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golang实现流量控制操作

 4 years ago
source link: https://studygolang.com/articles/26383
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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。

** 文章转自go语言中文文档 http://www.topgoer.com **

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：

package main

import (
	"log"
	"net/http"
	"text/template"
	"time"

	"github.com/julienschmidt/httprouter"
)

type middleWareHandler struct {
	r *httprouter.Router
	l *ConnLimiter
}

//NewMiddleWareHandler ...
func NewMiddleWareHandler(r *httprouter.Router, cc int) http.Handler {
	m := middleWareHandler{}
	m.r = r
	m.l = NewConnLimiter(cc)
	return m
}

func (m middleWareHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	if !m.l.GetConn() {
		defer func() { recover() }()
		log.Panicln("Too many requests")
		return
	}
	m.r.ServeHTTP(w, r)
	defer m.l.ReleaseConn()
}

//RegisterHandlers ...
func RegisterHandlers() *httprouter.Router {
	router := httprouter.New()
	router.GET("/ce", ce)
	return router
}

func ce(w http.ResponseWriter, r *http.Request, p httprouter.Params) {
	//为了演示效果这块设置了等待
	time.Sleep(time.Second * 100)
	t, _ := template.ParseFiles("./videos/ce.html")
	t.Execute(w, nil)
}

func main() {
	r := RegisterHandlers()
	//里面的参数2为设置的最大流量
	mh := NewMiddleWareHandler(r, 2)
	http.ListenAndServe(":9000", mh)
}

limiter.go文件代码

package main

import (
	"log"
)

//ConnLimiter 定义一个结构体
type ConnLimiter struct {
	concurrentConn int
	bucket         chan int
}

//NewConnLimiter ...
func NewConnLimiter(cc int) *ConnLimiter {
	return &ConnLimiter{
		concurrentConn: cc,
		bucket:         make(chan int, cc),
	}
}

//GetConn 获取通道里面的值
func (cl *ConnLimiter) GetConn() bool {
	if len(cl.bucket) >= cl.concurrentConn {
		log.Printf("Reached the rate limitation.")
		return false
	}

	cl.bucket <- 1
	return true
}

//ReleaseConn 释放通道里面的值
func (cl *ConnLimiter) ReleaseConn() {
	c := <-cl.bucket
	log.Printf("New connction coming: %d", c)
}

videos/ce.html文件代码

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
</head>
<body>
    欢迎访问www.5lmh.com
</body>
</html>

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