golang redigo 發佈訂閱使用

redigo 對 發佈訂閱的使用

redigo 對redis 的發佈訂閱機制放在pubsub.go 中
訂閱主題後 通過Receive() 函數接受發佈訂閱主題的消息

// 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())
}

返回的是一個空類型的interface{} , 由於空接口沒有方法， 因此所有的類型都實現了空接口， 也就是說可以返回任意類型。

具體返回的類型 在receiveInternal（） 方法裏面可以看到

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

訂閱的主題
收到消息之後通過註冊的回調函數處理的方式， 所以代碼中多了長map存放回調函數

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{ // 這段代碼的作用就是 阻止線程結束
		time.Sleep(1 * time.Second)
	}
}

運行main 文件 然後 看到

在redis 客戶端 執行 發佈信息

在控制檯 看到監控結果 回調函數 執行的結果

發佈

上面是訂閱的代碼和 代碼要處理 的回調函數
發佈直接使用默認的 Conn來Send Publish 就可以
redigo 的管道使用方法設計到三個函數 Do 函數也是下面這個函數的合併

• c.Send()
• c.Flush()
• c.Receive()

解釋：
send() 方法吧命令寫到緩衝區， flush() 把緩衝區的命令刷新到redis 服務器 receive() 函數接受redis 給予的 迴應， 三個操作共同完成一套命令流程。

代碼

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.")
  }

}