redigo 对redis的订阅机制放在pubsub.go里面
PubSubConn封装Conn以实现订阅者提供简便方法。Subscribe，PSubscribe，Unsubscribe和PUnsubscribe方法发送和刷新订阅。receive方法将推送的消息转换对应的类型
// 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())
}
返回的是一个空接口类型 interface{}，由于空接口没有方法，因此所有类型都实现了空接口，也就是说可以返回任意类型。
返回类型
具体会返回哪些类型在receiveInternal()里面可以看到，
目前返回的三种Message、Subscription、Pong都定义在了pubsub.go 里面。
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
}
r订阅示例
package main
import(
//"github.com/go-redis/redis"
"fmt"
"time"
//"reflect"
"unsafe"
"github.com/gomodule/redigo/redis"
log "github.com/astaxie/beego/logs"
)
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.Critical("redis dial failed.")
}
c.client = redis.PubSubConn{
conn}
c.cbMap = make(map[string]SubscribeCallback)
go func() {
for {
log.Debug("wait...")
//读取channel消息 并检测收到的消息类型
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:
//订阅成功,同时订阅多个时，这地方会收到多次
fmt.Printf("%s: %s %d\n", res.Channel, res.Kind, res.Count)
case error:
log.Error("error handle...")
//如果是长连接项目，这里最好return，否则客户端断开时，这里可能会造成死循环
return
}
}
}()
}
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.Critical("redis Subscribe error.")
}
c.cbMap[channel.(string)] = cb
}
func TestCallback1(chann, msg string){
log.Debug("TestCallback1 channel : ", chann, " message : ", msg)
}
func TestCallback2(chann, msg string){
log.Debug("TestCallback2 channel : ", chann, " message : ", msg)
}
func TestCallback3(chann, msg string){
log.Debug("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{
time.Sleep(1 * time.Second)
}
}
常见问题
这地方如果用redis的连接池的话，要注意不要设置读取数据的超时时间，否则到了超时时间，就会断开连接了，报错如下：
2022/07/12 15:43:14 wait...
test1: subscribe 1
2022/07/12 15:43:14 wait...
[GIN] 2022/07/12 - 15:43:26 | 200 | 1.129741ms | 222.128.58.255 | GET "
/gotest/pub"
2022/07/12 15:43:26 {test1 [104 101 108 108 111]}
2022/07/12 15:43:26 0xc00009e540 0xc00009e560
2022/07/12 15:43:26 wait...
2022/07/12 15:43:46 error handle... read tcp 10.10.2.8:57724->123.207.190.86:637
9: i/o timeout
2022/07/12 15:43:46 wait...
2022/07/12 15:43:46 error handle... read tcp 10.10.2.8:57724->123.207.190.86:637
9: use of closed network connection
2022/07/12 15:43:46 wait...
2022/07/12 15:43:46 error handle... read tcp 10.10.2.8:57724->123.207.190.86:637
9: use of closed network connection
2022/07/12 15:43:46 wait...
2022/07/12 15:43:46 error handle... read tcp 10.10.2.8:57724->123.207.190.86:637
9: use of closed network connection
2022/07/12 15:43:46 wait...
如果是长连接项目，case error 的情况下这里最好return，否则客户端断开时，这里可能会造成死循环（break只会退出switch，不会退出外边的for）
发布示例
发布直接使用默认的Conn来Send “Publish“ 命令即可.
redigo的管道的使用方法设计到三个函数，Do函数也是下面这三个函数的合并：
c.Send("SUBSCRIBE", "example")
c.Flush()
for {
reply, err := c.Receive()
if err != nil {
return err
}
// process pushed message
}send()方法把命令写到输出缓冲区，Flush()把缓冲区的命令刷新到redis服务器，Receive()函数接收redis给予的响应，三个操作共同完成一套命令流程。
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.")
}
}
PubSubConn
定义
type PubSubConn struct {
Conn Conn
}提供的方法：
1.Close 关闭连接
func (c PubSubConn) Close() error
2.PSubscribe 订阅channel支持通配符匹配
func (c PubSubConn) PSubscribe(channel ...interface{}) error3.PUnsubscribe 取消发布， 如果没有给定， 则取消所有
func (c PubSubConn) PUnsubscribe(channel ...interface{}) error4.Ping 指定的数据向服务器发送PING 调用此方法时，连接必须至少订阅一个通道或模式
func (c PubSubConn) Ping(data string) error
5.Receive 获取消息
func (c PubSubConn) Receive() interface{}6.ReceiveWithTimeout 带有超时时间的获取消息函数
func (c PubSubConn) ReceiveWithTimeout(timeout time.Duration) interface{}7.Subscribe 订阅
func (c PubSubConn) Subscribe(channel ...interface{}) error8.Unsubscribe 取消订阅
func (c PubSubConn) Unsubscribe(channel ...interface{}) errorgo redis发布订阅常用函数
Subscribe - 订阅channel
PSubscribe - 订阅channel支持通配符匹配
Publish - 将信息发送到指定的channel。
PubSub Channels - 查询活跃的channel
127.0.0.1:6379> pubsub channels 1) "forum_38" 2) "forum_99" 3) "forum_79"
PubSub NumSub - 查询指定的channel有多少个订阅者
127.0.0.1:6379> pubsub numsub forum_38 forum_10 1) "forum_38" 2) (integer) 1 3) "forum_10" 4) (integer) 1
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