curl/docs/libcurl/opts/CURLOPT_STREAM_WEIGHT.3

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.TH CURLOPT_STREAM_WEIGHT 3 "13 Sep 2015" "libcurl 7.46.0" "curl_easy_setopt options"
.SH NAME
CURLOPT_STREAM_WEIGHT \- numerical stream weight
.SH SYNOPSIS
.nf
#include <curl/curl.h>

CURLcode curl_easy_setopt(CURL *handle, CURLOPT_STREAM_WEIGHT, long weight);
.fi
.SH DESCRIPTION
Set the long \fIweight\fP 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 \fIhandle\fP. 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 \fICURLMOPT_PIPELINING(3)\fP.

This option can be set during transfer and will then cause 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:
https://httpwg.github.io/specs/rfc7540.html#StreamPriority

Streams with the same parent should be allocated resources proportionally
based on their weight. So if you have two streams going, stream A with weight
16 and stream B with weight 32, stream B will get two thirds (32/48) of the
available bandwidth (assuming the server can send off the data equally for
both streams).
.SH DEFAULT
If nothing is set, the HTTP/2 protocol itself will use its own default which
is 16.
.SH PROTOCOLS
HTTP/2
.SH EXAMPLE
.nf
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! */
}
.fi
.SH AVAILABILITY
Added in 7.46.0
.SH RETURN VALUE
Returns CURLE_OK if the option is supported, and CURLE_UNKNOWN_OPTION if not.
.SH "SEE ALSO"
.BR CURLOPT_STREAM_DEPENDS "(3), " CURLOPT_STREAM_DEPENDS_E "(3), "
.BR CURLOPT_PIPEWAIT "(3), " CURLMOPT_PIPELINING "(3), "