go语言七——连接redis

使用Redigo这个库

package main
import (
	"fmt"
	"redis"
	"time"
	"strconv"
)
var (
	server string = "192.168.1.105:6379"
	password string = "passwd"
)
var pool *redis.Pool
func test(i int) {
	c := pool.Get()
	defer c.Close()
	t:=strconv.Itoa(i)
	c.Do("SETEX","foo"+t,20,i)
	reply, err := redis.Int(c.Do("GET","foo"+t))
	if err == nil {
		fmt.Print(reply)
	} else {
		fmt.Print(err)
	}
	time.Sleep(1*time.Second)
}
func poolInit() (*redis.Pool) {
	//redis pool
	return &redis.Pool{
		MaxIdle: 3,
		IdleTimeout: 240 * time.Second,
		Dial: func () (redis.Conn, error) {
			c, err := redis.Dial("tcp", server)
			if err != nil {
				return nil, err
			}
			if _, err := c.Do("AUTH", password); err != nil {
				c.Close()
				return nil, err
			}
			//if _, err := c.Do("SELECT",1); err != nil {
				// c.Close()
				// return nil, err
			//}
			return c, err
		},
		TestOnBorrow: func(c redis.Conn, t time.Time) error {
			_, err := c.Do("PING")
			return err
		},
	}
}
func main() {
	pool = poolInit()
	for i:=0;i<1000000;i++ {
		test(i)
	}
}

如果服务器端口不可用或者服务i不可用,则c.Do会返回错误,端口不可用立即返回Connection Refused,而服务器不可达会等待一段时间超时再返回。下面这段代码实现先查找缓存,查询失败时查询mysql

type Record struct {
 Key string
 Val string
}
func fetch_key(key string) string {
 var val string
 out := make(chan string)
 timeout := make(chan string, 1)
 //超时两秒
 go func() {
 time.Sleep(2 * time.Second)
 timeout <- ""
 }()
 //查询缓存(Redis)
 c := G_pool.Get()
 defer c.Close()
 if reply, err := redis.String(c.Do("GET", key)); err == nil {
 go func(string) {
 out <- reply
 }(reply)
 } else {
 go func() {
 //查询数据库(Mysql)
 db, e := sql.Open("mysql", "username:password@tcp(mysqlip:mysqlport)/dbname?charset=utf8")
 if e != nil {
 out <- ""
 }
 defer db.Close()
 rows, e := db.Query("select key,val from dbname.tablename where key=" + key)
 if e != nil {
 out <- ""
 }
 if rows == nil {
 out <- ""
 }
 for rows.Next() {
 rec := new(Record)
 row_err := rows.Scan(&rec.Key,&rec.Val)
 if row_err != nil {
 out <- ""
 }
 //将结果存入缓存(Redis),超时1天
 c.Do("SETEX",key,86400,rec.Val)
 out <- rec.Size
 }
 out <- ""
 }()
 }
 //等待结果或者超时
 select {
 case val = <-timeout:
 case val = <-out:
 }
 return val
}

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