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

extern crate libc;
extern crate rand;

mod sys;
pub use sys::{
    Semaphore,
    SemaphoreGuard,
};

// These tests are taken from the Rust standard library semaphore implementation. Since we
// implement roughtly the same interface, it makes sense use the same tests as well.
#[cfg(test)]
mod tests {
    use std::sync::Arc;
    use super::Semaphore;
    use std::sync::mpsc::channel;
    use std::thread;

    #[test]
    fn test_sem_acquire_post() {
        let s = Semaphore::new(1);
        s.wait();
        s.post();
        s.wait();
    }

    #[test]
    fn test_sem_basic() {
        let s = Semaphore::new(1);
        let _g = s.take();
    }

    #[test]
    fn test_sem_as_mutex() {
        let s = Arc::new(Semaphore::new(1));
        let s2 = s.clone();
        let _t = thread::spawn(move|| {
            let _g = s2.take();
        });
        let _g = s.take();
    }

    #[test]
    fn test_sem_as_cvar() {
        /* Child waits and parent signals */
        let (tx, rx) = channel();
        let s = Arc::new(Semaphore::new(0));
        let s2 = s.clone();
        let _t = thread::spawn(move|| {
            s2.wait();
            tx.send(()).unwrap();
        });
        s.post();
        let _ = rx.recv();

        /* Parent waits and child signals */
        let (tx, rx) = channel();
        let s = Arc::new(Semaphore::new(0));
        let s2 = s.clone();
        let _t = thread::spawn(move|| {
            s2.post();
            let _ = rx.recv();
        });
        s.wait();
        tx.send(()).unwrap();
    }

    #[test]
    fn test_sem_multi_resource() {
        // Parent and child both get in the critical section at the same
        // time, and shake hands.
        let s = Arc::new(Semaphore::new(2));
        let s2 = s.clone();
        let (tx1, rx1) = channel();
        let (tx2, rx2) = channel();
        let _t = thread::spawn(move|| {
            let _g = s2.take();
            let _ = rx2.recv();
            tx1.send(()).unwrap();
        });
        let _g = s.take();
        tx2.send(()).unwrap();
        rx1.recv().unwrap();
    }

    #[test]
    fn test_sem_runtime_friendly_blocking() {
        let s = Arc::new(Semaphore::new(1));
        let s2 = s.clone();
        let (tx, rx) = channel();
        {
            let _g = s.take();
            thread::spawn(move|| {
                tx.send(()).unwrap();
                drop(s2.take());
                tx.send(()).unwrap();
            });
            rx.recv().unwrap(); // wait for child to come alive
        }
        rx.recv().unwrap(); // wait for child to be done
    }
}