xref: /aosp_15_r20/external/curl/docs/libcurl/curl_multi_timeout.md (revision 6236dae45794135f37c4eb022389c904c8b0090d)

---
c: Copyright (C) Daniel Stenberg, <[email protected]>, 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;
  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

The standard CURLMcode for multi interface error codes.