balance.go 源码阅读

import (

    //"fmt"

    "math/rand"

    "net"

    "stathat.com/c/consistent"

    "time"

)

// BackendSvr Type

type BackendSvr struct {

    svrStr    string

    isUp      bool // is Up or Down

    failTimes int

}

var (

    pConsisthash *consistent.Consistent

    pBackendSvrs map[string]*BackendSvr

)

func initBackendSvrs(svrs []string) { //遍历后端服务  并且添加到一致性哈希表中  另初始化pBackendSvrs  key为后端服务地址  value是BackendSvr结构体

    pConsisthash = consistent.New()

    pBackendSvrs = make(map[string]*BackendSvr)

    for _, svr := range svrs {

        pConsisthash.Add(svr)

        pBackendSvrs[svr] = &BackendSvr{

            svrStr:    svr,

            isUp:      true,

            failTimes: 0,

        }

    }

    go checkBackendSvrs()

}

//通过连接 获取后端服务地址 ，通过服务地址到哈希表中找对应的BackendSvr

func getBackendSvr(conn net.Conn) (*BackendSvr, bool) {

    remoteAddr := conn.RemoteAddr().String()

    svr, _ := pConsisthash.Get(remoteAddr)

    bksvr, ok := pBackendSvrs[svr]

    return bksvr, ok

}

func checkBackendSvrs() {  //判断后端服务器健康状态以及是否可以使用  是否达到设置失败次数

    // scheduler every 10 seconds

    rand.Seed(time.Now().UnixNano())

    t := time.Tick(time.Duration(10)*time.Second + time.Duration(rand.Intn(100))*time.Millisecond*100) //10s +随机毫秒数 后  执行下面代码

    for _ = range t {

        for _, v := range pBackendSvrs {

            if v.failTimes >= pConfig.FailOver && v.isUp == true {

                v.isUp = false

                pConsisthash.Remove(v.svrStr)

            }

        }

    }

}