curl/docs/libcurl/opts/CURLOPT_STREAM_DEPENDS_E.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

2.2 KiB

c SPDX-License-Identifier Title Section Source See-also Protocol Added-in
Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al. curl CURLOPT_STREAM_DEPENDS_E 3 libcurl
CURLMOPT_PIPELINING (3)
CURLOPT_HTTP_VERSION (3)
CURLOPT_STREAM_DEPENDS (3)
CURLOPT_STREAM_WEIGHT (3)
HTTP
7.46.0

NAME

CURLOPT_STREAM_DEPENDS_E - stream this transfer depends on exclusively

SYNOPSIS

#include <curl/curl.h>

CURLcode curl_easy_setopt(CURL *handle, CURLOPT_STREAM_DEPENDS_E,
                          CURL *dephandle);

DESCRIPTION

Pass a CURL pointer in dephandle to identify the stream within the same connection that this stream is depending upon exclusively. That means it depends on it and sets the Exclusive bit.

The spec says "Including a dependency expresses a preference to allocate resources to the identified stream rather than to the dependent stream."

Setting a dependency with the exclusive flag for a reprioritized stream causes all the dependencies of the new parent stream to become dependent on the reprioritized 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

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_E, 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).