From: "Ævar Arnfjörð Bjarmason" <avarab@gmail.com>
To: Git Mailing List <git@vger.kernel.org>
Cc: Thomas Rast <tr@thomasrast.ch>,
Junio C Hamano <gitster@pobox.com>, Jeff King <peff@peff.net>,
Johannes Schindelin <Johannes.Schindelin@gmx.de>
Subject: merge-base --is-ancestor A B is unreasonably slow with unrelated history B
Date: Tue, 09 Jan 2018 16:17:41 +0100 [thread overview]
Message-ID: <87608bawoa.fsf@evledraar.gmail.com> (raw)
This is a pathological case I don't have time to dig into right now:
git branch -D orphan;
git checkout --orphan orphan &&
git reset --hard &&
touch foo &&
git add foo &&
git commit -m"foo" &&
time git merge-base --is-ancestor master orphan
This takes around 5 seconds on linux.git to return 1. Which is around
the same time it takes to run current master against the first commit in
linux.git:
git merge-base --is-ancestor 1da177e4c3f4 master
This is obviously a pathological case, but maybe we should work slightly
harder on the RHS of and discover that it itself is an orphan commit.
I ran into this while writing a hook where we'd like to do:
git diff $master...topic
Or not, depending on if the topic is an orphan or just something
recently branched off, figured I could use --is-ancestor as on
optimization, and then discovered it's not much of an optimization.
next reply other threads:[~2018-01-09 15:17 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-09 15:17 Ævar Arnfjörð Bjarmason [this message]
2018-01-09 19:13 ` merge-base --is-ancestor A B is unreasonably slow with unrelated history B Junio C Hamano
2018-01-09 19:30 ` Derrick Stolee
2018-01-10 14:01 ` Ævar Arnfjörð Bjarmason
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
List information: http://vger.kernel.org/majordomo-info.html
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=87608bawoa.fsf@evledraar.gmail.com \
--to=avarab@gmail.com \
--cc=Johannes.Schindelin@gmx.de \
--cc=git@vger.kernel.org \
--cc=gitster@pobox.com \
--cc=peff@peff.net \
--cc=tr@thomasrast.ch \
/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.
Code repositories for project(s) associated with this public inbox
https://80x24.org/mirrors/git.git
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).