Redis实现分布式锁

发表于 | 分类于

分布式锁的实现方案

Spring早就提供了分布式锁的实现，早期，分布式锁的相关代码存在与Spring Cloud的子项目Spring Cloud Cluster中，后来被迁移到了Spring Integration中。

​ Spring Cloud Cluster的GitHub：https://github.com/spring-cloud/spring-cloud-cluster/

​ Spring Integration的GitHub：https://github.com/spring-projects/spring-integration/

官方对于Spring Integration的说法是 这是一个企业集成模式的实现。Spring Cloud Stream的底层也是Spring Integration。

Spring Integration提供了多种全局锁，现在我们在这里只介绍基于Redis的分布式锁

基于Spring Integration 实现Redis的分布式锁

1.依赖

1
2
3
4
5
6
7
8
9
10
11
12
<dependency>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-starter-integration</artifactId>
</dependency>
<dependency>
  <groupId>org.springframework.integration</groupId>
  <artifactId>spring-integration-redis</artifactId>
</dependency>
<dependency>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-starter-data-redis</artifactId>
</dependency>

2.Redis配置

1
2
3
4
spring:
  redis:
    port: 6379
    host: localhost

3.RedisLock初始化

1
2
3
4
5
6
7
@Configuration
public class RedisLockConfiguration {
  @Bean
  public RedisLockRegistry redisLockRegistry(RedisConnectionFactory redisConnectionFactory) {
    return new RedisLockRegistry(redisConnectionFactory, "RedisLockRegistry");
  }
}

​ org.springframework.integration.redis.util.RedisLockRegistry的注释详细描述了该类的特性以及使用方式。

4.测试代码

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
/**
 * @author Mr.zhang
 * @description
 * @date 1:43 PM 2019/3/26
 */
@Slf4j
@RestController
@RequestMapping("redisLock")
public class RedisLockController {

    @Autowired
    private RedisLockRegistry redisLockRegistry;

    @GetMapping("test")
    public void test() throws InterruptedException {
        Lock lock = redisLockRegistry.obtain("redisLock");
        boolean b1 = lock.tryLock(3, TimeUnit.SECONDS);
        log.info("b1 is : {}", b1);

        TimeUnit.SECONDS.sleep(5);

        boolean b2 = lock.tryLock(3, TimeUnit.SECONDS);
        log.info("b2 is : {}", b2);

        lock.unlock();
        lock.unlock();
    }
}
  • 启动1个实例,访问 http://localhost:8080/redisLock/test ，会看到类似如下的日志
1
2
2019-03-26 14:42:28.206  INFO 4913 --- [nio-8080-exec-1] c.r.lock.controller.RedisLockController  : b1 is : true
2019-03-26 14:42:33.212  INFO 4913 --- [nio-8080-exec-1] c.r.lock.controller.RedisLockController  : b2 is : true
  • 启动2个实例，并迅速访问两个实例的 /test 端点，会在第二个实例上看到类似如下日志
1
2
3
4
5
6
7
8
[nio-8081-exec-1] c.r.lock.controller.RedisLockController  : b1 is : false
[nio-8081-exec-1] c.r.lock.controller.RedisLockController  : b2 is : true
[nio-8081-exec-1] o.a.c.c.C.[.[.[/].[dispatcherServlet]    : Servlet.service() ...

java.lang.IllegalStateException: You do not own lock at RedisLockRegistry:redisLock
	at org.springframework.integration.redis.util.RedisLockRegistry$RedisLock.unlock(RedisLockRegistry.java:300) ~[spring-integration-redis-5.1.3.RELEASE.jar!/:5.1.3.RELEASE]
	at com.redis.lock.controller.RedisLockController.test(RedisLockController.java:38) ~[classes!/:0.0.1-SNAPSHOT]
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_144]

​ 说明第二个实例没有拿到锁，证明了分布式锁的存在

参考地址