CURLMOPT_TIMERFUNCTION(3)  curl_multi_setopt options CURLMOPT_TIMERFUNCTION(3)

NAME
       CURLMOPT_TIMERFUNCTION - set callback to receive timeout values

SYNOPSIS
       #include <curl/curl.h>

       int timer_callback(CURLM *multi,    /* multi handle */
                          long timeout_ms, /* see above */
                          void *userp);    /* private callback pointer */

       CURLMcode curl_multi_setopt(CURLM *handle, CURLMOPT_TIMERFUNCTION, timer_callback);

DESCRIPTION
       Pass a pointer to your callback function, which should match the proto-
       type shown above.

       Certain features, such as timeouts and retries,  require  you  to  call
       libcurl even when there is no activity on the file descriptors.

       Your  callback  function  timer_callback should install a non-repeating
       timer with an interval of timeout_ms. Each time that timer fires,  call
       either  curl_multi_socket_action(3) or curl_multi_perform(3), depending
       on which interface you use.

       A timeout_ms value of -1 means you should delete your timer.

       A    timeout_ms    value    of    0    means    you     should     call
       curl_multi_socket_action(3)  or curl_multi_perform(3) (once) as soon as
       possible.

       timer_callback will only be called when the timeout_ms changes.

       The userp pointer is set with CURLMOPT_TIMERDATA(3).

       The timer callback should return 0 on success, and -1  on  error.  This
       callback  can  be  used instead of, or in addition to, curl_multi_time-
       out(3).

DEFAULT
       NULL

PROTOCOLS
       All

EXAMPLE
       static gboolean timeout_cb(gpointer user_data) {
           if (user_data) {
               g_free(user_data);
               curl_multi_setopt(curl_handle, CURLMOPT_TIMERDATA, NULL);
           }
           int running;
           curl_multi_socket_action(multi, CURL_SOCKET_TIMEOUT, 0, &running);
           return G_SOURCE_REMOVE;
       }

       static int timerfunc(CURLM *multi, long timeout_ms, void *userp) {
           guint *id = userp;

           if (id)
               g_source_remove(*id);

           // -1 means we should just delete our timer.
           if (timeout_ms == -1) {
               g_free(id);
               id = NULL;
           } else {
               if (!id)
                   id = g_new(guint, 1);
               *id = g_timeout_add(timeout_ms, timeout_cb, id);
           }
           curl_multi_setopt(multi, CURLMOPT_TIMERDATA, id);
           return 0;
       }

       curl_multi_setopt(multi, CURLMOPT_TIMERFUNCTION, timerfunc);

AVAILABILITY
       Added in 7.16.0

RETURN VALUE
       Returns CURLM_OK if the option is supported,  and  CURLM_UNKNOWN_OPTION
       if not.

SEE ALSO
       CURLMOPT_TIMERDATA(3), CURLMOPT_SOCKETFUNCTION(3),

libcurl 7.54.0                 February 03, 2016     CURLMOPT_TIMERFUNCTION(3)