package chat.util;

import java.util.concurrent.atomic.AtomicReference;

public class SpinLock {
    //java中原子（CAS）操作
    AtomicReference<Thread> owner = new AtomicReference<>();//持有自旋锁的线程对象
    private int count;
    public void lock() {
        Thread cur = Thread.currentThread();
        //lock函数将owner设置为当前线程，并且预测原来的值为空。unlock函数将owner设置为null，并且预测值为当前线程。当有第二个线程调用lock操作时由于owner值不为空，导致循环

        //一直被执行，直至第一个线程调用unlock函数将owner设置为null，第二个线程才能进入临界区。
        while (!owner.compareAndSet(null, cur)){
        }
    }
    public void unLock() {
        Thread cur = Thread.currentThread();
        owner.compareAndSet(cur, null);
    }
}