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服务器之家 - 编程语言 - Java教程 - 利用consul在spring boot中实现分布式锁场景分析

利用consul在spring boot中实现分布式锁场景分析

2022-01-05 00:55wenwuxianren Java教程

这篇文章通过场景分析给大家介绍如何利用consul在spring boot中实现简单的分布式锁功能,代码简单易懂,对大家的学习或工作具有一定的参考借鉴价值,需要的朋友参考下吧

因为在项目实际过程中所采用的是微服务架构,考虑到承载量基本每个相同业务的服务都是多节点部署,所以针对某些资源的访问就不得不用到用到分布式锁了。

这里列举一个最简单的场景,假如有一个智能售货机,由于机器本身的原因不能同一台机器不能同时出两个商品,这就要求在在出货流程前针对同一台机器在同一时刻出现并发创建订单时只能有一笔订单创建成功,但是订单服务是多节点部署的,所以就不得不用到分布式锁了。

以上只是一种简单的业务场景,在各种大型互联网实际应用中,需要分布式锁的业务场景会更多,综合比较了业界基于各种中间件来实现的分布式锁方案,然后结合实际业务最终决定采用consul来实现,因为我们的项目中采用了consul做注册中心,并且consul天生可以保证一致性(这点类似zk),当然zk也能实现分布式锁,但是这里不对这点做过多讨论。

redis虽然也能实现分布式锁,但是可能因为场景比较复杂,如果redis采用cluster部署的话,如果某一主节点出现故障的话,有一定几率会出现脑裂现象,这样就可能会让竞争者在并发时同时获得到锁,这样可能会破坏掉后面的业务,当然出现这种情况的概率很低,但是也不能完全排除,因为redis的根本不能保证强一致性导致的。

好了,这里说的最简单的分布式锁的意思是,多个竞争者同一时间并发去获得锁时,获取失败的就直接返回了,获取成功的继续后续的流程,然后在合适的时间释放锁,并且为锁加了超时时间,防止获得到锁的进程或线程在未来得及释放锁时自己挂掉了,导致资源处于一直被锁定的状态无法得到释放。主要的实现逻辑就是这样,如果有人想实现获得锁失

败的竞争者一直继续尝试获得,可以基于该示例进行修改,加上自旋逻辑就OK。

以下是锁实现代码:

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package com.lyb.consullock;
 
import com.ecwid.consul.v1.ConsulClient;
import com.ecwid.consul.v1.agent.model.NewCheck;
import com.ecwid.consul.v1.kv.model.PutParams;
import com.ecwid.consul.v1.session.model.NewSession;
import com.ecwid.consul.v1.session.model.Session;
import lombok.Data;
 
 
import java.time.LocalDateTime;
import java.util.ArrayList;
import java.util.List;
 
 
public class DistributedLock{
    private ConsulClient consulClient;
 
    /**
     * 构造函数
     * @param consulHost 注册consul的client或服务端的Ip或主机名,或域名
     * @param consulPort 端口号
     */
    public DistributedLock(String consulHost,int consulPort){
        consulClient = new ConsulClient(consulHost,consulPort);
    }
 
    /**
     * 获得锁的方法
     * @param lockName 竞争的资源名
     * @param ttlSeconds 锁的超时时间,超过该时间自动释放
     * @return
     */
    public LockContext getLock(String lockName,int ttlSeconds){
        LockContext lockContext = new LockContext();
        if(ttlSeconds<10 || ttlSeconds > 86400) ttlSeconds = 60;
        String sessionId = createSession(lockName,ttlSeconds);
        boolean success = lock(lockName,sessionId);
        if(success == false){
            consulClient.sessionDestroy(sessionId,null);
            lockContext.setGetLock(false);
 
            return lockContext;
        }
 
        lockContext.setSession(sessionId);
        lockContext.setGetLock(true);
 
        return lockContext;
    }
 
    /**
     * 释放锁
     * @param sessionID
     */
    public void releaseLock(String sessionID){
        consulClient.sessionDestroy(sessionID,null);
    }
 
    private String createSession(String lockName,int ttlSeconds){
        NewCheck check = new NewCheck();
        check.setId("check "+lockName);
        check.setName(check.getId());
        check.setTtl(ttlSeconds+"s"); //该值和session ttl共同决定决定锁定时长
        check.setTimeout("10s");
        consulClient.agentCheckRegister(check);
        consulClient.agentCheckPass(check.getId());
 
