延迟队列与SpringBoot实战

概念

延时队列,队列内部是有序的，最重要的特性就体现在它的延时属性上，延时队列中的元素是希望在指定时间到了以后或之前取出和处理，简单来说，延时队列就是用来存放需要在指定时间被处理的元素的队列

TTL介绍

TTL 是什么呢？TTL 是 RabbitMQ 中一个消息或者队列的属性，表明一条消息或者该队列中的所有消息的最大存活时间，单位是毫秒。换句话说，如果一条消息设置了 TTL 属性或者进入了设置TTL 属性的队列，那么这条消息如果在TTL 设置的时间内没有被消费，则会成为"死信"。如果同时配置了队列的TTL 和消息的TTL，那么较小的那个值将会被使用，有两种方式设置 TTL。

设置TTL

• 消息设置TTL

  rabbitTemplate.convertAndSend("X", "XC", message + "ttl:" + ttl, msg -> {
              msg.getMessageProperties().setExpiration(ttl);
              return msg;
          });
  

• 队列设置TTL

  args.put("x-message-ttl",15000);
  QueueBuilder.durable(QUEUE_B).withArguments(args).build();
  

• 如果不设置 TTL，表示消息永远不会过期，如果将 TTL 设置为 0，则表示除非此时可以直接投递该消息到消费者，否则该消息将会被丢弃

代码实战

配置POM

<dependencies>
        <!--RabbitMQ 依赖-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-amqp</artifactId>
        </dependency>
        <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>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>fastjson</artifactId>
            <version>1.2.47</version>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
        </dependency>
        <!--swagger-->
        <dependency>
            <groupId>io.springfox</groupId>
            <artifactId>springfox-swagger2</artifactId>
            <version>2.9.2</version>
        </dependency>
        <dependency>
            <groupId>io.springfox</groupId>
            <artifactId>springfox-swagger-ui</artifactId>
            <version>2.9.2</version>
        </dependency>
        <!--RabbitMQ 测试依赖-->
        <dependency>
            <groupId>org.springframework.amqp</groupId>
            <artifactId>spring-rabbit-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

配置application

spring.rabbitmq.host=192.168.31.232
spring.rabbitmq.port=5672
spring.rabbitmq.username=admin
spring.rabbitmq.password=admin

配置Swagger

package com.vmware.config;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import springfox.documentation.builders.ApiInfoBuilder;
import springfox.documentation.service.ApiInfo;
import springfox.documentation.service.Contact;
import springfox.documentation.spi.DocumentationType;
import springfox.documentation.spring.web.plugins.Docket;
import springfox.documentation.swagger2.annotations.EnableSwagger2;

@Configuration
@EnableSwagger2
public class SwaggerConfig {
    @Bean
    public Docket webApiConfig() {
        return new Docket(DocumentationType.SWAGGER_2)
                .groupName("webApi")
                .apiInfo(webApiInfo())
                .select().build();
    }

    private ApiInfo webApiInfo() {
        return new ApiInfoBuilder()
                .title("rabbitmq 接口文档")
                .description("本文档描述了 rabbitmq 微服务接口定义")
                .version("1.0")
                .contact(new Contact("name", "url",
                        "email"))
                .build();
    }
}

代码架构图

创建两个队列 QA 和 QB，两者队列 TTL 分别设置为 10S 和 40S，然后在创建一个交换机 X 和死信交换机 Y，它们的类型都是direct，创建一个死信队列 QD，它们的绑定关系如下

RabbitMQ配置类

package com.vmware.config;

import org.springframework.amqp.core.*;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

import java.util.HashMap;
import java.util.Map;

@Configuration
public class RabbitConfig {
    //普通交换机
    private static final String X_EXCHANGE = "X";
    //死信交换机
    private static final String Y_EXCHANGE = "Y";
    //普通队列A
    private static final String QUEUE_A = "QA";
    //普通队列B
    private static final String QUEUE_B = "QB";
    //普通队列C
    private static final String QUEUE_C = "QC";
    //死信队列D
    private static final String QUEUE_D = "QD";


    @Bean("xExchange")
    public DirectExchange xExchange() {
        return new DirectExchange(X_EXCHANGE);
    }

    @Bean("yExchange")
    public DirectExchange yExchange() {
        return new DirectExchange(Y_EXCHANGE);
    }

