CURLMOPT_TIMERFUNCTION(3) curl_multi_setopt options CURLMOPT_TIMERFUNCTION(3)
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 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 expire time of timeout_ms milliseconds. When that timer
fires, call either curl_multi_socket_action(3) or curl_multi_per-
form(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),
libcurl 7.81.0 December 02, 2021 CURLMOPT_TIMERFUNCTION(3)
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