第 7 周 性能优化：性能优化是架构师展现自己技术全面性的时刻

package main

import (
	"flag"
	"fmt"
	"io/ioutil"
	"math"
	"net/http"
	"sort"
	"sync"
	"time"
)

func main()  {
	var n ,c int64
	var url string
	flag.Int64Var(&n, "n", 0, "请求总数")
	flag.Int64Var(&c,"c", 0, "请求并发数")
	flag.StringVar(&url, "url", "", "请求地址")
	flag.Parse()
	mod := int64(math.Mod(float64(n), float64(c)))
	num := int64(math.Floor(float64(n/c)))
	wg := &sync.WaitGroup{}
	wg.Add(int(c))
	var m sync.Mutex
	statData := []int64{}
	totalTime := int64(0)
	for i:=int64(0); i< c;i++{
		requestNum := num
		if i < mod {
			requestNum += 1
		}
		go run(requestNum, url, wg, func(t int64) {
			m.Lock()
			defer m.Unlock()
			totalTime += t
			statData = append(statData, t)
		})
	}
	wg.Wait()
	sort.Slice(statData, func(i, j int) bool { return statData[i] < statData[j] })
	index := int64(math.Max(math.Round(0.95 * float64(n)) - 1, 0))
	fmt.Printf("[总请求数：%d、 并发数：%d ]测试结果：平均响应时间：%s、 95%s响应时间：%s \n", n, c, time.Duration(totalTime/n).String(), "%",time.Duration(statData[index]).String())

}

func run(num int64, url string, wg *sync.WaitGroup, callback func(t int64))  {
	for i:=int64(0); i < num; i++ {
		startTime := time.Now()
		curl(url)
		elapsedTime := time.Since(startTime)
		callback(elapsedTime.Nanoseconds())
	}
	wg.Done()
}

func curl(url string) ([]byte, int) {
	resp,_ := http.Get(url)
	defer resp.Body.Close()
	body, _ := ioutil.ReadAll(resp.Body)
	return body, resp.StatusCode
}

go run test.go -c 10 -n 100 -url "http://www.baidu.com"