gemachain_runtime/
waitable_condvar.rs

1use std::{
2    sync::{Condvar, Mutex},
3    time::Duration,
4};
5
6// encapsulate complications of unneeded mutex and Condvar to give us event behavior of wait and notify
7// this will likely be wrapped in an arc somehow
8#[derive(Default, Debug)]
9pub struct WaitableCondvar {
10    pub mutex: Mutex<u8>,
11    pub event: Condvar,
12}
13
14impl WaitableCondvar {
15    pub fn notify_all(&self) {
16        self.event.notify_all();
17    }
18    pub fn notify_one(&self) {
19        self.event.notify_one();
20    }
21    pub fn wait_timeout(&self, timeout: Duration) -> bool {
22        let lock = self.mutex.lock().unwrap();
23        let res = self.event.wait_timeout(lock, timeout).unwrap();
24        if res.1.timed_out() {
25            return true;
26        }
27        false
28    }
29}
30
31#[cfg(test)]
32pub mod tests {
33    use super::*;
34    use std::{
35        sync::{
36            atomic::{AtomicBool, Ordering},
37            Arc,
38        },
39        thread::Builder,
40    };
41    #[ignore]
42    #[test]
43    fn test_waitable_condvar() {
44        let data = Arc::new(AtomicBool::new(false));
45        let data_ = data.clone();
46        let cv = Arc::new(WaitableCondvar::default());
47        let cv2 = Arc::new(WaitableCondvar::default());
48        let cv_ = cv.clone();
49        let cv2_ = cv2.clone();
50        let cv2__ = cv2.clone();
51        // several passes to check re-notification and drop one of the
52        let passes = 3;
53        let handle = Builder::new().spawn(move || {
54            for _pass in 0..passes {
55                let mut notified = false;
56                while cv2_.wait_timeout(Duration::from_millis(1)) {
57                    if !notified && data_.load(Ordering::Relaxed) {
58                        notified = true;
59                        cv_.notify_all();
60                    }
61                }
62                assert!(data_.swap(false, Ordering::Relaxed));
63            }
64        });
65        // just wait, but 1 less pass - verifies that notify_all works with multiple and with 1
66        let handle2 = Builder::new().spawn(move || {
67            for _pass in 0..(passes - 1) {
68                assert!(!cv2__.wait_timeout(Duration::from_millis(10000))); // long enough to not be intermittent, short enough to fail if we really don't get notified
69            }
70        });
71        for _pass in 0..passes {
72            assert!(cv.wait_timeout(Duration::from_millis(1)));
73            assert!(!data.swap(true, Ordering::Relaxed));
74            assert!(!cv.wait_timeout(Duration::from_millis(10000))); // should barely wait, but don't want intermittent
75            cv2.notify_all();
76        }
77        assert!(handle.unwrap().join().is_ok());
78        assert!(handle2.unwrap().join().is_ok());
79    }
80}
gemachain_runtime/waitable_condvar.rs

gemachain_runtime/
waitable_condvar.rs
