NAME

       curl_multi_wait - poll on all easy handles in a multi handle

SYNOPSIS

       #include <curl/curl.h>

       CURLMcode curl_multi_wait(CURLM *multi_handle,
                                 struct curl_waitfd extra_fds[],
                                 unsigned int extra_nfds,
                                 int timeout_ms,
                                 int *numfds);

DESCRIPTION

       curl_multi_wait(3)  polls  all file descriptors used by the curl easy handles contained in
       the given multi handle set. It blocks until activity is detected on at least  one  of  the
       handles  or  timeout_ms  has  passed.   Alternatively,  if  the multi handle has a pending
       internal timeout that has a shorter expiry time than  timeout_ms,  that  shorter  time  is
       being used instead to make sure timeout accuracy is reasonably kept.

       The  calling  application  may pass additional curl_waitfd structures which are similar to
       poll(2)'s pollfd structure to be waited on in the same call.

       On completion, if numfds is non-NULL, it gets populated with  the  total  number  of  file
       descriptors  on  which  interesting  events occurred. This number can include both libcurl
       internal descriptors as well as descriptors provided in extra_fds.

       If no extra file descriptors are provided and libcurl has no file descriptor to  offer  to
       wait  for,  this function returns immediately. (Consider using curl_multi_poll(3) to avoid
       this behavior.)

       This function is encouraged to be used instead of select(3) when using the multi interface
       to  allow  applications  to  easier  circumvent  the common problem with 1024 maximum file
       descriptors.

curl_waitfd

       struct curl_waitfd {
         curl_socket_t fd;
         short events;
         short revents;
       };

       CURL_WAIT_POLLIN
              Bit flag to curl_waitfd.events indicating the socket should  poll  on  read  events
              such as new data received.

       CURL_WAIT_POLLPRI
              Bit  flag  to curl_waitfd.events indicating the socket should poll on high priority
              read events such as out of band data.

       CURL_WAIT_POLLOUT
              Bit flag to curl_waitfd.events indicating the socket should poll  on  write  events
              such as the socket being clear to write without blocking.

PROTOCOLS

       This functionality affects all supported protocols

EXAMPLE

       int main(void)
       {
         CURL *easy;
         CURLM *multi = curl_multi_init();
         int still_running;

         /* add the individual easy handle */
         curl_multi_add_handle(multi, easy);

         do {
           CURLMcode mc;
           int numfds;

           mc = curl_multi_perform(multi, &still_running);

           if(mc == CURLM_OK) {
             /* wait for activity, timeout or "nothing" */
             mc = curl_multi_wait(multi, NULL, 0, 1000, &numfds);
           }

           if(mc != CURLM_OK) {
             fprintf(stderr, "curl_multi failed, code %d.\n", mc);
             break;
           }

         } while(still_running);

         curl_multi_remove_handle(multi, easy);
       }

AVAILABILITY

       Added in curl 7.28.0

RETURN VALUE

       CURLMcode type, general libcurl multi interface error code. See libcurl-errors(3)

SEE ALSO

       curl_multi_fdset(3), curl_multi_perform(3), curl_multi_poll(3)