c ++如何使用Curl多接口连续循环

Question

im试图使用curl多接口连续循环。我有一个计时器功能，需要一次连续地循环遍历4个网址，然后转到下一个4个网址，依此类推。等等。我已经成功地使curl轮询了我的手柄的状态，但是当手柄达到0时，我尝试使用新网址将curl句柄重置为再次循环，但无法正常工作。我的计时器功能保持应有的工作，但是curl多次停止，并使用相同的4个URL给我相同的curl响应，即使我每次都尝试重置手柄也是如此。请对此提供任何帮助，并谢谢..以下是我的代码的摘要。.

 // Timer function that fires every 30 seconds with 4 different URL's each time 
void timerFunction (QString url1,QString url2,QString url3,QString url4)
 {

      CURLMsg *msg = NULL;
      std::string url1_ = url1.toStdString();
      std::string url2_ = url2.toStdString();
      std::string url3_ = url3.toStdString();
      std::string url4_ = url4.toStdString();
      CURLM *curlm;
      int handle_count;
      curlm = curl_multi_init();

      CURL *curl1 = NULL;
      curl1 = curl_easy_init();

      CURL *curl2 = NULL;
      curl2 = curl_easy_init();

      CURL *curl3 = NULL;
      curl3 = curl_easy_init();

      CURL *curl4 = NULL;
      curl4 = curl_easy_init();

     if(curl1 && curl2 && curl3 && curl4)
     {
         curl_easy_setopt(curl1, CURLOPT_URL, url1_.c_str());
         curl_easy_setopt(curl1, CURLOPT_WRITEFUNCTION, writeCallback);
         curl_multi_add_handle(curlm, curl1);

         curl_easy_setopt(curl2, CURLOPT_URL, url2_.c_str());
         curl_easy_setopt(curl2, CURLOPT_WRITEFUNCTION, writeCallback);
         curl_multi_add_handle(curlm, curl2);

         curl_easy_setopt(curl3, CURLOPT_URL, url3_.c_str());
         curl_easy_setopt(curl3, CURLOPT_WRITEFUNCTION, writeCallback);
         curl_multi_add_handle(curlm, curl3);

         curl_easy_setopt(curl4, CURLOPT_URL, url4_.c_str());
         curl_easy_setopt(curl4, CURLOPT_WRITEFUNCTION, writeCallback);
         curl_multi_add_handle(curlm, curl4);

         CURLMcode code;
         while(1)
         {
             code = curl_multi_perform(curlm, &handle_count);
             if(handle_count == 0)
             {
                        qDebug() << "Handle is 0, CURL Processing is done -- Repeat Process ";
                        break;
             }

          while ((msg = curl_multi_info_read(curlm, &handle_count)))
          {
              if (msg->msg == CURLMSG_DONE) 
               {
                        qDebug()  << msg->msg;
                        curl_easy_reset(curl1);
                        curl_easy_reset(curl2);
                        curl_easy_reset(curl3);
                        curl_easy_reset(curl4);
                        handle_count = 4;
                        code = curl_multi_perform(curlm, &handle_count);
               }
       }   


        }
   }

Answer 1

curl_easy_reset清楚说明：

重新初始化以前在指定的CURL句柄上设置的所有选项设为默认值。这会将手柄恢复为与它刚好是用curl_easy_init创建的。

它不会更改以下内容信息保留在句柄中：live连接，会话ID缓存，DNS缓存，Cookie和股票。

您需要做的是，一旦完成响应，就对循环中的每个句柄使用curl_multi_remove_handle，然后使用curl_easy_cleanup。

但是您还需要在循环后使用curl_multi_cleanup删除所有句柄。

您的代码将如下所示：

// Timer function that fires every 30 seconds with 4 different URL's each time 
void timerFunction (QString url1,QString url2,QString url3,QString url4)
{

  CURLMsg *msg = NULL;
  std::string url1_ = url1.toStdString();
  std::string url2_ = url2.toStdString();
  std::string url3_ = url3.toStdString();
  std::string url4_ = url4.toStdString();
  CURLM *curlm;
  CURL* eh = NULL;
  int still_running = 0, i = 0, msgs_left = 0;

  curlm = curl_multi_init();

  CURL *curl1 = NULL;
  curl1 = curl_easy_init();

  CURL *curl2 = NULL;
  curl2 = curl_easy_init();

  CURL *curl3 = NULL;
  curl3 = curl_easy_init();

  CURL *curl4 = NULL;
  curl4 = curl_easy_init();

 if(curl1 && curl2 && curl3 && curl4)
 {
     curl_easy_setopt(curl1, CURLOPT_URL, url1_.c_str());
     curl_easy_setopt(curl1, CURLOPT_WRITEFUNCTION, writeCallback);
     curl_multi_add_handle(curlm, curl1);

     curl_easy_setopt(curl2, CURLOPT_URL, url2_.c_str());
     curl_easy_setopt(curl2, CURLOPT_WRITEFUNCTION, writeCallback);
     curl_multi_add_handle(curlm, curl2);

     curl_easy_setopt(curl3, CURLOPT_URL, url3_.c_str());
     curl_easy_setopt(curl3, CURLOPT_WRITEFUNCTION, writeCallback);
     curl_multi_add_handle(curlm, curl3);

     curl_easy_setopt(curl4, CURLOPT_URL, url4_.c_str());
     curl_easy_setopt(curl4, CURLOPT_WRITEFUNCTION, writeCallback);
     curl_multi_add_handle(curlm, curl4);

     while(1)
     {      
        curl_multi_perform(curlm, &still_running);

        do {

            int numfds = 0;

            CURLMcode res = curl_multi_wait(curlm, NULL, 0, MAX_WAIT_MSECS, &numfds);

            if (res != CURLM_OK) {
                // handle error your way
            }

            curl_multi_perform(curlm, &still_running);

        } while (still_running);

        while ((msg = curl_multi_info_read(curlm, &msgs_left)))
        {
            if (msg->msg == CURLMSG_DONE) 
            {
                eh = msg->easy_handle;

                qDebug()  << msg->msg;

                curl_multi_remove_handle(curlm, eh);
                curl_easy_cleanup(eh);
            }
        }  

        curl_multi_cleanup(cm);     
    }
}

尚未测试您的代码，但我对其进行了修改，以便您了解应如何做。