golang redigo发布订阅使用的方法

redigo 对发布订阅的使用

redigo 对redis 的发布订阅机制放在pubsub.go 中
订阅主题后通过Receive() 函数接受发布订阅主题的消息

// Receive returns a pushed message as a Subscription, Message, Pong or error.
// The return value is intended to be used directly in a type switch as
// illustrated in the PubSubConn example.
func (c PubSubConn) Receive() interface{} {
	return c.receiveInternal(c.Conn.Receive())
}

返回的是一个空类型的interface{} , 由于空接口没有方法，因此所有的类型都实现了空接口，也就是说可以返回任意类型。

具体返回的类型在receiveInternal（）方法里面可以看到

func (c PubSubConn) receiveInternal(replyArg interface{}, errArg error) interface{} {
	reply, err := Values(replyArg, errArg)
	if err != nil {
		return err
	}

	var kind string
	reply, err = Scan(reply, &kind)
	if err != nil {
		return err
	}

	switch kind {
	case "message":
		var m Message
		if _, err := Scan(reply, &m.Channel, &m.Data); err != nil {
			return err
		}
		return m
	case "pmessage":
		var m Message
		if _, err := Scan(reply, &m.Pattern, &m.Channel, &m.Data); err != nil {
			return err
		}
		return m
	case "subscribe", "psubscribe", "unsubscribe", "punsubscribe":
		s := Subscription{Kind: kind}
		if _, err := Scan(reply, &s.Channel, &s.Count); err != nil {
			return err
		}
		return s
	case "pong":
		var p Pong
		if _, err := Scan(reply, &p.Data); err != nil {
			return err
		}
		return p
	}
	return errors.New("redigo: unknown pubsub notification")
}

目前返回 Message Subscription Pone

订阅的主题

收到消息之后通过注册的回调函数处理的方式，所以代码中多了长map存放回调函数

package main

import (
	//"github.com/go-redis/redis"
	"fmt"
	"github.com/labstack/gommon/log"
	"github.com/gomodule/redigo/redis"
	"time"

	//"reflect"
	"unsafe"
)

type SubscribeCallback func (channel, message string)

type Subscriber struct {
	client redis.PubSubConn
	cbMap map[string]SubscribeCallback
}

func (c *Subscriber) Connect(ip string, port uint16) {
	conn, err := redis.Dial("tcp", "127.0.0.1:6379")
	if err != nil {
		log.Error("redis dial failed.")
	}

	c.client = redis.PubSubConn{conn}
	c.cbMap = make(map[string]SubscribeCallback)

	go func() {
		for {
			log.Info("wait...")
			switch res := c.client.Receive().(type) {
			case redis.Message:
				channel := (*string)(unsafe.Pointer(&res.Channel))
				message := (*string)(unsafe.Pointer(&res.Data))
				c.cbMap[*channel](*channel, *message)
			case redis.Subscription:
				fmt.Printf("%s: %s %d\n", res.Channel, res.Kind, res.Count)
			case error:
				log.Error("error handle...")
				continue
			}
		}
	}()

}

func (c *Subscriber) Close() {
	err := c.client.Close()
	if err != nil{
		log.Error("redis close error.")
	}
}

func (c *Subscriber) Subscribe(channel interface{}, cb SubscribeCallback) {
	err := c.client.Subscribe(channel)
	if err != nil{
		log.Error("redis Subscribe error.")
	}

	c.cbMap[channel.(string)] = cb
}

func TestCallback1(chann, msg string){
	log.Info("TestCallback1 channel : ", chann, " message : ", msg)
}

func TestCallback2(chann, msg string){
	log.Info("TestCallback2 channel : ", chann, " message : ", msg)
}

func TestCallback3(chann, msg string){
	log.Info("TestCallback3 channel : ", chann, " message : ", msg)
}

func main() {

	log.Info("===========main start============")

	var sub Subscriber
	sub.Connect("127.0.0.1", 6397)
	sub.Subscribe("test_chan1", TestCallback1)
	sub.Subscribe("test_chan2", TestCallback2)
	sub.Subscribe("test_chan3", TestCallback3)

	for{ // 这段代码的作用就是 阻止线程结束
		time.Sleep(1 * time.Second)
	}
}

运行main 文件然后看到

在redis 客户端执行发布信息

在控制台看到监控结果回调函数执行的结果

发布

上面是订阅的代码和代码要处理的回调函数
发布直接使用默认的 Conn来Send Publish 就可以
redigo 的管道使用方法设计到三个函数 Do 函数也是下面这个函数的合并

c.Send()
c.Flush()
c.Receive()

解释：
send() 方法吧命令写到缓冲区， flush() 把缓冲区的命令刷新到redis 服务器 receive() 函数接受redis 给予的回应，三个操作共同完成一套命令流程。

代码

package main

import(
  //"github.com/go-redis/redis"
  "github.com/gomodule/redigo/redis"
  log "github.com/astaxie/beego/logs"
)

func main() {

  client, err := redis.Dial("tcp", "127.0.0.1:6379")
  if err != nil {
      log.Critical("redis dial failed.")
  }
  defer client.Close()

  _, err = client.Do("Publish", "test_chan1", "hello")
  if err != nil {
    log.Critical("redis Publish failed.")
  }

  _, err = client.Do("Publish", "test_chan2", "hello")
  if err != nil {
    log.Critical("redis Publish failed.")
  }

  _, err = client.Do("Publish", "test_chan3", "hello")
  if err != nil {
    log.Critical("redis Publish failed.")
  }
}

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The End