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
}