curl/docs/libcurl/opts/CURLMOPT_PIPELINING.md
Daniel Stenberg e694c8284a
docs/libcurl/opts: clarify the return values
Expand a little.

- mention the type name of the return code
- avoid stating which exact return codes that might be returned, as that
  varies over time, builds and conditions
- avoid stating some always return OK
- refer to the manpage documenting all the return codes

Closes #15900
2025-01-02 17:13:33 +01:00

1.8 KiB

c SPDX-License-Identifier Title Section Source See-also Protocol Added-in
Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al. curl CURLMOPT_PIPELINING 3 libcurl
CURLMOPT_CHUNK_LENGTH_PENALTY_SIZE (3)
CURLMOPT_CONTENT_LENGTH_PENALTY_SIZE (3)
CURLMOPT_MAXCONNECTS (3)
CURLMOPT_MAX_HOST_CONNECTIONS (3)
CURLMOPT_MAX_PIPELINE_LENGTH (3)
CURLMOPT_PIPELINING_SITE_BL (3)
HTTP
7.16.0

NAME

CURLMOPT_PIPELINING - enable HTTP multiplexing

SYNOPSIS

#include <curl/curl.h>

CURLMcode curl_multi_setopt(CURLM *handle, CURLMOPT_PIPELINING, long bitmask);

DESCRIPTION

Pass in the correct value in the bitmask parameter to instruct libcurl to enable multiplexing for this multi handle.

With multiplexing enabled, libcurl attempts to do multiple transfers over the same connection when doing parallel transfers to the same hosts.

CURLPIPE_NOTHING (0)

Make no attempts at multiplexing.

CURLPIPE_HTTP1 (1)

This bit is deprecated and has no effect since version 7.62.0.

CURLPIPE_MULTIPLEX (2)

If this bit is set, libcurl tries to multiplex the new transfer over an existing connection if possible. This requires HTTP/2 or HTTP/3.

DEFAULT

CURLPIPE_MULTIPLEX

%PROTOCOLS%

EXAMPLE

int main(void)
{
  CURLM *m = curl_multi_init();
  /* try HTTP/2 multiplexing */
  curl_multi_setopt(m, CURLMOPT_PIPELINING, CURLPIPE_MULTIPLEX);
}

HISTORY

The multiplex support bit was added in 7.43.0. HTTP/1 Pipelining support was disabled in 7.62.0.

Since 7.62.0, CURLPIPE_MULTIPLEX is enabled by default.

Before that, default was CURLPIPE_NOTHING.

%AVAILABILITY%

RETURN VALUE

curl_multi_setopt(3) returns a CURLMcode indicating success or error.

CURLM_OK (0) means everything was OK, non-zero means an error occurred, see libcurl-errors(3).