curl/docs/libcurl/opts/CURLOPT_STREAM_WEIGHT.md
Daniel Stenberg e694c8284a
docs/libcurl/opts: clarify the return values
Expand a little.

- mention the type name of the return code
- avoid stating which exact return codes that might be returned, as that
  varies over time, builds and conditions
- avoid stating some always return OK
- refer to the manpage documenting all the return codes

Closes #15900
2025-01-02 17:13:33 +01:00

83 lines
2.0 KiB
Markdown

---
c: Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.
SPDX-License-Identifier: curl
Title: CURLOPT_STREAM_WEIGHT
Section: 3
Source: libcurl
See-also:
- CURLMOPT_PIPELINING (3)
- CURLOPT_PIPEWAIT (3)
- CURLOPT_STREAM_DEPENDS (3)
- CURLOPT_STREAM_DEPENDS_E (3)
Protocol:
- HTTP
Added-in: 7.46.0
---
# NAME
CURLOPT_STREAM_WEIGHT - numerical stream weight
# SYNOPSIS
~~~c
#include <curl/curl.h>
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_STREAM_WEIGHT, long weight);
~~~
# DESCRIPTION
Set the long *weight* to a number between 1 and 256.
When using HTTP/2, this option sets the individual weight for this particular
stream used by the easy *handle*. Setting and using weights only makes
sense and is only usable when doing multiple streams over the same
connections, which thus implies that you use CURLMOPT_PIPELINING(3).
This option can be set during transfer and causes the updated weight info get
sent to the server the next time an HTTP/2 frame is sent to the server.
See section 5.3 of RFC 7540 for protocol details.
Streams with the same parent should be allocated resources proportionally
based on their weight. If you have two streams going, stream A with weight 16
and stream B with weight 32, stream B gets two thirds (32/48) of the available
bandwidth (assuming the server can send off the data equally for both
streams).
# DEFAULT
16
# %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");
curl_easy_setopt(curl, CURLOPT_STREAM_WEIGHT, 10L);
/* the second has twice the weight */
curl_easy_setopt(curl2, CURLOPT_URL, "https://example.com/two");
curl_easy_setopt(curl2, CURLOPT_STREAM_WEIGHT, 20L);
/* then add both to a multi handle and transfer them */
}
}
~~~
# %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).