go语言七——连接redis

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　　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
}