GO + Redis 使用KeyspaceNotifications完成延时任务

淩亂°似流年 2022-10-07 12:58 55阅读 0赞

在使用之前需要先开启Redis的`键空间通知`开关，可参考 [《Redis 键空间通知》][Redis]，另外java版本的可以查看[《Springboot + Redis：整合键消息通知》][Springboot _ Redis]

我们利用redis键空间通知，订阅string的过期时间，来完成延时任务的操作

import (
    	"fmt"
    	"github.com/gomodule/redigo/redis"
    	"strconv"
    	"time"
    	"unsafe"
    )
    
    
    type PSubscribeCallback func (pattern, channel, message string)
    
    type PSubscriber struct { 
    	client redis.PubSubConn
    	cbMap map[string]PSubscribeCallback
    }
    
    func PConnect(ip, password string, port uint16) redis.Conn { 
    	conn, err := redis.Dial("tcp", ip + ":" + strconv.Itoa(int(port)))
    	if err != nil { 
    		print("redis dial failed.")
    	}
    	conn.Do("AUTH",password)
    	return conn
    }
    
    func (c *PSubscriber) ReceiveKeySpace(conn redis.Conn) { 
    	c.client = redis.PubSubConn{ conn}
    	c.cbMap = make(map[string]PSubscribeCallback)
    	go func() { 
    		for { 
    			switch res := c.client.Receive().(type) { 
    			case redis.Message:
    				pattern := &res.Pattern
    				channel := &res.Channel
    				message := (*string)(unsafe.Pointer(&res.Data))
    				c.cbMap[*channel](*pattern, *channel, *message)
    			case redis.Subscription:
    				fmt.Printf("%s: %s %d\n", res.Channel, res.Kind, res.Count)
    			case error:
    				print("error handle...")
    				continue
    			}
    		}
    	}()
    }
    
    const expired = "__keyevent@0__:expired"
    
    func (c *PSubscriber)Psubscribe() { 
    	err := c.client.PSubscribe(expired)
    	if err != nil{ 
    		print("redis Subscribe error.")
    	}
    	c.cbMap[expired] = PubCallback
    }
    
    func PubCallback(patter , channel, msg string){ 
    	print( "PubCallback patter : " + patter + " channel : ", channel, " message : ", msg)
    	// TODO:拿到msg后进行后续的业务代码
    }
    
    func main() { 
    
    	var sub PSubscriber
    	conn := PConnect("xx.xx.xx.xx","123456", 6379)
    	sub.ReceiveKeySpace(conn)
    	sub.Psubscribe()
    	for{ 
    		time.Sleep(time.Second)
    	}
    }

我们可以尝试set一个3s后过期的string  
![在这里插入图片描述][20210618112022797.png]  
等待3s后，能看到控制台打印出了我们所需的信息，此时再通过msg完成后续业务代码操作。  
![在这里插入图片描述][20210618111943453.png]

[Redis]: https://blog.csdn.net/lt326030434/article/details/106708021
[Springboot _ Redis]: https://jiandansuifeng.blog.csdn.net/article/details/106710977
[20210618112022797.png]: /images/20221005/7874102725b544f493045e6918910fe8.png
[20210618111943453.png]: /images/20221005/fb61547375cc49a9b0b132173efc4f20.png