curl / libcurl / API / curl_easy_setopt / CURLOPT_STREAM_DEPENDS

CURLOPT_STREAM_DEPENDS explained

Name

CURLOPT_STREAM_DEPENDS - stream this transfer depends on

Synopsis

#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 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.

Default

NULL

Protocols

This functionality affects http only

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, curl);
 
    /* then add both to a multi handle and transfer them */
  }
}

Availability

Added in curl 7.46.0

Return value

curl_easy_setopt returns a CURLcode indicating success or error.

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