talk is cheap, show me the code.

一、开启Redis key过期提醒

  • 方式二:修改配置文件

    redis.conf

    # 默认 notify-keyspace-events ""
    notify-keyspace-events Ex
    
  • 方式二:命令行开启

    CONFIG SET notify-keyspace-events Ex
    CONFIG GET notify-keyspace-events
    

二、notify-keyspace-events

notify-keyspace-events 选项的默认值为空

notify-keyspace-events 的参数可以是以下字符的任意组合, 它指定了服务器该发送哪些类型的通知。

字符 发送的通知
K 键空间通知,所有通知以 keyspace@ 为前缀
E 键事件通知,所有通知以 keyevent@ 为前缀
g DEL 、 EXPIRE 、 RENAME 等类型无关的通用命令的通知
$ 字符串命令的通知
l 列表命令的通知
s 集合命令的通知
h 哈希命令的通知
z 有序集合命令的通知
x 过期事件:每当有过期键被删除时发送
e 驱逐(evict)事件:每当有键因为 maxmemory 政策而被删除时发送
A 参数 g$lshzxe 的别名

三、Coding

  1. 初始化一个Spring Boot项目

  2. pom.xml

    <dependencies>
    		<dependency>
    			<groupId>org.springframework.boot</groupId>
    			<artifactId>spring-boot-starter-data-redis</artifactId>
    		</dependency>
    		<dependency>
    			<groupId>org.projectlombok</groupId>
    			<artifactId>lombok</artifactId>
    		</dependency>
    	</dependencies>
    
  3. 定义配置类RedisListenerConfig

    @Configuration
    public class RedisListenerConfig {
    
    	@Bean
    	RedisMessageListenerContainer container(RedisConnectionFactory connectionFactory) {
    		RedisMessageListenerContainer container = new RedisMessageListenerContainer();
    		container.setConnectionFactory(connectionFactory);
    		return container;
    	}
    
    }
    
  4. 定义数据生产类ProviderDataToRedis

    @Slf4j
    @Component
    public class ProviderDataToRedis implements CommandLineRunner {
    
    	@Autowired
    	private StringRedisTemplate stringRedisTemplate;
    
    	@Override
    	public void run(String... args) throws Exception {
    		int[] num = new int[]{1};
    		Random random = new Random();
    		while (true) {
    			int max = random.nextInt(5);
    			IntStream.range(0, max).forEach(n -> stringRedisTemplate.opsForValue().set(String.format("mq:s1:%s", ++num[0]), "已预订", 5, TimeUnit.SECONDS));
    			log.info("放了 {} 条数据到redis...", max);
    			TimeUnit.SECONDS.sleep(3);
    		}
    	}
    }
    
  5. 定义监听器 实现KeyExpirationEventMessageListener接口

    查看源码发现,该接口监听所有db的过期事件keyevent@*:expired"

    定义Status1ExpirationListener监听状态1到期

    @Slf4j
    @Component
    public class Status1ExpirationListener extends KeyExpirationEventMessageListener {
    
    	public Status1ExpirationListener(RedisMessageListenerContainer listenerContainer) {
    		super(listenerContainer);
    	}
    
    	@Autowired
    	private StringRedisTemplate stringRedisTemplate;
    
    	@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();
    		if (expiredKey.startsWith("mq:s1:")) {
    			log.info("-----------------------------------");
    			log.info(String.format("过期key[%s]", expiredKey));
    			String newKey = String.format("mq:s2:%s", expiredKey.substring(6));
    			String newValue = "行程中";
    			stringRedisTemplate.opsForValue().set(newKey, newValue, 3, TimeUnit.SECONDS);
    			log.info(String.format("%s: %s", newKey, newValue));
    			log.info("-----------------------------------");
    		}
    	}
    
    }
    

    定义Status2ExpirationListener监听状态2到期

    @Slf4j
    @Component
    public class Status2ExpirationListener extends KeyExpirationEventMessageListener {
    
    	public Status2ExpirationListener(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();
    		if (expiredKey.startsWith("mq:s2:")) {
    			log.info("***********************************");
    			log.info(String.format("过期key[%s]", expiredKey));
    			log.info("[{}]行程已完成,修改数据库状态。", newKey);
    			log.info("***********************************");
    		}
    	}
    
