All of lore.kernel.org
 help / color / mirror / Atom feed
From: Junio C Hamano <gitster@pobox.com>
To: Jeff King <peff@peff.net>
Cc: Piotr Krukowiecki <piotr.krukowiecki@gmail.com>,
	Git Mailing List <git@vger.kernel.org>
Subject: Re: [bug] git checkout lies about number of ahead commits when switching from detached HEAD
Date: Sun, 20 Mar 2011 12:00:38 -0700	[thread overview]
Message-ID: <7vd3llwrah.fsf@alter.siamese.dyndns.org> (raw)
In-Reply-To: <20110320090111.GA15641@sigill.intra.peff.net> (Jeff King's message of "Sun, 20 Mar 2011 05:01:11 -0400")

Jeff King <peff@peff.net> writes:

> For the case of 2 traversals, I suspect that clearing everything between
> is not so different from clearing from the tips, since most everything
> parsed was probably from the first traversal. But as we lib-ify more, we
> may end up with more and more traversals in a single program, so it's
> probably better to go the more efficient route from the beginning.

"Let the one that has more information to do the clearing" is not about
performance but about correctness and reusability potential.

When you insert a new traversal B in the existing codeflow before another
traversal C, B knows not just which commits it started from (hence knows
which commits were marked by it), but more importantly it also knows what
mark bits were potentially modified. If the existing codeflow had another
traversal A before you added B, and C took the marks A left on the objects
into account while doing its work, the only sensible clean-up is to clear
marks B touched (and no other marks) immediately after B, and we obviously
do not want C (and any later traversals in other codepaths that we may
later want to insert B) to have too much knowledge of which marks may have
been clobbered by B.

Of course, C could be coded defensively to clear marks other than what it
cares about (namely, the ones other than what A would have left and the
ones that would affect itself e.g. UNINTERESTING), and whoever inserts B
into existing codeflow needs to make sure that B does not stomp on marks
deliberately left by earlier traversals like A for later users like C
regardless of how the latter is coded.

> So how about this?
>
>   [1/3]: checkout: add basic tests for detached-orphan warning
>   [2/3]: checkout: clear commit marks after detached-orphan check
>   [3/3]: checkout: tweak detached-orphan warning format

Looks very sensible, except for the clear_marks(-1) that clears everything
I have a slight doubt about.

I think 3/3 was way overdue and it was my fault. Thanks for cleaning up my
mess.

  parent reply	other threads:[~2011-03-20 19:00 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-03-19 21:53 [bug] git checkout lies about number of ahead commits when switching from detached HEAD Piotr Krukowiecki
2011-03-19 22:28 ` Jeff King
2011-03-19 22:47   ` Jeff King
2011-03-20  0:35     ` Junio C Hamano
2011-03-20  9:01       ` Jeff King
2011-03-20  9:04         ` [PATCH 1/3] checkout: add basic tests for detached-orphan warning Jeff King
2011-03-20  9:09         ` [PATCH 2/3] checkout: clear commit marks after detached-orphan check Jeff King
2011-03-20 19:05           ` Junio C Hamano
2012-04-13 22:59           ` [PATCH] i18n: use test_i18ncmp in t2020 (checkout --detach) Jonathan Nieder
2012-04-13 23:25             ` [PATCH/RFC] checkout --detached test: write supporting files before start of tests Jonathan Nieder
2012-04-13 23:33               ` Jeff King
2012-04-13 23:49                 ` Jonathan Nieder
2012-04-14  2:26                   ` Jeff King
2012-04-13 23:30             ` [PATCH] i18n: use test_i18ncmp in t2020 (checkout --detach) Jeff King
2012-04-13 23:46               ` Jonathan Nieder
2012-04-14  2:24                 ` Jeff King
2012-04-14  4:44                   ` [PATCH v2 0/3] " Jonathan Nieder
2012-04-14  4:45                     ` [PATCH 1/3] test: do not rely on US English tracking-info messages Jonathan Nieder
2012-04-14  4:46                     ` [PATCH 2/3] test: use test_i18ncmp for "Patch format detection failed" message Jonathan Nieder
2012-04-14  4:48                     ` [PATCH 3/3] test: am of empty patch should not succeed Jonathan Nieder
2012-04-14  8:15                     ` [PATCH v2 0/3] Re: i18n: use test_i18ncmp in t2020 (checkout --detach) Jeff King
2012-04-14  5:02                   ` [PATCH] " Jonathan Nieder
2012-04-14  8:22                     ` Jeff King
2012-04-14 12:47                       ` Jonathan Nieder
2011-03-20  9:19         ` [PATCH 3/3] checkout: tweak detached-orphan warning format Jeff King
2011-03-20 19:00         ` Junio C Hamano [this message]
2011-03-21 10:35           ` [bug] git checkout lies about number of ahead commits when switching from detached HEAD Jeff King
2011-03-21 15:17             ` Junio C Hamano

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=7vd3llwrah.fsf@alter.siamese.dyndns.org \
    --to=gitster@pobox.com \
    --cc=git@vger.kernel.org \
    --cc=peff@peff.net \
    --cc=piotr.krukowiecki@gmail.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.