通过Redisson构建延时队列并实现注解式消费

一、序言

两个月前接了一个4万的私活，做一个线上商城小程序，在交易过程中不可避免的一个问题就是用户下单后的订单自动取消。

目前成熟的方案有通过RabbitMQ+死信队列、RabbitMQ+延迟消息插件、RocketMQ定时消息推送、Redisson延时队列来实现。

考虑到商城的定位和用户体量，以及系统维护成本，其实完全没有必要引入消息中间件，借助Redis其实就可以轻松实现这个需求。

加上Redisson客户端本身就已经实现了很多分布式集合工具类，借助阻塞队列和延时队列就可轻松搞定。

当然，为了使用方便以及团队协作，顺便模仿@RabbitListener封装了一套基于注解的消息消费，废话不多说，直接上代码。

二、延迟队列实现

Redisson_15">1、Redisson延时消息监听注解和消息体

延迟消息监听器定义：

/*** Redisson延时队列监听器** @author Nick Liu* @date 2024/11/13*/
@Documented
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.METHOD)
public @interface RedissonDelayedQueueListener {/*** 队列名称* @return*/String queueName();
}

消息体定义：

@Data
@Builder
@AllArgsConstructor
@NoArgsConstructor
public class RedisDelayedMsgDTO {/*** 消息内容*/private String msg;/*** 队列名称*/private String queueName;/*** 延时时间*/private long delayTime;private TimeUnit timeUnit;
}

Redisson_62">2、Redisson延时消息发布器

@Slf4j
@Component
@RequiredArgsConstructor
public class RedissonDelayedMsgPublisher {private final RedissonClient redissonClient;/*** 发布延时信息* @param delayedMsgDTO*/public void publishDelayedMsg(RedisDelayedMsgDTO delayedMsgDTO) {log.info("开始发布延迟消息: {}", FastJsonUtils.toJsonString(delayedMsgDTO));RBlockingQueue<String> blockingQueue = redissonClient.getBlockingQueue(delayedMsgDTO.getQueueName());RDelayedQueue<String> delayedQueue = redissonClient.getDelayedQueue(blockingQueue);delayedQueue.offer(delayedMsgDTO.getMsg(), delayedMsgDTO.getDelayTime(), delayedMsgDTO.getTimeUnit());}
}

这里我们借助RBlockingQueue和RDelayedQueue来实现，只有当延迟消息快到期时，消费者才能从阻塞队列拉取到消息，否则消费者将一直阻塞。

Redisson_86">3、Redisson延时消息监听处理器

这里我们定义了一个BeanPostProcessor 的实现，目的就是为了扫描Spring容器中所有带RedissonDelayedQueueListener注解的Bean实例和方法。

/*** Redisson延迟队列Bean后处理器* @author Nick Liu* @date 2025/1/3*/
@Slf4j
@Component
@RequiredArgsConstructor
public class RedissonDelayedQueuePostProcessor implements BeanPostProcessor {private final RedissonClient redissonClient;@Overridepublic Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {// 获取最终的目标运行时对象Class<?> clazz = AopProxyUtils.ultimateTargetClass(bean);Method[] methods = clazz.getDeclaredMethods();for (Method m : methods) {if (!m.isAnnotationPresent(RedissonDelayedQueueListener.class)) {continue;}// 如果Bean上的方法有Redisson队列监听注解，则启动一个线程监听队列RedissonDelayedQueueListener annotation = m.getAnnotation(RedissonDelayedQueueListener.class);CompletableFuture.runAsync(() -> {log.info("开始监听Redisson延时队列[{}]消息", annotation.queueName());while (true) {RBlockingQueue<String> blockingQueue = redissonClient.getBlockingQueue(annotation.queueName());redissonClient.getDelayedQueue(blockingQueue);try {String msg = blockingQueue.take();MDC.put(CommonConst.X_REQUEST_ID, SerialNoUtils.generateSimpleUUID());log.info("监听到队列[{}]延时消息: {}", annotation.queueName(), msg);m.invoke(bean, msg);MDC.remove(CommonConst.X_REQUEST_ID);} catch (Exception e) {log.error(e.getMessage(), e);}}});}return bean;}}

这里我们扫描到指定Bean的方法后，会开启一个异步线程，并轮询拉取延时消息，如果消息没过期，异步线程将会一直阻塞等待。

三、测试用例

/*** @author Nick Liu* @date 2025/2/2*/
@Slf4j
@RestController
@RequiredArgsConstructor
public class RedissonDelayedMsgController {private static final String DELAYED_QUEUE = "redisson:delayed:queue";private final RedissonDelayedMsgPublisher redissonDelayedMsgPublisher;@GetMapping("/delayed/msg")public ResponseEntity<RedisDelayedMsgDTO> publishDelayedMsg() {RedisDelayedMsgDTO redisDelayedMsgDTO = new RedisDelayedMsgDTO();redisDelayedMsgDTO.setQueueName(DELAYED_QUEUE);redisDelayedMsgDTO.setMsg("This is a delayed msg");redisDelayedMsgDTO.setDelayTime(10);redisDelayedMsgDTO.setTimeUnit(TimeUnit.SECONDS);redissonDelayedMsgPublisher.publishDelayedMsg(redisDelayedMsgDTO);return ResponseEntity.ok(redisDelayedMsgDTO);}@RedissonDelayedQueueListener(queueName = DELAYED_QUEUE)public void handleDelayedMsg(String msg) {log.info("Received delayed msg: {}", msg);}
}

启动服务后，Bean后处理器会启动异步线程监听延时消息，如下：

2025-02-02 16:46:04.271 INFO  [] [ForkJoinPool.commonPool-worker-2] [c.xlyj.common.message.RedissonDelayedQueuePostProcessor.lambda$postProcessAfterInitialization$0():44] - 开始监听Redisson延时队列[redisson:delayed:queue]消息

浏览器直接输入http://localhost:8000/delayed/msg发布延时消息，10s后消费者进行处理，如下：

2025-02-02 16:43:11.107 INFO  [e810d175b0e24e71a4b9e517366b4aa6] [ForkJoinPool.commonPool-worker-2] [c.xlyj.common.message.RedissonDelayedQueuePostProcessor.lambda$postProcessAfterInitialization$0():51] - 监听到队列[redisson:delayed:queue]延时消息: This is a delayed msg
2025-02-02 16:43:11.108 INFO  [e810d175b0e24e71a4b9e517366b4aa6] [ForkJoinPool.commonPool-worker-2] [com.xlyj.contoller.RedissonDelayedMsgController.handleDelayedMsg():40] - Received delayed msg: This is a delayed msg