利用zookeeper 實現分佈式鎖

利用Curator(流行的 zk 客戶端工具包) 的 InterProcessMute 類

import org.apache.curator.framework.CuratorFramework;
import org.apache.curator.framework.CuratorFrameworkFactory;
import org.apache.curator.framework.recipes.locks.InterProcessLock;
import org.apache.curator.framework.recipes.locks.InterProcessMutex;
import org.apache.curator.retry.ExponentialBackoffRetry;

import java.util.Random;
import java.util.concurrent.CountDownLatch;

/**
 * 文件功能：zookeeper分佈式鎖
 * 故事：5個線程（模擬分佈式進程）爭奪分佈式鎖
 */
public class CuratorLocksExample {

    private static  InterProcessLock distributeLock=null;
    private static CountDownLatch count=new CountDownLatch(5);

    public static void main(String[] args) {
        CuratorFramework client = CuratorFrameworkFactory.newClient("192.168.64.128:2181", new ExponentialBackoffRetry(1000, 3));
        client.start();
        distributeLock=new InterProcessMutex(client,"/mylock");
        for(int i=0;i<5;i++){
            new Thread(new MyHostThread("線程"+i,client,distributeLock,count)).start();
        }

        try {
            count.await();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }finally {
            System.out.println("釋放客戶端,斷開zk鏈接");
            client.close();
        }

    }
}


class MyHostThread implements Runnable{

    private String name;
    private CuratorFramework client;
    private InterProcessLock lock;
    private  CountDownLatch count;
    public MyHostThread(String name,CuratorFramework client,InterProcessLock lock,CountDownLatch count){
        this.name=name;
        this.client=client;
        this.lock=lock;
        this.count=count;
    }

    @Override
    public void run() {
        System.out.println(this.name + "開始競爭鎖");
        try {
            lock.acquire();//阻塞等待..
            System.out.println(this.name + "獲取到鎖");
            Thread.sleep(new Random().nextInt(2000));//模擬業務處理2s內
        } catch (Exception e) {
            e.printStackTrace();
        }finally {
            try {
                System.out.println(this.name + "業務處理完，釋放鎖");
                lock.release();//釋放鎖
                count.countDown();
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }
}

預期輸出：

線程3開始競爭鎖
線程0開始競爭鎖
線程4開始競爭鎖
線程1開始競爭鎖
線程2開始競爭鎖
線程0獲取到鎖
線程0業務處理完，釋放鎖
線程4獲取到鎖
線程4業務處理完，釋放鎖
線程1獲取到鎖
線程1業務處理完，釋放鎖
線程3獲取到鎖
線程3業務處理完，釋放鎖
線程2獲取到鎖
線程2業務處理完，釋放鎖
釋放客戶端,斷開zk鏈接