Re: HTTP/2 Header Encoding Status Update

James Cloos <cloos@jhcloos.com> Thu, 28 February 2013 01:40 UTC

Return-Path: <ietf-http-wg-request@listhub.w3.org>
X-Original-To: ietfarch-httpbisa-archive-bis2Juki@ietfa.amsl.com
Delivered-To: ietfarch-httpbisa-archive-bis2Juki@ietfa.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id 82A0821F84C9 for <ietfarch-httpbisa-archive-bis2Juki@ietfa.amsl.com>; Wed, 27 Feb 2013 17:40:09 -0800 (PST)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -7.501
X-Spam-Level:
X-Spam-Status: No, score=-7.501 tagged_above=-999 required=5 tests=[AWL=3.098, BAYES_00=-2.599, RCVD_IN_DNSWL_HI=-8]
Received: from mail.ietf.org ([64.170.98.30]) by localhost (ietfa.amsl.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id yweIFzVth-Ha for <ietfarch-httpbisa-archive-bis2Juki@ietfa.amsl.com>; Wed, 27 Feb 2013 17:40:08 -0800 (PST)
Received: from frink.w3.org (frink.w3.org [128.30.52.56]) by ietfa.amsl.com (Postfix) with ESMTP id 6F42821F8499 for <httpbisa-archive-bis2Juki@lists.ietf.org>; Wed, 27 Feb 2013 17:40:01 -0800 (PST)
Received: from lists by frink.w3.org with local (Exim 4.72) (envelope-from <ietf-http-wg-request@listhub.w3.org>) id 1UAsSI-0007ZG-FV for ietf-http-wg-dist@listhub.w3.org; Thu, 28 Feb 2013 01:38:42 +0000
Resent-Date: Thu, 28 Feb 2013 01:38:42 +0000
Resent-Message-Id: <E1UAsSI-0007ZG-FV@frink.w3.org>
Received: from lisa.w3.org ([128.30.52.41]) by frink.w3.org with esmtp (Exim 4.72) (envelope-from <cloos@jhcloos.com>) id 1UAsS9-0007XR-21 for ietf-http-wg@listhub.w3.org; Thu, 28 Feb 2013 01:38:33 +0000
Received: from eagle.jhcloos.com ([207.210.242.212]) by lisa.w3.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.72) (envelope-from <cloos@jhcloos.com>) id 1UAsS8-0000fb-Aw for ietf-http-wg@w3.org; Thu, 28 Feb 2013 01:38:33 +0000
Received: by eagle.jhcloos.com (Postfix, from userid 10) id 4773D400FF; Thu, 28 Feb 2013 01:37:46 +0000 (UTC)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=jhcloos.com; s=eagle; t=1362015490; bh=ZQAtTCfl0n+UpDAJKe5pFQVMShP169F2zPubFjk2cdQ=; h=From:To:Cc:Subject:In-Reply-To:References:Date:Message-ID: MIME-Version:Content-Type; b=XzDnuRaOeB7b9VEMDC+nVKxCDGR/GKVenpv3l6dcGeEzbm91fDdpQ6jraJybbKuFu pIDpmDi8sO+arE3MkwNfyQpL7TXq3jX0U0GTAzlsT3ZrKwQgtOnP0QC48IGmCABB/W 6FKaILgf0Z3cEjLh1bH657yEHXDy+IClCj990Cnc=
Received: by carbon.jhcloos.org (Postfix, from userid 500) id 0866B6001F; Thu, 28 Feb 2013 01:24:42 +0000 (UTC)
From: James Cloos <cloos@jhcloos.com>
To: ietf-http-wg <ietf-http-wg@w3.org>
Cc: James M Snell <jasnell@gmail.com>, Mark Nottingham <mnot@mnot.net>
In-Reply-To: <CABP7Rbcm9Nt+sFvrk9XzOnPO+_sbkU=yWgERp-y2A48JN=g8xQ@mail.gmail.com> (James M. Snell's message of "Wed, 27 Feb 2013 15:12:25 -0800")
References: <CABP7RbfK9jT=-wXqv8wo6fJr8Wg0g9SYTZ3FeXHC=4yhihdsug@mail.gmail.com> <4D326297-42A8-487E-9450-7A971754C901@mnot.net> <CABP7Rbcm9Nt+sFvrk9XzOnPO+_sbkU=yWgERp-y2A48JN=g8xQ@mail.gmail.com>
User-Agent: Gnus/5.130006 (Ma Gnus v0.6) Emacs/24.3.50 (gnu/linux)
Face: iVBORw0KGgoAAAANSUhEUgAAABAAAAAQAgMAAABinRfyAAAACVBMVEX///8ZGXBQKKnCrDQ3 AAAAJElEQVQImWNgQAAXzwQg4SKASgAlXIEEiwsSIYBEcLaAtMEAADJnB+kKcKioAAAAAElFTkSu QmCC
Copyright: Copyright 2013 James Cloos
OpenPGP: ED7DAEA6; url=http://jhcloos.com/public_key/0xED7DAEA6.asc
OpenPGP-Fingerprint: E9E9 F828 61A4 6EA9 0F2B 63E7 997A 9F17 ED7D AEA6
Date: Wed, 27 Feb 2013 20:24:42 -0500
Message-ID: <m3fw0h9qmk.fsf@carbon.jhcloos.org>
Lines: 29
MIME-Version: 1.0
Content-Type: text/plain
X-Hashcash: 1:30:130228:ietf-http-wg@w3.org::4bG9nWgoEvOIe0jM:00000000000000000000000000000000000000000IW2QY
X-Hashcash: 1:30:130228:jasnell@gmail.com::HSUBx8shf3WnhYQw:0000000000000000000000000000000000000000000Gud6K
X-Hashcash: 1:30:130228:mnot@mnot.net::q/2v6gcf4A3TpUVk:000BYke6
Received-SPF: pass client-ip=207.210.242.212; envelope-from=cloos@jhcloos.com; helo=eagle.jhcloos.com
X-W3C-Hub-Spam-Status: No, score=-3.9
X-W3C-Hub-Spam-Report: AWL=-3.098, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, RP_MATCHES_RCVD=-0.703, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001
X-W3C-Scan-Sig: lisa.w3.org 1UAsS8-0000fb-Aw 7828aae2f19bf35eb659fc76b441dde1
X-Original-To: ietf-http-wg@w3.org
Subject: Re: HTTP/2 Header Encoding Status Update
Archived-At: <http://www.w3.org/mid/m3fw0h9qmk.fsf@carbon.jhcloos.org>
Resent-From: ietf-http-wg@w3.org
X-Mailing-List: <ietf-http-wg@w3.org> archive/latest/16919
X-Loop: ietf-http-wg@w3.org
Resent-Sender: ietf-http-wg-request@w3.org
Precedence: list
List-Id: <ietf-http-wg.w3.org>
List-Help: <http://www.w3.org/Mail/>
List-Post: <mailto:ietf-http-wg@w3.org>
List-Unsubscribe: <mailto:ietf-http-wg-request@w3.org?subject=unsubscribe>

