curl/docs/libcurl/opts/CURLOPT_STREAM_DEPENDS.md
Stefan Eissing bfbff7852f
http2: remove stream dependency tracking
The HTTP/2 feature is deprecated, few servers implement it and our
implementation is complicated by its state management. Make the two
CURLOPT_* involved a nop and deprecate them.

Closes #21723
2026-05-22 09:44:08 +02:00

87 lines
2.1 KiB
Markdown

---
c: Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.
SPDX-License-Identifier: curl
Title: CURLOPT_STREAM_DEPENDS
Section: 3
Source: libcurl
See-also:
- CURLMOPT_PIPELINING (3)
- CURLOPT_HTTP_VERSION (3)
- CURLOPT_STREAM_DEPENDS_E (3)
- CURLOPT_STREAM_WEIGHT (3)
Protocol:
- HTTP
Added-in: 7.46.0
---
# NAME
CURLOPT_STREAM_DEPENDS - stream this transfer depends on
# SYNOPSIS
~~~c
#include <curl/curl.h>
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_STREAM_DEPENDS,
CURL *dephandle);
~~~
# DESCRIPTION
Pass a CURL pointer in *dephandle* to identify the stream within the same
connection that this stream is depending upon. This option clears the
exclusive bit and is mutually exclusive to the CURLOPT_STREAM_DEPENDS_E(3)
option.
The spec says "Including a dependency expresses a preference to allocate
resources to the identified stream rather than to the dependent stream."
This option can be set during transfer.
*dephandle* must not be the same as *handle*, that makes this function return
an error. It must be another easy handle, and it also needs to be a handle of
a transfer that is about to be sent over the same HTTP/2 connection for this
option to have an actual effect.
Since version 8.21.0 setting this option no longer has an effect. HTTP/2
stream dependencies were introduced in RFC 7540 and then later deprecated
in RFC 9113.
# DEFAULT
NULL
# %PROTOCOLS%
# EXAMPLE
~~~c
int main(void)
{
CURL *curl = curl_easy_init();
CURL *curl2 = curl_easy_init(); /* a second handle */
if(curl) {
curl_easy_setopt(curl, CURLOPT_URL, "https://example.com/one");
/* the second depends on the first */
curl_easy_setopt(curl2, CURLOPT_URL, "https://example.com/two");
curl_easy_setopt(curl2, CURLOPT_STREAM_DEPENDS, curl);
/* then add both to a multi handle and transfer them */
}
}
~~~
# DEPRECATED
Deprecated since 8.21.0.
# %AVAILABILITY%
# RETURN VALUE
curl_easy_setopt(3) returns a CURLcode indicating success or error.
CURLE_OK (0) means everything was OK, non-zero means an error occurred, see
libcurl-errors(3).