package com.xycode.spinlock;

import java.util.concurrent.TimeUnit;

import java.util.concurrent.atomic.AtomicReference;

/**

* ClassName: MySpinLock

*

* @Author: xycode

* @Date: 2019/10/28

**/

public class MySpinLock {

private AtomicReference<Thread> atomicReference=new AtomicReference<>(null);

public void lock(){//实现自旋锁,CPU占用较高

Thread thread=Thread.currentThread();

while(!atomicReference.compareAndSet(null,thread)){

// System.err.println("Thread-"+thread.getId()+" fail to acquire lock");

thread.yield();//让出CPU,减少锁竞争,不过不保证一定有效...

}

}

public void unlock(){

Thread thread=Thread.currentThread();

atomicReference.compareAndSet(thread,null);

}

public static void main(String[] args) {

Thread[] t=new Thread[5];

MySpinLock spinLock=new MySpinLock();

for(int i=0;i<t.length;++i){

t[i]=new Thread(()->{

try {

spinLock.lock();

System.out.println("Thread-"+Thread.currentThread().getId()+" acquire lock");

System.out.println("Thread-"+Thread.currentThread().getId()+" working...");

try {

TimeUnit.SECONDS.sleep(2);

} catch (InterruptedException e) {

e.printStackTrace();

}

System.out.println("Thread-"+Thread.currentThread().getId()+" release lock");

System.out.println();

}finally {

spinLock.unlock();

}

});

}

for(Thread thread:t) thread.start();

}

}