高性能分布式锁-redisson的使用

1，概述：在一些高并发的场景中，比如秒杀，抢票，抢购这些场景，都存在对核心资源，商品库存的争夺，控制不好，库存数量可能被减少到负数，出现超卖的情况，或者 产生唯一的一个递增ID，由于web应用部署在多个机器上，简单的同步加锁是无法实现的，给数据库加锁的话，对于高并发，1000/s的并发，数据库可能由行锁变成表锁，性能下降会厉害。那相对而言，redis的分布式锁，相对而言，是个很好的选择，redis官方推荐使用的Redisson就提供了分布式锁和相关服务。 
下面介绍下如何使用Redisson。

2，Redisson的使用方式十分简单，详见官方文档：https://github.com/redisson/redisson/wiki/2.-%E9%85%8D%E7%BD%AE%E6%96%B9%E6%B3%95

3，加入jar包的依赖：

<--  和RedisTemplate整合 -->

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-data-redis</artifactId>
</dependency>
<dependency>
    <groupId>org.redisson</groupId>
    <artifactId>redisson-spring-boot-starter</artifactId>
    <version>3.10.2</version>
</dependency>
<dependency>
    <groupId>org.redisson</groupId>
    <artifactId>redisson-spring-data-20</artifactId>
    <version>3.10.2</version>
</dependency>

4，配置Redisson

yml配置

redis:
  jedis:
    pool:
      max-active: 8
      max-idle: 8
      min-idle: 0
      max-wait: -1
  database: 0
  timeout: 2000
  password:
  #方式一： 集群
  cluster:
    nodes: 192.168.56.99:6379，192.168.59.100:6379

  #方式二： 单机  二选一

  port: 6379
  host: 192.168.56.99

package com.chitic.supplywater.update.config.redis;

import com.fasterxml.jackson.annotation.JsonAutoDetect;
import com.fasterxml.jackson.annotation.PropertyAccessor;
import com.fasterxml.jackson.databind.ObjectMapper;
import lombok.AllArgsConstructor;
import lombok.extern.slf4j.Slf4j;
import org.redisson.Redisson;
import org.redisson.api.RedissonClient;
import org.redisson.config.Config;
import org.redisson.spring.data.connection.RedissonConnectionFactory;
import org.springframework.boot.autoconfigure.data.redis.RedisProperties;
import org.springframework.cache.Cache;
import org.springframework.cache.CacheManager;
import org.springframework.cache.annotation.EnableCaching;
import org.springframework.cache.interceptor.CacheErrorHandler;
import org.springframework.cache.interceptor.KeyGenerator;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.data.redis.cache.RedisCacheManager;
import org.springframework.data.redis.connection.RedisConnectionFactory;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.data.redis.serializer.Jackson2JsonRedisSerializer;
import org.springframework.data.redis.serializer.RedisSerializer;
import org.springframework.data.redis.serializer.StringRedisSerializer;

import java.util.HashSet;
import java.util.List;
import java.util.Set;

@Configuration
@EnableCaching
@Slf4j
@AllArgsConstructor
public class RedissonConfig {

    private final RedisProperties redisProperties;

    @Bean
    public RedissonConnectionFactory redissonConnectionFactory(RedissonClient redisson) {
        return new RedissonConnectionFactory(redisson);
    }

    @Bean
    public RedissonClient redissonClient() {
        Config config = new Config();
        //redis服务器地址，多个逗号分隔
        RedisProperties.Cluster cluster = redisProperties.getCluster();
        List<String> nodes = cluster.getNodes();
        Set<String> nodeSet = new HashSet<>();
        for (String node : nodes) {
            nodeSet.add("redis://" + node);
        }
        //单机
        config.useSingleServer()
                .setAddress("redis://" + nodes.get(0))
                ;
        //集群
        //config.useClusterServers()
        //        .setScanInterval(2000)
        //        .addNodeAddress(nodeSet.toArray(new String[nodeSet.size()]))
        //        ;
        return Redisson.create(config);
    }

    @Bean
    public KeyGenerator keyGenerator() {
        //  设置自动key的生成规则，配置spring boot的注解，进行方法级别的缓存
        // 使用：进行分割，可以很多显示出层级关系
        // 这里其实就是new了一个KeyGenerator对象，只是这是lambda表达式的写法，我感觉很好用，大家感兴趣可以去了解下
        return (target, method, params) -> {
            StringBuilder sb = new StringBuilder();
            sb.append(target.getClass().getName());
            sb.append(":");
            sb.append(method.getName());
            for (Object obj : params) {
                sb.append(":" + String.valueOf(obj));
            }
            String rsToUse = String.valueOf(sb);
            log.info("自动生成Redis Key -> [{}]", rsToUse);
            return rsToUse;
        };
    }