    }
    

四、测试输出

...
2021-01-25 23:16:58.012  INFO 55511 --- [           main] n.y.tools.listener.ProviderDataToRedis      : 放了 4 条数据到redis...
2021-01-25 23:17:00.037  INFO 55511 --- [ container-1070] c.i.r.l.Status1ExpirationListener        : -----------------------------------
2021-01-25 23:17:00.037  INFO 55511 --- [ container-1070] c.i.r.l.Status1ExpirationListener        : 过期key[mq:s1:272]
2021-01-25 23:17:00.037  INFO 55511 --- [ container-1072] c.i.r.l.Status1ExpirationListener        : -----------------------------------
2021-01-25 23:17:00.037  INFO 55511 --- [ container-1072] c.i.r.l.Status1ExpirationListener        : 过期key[mq:s1:271]
2021-01-25 23:17:00.039  INFO 55511 --- [ container-1070] c.i.r.l.Status1ExpirationListener        : mq:s2:272: 行程中
2021-01-25 23:17:00.039  INFO 55511 --- [ container-1072] c.i.r.l.Status1ExpirationListener        : mq:s2:271: 行程中
2021-01-25 23:17:00.039  INFO 55511 --- [ container-1070] c.i.r.l.Status1ExpirationListener        : -----------------------------------
2021-01-25 23:17:00.039  INFO 55511 --- [ container-1072] c.i.r.l.Status1ExpirationListener        : -----------------------------------
2021-01-25 23:17:00.140  INFO 55511 --- [ container-1075] c.i.r.l.Status2ExpirationListener        : ***********************************
2021-01-25 23:17:00.140  INFO 55511 --- [ container-1075] c.i.r.l.Status2ExpirationListener        : 过期key[mq:s2:270]
2021-01-25 23:17:00.140  INFO 55511 --- [ container-1075] c.i.r.l.Status2ExpirationListener        : [270]行程已完成,修改数据库状态。
2021-01-25 23:17:00.140  INFO 55511 --- [ container-1075] c.i.r.l.Status2ExpirationListener        : ***********************************
2021-01-25 23:17:00.242  INFO 55511 --- [ container-1077] c.i.r.l.Status2ExpirationListener        : ***********************************
2021-01-25 23:17:00.242  INFO 55511 --- [ container-1077] c.i.r.l.Status2ExpirationListener        : 过期key[mq:s2:269]
2021-01-25 23:17:00.242  INFO 55511 --- [ container-1079] c.i.r.l.Status2ExpirationListener        : ***********************************
2021-01-25 23:17:00.242  INFO 55511 --- [ container-1079] c.i.r.l.Status2ExpirationListener        : 过期key[mq:s2:268]
2021-01-25 23:17:00.242  INFO 55511 --- [ container-1077] c.i.r.l.Status2ExpirationListener        : [269]行程已完成,修改数据库状态。
2021-01-25 23:17:00.242  INFO 55511 --- [ container-1077] c.i.r.l.Status2ExpirationListener        : ***********************************
2021-01-25 23:17:00.242  INFO 55511 --- [ container-1079] c.i.r.l.Status2ExpirationListener        : [268]行程已完成,修改数据库状态。
2021-01-25 23:17:00.242  INFO 55511 --- [ container-1079] c.i.r.l.Status2ExpirationListener        : ***********************************
2021-01-25 23:17:00.546  INFO 55511 --- [ container-1081] c.i.r.l.Status2ExpirationListener        : ***********************************
2021-01-25 23:17:00.546  INFO 55511 --- [ container-1081] c.i.r.l.Status2ExpirationListener        : 过期key[mq:s2:267]
2021-01-25 23:17:00.546  INFO 55511 --- [ container-1081] c.i.r.l.Status2ExpirationListener        : [267]行程已完成,修改数据库状态。
2021-01-25 23:17:00.546  INFO 55511 --- [ container-1081] c.i.r.l.Status2ExpirationListener        : ***********************************
...

五、一直增加的线程数

从测试输出的日志中可以看出,线程一直在增加,这个问题还有待解决!

六、参考

http://redisdoc.com/topic/notification.html

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