    @Bean("queueA")
    public Queue queueA() {
        Map<String, Object> args = new HashMap<>();
        //设置死信交换机
        args.put("x-dead-letter-exchange", Y_EXCHANGE);
        //设置死信Routing Key
        args.put("x-dead-letter-routing-key", "YD");
        //设置超时
        args.put("x-message-ttl", 10000);
        //构建队列
        return QueueBuilder.durable(QUEUE_A).withArguments(args).build();
    }

    @Bean("queueB")
    public Queue queueB() {
        Map<String, Object> args = new HashMap<>();
        //设置死信交换机
        args.put("x-dead-letter-exchange", Y_EXCHANGE);
        //设置死心Routing Key
        args.put("x-dead-letter-routing-key", "YD");
        //设置超时ttl
        args.put("x-message-ttl",15000);
        //构建队列
        return QueueBuilder.durable(QUEUE_B).withArguments(args).build();
    }

    @Bean("queueC")
    public Queue queueC(){
        Map<String,Object> args=new HashMap<>();
        //设置死信交换机
        args.put("x-dead-letter-exchange", Y_EXCHANGE);
        //设置死信Routing Key
        args.put("x-dead-letter-routing-key", "YD");
        //构建队列
        return QueueBuilder.durable(QUEUE_C).withArguments(args).build();
    }

    @Bean("queueD")
    public Queue queueD(){
        //构建死信队列D
        return QueueBuilder.durable(QUEUE_D).build();
    }

    //绑定普通交换机和队列A
    @Bean
    public Binding queueABindingX(){
        return BindingBuilder.bind(queueA()).to(xExchange()).with("XA");
    }

    //绑定普通交换机与队列B
    @Bean
    public Binding queueBBindingX(){
        return BindingBuilder.bind(queueB()).to(xExchange()).with("XB");
    }

    //绑定普通交换机与队列C
    @Bean
    public Binding queueCBindingX(){
        return BindingBuilder.bind(queueC()).to(xExchange()).with("XC");
    }

    //绑定死信交换机与死信队列
    @Bean
    public Binding queueDBindingY(){
        return BindingBuilder.bind(queueD()).to(yExchange()).with("YD");
    }
}

生产者

package com.vmware.controller;

import lombok.extern.slf4j.Slf4j;
import org.springframework.amqp.rabbit.core.RabbitTemplate;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;

import java.util.Date;

@RestController
@RequestMapping("/ttl")
@Slf4j
public class SendMsgController {
    @Autowired
    private RabbitTemplate rabbitTemplate;

    /**
     * @param message 消息
     * @apiNote 生产者代码
     */
    @GetMapping("/sendMsg/{message}")
    public void sendMsg(@PathVariable String message) {
        log.info("当前时间:{},发送消息给两个队列:{}", new Date(), message);
        rabbitTemplate.convertAndSend("X", "XA", "消息来自ttl为10秒的队列" + message);
        rabbitTemplate.convertAndSend("X", "XB", "消息来自ttl为15秒的队列" + message);
    }

    @GetMapping("/sendMsg/{message}/{ttl}")
    public void sendMsg(@PathVariable String message, @PathVariable String ttl) {
        rabbitTemplate.convertAndSend("X", "XC", message + "ttl:" + ttl, msg -> {
            msg.getMessageProperties().setExpiration(ttl);
            return msg;
        });
        log.info("当前时间:{},发送消息:{}给队列:XC，ttl:{}", new Date(), message, ttl);
    }
}

消费者

package com.vmware.consumer;

import com.rabbitmq.client.Channel;
import lombok.extern.slf4j.Slf4j;
import org.springframework.amqp.core.Message;
import org.springframework.amqp.rabbit.annotation.RabbitListener;
import org.springframework.stereotype.Component;

import java.util.Date;

@Slf4j
@Component
public class DeadLetterQueueConsumer {
    @RabbitListener(queues = {"QD"})
    public void receiveD(Message message, Channel channel) {
        log.info("当前时间:{} 死信队列收到消息:{}", new Date(), message);
    }
}

存在的问题

当生产者发布消息到延迟队列后，消息只能按顺序被消费者消费，当某一消息阻塞时间很长时则会导致其他消息一同阻塞，不能达到ttl到期优先被延时队列的消费者所消费的效果

优化

下载插件rabbitmq_delayed_message_exchange到rabbit的plugin目录下

• 官网:https://www.rabbitmq.com/community-plugins.html

• ubuntu下载方式

  cd /usr/lib/rabbitmq/lib/rabbitmq_server-3.8.2/plugins
  sudo wget https://github.com/rabbitmq/rabbitmq-delayed-message-exchange/releases/download/v3.8.0/rabbitmq_delayed_message_exchange-3.8.0.ez
  

