curl/docs/libcurl/curl_multi_timeout.md
Daniel Stenberg eefcc1bda4
docs: introduce "curldown" for libcurl man page format
curldown is this new file format for libcurl man pages. It is markdown
inspired with differences:

- Each file has a set of leading headers with meta-data
- Supports a small subset of markdown
- Uses .md file extensions for editors/IDE/GitHub to treat them nicely
- Generates man pages very similar to the previous ones
- Generates man pages that still convert nicely to HTML on the website
- Detects and highlights mentions of curl symbols automatically (when
  their man page section is specified)

tools:

- cd2nroff: converts from curldown to nroff man page
- nroff2cd: convert an (old) nroff man page to curldown
- cdall: convert many nroff pages to curldown versions
- cd2cd: verifies and updates a curldown to latest curldown

This setup generates .3 versions of all the curldown versions at build time.

CI:

Since the documentation is now technically markdown in the eyes of many
things, the CI runs many more tests and checks on this documentation,
including proselint, link checkers and tests that make sure we capitalize the
first letter after a period...

Closes #12730
2024-01-23 00:29:02 +01:00

90 lines
2.4 KiB
Markdown

---
c: Copyright (C) Daniel Stenberg, <daniel.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)
---
# 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.
# 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
This function was added in libcurl 7.15.4.
# RETURN VALUE
The standard CURLMcode for multi interface error codes.