1. 流量控

利用go channel实现限流量控制，原理：设置一个缓冲通道，设置访问中间键，当用户请求连接时判断channel里面长度是不是大于设定的缓冲值，如果没有就存入一个值进入channel，如果大于缓冲值，channel自动阻塞。当用户请求结束的时候，取出channel里面的值。

如果想限制用户HTTP请求进行速率限制可以参考 https://github.com/didip/tollbooth 这个中间键

目录：

-videos

—ce.html

-limiter.go

-main.go

main.go文件代码：

  1. package main
  3. import (
  4.     "log"
  5.     "net/http"
  6.     "text/template"
  7.     "time"
  9.     "github.com/julienschmidt/httprouter"
  10. )
  12. type middleWareHandler struct {
  13.     r *httprouter.Router
  14.     l *ConnLimiter
  15. }
  17. //NewMiddleWareHandler ...
  18. func NewMiddleWareHandler(r *httprouter.Router, cc int) http.Handler {
  19.     m := middleWareHandler{}
  20.     m.r = r
  21.     m.l = NewConnLimiter(cc)
  22.     return m
  23. }
  25. func (m middleWareHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
  26.     if !m.l.GetConn() {
  27.         defer func() { recover() }()
  28.         log.Panicln("Too many requests")
  29.         return
  30.     }
  31.     m.r.ServeHTTP(w, r)
  32.     defer m.l.ReleaseConn()
  33. }
  35. //RegisterHandlers ...
  36. func RegisterHandlers() *httprouter.Router {
  37.     router := httprouter.New()
  38.     router.GET("/ce", ce)
  39.     return router
  40. }
  42. func ce(w http.ResponseWriter, r *http.Request, p httprouter.Params) {
  43.     //为了演示效果这块设置了等待
  44.     time.Sleep(time.Second * 100)
  45.     t, _ := template.ParseFiles("./videos/ce.html")
  46.     t.Execute(w, nil)
  47. }
  49. func main() {
  50.     r := RegisterHandlers()
  51.     //里面的参数2为设置的最大流量
  52.     mh := NewMiddleWareHandler(r, 2)
  53.     http.ListenAndServe(":9000", mh)
  54. }

limiter.go文件代码

  1. package main
  3. import (
  4.     "log"
  5. )
  7. //ConnLimiter 定义一个结构体
  8. type ConnLimiter struct {
  9.     concurrentConn int
  10.     bucket         chan int
  11. }
  13. //NewConnLimiter ...
  14. func NewConnLimiter(cc int) *ConnLimiter {
  15.     return &ConnLimiter{
  16.         concurrentConn: cc,
  17.         bucket:         make(chan int, cc),
  18.     }
  19. }
  21. //GetConn 获取通道里面的值
  22. func (cl *ConnLimiter) GetConn() bool {
  23.     if len(cl.bucket) >= cl.concurrentConn {
  24.         log.Printf("Reached the rate limitation.")
  25.         return false
  26.     }
  28.     cl.bucket <- 1
  29.     return true
  30. }
  32. //ReleaseConn 释放通道里面的值
  33. func (cl *ConnLimiter) ReleaseConn() {
  34.     c := <-cl.bucket
  35.     log.Printf("New connction coming: %d", c)
  36. }

videos/ce.html文件代码

  1. <!DOCTYPE html>
  2. <html lang="en">
  3. <head>
  4.     <meta charset="UTF-8">
  5.     <meta name="viewport" content="width=device-width, initial-scale=1.0">
  6.     <meta http-equiv="X-UA-Compatible" content="ie=edge">
  7.     <title>Document</title>
  8. </head>
  9. <body>
  10.     www.topgoer.com是个不错的go语言中文文档
  11. </body>
  12. </html>