    @Bean
    public CacheManager cacheManager(RedisConnectionFactory redisConnectionFactory) {
        // 初始化缓存管理器，在这里我们可以缓存的整体过期时间什么的，我这里默认没有配置
        log.info("初始化 -> [{}]", "CacheManager RedisCacheManager Start");
        RedisCacheManager.RedisCacheManagerBuilder builder = RedisCacheManager
                .RedisCacheManagerBuilder
                .fromConnectionFactory(redisConnectionFactory);
        return builder.build();
    }

    @Bean
    public RedisTemplate<String, Object> redisTemplate(RedisConnectionFactory redisConnectionFactory ) {
        //设置序列化
        Jackson2JsonRedisSerializer jackson2JsonRedisSerializer = new Jackson2JsonRedisSerializer(Object.class);
        ObjectMapper om = new ObjectMapper();
        om.setVisibility(PropertyAccessor.ALL, JsonAutoDetect.Visibility.ANY);
        om.enableDefaultTyping(ObjectMapper.DefaultTyping.NON_FINAL);
        jackson2JsonRedisSerializer.setObjectMapper(om);
        // 配置redisTemplate
        RedisTemplate<String, Object> redisTemplate = new RedisTemplate<String, Object>();
        redisTemplate.setConnectionFactory(redisConnectionFactory);
        RedisSerializer stringSerializer = new StringRedisSerializer();
        redisTemplate.setKeySerializer(stringSerializer); // key序列化
        redisTemplate.setValueSerializer(jackson2JsonRedisSerializer); // value序列化
        redisTemplate.setHashKeySerializer(stringSerializer); // Hash key序列化
        redisTemplate.setHashValueSerializer(jackson2JsonRedisSerializer); // Hash value序列化
        redisTemplate.afterPropertiesSet();
        return redisTemplate;
    }

    @Bean
    public CacheErrorHandler errorHandler() {
        // 异常处理，当Redis发生异常时，打印日志，但是程序正常走
        log.info("初始化 -> [{}]", "Redis CacheErrorHandler");
        CacheErrorHandler cacheErrorHandler = new CacheErrorHandler() {
            @Override
            public void handleCacheGetError(RuntimeException e, Cache cache, Object key) {
                log.error("Redis occur handleCacheGetError：key -> [{}]", key, e);
            }

            @Override
            public void handleCachePutError(RuntimeException e, Cache cache, Object key, Object value) {
                log.error("Redis occur handleCachePutError：key -> [{}]；value -> [{}]", key, value, e);
            }

            @Override
            public void handleCacheEvictError(RuntimeException e, Cache cache, Object key)    {
                log.error("Redis occur handleCacheEvictError：key -> [{}]", key, e);
            }

            @Override
            public void handleCacheClearError(RuntimeException e, Cache cache) {
                log.error("Redis occur handleCacheClearError：", e);
            }
        };
        return cacheErrorHandler;
    }

}

5，锁的获取和释放

public class DistributedRedisLock {
   //从配置类中获取redisson对象
    private static Redisson redisson = RedissonManager.getRedisson();
    private static final String LOCK_TITLE = "redisLock_";
   //加锁
    public static boolean acquire(String lockName){
       //声明key对象
        String key = LOCK_TITLE + lockName;
       //获取锁对象
        RLock mylock = redisson.getLock(key);
       //加锁，并且设置锁过期时间，防止死锁的产生
        mylock.lock(2, TimeUnit.MINUTES); 
        System.err.println("======lock======"+Thread.currentThread().getName());
       //加锁成功
        return  true;
    }
  //锁的释放
    public static void release(String lockName){
       //必须是和加锁时的同一个key
        String key = LOCK_TITLE + lockName;
       //获取所对象
        RLock mylock = redisson.getLock(key);
      //释放锁（解锁）
        mylock.unlock();
        System.err.println("======unlock======"+Thread.currentThread().getName());
    }
}

6，业务逻辑中使用分布式锁

@RequestMapping("/redder")
    @ResponseBody
    public String redder() throws IOException{
         String key = "test123";
        //加锁 
        DistributedRedisLock.acquire(key);
        //执行具体业务逻辑
        dosoming
        //释放锁
        DistributedRedisLock.release(key);
       //返回结果
        return soming; 
    }