1、接口（轮训和随机调度两个接口）

balance.go

package balance

//调用那种轮训方式接口
type Balancer interface {
    DoBalance([]*Instance) (*Instance, error)
}

2、定义主机列表

instance.go

package balance

//主机列表
type Instance struct {
    host string
    port int
}

// 因为上面为小写开头不支持外部访问，下面为封装后外部可直接调用

func NewInstance(host string, port int) *Instance {
    return &Instance{
        host: host,
        port: port,
    }
}

func (p *Instance) GetHost() string {
    return p.host
}

func (p *Instance) GetPort() int {
    return p.port
}

3、随机调度

random.go

package balance

import (
    "errors"
    "math/rand"
)

//初始化，调用此文件轮训方式为随机
func init() {
    RegisterBalancer("random", &RandomBalance{})
}

type RandomBalance struct {
}

func (p *RandomBalance) DoBalance(insts []*Instance) (inst *Instance, err error) {

    if len(insts) == 0 {
        err = errors.New("No instance")
        return
    }
    lens := len(insts)
    index := rand.Intn(lens)
    inst = insts[index]
    return
}

4、轮训调度

roudrobin.go

package balance

import "errors"

func init() {
    RegisterBalancer("roundrobin", &RoundRobinBalance{})
}

type RoundRobinBalance struct {
    curIndex int
}

func (p *RoundRobinBalance) DoBalance(insts []*Instance) (inst *Instance, err error) {
    if len(insts) == 0 {
        err = errors.New("No instance")
        return
    }

    lens := len(insts)
    if p.curIndex >= lens {
        p.curIndex = 0
    }

    inst = insts[p.curIndex]
    p.curIndex = (p.curIndex + 1) % lens
    return
}

5、管理文件

mgr.go

package balance

import (
    "fmt"
)

type BalanceMgr struct {
    allBalancer map[string]Balancer
}

var mgr = BalanceMgr{
    allBalancer: make(map[string]Balancer),
}

func (p *BalanceMgr) registerBalancer(name string, b Balancer) {
    p.allBalancer[name] = b
}

func RegisterBalancer(name string, b Balancer) {
    mgr.registerBalancer(name, b)
}

func DoBalance(name string, insts []*Instance) (inst *Instance, err error) {
    balancer, ok := mgr.allBalancer[name]
    if !ok {
        err = fmt.Errorf("Not found %s balancer", name)
        return
    }
    fmt.Printf("use %s balance\n", name)
    inst, err = balancer.DoBalance(insts)
    return
}

6、入口函数

main.go

package main

import (
    "fmt"
    "go_dev/day7/example3/balance"
    "math/rand"

    "os"
    "time"
)

func main() {
    var insts []*balance.Instance
    for i := 0; i < 10; i++ {
        host := fmt.Sprintf("192.168.%d.%d", rand.Intn(255), rand.Intn(255))
        one := balance.NewInstance(host, 8080)
        insts = append(insts, one)
    }

    var balanceName = "random"

    if len(os.Args) > 1 {
        balanceName = os.Args[1]
    }

    for {
        inst, err := balance.DoBalance(balanceName, insts)
        if err != nil {
            fmt.Println("do balance err:", err)
            continue
        }
        fmt.Println(inst)
        time.Sleep(time.Second)
    }
}