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---
c: Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.
SPDX-License-Identifier: curl
Title: curl_multi_timeout
Section: 3
Source: libcurl
See-also:
- curl_multi_fdset (3)
- curl_multi_info_read (3)
- curl_multi_setopt (3)
- curl_multi_socket (3)
Protocol:
- All
Added-in: 7.15.4
---
# NAME
curl_multi_timeout - how long to wait for action before proceeding
# SYNOPSIS
~~~c
#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%
# EXAMPLE
~~~c
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%
# 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).
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