curl_multi_timeout(3)

NAME
curl_multi_timeout - how long to wait for action before proceeding

SYNOPSIS
#include <curl/curl.h>

CURLMcode curl_multi_timeout(CURLM *multi_handle, long *timeout);

DESCRIPTION
An application using the libcurl multi interface should call curl_multi_timeout(3) to figure out how long it should wait for socket actions - at most - before proceeding.

Proceeding means either doing the socket-style timeout action: call the curl_multi_socket_action(3) function with the sockfd argument set to CURL_SOCKET_TIMEOUT, or call curl_multi_perform(3) if you are using the simpler and older multi interface approach.

The timeout value returned in the long timeout points to, is in number of milliseconds at this moment. If 0, it means you should proceed immediately without waiting for anything. If it returns -1, there is no timeout at all set.

An application that uses the multi_socket API should not use this function. It should instead use the CURLMOPT_TIMERFUNCTION(3) option for proper and desired behavior.

Note: if libcurl returns a -1 timeout here, it just means that libcurl currently has no stored timeout value. You must not wait too long (more than a few seconds perhaps) before you call curl_multi_perform(3) again.

PROTOCOLS
This functionality affects all supported protocols

EXAMPLE
int main(void)
{
  struct timeval timeout;
  long timeo;
  fd_set fdread;
  fd_set fdwrite;
  fd_set fdexcep;
  int maxfd = 2;
  CURLM *multi = curl_multi_init();

  curl_multi_timeout(multi, &timeo);
  if(timeo < 0)
    /* no set timeout, use a default */
    timeo = 980;

  timeout.tv_sec = timeo / 1000;
  timeout.tv_usec = (timeo % 1000) * 1000;

  /* wait for activities no longer than the set timeout */
  select(maxfd + 1, &fdread, &fdwrite, &fdexcep, &timeout);
}

TYPICAL USAGE
Call curl_multi_timeout(3), then wait for action on the sockets. Figure out which sockets to wait for by calling curl_multi_fdset(3).

When there is activity or timeout, call curl_multi_perform(3) and then loop - until all transfers are complete.

AVAILABILITY
Added in curl 7.15.4

RETURN VALUE
This function returns a CURLMcode indicating success or error.

CURLM_OK (0) means everything was OK, non-zero means an error occurred, see libcurl-errors(3).

SEE ALSO
curl_multi_fdset(3), curl_multi_info_read(3), curl_multi_setopt(3), curl_multi_socket(3)