NAME

       CURLMOPT_TIMERFUNCTION - callback to receive timeout values

SYNOPSIS

       #include <curl/curl.h>

       int timer_callback(CURLM *multi,    /* multi handle */
                          long timeout_ms, /* timeout in number of ms */
                          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 prototype 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  expire
       time    of    timeout_ms    milliseconds.    When    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 passed to this callback means you should delete the timer. All
       other values are valid expire times in number of milliseconds.

       The timer_callback will only be called when the timeout expire time is changed.

       The userp pointer is set with CURLMOPT_TIMERDATA(3).

       The timer callback should return 0 on success, and -1 on error. If this  callback  returns
       error, all transfers currently in progress in this multi handle will be aborted and fail.

       This callback can be used instead of, or in addition to, curl_multi_timeout(3).

       WARNING:  even  if  it  feels  tempting,  avoid  calling  libcurl directly from within the
       callback itself when the timeout_ms value is zero, since it risks triggering an unpleasant
       recursive  behavior  that  immediately  calls  another  call  to  the callback with a zero
       timeout...

DEFAULT

       NULL

PROTOCOLS

       All

EXAMPLE

       static gboolean timeout_cb(gpointer user_data)
       {
         int running;
         if(user_data) {
           g_free(user_data);
           curl_multi_setopt(curl_handle, CURLMOPT_TIMERDATA, NULL);
         }
         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),