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Re: Header Table and Static Table Indicies Switched

From: Jeff Pinner <jpinner@twitter.com>
Date: Wed, 6 Aug 2014 08:07:22 -0700
Message-ID: <CA+pLO_ghdPfDMPbrE9O2d7ohZXV2a-_Sbv-Zoen5Zx1f7FiKjQ@mail.gmail.com>
To: Greg Wilkins <gregw@intalio.com>
Cc: Ilari Liusvaara <ilari.liusvaara@elisanet.fi>, HTTP Working Group <ietf-http-wg@w3.org>
> There is also another good benefit for encoding with static indexes low.
> Because the index does not change for fields like Date and Server, you can
> every second pre-encode the bytes for fields like:
>
>   server: jetty-9.3.0
>   date: Wed, 06 Aug 2014 05:19:19 GMT
>
> With the static index's low, this pre-encoded value is the same for all
> connection, as it is not a function of the size of the dynamic table of each
> connection.   Thus the same pre-encoded value may be used 10s of thousands
> of times, rather than encoding these fields on each and every response for
> each and every connection.
>
> cheers

you still pre-encode the huffman strings

are you talking about pre-encoding the index for "date" to 33 instead
of 33 + headerTable.length() ?

if so, i'd argue that the pre-encoded huffman buys you way more than
the bit of arithmetic before you copy into the send buffer and doing
the addition is well worth the tradeoff
Received on Wednesday, 6 August 2014 15:07:50 UTC

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