Re: [RFC PATCH v2] Add 'human' date format

From: Linus Torvalds <torvalds@linux-foundation.org>
Date: Jul 11, 2018, 21:49 UTC
Message-ID: <CA+55aFw2srtqU2B60wWo9h38pTTwT4zCDHZDwb+WMpMAbc0wOg@mail.gmail.com>
In-Reply-To: <87h8l5cvp3.fsf@evledraar.gmail.com>

On Wed, Jul 11, 2018 at 2:24 PM Ævar Arnfjörð Bjarmason <avarab@gmail.com> wrote:

Show 8 quoted lines

>
> I think that's true for the likes of linux.git & git.git, but a lot of
> users of git say work in some corporate setting entirely or mostly in
> the same timezone.
>
> In that case, knowing if some commit whose sole message was "fix"[1] was
> made at 3am or in the afternoon, even if it's really old, is really
> useful information, even years later.

Heh.

Maybe. But if you care about that kind of information, would you actually want to use the "human" date? Wouldn't you want to use the strftime thing instead, which gets you whatever field you care about, and gets it consistently regardless of how old the data is?

That said, I do acknowledge that the "human" format may be a bit inflexible and ad-hoc. Of course some more generic way that allowed arbitrary rules might be better for some uses.

I'll just explain the cases that made me zero in on what that last patch did:

 (a) I do like the "relative" date for recent stuff.

Quite often, I look at how recent the commits are, for example, and then I really like seeing "2 hours ago" rather than a time with a timezone (which is a lot harder for me to mentally parse)

This was the primary impetus for my original "auto" patch many years ago, that was (rightly) not merged. It really boiled down to just "default or relative, depending on how recent it was".

 (b) I noticed that I was distracted by dates that were *too* terse.

My first patch had _just_ the time when it was today and the same timezone (but older than two hours, so the original relative logic didn't trigger).

That initially sounded great to me, which is why it was that first time.

But after _using_ it for a while, I actually found that it didn't have enough context for me (visually) to really trigger my date parsing at all.

So "five hours ago" actually parsed better than just "9:48" to me. I didn't think it would do that, but it did. Which was why I changed the "relative" time to trigger every time if it was the exact same date (and in the past) - just to avoid the really terse model.

 (c) when I played around with other commands than just "git log", I
also noticed that a consistent length mattered.,

Again, my first version was more along the lines of "if it's long ago, just use the full format, exactly like the default date". It wasn't *quite* that, because it would always skip the seconds, but it was close.

And with "git log", that worked fine, because dates were fairly uniformly increasing, so the date format would slowly get longer, and that was fine.

But then when I played with "git blame -C --date=human", I noticed that not only did the human date actually make sense there too, it actually made it easier for me to read - and that in particular, the "extra" info was just annoying.

So now I find that shortened "only show the date" format to be really good _particularly_ for "git blame". You can see very clearly whether it's something recent or something old.

Maybe my use of "git blame" is unusual, but I don't think so. I tend to do "git blame -C" when I'm looking for a bug, and then seeing something like this:

        ...
          Apr 16 2005       437)
          Apr 16 2005       438)
          Jan 14 2016       439)
          Apr 16 2005       440)
          Apr 16 2005       441)
          Apr 16 2005       442)
          Thu Jun 14 15:26  443)
          Thu Jun 14 15:26  444)
          Thu Jun 14 15:26  445)
          Thu Jun 14 15:26  446)
          Thu Jun 14 15:26  447)
          Thu Jun 14 15:26  448)
          Thu Jun 14 15:26  449)
          Thu Jun 14 15:26  450)
          Apr 16 2005       451)
          Jul 30 2012       452)
          Jul 30 2012       453)
          Feb 13 2012       454)
          Apr 16 2005       455)
          Apr 16 2005       456)
        ....

in that date field (yeah. that happens to be "kernel/fork.c" in the current kernel - I just edited out all the other stuff than time and line number) is actually very visually easy to see what parts are old, and which ones are recent, because it changes the format pretty clearly and unambiguously, without changing the size of that field _dramatically_.

(Sure, the size changes, but it's not a radical difference, it's a fairly small variation, and the variation only highlights the different time range, without making it compltely unbalanced).

Anyway, enough excuses. I'l just trying to explain some of the things that I noticed simply _while_ making some of the decisions I made.

Are they the "right" decisions? I don't know. But I've been running with that

        git config --add log.date auto

in my kernel repo since I posted the patches, and so far I'm still liking it.

                 Linus