如何在C语言中正确确定最快的CDN、镜像和下载服务器++

我正在纠结的问题是如何确定 c++ 客户端连接最快的服务器 git 从克隆或下载 tarball 。所以基本上我想从 已知 镜像将用于从中下载内容的镜像。

遵循我编写的代码 演示 也许我想更清楚地实现什么,但我相信这不是我们应该在生产中使用的东西:)。

假设我有两个已知的源镜像 git-1.exmple.com 和 git-2.example.com 我想下载 tag-x.tar.gz 从客户端具有最佳连接的服务器。

加元.h

#include <iostream>
#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <netdb.h>
#include <arpa/inet.h>
#include <sys/time.h>
using namespace std;

class CDN {
public:
    long int dl_time;
    string host;
    string proto;
    string path;
    string dl_speed;
    double kbs;
    double mbs;
    double sec;
    long int ms;
    CDN(string, string, string);
    void get_download_speed();
    bool operator < (const CDN&);
};
#endif

CDN.cpp公司

#include "CND.h"
CDN::CDN(string protocol, string hostname, string downloadpath)
{
    proto = protocol;
    host = hostname;
    path = downloadpath;
    dl_time = ms = sec = mbs = kbs = 0;
    get_download_speed();
}
void CDN::get_download_speed()
{
    struct timeval dl_started;
    gettimeofday(&dl_started, NULL);
    long int download_start = ((unsigned long long) dl_started.tv_sec * 1000000) + dl_started.tv_usec;
    char buffer[256];
    char cmd_output[32];
    sprintf(buffer,"wget -O /dev/null --tries=1 --timeout=2 --no-dns-cache --no-cache %s://%s/%s 2>&1 | grep -o --color=never \"[0-9.]\\+ [KM]*B/s\"",proto.c_str(),host.c_str(),path.c_str());
    fflush(stdout);
    FILE *p = popen(buffer,"r");

    fgets(cmd_output, sizeof(buffer), p);
    cmd_output[strcspn(cmd_output, "\n")] = 0;
    pclose(p);

    dl_speed = string(cmd_output);
    struct timeval download_ended;
    gettimeofday(&download_ended, NULL);
    long int download_end = ((unsigned long long)download_ended.tv_sec * 1000000) + download_ended.tv_usec;

    size_t output_type_k = dl_speed.find("KB/s");
    size_t output_type_m = dl_speed.find("MB/s");

    if(output_type_k!=string::npos) {
        string dl_bytes = dl_speed.substr(0,output_type_k-1);
        double dl_mb = atof(dl_bytes.c_str()) / 1000;
        kbs = atof(dl_bytes.c_str());
        mbs = dl_mb;
    } else if(output_type_m!=string::npos) {
        string dl_bytes = dl_speed.substr(0,output_type_m-1);
        double dl_kb = atof(dl_bytes.c_str()) * 1000;
        kbs = dl_kb;
        mbs = atof(dl_bytes.c_str());
    } else {
        cout << "Should catch the errors..." << endl;
    }
    ms = download_end-download_start;
    sec = ((float)ms)/CLOCKS_PER_SEC;
}
bool CDN::operator < (const CDN& other)
{
    if (dl_time < other.dl_time)
       return true;
    else
       return false;
}

主.cpp

#include "CDN.h"
int main() 
{
    cout << "Checking CDN's" << endl;
    char msg[128];
    CDN cdn_1 = CDN("http","git-1.example.com","test.txt");
    CDN cdn_2 = CDN("http","git-2.example.com","test.txt");
    if(cdn_2 > cdn_1)
    {
        sprintf(msg,"Downloading tag-x.tar.gz from %s %s since it's faster than %s %s",
        cdn_1.host.c_str(),cdn_1.dl_speed.c_str(),cdn_2.host.c_str(),cdn_2.dl_speed.c_str());
        cout << msg << endl;

    }
    else
    {
        sprintf(msg,"Downloading tag-x.tar.gz from %s %s since it's faster than %s %s",
        cdn_2.host.c_str(),cdn_2.dl_speed.c_str(),cdn_1.host.c_str(),cdn_1.dl_speed.c_str());
        cout << msg << endl;
    }
    return 0;
}

那么你的想法是什么,你将如何处理这一点。有什么替代方案 wget 并在c中实现相同的清洁方式++

编辑: 正如@molbdnilo正确指出的那样

ping测量延迟,但您对吞吐量感兴趣。

因此,我编辑了演示代码以反映这一点,但问题仍然存在