latches 0.1.0

A downward counter (CountDownLatch) which can be used to synchronize threads or coordinate tasks
Documentation 
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use std::{sync::Arc, thread, time::Duration};

use super::Latch;

#[test]
fn test_single_thread() {
    let latch = Latch::new(3);

    latch.count_down();
    latch.count_down();
    latch.count_down();

    latch.wait();
    assert_eq!(latch.count(), 0);
}

#[test]
fn test_arrive() {
    let latch = Latch::new(3);

    latch.arrive(3);
    latch.wait();

    assert_eq!(latch.count(), 0);
}

#[test]
fn test_arrive_zero() {
    let latch = Latch::new(2);

    latch.arrive(0);

    assert_eq!(latch.count(), 2);
}

#[test]
fn test_try_wait() {
    let latch = Latch::new(0);

    assert_eq!(latch.try_wait(), Ok(()));
}

#[test]
fn test_try_wait_err() {
    let latch = Latch::new(3);

    assert_eq!(latch.try_wait(), Err(3));
}

#[test]
fn test_last_one_signal() {
    let latch = Arc::new(Latch::new(3));
    let l1 = latch.clone();

    latch.count_down();
    latch.count_down();

    let t = thread::spawn(move || {
        thread::sleep(Duration::from_millis(32));
        l1.count_down()
    });

    latch.wait();
    assert_eq!(latch.count(), 0);
    t.join().unwrap();
}

#[test]
fn test_gate_wait() {
    let latch = Arc::new(Latch::new(1));
    let handles: Vec<_> = (0..4)
        .map(|_| {
            let latch = latch.clone();

            thread::spawn(move || latch.wait())
        })
        .collect();

    latch.count_down();

    for t in handles {
        t.join().unwrap();
    }
}

#[test]
fn test_multi_threads() {
    let latch = Arc::new(Latch::new(5));
    let handles: Vec<_> = (0..5)
        .map(|_| {
            let latch = latch.clone();

            thread::spawn(move || {
                thread::sleep(Duration::from_millis(10));
                latch.count_down()
            })
        })
        .collect();

    latch.wait();
    assert_eq!(latch.count(), 0);

    for t in handles {
        t.join().unwrap();
    }
}

#[test]
fn test_more_count_down() {
    let latch = Arc::new(Latch::new(3));
    let handles: Vec<_> = (0..5)
        .map(|_| {
            let latch = latch.clone();

            thread::spawn(move || {
                thread::sleep(Duration::from_millis(10));
                latch.count_down()
            })
        })
        .collect();

    latch.wait();
    assert_eq!(latch.count(), 0);
    latch.count_down();
    assert_eq!(latch.count(), 0);
    latch.count_down();

    for t in handles {
        t.join().unwrap();
    }

    assert_eq!(latch.count(), 0);
}

#[test]
fn test_more_arrive() {
    let latch = Latch::new(10);

    for _ in 0..4 {
        latch.arrive(3);
    }
    latch.wait();

    assert_eq!(latch.count(), 0);
}

#[test]
fn test_debug() {
    let latch = Latch::new(3);
    let stringified = format!("{:?}", latch);

    assert!(stringified.contains("Latch"));
    assert!(stringified.contains('3'));
}