From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on dcvr.yhbt.net X-Spam-Level: X-Spam-ASN: AS31976 209.132.180.0/23 X-Spam-Status: No, score=-4.0 required=3.0 tests=AWL,BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI shortcircuit=no autolearn=ham autolearn_force=no version=3.4.2 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by dcvr.yhbt.net (Postfix) with ESMTP id F29D11F461 for ; Thu, 16 May 2019 04:14:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725999AbfEPEOr (ORCPT ); Thu, 16 May 2019 00:14:47 -0400 Received: from cloud.peff.net ([104.130.231.41]:58988 "HELO cloud.peff.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1725818AbfEPEOq (ORCPT ); Thu, 16 May 2019 00:14:46 -0400 Received: (qmail 4903 invoked by uid 109); 16 May 2019 04:14:48 -0000 Received: from Unknown (HELO peff.net) (10.0.1.2) by cloud.peff.net (qpsmtpd/0.94) with SMTP; Thu, 16 May 2019 04:14:48 +0000 Authentication-Results: cloud.peff.net; auth=none Received: (qmail 27136 invoked by uid 111); 16 May 2019 04:15:25 -0000 Received: from sigill.intra.peff.net (HELO sigill.intra.peff.net) (10.0.0.7) by peff.net (qpsmtpd/0.94) with (ECDHE-RSA-AES256-GCM-SHA384 encrypted) SMTP; Thu, 16 May 2019 00:15:25 -0400 Authentication-Results: peff.net; auth=none Received: by sigill.intra.peff.net (sSMTP sendmail emulation); Thu, 16 May 2019 00:14:44 -0400 Date: Thu, 16 May 2019 00:14:44 -0400 From: Jeff King To: =?utf-8?B?w4Z2YXIgQXJuZmrDtnLDsA==?= Bjarmason Cc: "Eric S. Raymond" , git@vger.kernel.org Subject: Re: Finer timestamps and serialization in git Message-ID: <20190516041444.GG4596@sigill.intra.peff.net> References: <20190515191605.21D394703049@snark.thyrsus.com> <871s0zwjv0.fsf@evledraar.gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <871s0zwjv0.fsf@evledraar.gmail.com> Sender: git-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org On Wed, May 15, 2019 at 10:20:03PM +0200, Ævar Arnfjörð Bjarmason wrote: > > Since this is going to have to happen anyway > > The SHA-1 <-> SHA-256 transition is planned to happen, but there's some > strong opinions that this should be *only* for munging the content for > hashing, not adding new stuff while we're at it (even if optional). See > : https://public-inbox.org/git/87ftyyedqd.fsf@evledraar.gmail.com/ One reason for this is that the transition plan calls for being able to convert between the sha1 and sha256 representations losslessly (which makes interoperability possible and avoids a flag day). So even if the sha256 format understood floating-point timestamps in the committer header, we'd have to have some way of representing that same information in the sha1 format. Which implies putting it into a new header, as you described below. And if it's in a new header in sha1, then is there any real advantage in having it somewhere else in the sha256 version? I dunno. Maybe a little, as eventually all of the sha1 formats would die off, after everybody has transitioned. -Peff