#include <string>#include <iostream>#include <curl/curl.h>#include <sys/time.h>#include <unistd.h>using namespace std;size_t curl_writer(void *buffer, size_t size, size_t count, void * stream){    std::string * pStream = static_cast<std::string *>(stream);    (*pStream).append((char *)buffer, size * count);    return size * count;};/** * 生成一个easy curl对象，进行一些简单的设置操作 */CURL * curl_easy_handler(const std::string & sUrl,                         const std::string & sProxy,                         std::string & sRsp,                         unsigned int uiTimeout){    CURL * curl = curl_easy_init();    curl_easy_setopt(curl, CURLOPT_URL, sUrl.c_str());    curl_easy_setopt(curl, CURLOPT_NOSIGNAL, 1);    if (uiTimeout > 0)    {        curl_easy_setopt(curl, CURLOPT_TIMEOUT_MS, uiTimeout);    }    if (!sProxy.empty())    {        curl_easy_setopt(curl, CURLOPT_PROXY, sProxy.c_str());    }    // write function //    curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, curl_writer);    curl_easy_setopt(curl, CURLOPT_WRITEDATA, &sRsp);    return curl;}/** * 使用select函数监听multi curl文件描述符的状态 * 监听成功返回0，监听失败返回-1 */int curl_multi_select(CURLM * curl_m){    int ret = 0;    struct timeval timeout_tv;    fd_set  fd_read;    fd_set  fd_write;    fd_set  fd_except;    int     max_fd = -1;    // 注意这里一定要清空fdset,curl_multi_fdset不会执行fdset的清空操作  //    FD_ZERO(&fd_read);    FD_ZERO(&fd_write);    FD_ZERO(&fd_except);    // 设置select超时时间  //    timeout_tv.tv_sec = 1;    timeout_tv.tv_usec = 0;    // 获取multi curl需要监听的文件描述符集合 fd_set //    curl_multi_fdset(curl_m, &fd_read, &fd_write, &fd_except, &max_fd);    /**     * When max_fd returns with -1,     * you need to wait a while and then proceed and call curl_multi_perform anyway.     * How long to wait? I would suggest 100 milliseconds at least,     * but you may want to test it out in your own particular conditions to find a suitable value.     */    if (-1 == max_fd)    {        return -1;    }    /**     * 执行监听，当文件描述符状态发生改变的时候返回     * 返回0，程序调用curl_multi_perform通知curl执行相应操作     * 返回-1，表示select错误     * 注意：即使select超时也需要返回0，具体可以去官网看文档说明     */    int ret_code = ::select(max_fd + 1, &fd_read, &fd_write, &fd_except, &timeout_tv);    switch(ret_code)    {    case -1:        /* select error */        ret = -1;        break;    case 0:        /* select timeout */    default:        /* one or more of curl‘s file descriptors say there‘s data to read or write*/        ret = 0;        break;    }    return ret;}#define MULTI_CURL_NUM 3// 这里设置你需要访问的url //std::string     URL     = "http://website.com";// 这里设置代理ip和端口  //std::string     PROXY   = "ip:port";// 这里设置超时时间  //unsigned int    TIMEOUT = 2000; /* ms *//** * multi curl使用demo */int curl_multi_demo(int num){    // 初始化一个multi curl 对象 //    CURLM * curl_m = curl_multi_init();    std::string     RspArray[num];    CURL *          CurlArray[num];    // 设置easy curl对象并添加到multi curl对象中  //    for (int idx = 0; idx < num; ++idx)    {        CurlArray[idx] = NULL;        CurlArray[idx] = curl_easy_handler(URL, PROXY, RspArray[idx], TIMEOUT);        if (CurlArray[idx] == NULL)        {            return -1;        }        curl_multi_add_handle(curl_m, CurlArray[idx]);    }    /*     * 调用curl_multi_perform函数执行curl请求     * url_multi_perform返回CURLM_CALL_MULTI_PERFORM时，表示需要继续调用该函数直到返回值不是CURLM_CALL_MULTI_PERFORM为止     * running_handles变量返回正在处理的easy curl数量，running_handles为0表示当前没有正在执行的curl请求     */    int running_handles;    while (CURLM_CALL_MULTI_PERFORM == curl_multi_perform(curl_m, &running_handles))    {        cout << running_handles << endl;    }    /**     * 为了避免循环调用curl_multi_perform产生的cpu持续占用的问题，采用select来监听文件描述符     */    while (running_handles)    {        if (-1 == curl_multi_select(curl_m))        {            cerr << "select error" << endl;            break;        } else {            // select监听到事件，调用curl_multi_perform通知curl执行相应的操作 //            while (CURLM_CALL_MULTI_PERFORM == curl_multi_perform(curl_m, &running_handles))            {                cout << "select: " << running_handles << endl;            }        }        cout << "select: " << running_handles << endl;    }    // 输出执行结果 //    int         msgs_left;    CURLMsg *   msg;    while((msg = curl_multi_info_read(curl_m, &msgs_left)))    {        if (CURLMSG_DONE == msg->msg)        {            int idx;            for (idx = 0; idx < num; ++idx)            {                if (msg->easy_handle == CurlArray[idx]) break;            }            if (idx == num)            {                cerr << "curl not found" << endl;            } else            {                cout << "curl [" << idx << "] completed with status: "                        << msg->data.result << endl;                cout << "rsp: " << RspArray[idx] << endl;            }        }    }    // 这里要注意cleanup的顺序 //    for (int idx = 0; idx < num; ++idx)    {        curl_multi_remove_handle(curl_m, CurlArray[idx]);    }    for (int idx = 0; idx < num; ++idx)    {        curl_easy_cleanup(CurlArray[idx]);    }    curl_multi_cleanup(curl_m);    return 0;}/** * easy curl使用demo */int curl_easy_demo(int num){    std::string     RspArray[num];    for (int idx = 0; idx < num; ++idx)    {        CURL * curl = curl_easy_handler(URL, PROXY, RspArray[idx], TIMEOUT);        CURLcode code = curl_easy_perform(curl);        cout << "curl [" << idx << "] completed with status: "                << code << endl;        cout << "rsp: " << RspArray[idx] << endl;        // clear handle //        curl_easy_cleanup(curl);    }    return 0;}#define USE_MULTI_CURLstruct timeval begin_tv, end_tv;int main(int argc, char * argv[]){    if (argc < 2)    {        return -1;    }    int num = atoi(argv[1]);    // 获取开始时间 //    gettimeofday(&begin_tv, NULL);#ifdef USE_MULTI_CURL    // 使用multi接口进行访问 //    curl_multi_demo(num);#else    // 使用easy接口进行访问 //    curl_easy_demo(num);#endif    // 获取结束时间  //    struct timeval end_tv;    gettimeofday(&end_tv, NULL);    // 计算执行延时并输出，用于比较  //    int eclapsed = (end_tv.tv_sec - begin_tv.tv_sec) * 1000 +                   (end_tv.tv_usec - begin_tv.tv_usec) / 1000;    cout << "eclapsed time:" << eclapsed << "ms" << endl;    return 0;}