curl / libcurl / API / curl_easy_setopt / CURLOPT_STREAM_DEPENDS_E

CURLOPT_STREAM_DEPENDS_E explained

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.

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

Availability

Added in curl 7.46.0

Return value

Returns CURLE_OK if the option is supported, and CURLE_UNKNOWN_OPTION if not.