Redis监听过期的key实现流程详解

2023-02-28 11:02:49 过期 监听 详解

一、简介

  本文今天主要是讲Redis中对过期key的监听,可能很多小伙伴不会,或者使用会出现一些不可思议的问题,比如在系统中设置了一个缓存,希望在缓存失效后去做什么操作,但是实际中可能又出现了操作重复的问题。所以今天来讨论下怎么正确使用。我们来个最简单的集群架构,如下图:

  我们上面图中看到是服务A和服务B就是同一个服务的不同实例。

二、maven依赖

pom.xml

<?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 https://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>2.6.0</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.alian</groupId>
    <artifactId>expiration</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>expiration</name>
    <description>redis-key-expiration-listener</description>
    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <project.package.directory>target</project.package.directory>
        <java.version>1.8</java.version>
        <!--com.fasterxml.jackson 版本-->
        <jackson.version>2.9.10</jackson.version>
        <!--阿里巴巴fastJSON 版本-->
        <fastjson.version>1.2.68</fastjson.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-WEB</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
        </dependency>
        <!--redis依赖-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-redis</artifactId>
            <version>${parent.version}</version>
        </dependency>
        <!--用于序列化-->
        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-databind</artifactId>
            <version>${jackson.version}</version>
        </dependency>
        <!--java 8时间序列化-->
        <dependency>
            <groupId>com.fasterxml.jackson.datatype</groupId>
            <artifactId>jackson-datatype-jsr310</artifactId>
            <version>${jackson.version}</version>
        </dependency>
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>fastjson</artifactId>
            <version>1.2.68</version>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.16.14</version>
        </dependency>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.13.2</version>
            <scope>test</scope>
        </dependency>
    </dependencies>
    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>
</project>

三、编码实现

3.1、application.properties

# 端口
server.port=8090
# 上下文路径
server.servlet.context-path=/expiration

# Redis数据库索引(默认为0)
spring.redis.database=0
# Redis服务器地址
spring.redis.host=192.168.0.193
#spring.redis.host=127.0.0.1
# Redis服务器连接端口
spring.redis.port=6379
# Redis服务器连接密码(默认为空)
spring.redis.passWord=
# 连接池最大连接数(使用负值表示没有限制)
spring.redis.jedis.pool.max-active=20
# 连接池中的最小空闲连接
spring.redis.jedis.pool.min-idle=10
# 连接池中的最大空闲连接
spring.redis.jedis.pool.max-idle=10
# 连接池最大阻塞等待时间(使用负值表示没有限制)
spring.redis.jedis.pool.max-wait=20000
# 读时间(毫秒)
spring.redis.timeout=10000
# 连接超时时间(毫秒)
spring.redis.connect-timeout=10000

3.2、Redis配置类

RedisConfig

package com.alian.expiration.config;
import com.fasterxml.jackson.annotation.JsonAutoDetect;
import com.fasterxml.jackson.annotation.PropertyAccessor;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.SerializationFeature;
import com.fasterxml.jackson.datatype.jsr310.JavaTimeModule;
import com.fasterxml.jackson.datatype.jsr310.deser.LocalDateDeserializer;
import com.fasterxml.jackson.datatype.jsr310.deser.LocalDateTimeDeserializer;
import com.fasterxml.jackson.datatype.jsr310.deser.LocalTimeDeserializer;
import com.fasterxml.jackson.datatype.jsr310.ser.LocalDateSerializer;
import com.fasterxml.jackson.datatype.jsr310.ser.LocalDateTimeSerializer;
import com.fasterxml.jackson.datatype.jsr310.ser.LocalTimeSerializer;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.data.redis.connection.RedisConnectionFactory;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.data.redis.listener.RedisMessageListenerContainer;
import org.springframework.data.redis.serializer.Jackson2JsonRedisSerializer;
import org.springframework.data.redis.serializer.RedisSerializer;
import org.springframework.data.redis.serializer.StringRedisSerializer;
import java.time.LocalDate;
import java.time.LocalDateTime;
import java.time.LocalTime;
import java.time.fORMat.DateTimeFormatter;
@Configuration
public class RedisConfig {
    
    @Bean
    public RedisTemplate<String, Object> redisTemplate(RedisConnectionFactory redisConnectionFactory) {
        // 实例化redisTemplate
        RedisTemplate<String, Object> redisTemplate = new RedisTemplate<>();
        //设置连接工厂
        redisTemplate.setConnectionFactory(redisConnectionFactory);
        // key采用String的序列化
        redisTemplate.seTKEySerializer(keySerializer());
        // value采用jackson序列化
        redisTemplate.setValueSerializer(valueSerializer());
        // Hash key采用String的序列化
        redisTemplate.setHashKeySerializer(keySerializer());
        // Hash value采用jackson序列化
        redisTemplate.setHashValueSerializer(valueSerializer());
        // 支持事务
        // redisTemplate.setEnableTransactionSupport(true);
        //执行函数,初始化RedisTemplate
        redisTemplate.afterPropertiesSet();
        return redisTemplate;
    }
    
