From: "Eric S. Raymond" <esr@thyrsus.com>
To: Junio C Hamano <gitster@pobox.com>
Cc: Jeff King <peff@peff.net>, Shawn Pearce <spearce@spearce.org>,
Felipe Contreras <felipe.contreras@gmail.com>,
git <git@vger.kernel.org>
Subject: Re: Millisecond precision in timestamps?
Date: Wed, 28 Nov 2012 02:58:08 -0500 [thread overview]
Message-ID: <20121128075807.GA9912@thyrsus.com> (raw)
In-Reply-To: <7v7gp6i3rx.fsf@alter.siamese.dyndns.org>
Junio C Hamano <gitster@pobox.com>:
> Roundtrip conversions may benefit from sub-second timestamps, but
> personally I think negative timestamps are more interesting and of
> practical use.
You mean, as in times before the Unix epoch 1970-01-01T00:00:00Z?
Interesting. I hadn't thought of that. I've never seen a software
project under version control with bits that old, which is significant
because I've probably done more digging into ancient software than
anybody other than a specialist historian or two.
They would have to have been restrospective dates from the get-go.
SCCS wasn't built until 1972.
> And if we were to add "committer-timestamp" and friends to support
> negative timestamps anyway (because older tools will not support
> them), supporting sub-second part might be something we want to
> think about at the same time.
That seems eminently reasonable.
> We would however need to be extra careful. How should we express
> half-second past Tue Nov 27 23:24:16 2012 (US/Pacific)? Would we
> spell it 1354087456.5? 1354087456.500? Would we require decimal
> representation of floating point numbers to be normalized in some
> way (e.g. minimum number of digits without losing precision)? The
> same timestamp needs to be expressed the same way, or we will end up
> with different commit objects, which defeats the whole purpose of
> introducing subsecond timestamps to support round-trip conversions.
>
> If we were to use a separate "subsecond" fields, another thing we
> need to be careful about is the order of these extra fields, exactly
> for the same reason.
I think minimum number of digits without losing precision is about the
only alternative that is future-proof - I was going to suggest it for
that reason.
--
<a href="http://www.catb.org/~esr/">Eric S. Raymond</a>
next prev parent reply other threads:[~2012-11-28 7:58 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-11-27 20:48 Millisecond precision in timestamps? Eric S. Raymond
2012-11-27 21:41 ` Shawn Pearce
2012-11-27 22:06 ` Junio C Hamano
2012-11-27 23:04 ` Eric S. Raymond
2012-11-27 23:49 ` Shawn Pearce
2012-11-28 0:12 ` Eric S. Raymond
2012-11-28 0:22 ` David Lang
2012-11-28 0:26 ` Felipe Contreras
2012-11-28 1:07 ` Shawn Pearce
2012-11-28 1:17 ` Jeff King
2012-11-28 1:29 ` Jason Pyeron
2012-11-28 1:42 ` Felipe Contreras
2012-11-28 3:23 ` Eric S. Raymond
2012-11-28 3:30 ` Jeff King
2012-11-28 3:44 ` Felipe Contreras
2012-11-28 3:47 ` Eric S. Raymond
2012-11-28 4:07 ` Jeff King
2012-11-28 4:25 ` Eric S. Raymond
2012-11-28 7:29 ` Junio C Hamano
2012-11-28 7:58 ` Eric S. Raymond [this message]
2012-11-28 8:04 ` David Aguilar
2012-11-28 10:14 ` Andreas Ericsson
2012-12-05 23:37 ` Robin Rosenberg
2012-12-10 20:56 ` James Cloos
2012-11-28 8:19 ` Thomas Berg
2012-11-28 8:44 ` Felipe Contreras
2012-11-28 9:10 ` Thomas Berg
[not found] ` <E4C993F4-B7A4-4CB6-A9EA-BFE98BE3A381@gmail.com>
2012-11-29 6:16 ` Eric S. Raymond
2012-11-29 7:11 ` Junio C Hamano
2012-11-29 7:22 ` Felipe Contreras
2012-11-29 10:38 ` Eric S. Raymond
2012-11-29 16:42 ` Junio C Hamano
2012-11-29 19:02 ` Eric S. Raymond
2012-11-28 17:57 ` Junio C Hamano
2012-11-28 10:10 ` Andreas Ericsson
2012-11-29 19:14 ` Phil Hord
2012-11-29 20:01 ` Jeff King
2012-11-28 1:11 ` Eric S. Raymond
2012-11-28 1:36 ` Felipe Contreras
2012-11-28 2:01 ` Junio C Hamano
2012-11-27 21:44 ` Pyeron, Jason J CTR (US)
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