贝利信息

Redis如何实现延迟队列

日期:2023-05-26 00:00 / 作者:WBOY

使用

依赖配置



    4.0.0
    
        org.springframework.boot
        spring-boot-starter-parent
        2.3.12.RELEASE
         
    
    com.homeey
    redis-delay-queue
    0.0.1-SNAPSHOT
    redis-delay-queue
    redis-delay-queue
    
        1.8
    
    
        
            org.springframework.boot
            spring-boot-starter-data-redis
        
        
            org.springframework.boot
            spring-boot-starter-web
        
        
        
            org.redisson
            redisson-spring-boot-starter
            3.19.3
        
        
            org.redisson
            redisson-spring-data-23
            3.19.3
        
    

    
        
            
                org.springframework.boot
                spring-boot-maven-plugin
                
                    
                        
                            org.projectlombok
                            lombok
                        
                    
                
            
        
    

备注:处理redisson和springboot兼容性问题

配置文件

springboot整合redisson有三种方式

详细的整合查看 springboot整合redisson配置

spring:
  redis:
    database: 0
    host: localhost
    port: 6379
    timeout: 10000
    lettuce:
      pool:
        max-active: 8
        max-wait: -1
        min-idle: 0
        max-idle: 8

demo代码

package com.homeey.redisdelayqueue.delay;

import lombok.RequiredArgsConstructor;
import lombok.extern.slf4j.Slf4j;
import org.redisson.api.RBlockingQueue;
import org.redisson.api.RDelayedQueue;
import org.redisson.api.RedissonClient;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.stereotype.Component;

import javax.annotation.PostConstruct;
import java.util.concurrent.Executo

rService; import java.util.concurrent.Executors; import java.util.concurrent.TimeUnit; /** * 明天的你会因今天到的努力而幸运 * * @author jt4mrg@qq.com * 23:11 2025-02-19 2025 **/ @Slf4j @Component @RequiredArgsConstructor public class RedissonDelayQueue { private final RDelayedQueue delayedQueue; private final RBlockingQueue blockingQueue; @PostConstruct public void init() { ExecutorService executorService = Executors.newFixedThreadPool(1); executorService.submit(() -> { while (true) { try { String task = blockingQueue.take(); log.info("rev delay task:{}", task); } catch (Exception e) { log.error("occur error", e); } } }); } public void offerTask(String task, long seconds) { log.info("add delay task:{},delay time:{}s", task, seconds); delayedQueue.offer(task, seconds, TimeUnit.SECONDS); } @Configuration static class RedissonDelayQueueConfigure { @Bean public RBlockingQueue blockingQueue(RedissonClient redissonClient) { return redissonClient.getBlockingQueue("TOKEN-RENEWAL"); } @Bean public RDelayedQueue delayedQueue(RBlockingQueue blockingQueue, RedissonClient redissonClient) { return redissonClient.getDelayedQueue(blockingQueue); } } }

执行效果

原理分析

RedissonDelayedQueue实现中我们看到有四个角色

队列创建

RedissonDelayedQueue延迟队列创建时,指定了队列转移服务,以及实现延迟队列的四个重要校色的key。核心代码是指定队列转移任务

 QueueTransferTask task = new QueueTransferTask(commandExecutor.getConnectionManager()) {
            
            @Override
            protected RFuture pushTaskAsync() {
                return commandExecutor.evalWriteAsync(getRawName(), LongCodec.INSTANCE, RedisCommands.EVAL_LONG,
                        "local expiredValues = redis.call('zrangebyscore', KEYS[2], 0, ARGV[1], 'limit', 0, ARGV[2]); "//拿到zset中过期的值列表
                      + "if #expiredValues > 0 then " //如果有
                          + "for i, v in ipairs(expiredValues) do "
                              + "local randomId, value = struct.unpack('dLc0', v);"//解构消息,在提交任务时打包的消息
                              + "redis.call('rpush', KEYS[1], value);" //放入无前缀的list 队头
                              + "redis.call('lrem', KEYS[3], 1, v);"//移除带前缀list 队尾元素
                          + "end; "
                          + "redis.call('zrem', KEYS[2], unpack(expiredValues));" //移除zset中本次读取的过期元素
                      + "end; "
                        // get startTime from scheduler queue head task
                      + "local v = redis.call('zrange', KEYS[2], 0, 0, 'WITHSCORES'); "//取zset最小分值的元素
                      + "if v[1] ~= nil then "
                         + "return v[2]; " //返回分值,即过期时间
                      + "end "
                      + "return nil;",
                      Arrays.asList(getRawName(), timeoutSetName, queueName),
                      System.currentTimeMillis(), 100);
            }
            
            @Override
            protected RTopic getTopic() {
                return RedissonTopic.createRaw(LongCodec.INSTANCE, commandExecutor, channelName);
            }
        };

生产者

核心代码RedissonDelayedQueue#offerAsync

 return commandExecutor.evalWriteNoRetryAsync(getRawName(), codec, RedisCommands.EVAL_VOID,
                "local value = struct.pack('dLc0', tonumber(ARGV[2]), string.len(ARGV[3]), ARGV[3]);" //打包消息体:消息id,消息长度,消息值
              + "redis.call('zadd', KEYS[2], ARGV[1], value);"//zset中加入消息及其超时分值
              + "redis.call('rpush', KEYS[3], value);" //向带前缀的list中添加消息
              // if new object added to queue head when publish its startTime 
              // to all scheduler workers 
              + "local v = redis.call('zrange', KEYS[2], 0, 0); "//取出zset中第一个元素
              + "if v[1] == value then " //如果最快过期的元素就是这次发送的消息
                 + "redis.call('publish', KEYS[4], ARGV[1]); " //channel中发布一下超时时间
              + "end;",
              Arrays.asList(getRawName(), timeoutSetName, queueName, channelName),
              timeout, randomId, encode(e));

消费者

消费者最简单,直接从不带前缀的list中BLPOP读取就可以