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Re: Proposal: drop QPACK encoder stream framing

Dmitri Tikhonov <dtikhonov@litespeedtech.com> Tue, 07 August 2018 00:20 UTC

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Date: Mon, 6 Aug 2018 20:20:05 -0400
From: Dmitri Tikhonov <dtikhonov@litespeedtech.com>
To: Alan Frindell <afrind@fb.com>, Kazuho Oku <kazuhooku@gmail.com>, Martin Thomson <martin.thomson@gmail.com>, QUIC WG <quic@ietf.org>
Subject: Re: Proposal: drop QPACK encoder stream framing
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Mail-Followup-To: Alan Frindell <afrind@fb.com>, Kazuho Oku <kazuhooku@gmail.com>, Martin Thomson <martin.thomson@gmail.com>, QUIC WG <quic@ietf.org>
References: <20180607151112.GA28823@ubuntu-dmitri> <CABkgnnXbfkVbq6vCvud100h6wr3+9ir3iO7dD6-qaykOmK3JBQ@mail.gmail.com> <CANatvzzzXF8WCXgDCahTa_7JWZ1c1i-9rU_c8c9QWk5_O5u4Ow@mail.gmail.com> <F04D1BA6-8EC6-43EB-ABEC-34C4B30352AB@fb.com> <20180609155530.GA6795@ubuntu-dmitri>
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On Sat, Jun 09, 2018 at 11:55:30AM -0400, Dmitri Tikhonov wrote:
> And I hope I have demonstrated that the complexity increase is
> minimal.  Soon, I will demonstrate the same using C code.

Here is working code.  The function lsqpack_enc_dec_in() ingests
the next chunk of the encoder stream -- any number of bytes.  It
never buffers any of the bytes it reads; nor does it reparse.

https://github.com/litespeedtech/ls-qpack/blob/e5fd044d52c3a9c6b0891993e3f7ec9f3f7274cb/src/lsqpack.c#L3174

The increase in complexity -- saving state -- is offset handsomely
by not having to buffer anything inside or outside the QPACK library.
This makes the interface simple: have more encoder bytes? pass them
to the decoder.

  - Dmitri.

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