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1---
2c: Copyright (C) Daniel Stenberg, <daniel.se>, et al.
3SPDX-License-Identifier: curl
4Title: curl_multi_timeout
5Section: 3
6Source: libcurl
7See-also:
8  - curl_multi_fdset (3)
9  - curl_multi_info_read (3)
10  - curl_multi_setopt (3)
11  - curl_multi_socket (3)
12---
13
14# NAME
15
16curl_multi_timeout - how long to wait for action before proceeding
17
18# SYNOPSIS
19
20~~~c
21#include <curl/curl.h>
22
23CURLMcode curl_multi_timeout(CURLM *multi_handle, long *timeout);
24~~~
25
26# DESCRIPTION
27
28An application using the libcurl multi interface should call
29curl_multi_timeout(3) to figure out how long it should wait for socket
30actions - at most - before proceeding.
31
32Proceeding means either doing the socket-style timeout action: call the
33curl_multi_socket_action(3) function with the **sockfd** argument set
34to CURL_SOCKET_TIMEOUT, or call curl_multi_perform(3) if you are using
35the simpler and older multi interface approach.
36
37The timeout value returned in the long **timeout** points to, is in number
38of milliseconds at this moment. If 0, it means you should proceed immediately
39without waiting for anything. If it returns -1, there is no timeout at all set.
40
41An application that uses the *multi_socket* API should not use this function.
42It should instead use the CURLMOPT_TIMERFUNCTION(3) option for proper and
43desired behavior.
44
45Note: if libcurl returns a -1 timeout here, it just means that libcurl
46currently has no stored timeout value. You must not wait too long (more than a
47few seconds perhaps) before you call curl_multi_perform(3) again.
48
49# EXAMPLE
50
51~~~c
52int main(void)
53{
54  struct timeval timeout;
55  long timeo;
56  fd_set fdread;
57  fd_set fdwrite;
58  fd_set fdexcep;
59  int maxfd;
60  CURLM *multi = curl_multi_init();
61
62  curl_multi_timeout(multi, &timeo);
63  if(timeo < 0)
64    /* no set timeout, use a default */
65    timeo = 980;
66
67  timeout.tv_sec = timeo / 1000;
68  timeout.tv_usec = (timeo % 1000) * 1000;
69
70  /* wait for activities no longer than the set timeout */
71  select(maxfd + 1, &fdread, &fdwrite, &fdexcep, &timeout);
72}
73~~~
74
75# TYPICAL USAGE
76
77Call curl_multi_timeout(3), then wait for action on the sockets. Figure
78out which sockets to wait for by calling curl_multi_fdset(3).
79
80When there is activity or timeout, call curl_multi_perform(3) and then
81loop - until all transfers are complete.
82
83# AVAILABILITY
84
85This function was added in libcurl 7.15.4.
86
87# RETURN VALUE
88
89The standard CURLMcode for multi interface error codes.
90