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Re: #578: Header Table and Static Table Indices Switched

From: Greg Wilkins <gregw@intalio.com>
Date: Wed, 1 Oct 2014 01:39:45 +1000
Message-ID: <CAH_y2NEOk-20yeq_74bW=BESTP2o7b+wo7bTG65WeVrrjL9E9Q@mail.gmail.com>
To: Jeff Pinner <jpinner@twitter.com>
Cc: RUELLAN Herve <Herve.Ruellan@crf.canon.fr>, Willy Tarreau <w@1wt.eu>, Mark Nottingham <mnot@mnot.net>, HTTP Working Group <ietf-http-wg@w3.org>
On 1 October 2014 01:22, Jeff Pinner <jpinner@twitter.com> wrote:

> What are these other benefits? I certainly don't believe there are any
> -- having to know the size of the dynamic table to compute a static
> index offset?
>

At least one benefit is that you have the ability to pre compute values for
statics fields, or even series of static fields, so they do not need to be
calculated on every generation.
Now that we don't copy static entries to the dynamic field this generate
once use many times extends to fields using a static name and custom value.

Why was the change put in, without a discussion on the list, when it
> admittedly had a negative impact on compression in your testing?


There was definitely discussion on the list at the time.   It had also been
discussed previously and there were reasons not to make the change earlier,
but they evaporated with the removal of the reference set.

My tests (also published in the list) with test headers available (and used
for other decisions here) showed a small but positive change.

cheers




-- 
Greg Wilkins <gregw@intalio.com>
http://eclipse.org/jetty HTTP, SPDY, Websocket server and client that scales
http://www.webtide.com  advice and support for jetty and cometd.
Received on Tuesday, 30 September 2014 15:40:14 UTC

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