• 启用插件

  rabbitmq-plugins enable rabbitmq_delayed_message_exchange
  

• 重启服务

  systemctl restart rabbitmq-server
  

• 安装完成后可以在rabbit交换机页面看到x-delayed-message
  

基于插件的延时队列代码实战

在我们自定义的交换机中，这是一种新的交换类型，该类型消息支持延迟投递机制 消息传递后并不会立即投递到目标队列中，而是存储在 mnesia(一个分布式数据系统)表中，当达到投递时间时，才投递到目标队列中

配置延时队列与交换机

package com.vmware.config;

import org.springframework.amqp.core.Binding;
import org.springframework.amqp.core.BindingBuilder;
import org.springframework.amqp.core.CustomExchange;
import org.springframework.amqp.core.Queue;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

import java.util.HashMap;
import java.util.Map;

@Configuration
public class DelayQueueConfig {
    private static final String DELAY_QUEUE_NAME = "delayed.queue";
    private static final String DELAY_EXCHANGE_NAME = "delayed.exchange";
    private static final String DELAY_ROUTING_KEY = "delayed.routingkey";

    @Bean
    public Queue delayQueue(){
        return new Queue(DELAY_QUEUE_NAME);
    }

    @Bean
    public CustomExchange delayExchange(){
        Map<String,Object> args =new HashMap<>();
        args.put("x-delayed-type", "direct");
        /**
         * 1.交换机名称
         * 2.交换机类型：插件类型
         * 3.是否持久化
         * 4.是否自动删除
         */
        return new CustomExchange(DELAY_EXCHANGE_NAME,"x-delayed-message",true,false,args);
    }

    @Bean
    public Binding delayQueueBindExchange(){
        return BindingBuilder.bind(delayQueue()).to(delayExchange()).with(DELAY_ROUTING_KEY).noargs();
    }
}

生产者

package com.vmware.controller;

import lombok.extern.slf4j.Slf4j;
import org.springframework.amqp.rabbit.core.RabbitTemplate;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;

import java.util.Date;

@RestController
@RequestMapping("/ttl")
@Slf4j
public class SendMsgController {
    @Autowired
    private RabbitTemplate rabbitTemplate;

    @GetMapping("/sendDelayMsg/{message}/{delayTime}")
    public void sendMsg(@PathVariable String message, @PathVariable Integer delayTime) {
        rabbitTemplate.convertAndSend("delayed.exchange", "delayed.routingkey", message, msg -> {
            msg.getMessageProperties().setDelay(delayTime);
            return msg;
        });
        log.info("当前时间:{},发送一条延迟{}毫秒的信息给队列 delayed.queue:{}", new Date(), delayTime, message);
    }
}

消费者

package com.vmware.consumer;

import com.rabbitmq.client.Channel;
import lombok.extern.slf4j.Slf4j;
import org.springframework.amqp.core.Message;
import org.springframework.amqp.rabbit.annotation.RabbitListener;
import org.springframework.stereotype.Component;
import java.util.Date;

@Slf4j
@Component
public class DeadLetterQueueConsumer {
    @RabbitListener(queues = {"delayed.queue"})
    public void receiveDelayedQueue(Message message) {
        String msg = new String(message.getBody());
        log.info("当前时间：{},收到延时队列的消息：{}", new Date(), msg);
    }
}

实际效果

2022-07-19 23:33:18.021  INFO 23040 --- [nio-8080-exec-4] com.vmware.controller.SendMsgController  : 当前时间:Tue Jul 19 23:33:18 CST 2022,发送一条延迟20000毫秒的信息给队列 delayed.queue:哈哈哈
2022-07-19 23:33:23.349  INFO 23040 --- [nio-8080-exec-5] com.vmware.controller.SendMsgController  : 当前时间:Tue Jul 19 23:33:23 CST 2022,发送一条延迟2000毫秒的信息给队列 delayed.queue:哈
2022-07-19 23:33:25.332  INFO 23040 --- [ntContainer#0-1] c.v.consumer.DeadLetterQueueConsumer     : 当前时间：Tue Jul 19 23:33:25 CST 2022,收到延时队列的消息：哈
2022-07-19 23:33:37.830  INFO 23040 --- [ntContainer#0-1] c.v.consumer.DeadLetterQueueConsumer     : 当前时间：Tue Jul 19 23:33:37 CST 2022,收到延时队列的消息：哈哈哈

• 可以看到前一条延时消息并没有阻塞到后面的消息