ch2-11-increment-with-compare-exchange.rs

use std::sync::atomic::AtomicU32;
use std::sync::atomic::Ordering::Relaxed;

fn increment(a: &AtomicU32) {
    let mut current = a.load(Relaxed);
    loop {
        let new = current + 1;
        match a.compare_exchange(current, new, Relaxed, Relaxed) {
            Ok(_) => return,
            Err(v) => current = v,
        }
    }
}

fn main() {
    let a = AtomicU32::new(0);
    increment(&a);
    increment(&a);
    assert_eq!(a.into_inner(), 2);
}