name_ref() is called for each ref and checks if its a better name for
the referenced commit. If that's the case it remembers it and checks if
a name based on it is better for its ancestors as well. This in done in
the the order for_each_ref() imposes on us.
That might not be optimal. If bad names happen to be encountered first
(as defined by is_better_name()), names derived from them may spread to
a lot of commits, only to be replaced by better names later. Setting
better names first can avoid that.
is_better_name() prefers tags, short distances and old references. The
distance is a measure that we need to calculate for each candidate
commit, but the other two properties are not dependent on the
relationships of commits. Sorting the refs by them should yield better
performance than the essentially random order we currently use.
And applying older references first should also help to reduce rework
due to the fact that older commits have less ancestors than newer ones.
So add all details of names to the tip table first, then sort them
to prefer tags and older references and then apply them in this order.
Here's the performance as measures by hyperfine for the Linux repo
before:
Benchmark #1: ./git -C ../linux/ name-rev --all
Time (mean ± σ): 851.1 ms ± 4.5 ms [User: 806.7 ms, System: 44.4 ms]
Range (min … max): 845.9 ms … 859.5 ms 10 runs
... and with this patch:
Benchmark #1: ./git -C ../linux/ name-rev --all
Time (mean ± σ): 736.2 ms ± 8.7 ms [User: 688.4 ms, System: 47.5 ms]
Range (min … max): 726.0 ms … 755.2 ms 10 runs
Signed-off-by: René Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Git - fast, scalable, distributed revision control system
Git is a fast, scalable, distributed revision control system with an
unusually rich command set that provides both high-level operations
and full access to internals.
Git is an Open Source project covered by the GNU General Public
License version 2 (some parts of it are under different licenses,
compatible with the GPLv2). It was originally written by Linus
Torvalds with help of a group of hackers around the net.
Please read the file INSTALL for installation instructions.
Many Git online resources are accessible from https://git-scm.com/
including full documentation and Git related tools.
See Documentation/gittutorial.txt to get started, then see
Documentation/giteveryday.txt for a useful minimum set of commands, and
Documentation/git-<commandname>.txt for documentation of each command.
If git has been correctly installed, then the tutorial can also be
read with man gittutorial or git help tutorial, and the
documentation of each command with man git-<commandname> or git help <commandname>.
CVS users may also want to read Documentation/gitcvs-migration.txt
(man gitcvs-migration or git help cvs-migration if git is
installed).
Issues which are security relevant should be disclosed privately to
the Git Security mailing list git-security@googlegroups.com.
The maintainer frequently sends the "What's cooking" reports that
list the current status of various development topics to the mailing
list. The discussion following them give a good reference for
project status, development direction and remaining tasks.
The name "git" was given by Linus Torvalds when he wrote the very
first version. He described the tool as "the stupid content tracker"
and the name as (depending on your mood):
random three-letter combination that is pronounceable, and not
actually used by any common UNIX command. The fact that it is a
mispronunciation of "get" may or may not be relevant.
stupid. contemptible and despicable. simple. Take your pick from the
dictionary of slang.
"global information tracker": you're in a good mood, and it actually
works for you. Angels sing, and a light suddenly fills the room.
"goddamn idiotic truckload of sh*t": when it breaks
