use std::sync::{Arc, Condvar, Mutex};
use std::thread;
use std::time::Duration;

let pair = Arc::new((Mutex::new(false), Condvar::new()));
let pair2 = Arc::clone(&pair);

thread::spawn(move || {
    let (lock, cvar) = &*pair2;

    // Let's wait 20 milliseconds before notifying the condvar.
    thread::sleep(Duration::from_millis(20));

    let mut started = lock.lock().unwrap();
    // We update the boolean value.
    *started = true;
    cvar.notify_one();
});

// Wait for the thread to start up.
let (lock, cvar) = &*pair;
loop {
    // Let's put a timeout on the condvar's wait.
    let result = cvar.wait_timeout(lock.lock().unwrap(), Duration::from_millis(10)).unwrap();
    // 10 milliseconds have passed.
    if result.1.timed_out() {
        // timed out now and we can leave.
        break
    }
}