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.TH CURLMOPT_TIMERFUNCTION 3 "17 Jun 2014" "libcurl 7.37.0" "curl_multi_setopt options"
.SH NAME
CURLMOPT_TIMERFUNCTION \- set callback to receive timeout values
.SH SYNOPSIS
.nf
#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);
.SH DESCRIPTION
Pass a pointer to your callback function, which should match the prototype
shown above.

This callback function will be called when the timeout value changes. The
\fBtimeout_ms\fP value is at what latest time the application should call one
of the \&"performing" functions of the multi interface
(\fIcurl_multi_socket_action(3)\fP and \fIcurl_multi_perform(3)\fP) - to allow
libcurl to keep timeouts and retries etc to work. A \fBtimeout_ms\fP value of
-1 means that there is no timeout at all, and 0 means that the timeout is
already expired. libcurl attempts to limit calling this only when the fixed
future timeout time actually changes.

The \fBuserp\fP pointer is set with \fICURLMOPT_TIMERDATA(3)\fP.

The timer callback should return 0 on success, and -1 on error. This callback
can be used instead of, or in addition to, \fIcurl_multi_timeout(3)\fP.
.SH DEFAULT
NULL
.SH PROTOCOLS
All
.SH EXAMPLE
TODO
.SH AVAILABILITY
Added in 7.16.0
.SH RETURN VALUE
Returns CURLM_OK if the option is supported, and CURLM_UNKNOWN_OPTION if not.
.SH "SEE ALSO"
.BR CURLMOPT_TIMERDATA "(3), " CURLMOPT_SOCKETFUNCTION "(3), "