CAS | Tech

CAS概念

运用在并发场合下，实现不能被打断的数据交换操作
我认为V值应该是X，如果是的话就修改成Y，如果不是就说明被别人修改过，那我就不修改了，避免多人同时修改导致出错，最后返回V的值

模拟CAS代码案例

public class SimulatedCAS implements Runnable{

    private volatile int value;

    public synchronized int compareAndSwap(int expectedValue, int newValue) {
        int oldValue = value;
        if (oldValue == expectedValue) {
            value = newValue;
        }
        return oldValue;
    }

    public static void main(String[] args) throws InterruptedException {
        SimulatedCAS simulatedCAS = new SimulatedCAS();
        simulatedCAS.value = 0;
        Thread thread1 = new Thread(simulatedCAS,"Thread1");
        Thread thread2 = new Thread(simulatedCAS,"Thread2");
        thread1.start();
        thread2.start();
        thread1.join();
        thread2.join();
        System.out.println(simulatedCAS.value);
    }

    @Override
    public void run() {
        compareAndSwap(0, 1);
    }
}