration::from_millis(10));
        assert_eq!(timer.signal(), Signal::empty());

        std::thread::sleep(Duration::from_millis(15));
        assert_eq!(timer.signal(), Signal::SIGNALED);

        timer.set(timer_now() + Duration::from_millis(10), Duration::default());
        assert_eq!(timer.signal(), Signal::empty());
    }

    #[test]
    fn cancel() {
        let timer = Timer::new();
        timer.set(timer_now() + Duration::from_millis(10), Duration::default());

        std::thread::sleep(Duration::from_millis(5));
        timer.cancel();

        std::thread::sleep(Duration::from_millis(50));
        assert_eq!(timer.signal(), Signal::empty());
    }
}