    private RedisSerializer<String> keySerializer() {
        return new StringRedisSerializer();
    }
    
    private RedisSerializer<Object> valueSerializer() {
        //设置jackson序列化
        Jackson2JsonRedisSerializer<Object> jackson2JsonRedisSerializer = new Jackson2JsonRedisSerializer<>(Object.class);
        //设置序列化对象
        jackson2JsonRedisSerializer.setObjectMapper(getMapper());
        return jackson2JsonRedisSerializer;
    }
    
    private ObjectMapper getMapper() {
        ObjectMapper mapper = new ObjectMapper();
        //设置可见性
        mapper.setVisibility(PropertyAccessor.ALL, JsonAutoDetect.Visibility.ANY);
        //默认键入对象
        mapper.enableDefaultTyping(ObjectMapper.DefaultTyping.NON_FINAL);
        //设置Java 8 时间序列化
        JavaTimeModule timeModule = new JavaTimeModule();
        timeModule.addSerializer(LocalDateTime.class, new LocalDateTimeSerializer(DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss")));
        timeModule.addSerializer(LocalDate.class, new LocalDateSerializer(DateTimeFormatter.ofPattern("yyyy-MM-dd")));
        timeModule.addSerializer(LocalTime.class, new LocalTimeSerializer(DateTimeFormatter.ofPattern("HH:mm:ss")));
        timeModule.aDDDeserializer(LocalDateTime.class, new LocalDateTimeDeserializer(DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss")));
        timeModule.addDeserializer(LocalDate.class, new LocalDateDeserializer(DateTimeFormatter.ofPattern("yyyy-MM-dd")));
        timeModule.addDeserializer(LocalTime.class, new LocalTimeDeserializer(DateTimeFormatter.ofPattern("HH:mm:ss")));
        //禁用把时间转为时间戳
        mapper.configure(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS, false);
        mapper.reGISterModule(timeModule);
        return mapper;
    }
    @Bean
    RedisMessageListenerContainer container(RedisConnectionFactory connectionFactory) {
        RedisMessageListenerContainer container = new RedisMessageListenerContainer();
        container.setConnectionFactory(connectionFactory);
        return container;
    }
}

  和我们之前整合redis差不多,只不过在最后增加了一个redis消息监听监听容器RedisMessageListenerContainer

3.3、监听器

RedisKeyExpirationListener

package com.alian.expiration.listener;
import com.alian.expiration.service.RedisExpirationService;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.redis.connection.Message;
import org.springframework.data.redis.listener.KeyExpirationEventMessageListener;
import org.springframework.data.redis.listener.RedisMessageListenerContainer;
import org.springframework.stereotype.Component;
@Slf4j
@Component
public class RedisKeyExpirationListener extends KeyExpirationEventMessageListener {
    @Autowired
    private RedisExpirationService redisExpirationService;
	// 把我们上面一步配置的bean注入进去
    public RedisKeyExpirationListener(RedisMessageListenerContainer listenerContainer) {
        super(listenerContainer);
    }
    
    @Override
    public void onMessage(Message message, byte[] pattern) {
        // 用户做自己的业务处理即可,注意message.toString()可以获取失效的key
        String expiredKey = message.toString();
        log.info("onMessage --> redis 过期的key是:{}", expiredKey);
        try {
            // 对过期key进行处理
            redisExpirationService.processingExpiredKey(expiredKey);
            log.info("过期key处理完成:{}", expiredKey);
        } catch (Exception e) {
            e.printStackTrace();
            log.error("处理redis 过期的key异常:{}", expiredKey, e);
        }
    }
}

  实现的步骤如下:

  • 继承KeyExpirationEventMessageListener
  • 把redis消息监听监听容器RedisMessageListenerContainer 注入到密钥空间事件消息侦 听器中
  • 重写onMessage方法
  • 通过Message 的 toString() 方法就可以获取到过期的key
  • 对key中关键信息进行业务处理,比如 id

3.4、服务类

RedisExpirationService

package com.alian.expiration.service;
import com.alian.expiration.util.SignUtils;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.stereotype.Service;
import java.util.concurrent.TimeUnit;
@Slf4j
@Service
public class RedisExpirationService {
    @Autowired
    private RedisTemplate<String, Object> redisTemplate;
    public void processingExpiredKey(String expiredKey) {
        // 如果是优惠券的key(一定要规范命名)
        if (expiredKey.startsWith("com.mall.coupon.id")) {
            // 临时key,此key可以在业务处理完,然后延迟一定时间删除,或者不处理
            String tempKey = SignUtils.md5(expiredKey, "UTF-8");
            // 临时key不存在才设置值,key超时时间为10秒(此处相当于分布式的应用)
            Boolean exist = redisTemplate.opsForValue().setIfAbsent(tempKey, "1", 10, TimeUnit.SECONDS);
            if (Boolean.TRUE.equals(exist)) {
                log.info("Business Handing...");
                // 比如截取里面的id,然后关联数据库进行处理
            } else {
                log.info("Other service is handing...");
            }
        } else {
            log.info("Expired keys without processing");
        }
    }
}

