package util
import (
"fmt"
"hash/crc32"
"math/rand"
"time"
)
type HttpServer struct { //目标server类
Host string
Weight int
}
func NewHttpServer(host string, weight int) *HttpServer {
return &HttpServer{Host: host, Weight: weight}
}
type LoadBalance struct { //负载均衡类
Servers []*HttpServer
}
func NewLoadBalance() *LoadBalance {
return &LoadBalance{Servers: make([]*HttpServer, 0)}
}
func (this *LoadBalance) AddServer(server *HttpServer) {
this.Servers = append(this.Servers, server)
}
func (this *LoadBalance) SelectForRand() *HttpServer {
rand.Seed(time.Now().UnixNano())
index := rand.Intn(len(this.Servers)) //这里因为权重表为15个1和5个0组成，所以产生0到19的随机数
return this.Servers[ServerIndices[index]] //通过随机数的索引获得服务器索引进而获得地址
}
func (this *LoadBalance) SelectByIpHash(ip string) *HttpServer {
index := int(crc32.ChecksumIEEE([]byte(ip))) % len(this.Servers) //通过取余永远index都不会大于this.servers的长度
return this.Servers[index]
}
func (this *LoadBalance) SelectByWeight(ip string) *HttpServer { //加权随机算法
rand.Seed(time.Now().UnixNano())
index := rand.Intn(len(ServerIndices))
return this.Servers[index]
}
var LB *LoadBalance
var ServerIndices []int
func init() {
LB := NewLoadBalance()
LB.AddServer(NewHttpServer("http://localhost:8001/web1", 5)) //web1
LB.AddServer(NewHttpServer("http://localhost:8002/web2", 15)) //web2
for index, server := range LB.Servers {
if server.Weight > 0 {
for i := 0; i < server.Weight; i++ {
ServerIndices = append(ServerIndices, index)
}
}
}
fmt.Println(ServerIndices)
}
调用算法
package main
import (
"log"
"net/http"
"net/http/httputil"
url2 "net/url"
"os"
"os/signal"
"反向代理/util"
)
type ProxyHandler struct {
}
func (*ProxyHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
defer func() {
if err := recover(); err != nil {
w.WriteHeader(500)
log.Println(err)
}
}()
url, _ := url2.Parse(util.LB.SelectByWeight(r.RemoteAddr).Host) //调用加权随机算法
proxy := httputil.NewSingleHostReverseProxy(url)
proxy.ServeHTTP(w, r)
}
func main() {
http.ListenAndServe(":8080", &ProxyHandler{})
c := make(chan os.Signal)
signal.Notify(c, os.Interrupt)
s := <-c
log.Println(s)
}