Golang加权轮询负载均衡的实现

目录

• 实现加权轮询负载均衡思路

• 加权轮询负载均衡代码

• 测试代码

实现加权轮询负载均衡思路

代码实现一个加权负载均衡

• Weight            初始化时对节点约定的权重

• currentWeight     节点临时权重，每轮都会变化

• effectiveWeight   节点有效权重，默认与Weight相同

• totalWeight       所有节点有效权重之和：sum(effectiveWeight)

代码实现一个加权负载均衡

• currentWeight = currentWeight+effecitveWeight

• 选中最大的 currentWeight 节点为选中节点

• currentWeight = currentWeight-totalWeight  (4+3+2=9)

所以我们能够 在表格模拟运行情况：

加权轮询负载均衡代码

package load_balance

import (
"errors"
"strconv"

)

type WeightRoundRobinBalance struct {
curIndex int
rss      []*WeightNode
rsw      []int

//观察主体
conf LoadBalanceConf
}

// 配置主题
type LoadBalanceConf interface {
GetConf() []string
WatchConf()
UpdateConf(conf []string)
}

type WeightNode struct {
addr            string // 服务器地址
weight          int //权重值
currentWeight   int //节点当前权重
effectiveWeight int //有效权重
}

func (r *WeightRoundRobinBalance) Add(params ...string) error {
if len(params) != 2 {
 return errors.New("param len need 2")
}
parInt, err := strconv.ParseInt(params[1], 10, 64)
if err != nil {
 return err
}
node := &WeightNode{addr: params[0], weight: int(parInt)}
node.effectiveWeight = node.weight
r.rss = append(r.rss, node)
return nil
}

func (r *WeightRoundRobinBalance) Next() string {
total := 0
var best *WeightNode
for i := 0; i < len(r.rss); i++ {
 w := r.rss[i]
 //step 1 统计所有有效权重之和
 total += w.effectiveWeight

//step 2 变更节点临时权重为的节点临时权重+节点有效权重
 w.currentWeight += w.effectiveWeight

//step 3 有效权重默认与权重相同，通讯异常时-1, 通讯成功+1，直到恢复到weight大小
 if w.effectiveWeight < w.weight {
  w.effectiveWeight++
 }
 //step 4 选择最大临时权重点节点
 if best == nil || w.currentWeight > best.currentWeight {
  best = w
 }
}
if best == nil {
 return ""
}
//step 5 变更临时权重为 临时权重-有效权重之和
best.currentWeight -= total
return best.addr
}

func (r *WeightRoundRobinBalance) Get(key string) (string, error) {
return r.Next(), nil
}

func (r *WeightRoundRobinBalance) SetConf(conf LoadBalanceConf) {
r.conf = conf
}

测试代码

package load_balance

import (
"fmt"
"testing"
)

func TestLB(t *testing.T) {
rb := &WeightRoundRobinBalance{}
rb.Add("127.0.0.1:2003", "4") //0
// rb.Add("127.0.0.1:2004", "3") //1
rb.Add("127.0.0.1:2005", "2") //2

fmt.Println(rb.Next())
fmt.Println(rb.Next())
fmt.Println(rb.Next())
fmt.Println(rb.Next())
fmt.Println(rb.Next())
fmt.Println(rb.Next())
fmt.Println(rb.Next())
fmt.Println(rb.Next())
fmt.Println(rb.Next())
fmt.Println(rb.Next())
fmt.Println(rb.Next())
fmt.Println(rb.Next())
fmt.Println(rb.Next())
fmt.Println(rb.Next())
}

测试结果

$ go test
127.0.0.1:2003
127.0.0.1:2005
127.0.0.1:2003
127.0.0.1:2003
127.0.0.1:2005
127.0.0.1:2003
127.0.0.1:2003
127.0.0.1:2005
127.0.0.1:2003
127.0.0.1:2003
127.0.0.1:2005
127.0.0.1:2003
127.0.0.1:2003
127.0.0.1:2005
PASS
ok      gateway/_test/demo      0.080s

## 127.0.0.1:2003 为 127.0.0.1:2005 权重两倍。而从答应结果上看，符合要求

来源：https://juejin.cn/post/6974775746807988232