  基本流程如下:

  • 判断是否是需要处理的key,一般这种key通过命名规范加以处理
  • 以当前key生成一个新的key作为分布式key
  • 如果redis中不存在这个新的key,则为新的key设置一个值,达到分布式服务处理(核心)
  • 设置成功的,进行业务处理;设置失败了,说明其他服务正在处理这个key
  • 根据 key 的关键信息(比如截取id),进行业务处理

3.5、工具类

SignUtils

package com.alian.expiration.util;
import java.security.MessageDigest;
public class SignUtils {
    public static final String md5(String s, String charset) {
        char[] hexDigits = new char[]{'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F'};
        try {
            byte[] btInput = s.getBytes(charset);
            MessageDigest mdInst = MessageDigest.getInstance("MD5");
            mdInst.update(btInput);
            byte[] md = mdInst.digest();
            int j = md.length;
            char[] str = new char[j * 2];
            int k = 0;
            for (byte byte0 : md) {
                str[k++] = hexDigits[byte0 >>> 4 & 15];
                str[k++] = hexDigits[byte0 & 15];
            }
            return new String(str);
        } catch (Exception var11) {
            return "";
        }
    }
}

四、测试

4.1、测试类

  简单模拟下发送一个优惠券数据到redis,然后设置超时时间

package com.alian.expiration;
import lombok.extern.slf4j.Slf4j;
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.data.redis.core.RedisTemplate;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.TimeUnit;
@Slf4j
@RunWith(SpringJUnit4ClassRunner.class)
@SpringBootTest
public class RedisKeyExpirationTest {
    @Autowired
    private RedisTemplate<String, Object> redisTemplate;
    @Test
    public void keyExpiration() {
        // 优惠券信息
        String id = "2023021685264735";
        Map<String, String> map = new HashMap<>();
        map.put("id", id);
        map.put("amount", "1000");
        map.put("type", "1001");
        map.put("describe", "满减红包");
        // 缓存到redis
        redisTemplate.opsForHash().putAll("com.mall.coupon.id." + id, map);
        // 设置过期时间
        redisTemplate.expire("com.mall.coupon.id." + id, 10, TimeUnit.SECONDS);
    }
}

4.2、单实例

  单实例就是服务只部署了一份,我们启动一份,端口是8090,然后通过上面的测试类,发送一个消息,结果如下:

10:23:39 701 INFO [container-2]:onMessage --> redis 过期的key是:com.mall.coupon.id.2023021685264735
10:23:39 988 INFO [container-2]:Business Handing...
10:23:39 989 INFO [container-2]:过期key处理完成:com.mall.coupon.id.2023021685264735
10:23:50 005 INFO [container-3]:onMessage --> redis 过期的key是:450FCC35415BADC16805962CA5BC7E12
10:23:50 005 INFO [container-3]:Expired keys without processing
10:23:50 005 INFO [container-3]:过期key处理完成:450FCC35415BADC16805962CA5BC7E12

4.3、多实例

  多实例就是服务部署了多份,比如我们启动两份,端口分别为8090和8091,然后通过上面的测试类,发送一个消息,8090端口的服务结果如下(Business Handing…):

11:39:06 691 INFO [container-2]:onMessage --> redis 过期的key是:com.mall.coupon.id.2023021685264735
11:39:06 707 INFO [container-2]:Business Handing...
11:39:06 707 INFO [container-2]:过期key处理完成:com.mall.coupon.id.2023021685264735
11:39:16 796 INFO [container-3]:onMessage --> redis 过期的key是:450FCC35415BADC16805962CA5BC7E12
11:39:16 796 INFO [container-3]:Expired keys without processing
11:39:16 796 INFO [container-3]:过期key处理完成:450FCC35415BADC16805962CA5BC7E12

  8091端口的服务结果如下(Other service is handing…):

11:39:06 691 INFO [container-2]:onMessage --> redis 过期的key是:com.mall.coupon.id.2023021685264735
11:39:06 707 INFO [container-2]:Other service is handing...
11:39:06 707 INFO [container-2]:过期key处理完成:com.mall.coupon.id.2023021685264735
11:39:16 796 INFO [container-3]:onMessage --> redis 过期的key是:450FCC35415BADC16805962CA5BC7E12
11:39:16 796 INFO [container-3]:Expired keys without processing
11:39:16 796 INFO [container-3]:过期key处理完成:450FCC35415BADC16805962CA5BC7E12

  结果分析:

  • 多实例的情况下,每个实例都会收到过期key通知
  • 通过redis分布式锁,实现只有一个实例会进行业务处理,防止重复
  • 使用分布式锁会有一个新的key过期,并且收到该key的通知,你可以业务执行完延迟一定时间(避免重复执行),再删除,也可以不处理(因为本就不是要处理业务的key)

结语

  多实例的情况下,每个实例都会收到过期key通知,可以通过分布式锁的方式去处理业务,避免业务重复执行

到此这篇关于Redis监听过期的key实现流程详解的文章就介绍到这了,更多相关Redis监听key内容请搜索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!

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