记一次 “排它锁" 和 "自旋锁" 的简单实现

记一次`排它锁`和`自旋锁`的简单实现

定义一个lock接口

public interface PutMessageLock {
    void lock();

    void unlock();
}

排它锁实现

使用java自带的 ReentrantLock即可

public class PutMessageReentrantLock implements PutMessageLock {
    private ReentrantLock putMessageNormalLock = new ReentrantLock(); // NonfairSync

    @Override
    public void lock() {
        putMessageNormalLock.lock();
    }

    @Override
    public void unlock() {
        putMessageNormalLock.unlock();
    }
}

自旋锁实现

使用 cas + 循环来实现

public class PutMessageSpinLock implements PutMessageLock {
    //true: Can lock, false : in lock.
    private AtomicBoolean putMessageSpinLock = new AtomicBoolean(true);

    @Override
    public void lock() {
        boolean flag;
        do {
            flag = this.putMessageSpinLock.compareAndSet(true, false);
        }
        while (!flag);
    }

    @Override
    public void unlock() {
        this.putMessageSpinLock.compareAndSet(false, true);
    }
}

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