tree b9d33d01fb32ca626c3be880943a880bdf2ead01
parent 2871e0cb64e47e47ba7466fad6e11562caf99563
author Kévin Dunglas <kevin@dunglas.fr> 1652481160 +0000
committer Damien Neil <dneil@google.com> 1652481837 +0000

http2: allow sending 1xx responses

Currently, it's not possible to send informational responses such as
103 Early Hints or 102 Processing.

This patch allows calling WriteHeader() multiple times in order
to send informational responses before the final one.

If the status code is in the 1xx range, the current content of the header map
is also sent. Its content is not removed after the call to WriteHeader()
because the headers must also be included in the final response.

The Chrome and Fastly teams are starting a large-scale experiment to measure
the real-life impact of the 103 status code.
Using Early Hints is proposed as a (partial) alternative to Server Push,
which are going to be removed from Chrome:
https://groups.google.com/a/chromium.org/g/blink-dev/c/K3rYLvmQUBY/m/21anpFhxAQAJ

Being able to send this status code from servers implemented using Go would
help to see if implementing it in browsers is worth it.

Fixes golang/go#26089.
Fixes golang/go#36734.
Updates golang/go#26088.

Change-Id: Iadb7be92844a3588ef4ce044f887ef5c1792f431
GitHub-Last-Rev: eee95b58b3b259781fc1052ed6143a0aa9284e04
GitHub-Pull-Request: golang/net#96
Reviewed-on: https://go-review.googlesource.com/c/net/+/291029
Run-TryBot: Damien Neil <dneil@google.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Reviewed-by: Damien Neil <dneil@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>