>>>>> "JMS" == James M Snell <jasnell@gmail.com> writes:

JMS> Not much really... assuming we're representing the value as a 64-bit
JMS> long, the maximum number of uvarint bytes we can ever encode for each
JMS> date is 10. Using the original epoch, I think we use six bytes
JMS> currently. The new epoch uses five. As it is, the use of the uvarint
JMS> gives us plenty of room to grow with or without the new epoch so I'd
JMS> be perfectly fine without that detail.

A quick test reminds one that the tick before 1990/01/01 00:00:00 UTC was
1989/12/31 23:59:60 UTC, a leap second.  So the reference will differ
depending on right vs posix localtime rules and be extra ambiguous because
it is just after a leap second.

  :; TZ=posix/UTC perl -e 'print localtime(631152000)."\n"'
  Mon Jan  1 00:00:00 1990

  :; TZ=right/UTC perl -e 'print localtime(631152015)."\n"'
  Mon Jan  1 00:00:00 1990

It probably would be better to define a specific offset from time_t 0 or
a specific offset from the GPS epoch.  Or even better define time zero
to be a specific 128-bit ntp time.

But it would be easier to use either time_t or an ntp timestamp directly.

-JimC
-- 
James Cloos <cloos@jhcloos.com>         OpenPGP: 1024D/ED7DAEA6