From: Paul Eggert <eggert@cs.ucla.edu>
To: Eli Zaretskii <eliz@gnu.org>
Cc: manikulin@gmail.com, emacs-devel@gnu.org
Subject: Time resolution in Emacs
Date: Mon, 25 Apr 2022 08:34:04 -0700 [thread overview]
Message-ID: <3008dea1-572b-9010-f3c4-15272145fd8a@cs.ucla.edu> (raw)
In-Reply-To: <83bkwspa1r.fsf@gnu.org>
On 4/22/22 23:51, Eli Zaretskii wrote:
>> There are Gnulib library functions to
>> deal with this sort of thing; it's not a new problem.
>
> Doesn't that slow down applications?
Not significantly, no. file-attributes already has the file's filesystem
ID and timestamps so Emacs can easily cache that (it's a small cache
with only one entry per filesystem). There's no need to traipse through
the filesystem looking at other files. This is what coreutils does and
it works well in practice. It's not expensive and not that complicated.
Your suggestion of maintaining a static table for known filesystem types
is a good one; we could do that to improve common cases. I would like to
take a look into doing this. If successful, it should improve coreutils
and other GNU apps even if Emacs makes no changes in this area. In the
meantime I'll withdraw the proposed changes that would cause Emacs to
communicate OS timestamp resolution to the user; that sort of thing can
wait until after I've had that look (assuming I ever find the time :-).
> what about other sources of time data? For example, timestamps
> from other systems (like in your NTP example), timestamps that are
> reported by Tramp functions, etc.? How do we reliably estimate the
> accuracy of those?
For example, if Emacs imports from the network a timestamp with three
digits after the decimal point, it should convert it to an internal
timestamp with millisecond resolution. Conversely when sending a textual
timestamp, Emacs should generate only as many trailing digits as needed.
This sort of thing is not perfect (nothing to do with timestamps is :-),
but it is better than losing whatever resolution information is available.
next prev parent reply other threads:[~2022-04-25 15:34 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <5ed963b2-3fa8-48d8-627e-bc0571d15b43@gmail.com>
[not found] ` <149de00f-115b-5367-414f-c7700ef8966b@cs.ucla.edu>
[not found] ` <c6525aa8-1496-8ebe-cf2a-24f65cc44672@gmail.com>
[not found] ` <2dd15844-01b3-0144-740c-185ec8488a81@cs.ucla.edu>
[not found] ` <4a23f3a4-fe8f-d396-49d8-10034803be63@gmail.com>
[not found] ` <52fb10fb-892a-f273-3be8-28793f27e204@cs.ucla.edu>
[not found] ` <5cd820d4-ae67-43d4-9e63-c284d51ff1e4@gmail.com>
[not found] ` <f9d9d26c-1974-b52a-8f4d-49167676c102@cs.ucla.edu>
[not found] ` <83tuapvcxs.fsf@gnu.org>
[not found] ` <6efc5d24-34a2-fd30-cd20-fe4ac3e48310@cs.ucla.edu>
[not found] ` <83fsm8tdzl.fsf@gnu.org>
[not found] ` <9e4781b2-2ffa-b1ce-09b4-ead82cad9038@cs.ucla.edu>
[not found] ` <83ilr3siku.fsf@gnu.org>
[not found] ` <4e41671c-fae8-61c4-845c-4c7ba4317e88@cs.ucla.edu>
[not found] ` <83fsm7sh2s.fsf@gnu.org>
[not found] ` <e4cc58ca-51f9-395e-05f5-5f06cb9d439d@cs.ucla.edu>
[not found] ` <83czhbsgc2.fsf@gnu.org>
[not found] ` <33fb24fb-282b-cc13-a597-e7b63f19982d@cs.ucla.edu>
[not found] ` <83y1zzq6kd.fsf@gnu.org>
[not found] ` <aa2bc0a0-1bec-37ff-919d-c20fcdfdab68@cs.ucla.edu>
2022-04-22 5:23 ` Time resolution in Emacs argument optional ones Eli Zaretskii
2022-04-22 18:22 ` Paul Eggert
2022-04-22 18:52 ` Corwin Brust
2022-04-22 21:26 ` Paul Eggert
2022-04-23 6:27 ` Time resolution in Emacs Eli Zaretskii
2022-04-24 0:56 ` Paul Eggert
2022-04-24 6:10 ` Eli Zaretskii
2022-04-24 11:47 ` Max Nikulin
2022-04-24 12:23 ` Eli Zaretskii
2022-04-25 15:32 ` Paul Eggert
2022-04-25 16:01 ` Eli Zaretskii
2022-04-22 19:35 ` Time resolution in Emacs argument optional ones Eli Zaretskii
2022-04-22 21:52 ` Paul Eggert
2022-04-23 6:51 ` Time resolution in Emacs Eli Zaretskii
2022-04-25 15:34 ` Paul Eggert [this message]
2022-04-25 16:10 ` Eli Zaretskii
2022-04-25 16:38 ` Paul Eggert
2022-04-25 16:57 ` Eli Zaretskii
2022-04-25 16:54 ` Max Nikulin
2022-04-25 17:02 ` Eli Zaretskii
2022-04-25 19:27 ` Paul Eggert
2022-04-29 15:19 ` Max Nikulin
2022-04-29 16:07 ` Eli Zaretskii
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