1---
2c: Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.
3SPDX-License-Identifier: curl
4Title: CURLOPT_STREAM_DEPENDS
5Section: 3
6Source: libcurl
7See-also:
8  - CURLMOPT_PIPELINING (3)
9  - CURLOPT_HTTP_VERSION (3)
10  - CURLOPT_STREAM_DEPENDS_E (3)
11  - CURLOPT_STREAM_WEIGHT (3)
12Protocol:
13  - HTTP
14---
15
16# NAME
17
18CURLOPT_STREAM_DEPENDS - stream this transfer depends on
19
20# SYNOPSIS
21
22~~~c
23#include <curl/curl.h>
24
25CURLcode curl_easy_setopt(CURL *handle, CURLOPT_STREAM_DEPENDS,
26                          CURL *dephandle);
27~~~
28
29# DESCRIPTION
30
31Pass a CURL pointer in *dephandle* to identify the stream within the same
32connection that this stream is depending upon. This option clears the
33exclusive bit and is mutually exclusive to the CURLOPT_STREAM_DEPENDS_E(3)
34option.
35
36The spec says "Including a dependency expresses a preference to allocate
37resources to the identified stream rather than to the dependent stream."
38
39This option can be set during transfer.
40
41*dephandle* must not be the same as *handle*, that makes this function return
42an error. It must be another easy handle, and it also needs to be a handle of
43a transfer that is about to be sent over the same HTTP/2 connection for this
44option to have an actual effect.
45
46# DEFAULT
47
48NULL
49
50# EXAMPLE
51
52~~~c
53int main(void)
54{
55  CURL *curl = curl_easy_init();
56  CURL *curl2 = curl_easy_init(); /* a second handle */
57  if(curl) {
58    curl_easy_setopt(curl, CURLOPT_URL, "https://example.com/one");
59
60    /* the second depends on the first */
61    curl_easy_setopt(curl2, CURLOPT_URL, "https://example.com/two");
62    curl_easy_setopt(curl2, CURLOPT_STREAM_DEPENDS, curl);
63
64    /* then add both to a multi handle and transfer them! */
65  }
66}
67~~~
68
69# AVAILABILITY
70
71Added in 7.46.0
72
73# RETURN VALUE
74
75Returns CURLE_OK if the option is supported, and CURLE_UNKNOWN_OPTION if not.
76