        NewSession session = new NewSession();
        session.setBehavior(Session.Behavior.RELEASE);
        session.setName("session "+lockName);
        session.setLockDelay(1);
        session.setTtl(ttlSeconds + "s"); //和check ttl共同决定锁时长
        List<String> checks = new ArrayList<>();
        checks.add(check.getId());
        session.setChecks(checks);
        String sessionId = consulClient.sessionCreate(session,null).getValue();
 
        return sessionId;
    }
 
    private boolean lock(String lockName,String sessionId){
        PutParams putParams = new PutParams();
        putParams.setAcquireSession(sessionId);
 
        boolean isSuccess = consulClient.setKVValue(lockName,"lock:"+ LocalDateTime.now(),putParams).getValue();
 
        return isSuccess;
    }
 
    /**
     * 竞争锁时返回的对象
     */
    @Data
    public class LockContext{
        /**
         * 获得锁成功返回该值,比便后面用该值来释放锁
         */
        private String session;
        /**
         * 是否获得到锁
         */
        private boolean isGetLock;
    }
}

pom文件

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<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.1.6.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.lyb</groupId>
    <artifactId>consul-lock</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>consul-lock</name>
    <description>Demo project for Spring Boot</description>
 
    <properties>
        <java.version>1.8</java.version>
        <spring-cloud.version>Greenwich.SR2</spring-cloud.version>
    </properties>
 
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-consul-discovery</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.18.8</version>
            <optional>true</optional>
        </dependency>
 
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>
 
    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>${spring-cloud.version}</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>
 
    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>
 
</project>

测试代码:

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package com.lyb.consullock;
 
import org.junit.Assert;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.context.junit4.SpringRunner;
 
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;
 
@RunWith(SpringRunner.class)
@SpringBootTest
public class ConsulLockApplicationTests {
    @Autowired
    private ServiceConfig serviceConfig;
    @Test
    public void lockSameResourer() {
        //针对相同资源在同一时刻只有一个线程会获得锁
        ExecutorService threadPool = Executors.newFixedThreadPool(10);
        for (int a=0;a<20;a++){
            threadPool.submit(
                    () -> {
                        for (int i = 0;i < 100; i++) {
                            DistributedLock lock = new DistributedLock(
                                    serviceConfig.getConsulRegisterHost(),
                                    serviceConfig.getConsulRegisterPort());
 
                            DistributedLock.LockContext lockContext = lock.getLock("test lock", 10);
                            if (lockContext.isGetLock()) {
                                System.out.println(Thread.currentThread().getName() + "获得了锁");
                                try {
                                    TimeUnit.SECONDS.sleep(1);
                                    lock.releaseLock(lockContext.getSession());
                                } catch (InterruptedException e) {
                                    e.printStackTrace();
                                }
                            }else {
                                //System.out.println(Thread.currentThread().getName() + "没有获得锁");
                            }
                        }
                    });
        }
 
        try {
            TimeUnit.MINUTES.sleep(2);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
 
    @Test
    public void lockDiffResource(){
        //针对不通的资源所有线程都应该能获得锁
        ExecutorService threadPool = Executors.newFixedThreadPool(10);
        for (int a=0;a<20;a++){
            threadPool.submit(
                    () -> {
                        for (int i = 0;i < 100; i++) {
                            DistributedLock lock = new DistributedLock(
                                    serviceConfig.getConsulRegisterHost(),
                                    serviceConfig.getConsulRegisterPort());
 
                            DistributedLock.LockContext lockContext = lock.getLock("test lock"+Thread.currentThread().getName(), 10);
                            if (lockContext.isGetLock()) {
                                System.out.println(Thread.currentThread().getName() + "获得了锁");
                                try {
                                    TimeUnit.SECONDS.sleep(1);
                                    lock.releaseLock(lockContext.getSession());
                                } catch (InterruptedException e) {
                                    e.printStackTrace();
                                }
                            }else {
                                //System.out.println(Thread.currentThread().getName() + "没有获得锁");
                                Assert.assertTrue(lockContext.isGetLock());
                            }
                        }
                    });
        }
 
        try {
            TimeUnit.MINUTES.sleep(2);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
}

项目路径:

https://github.com/wenwuxianren/consul-lock

到此这篇关于利用consul在spring boot中实现最简单的分布式锁的文章就介绍到这了,更多相关spring boot分布式锁内容请搜索服务器之家以前的文章或继续浏览下面的相关文章希望大家以后多多支持服务器之家!

原文链接:https://www.cnblogs.com/wenwuxianren/p/11181786.html

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