06a604e670
If we have never seen attr 'X' in any .gitattributes file we have examined so far, we can be sure that 'X' is not defined. So no need to go over all the attr stack to look for attr 'X'. This is the purpose behind this new field maybe_real. This optimization breaks down if macros are involved because we can't know for sure what macro would expand to 'X' at attr parsing time. But if we go the pessimistic way and assume all macros are expanded, we hit the builtin "binary" macro. At least the "diff" attr defined in this macro will disable this optimization for git-grep. So we wait until any attr lines _may_ reference to a macro before we turn this off. In git.git, this reduces the number of fill_one() call for "git grep abcdefghi" from ~5348 to 2955. The optimization stops when it reads t/.gitattributes, which uses 'binary' macro. We could probably reduce it further by limiting the 'binary' reference to t/ and subdirs only in this case. "git grep" is actually a good example to justify this patch. The command checks "diff" attribute on every file. People usually don't define this attribute. But they pay the attr lookup penalty anyway without this patch, proportional to the number of attr lines they have in repo. Helped-by: Junio C Hamano <gitster@pobox.com> Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
////////////////////////////////////////////////////////////////
Git - the stupid content tracker
////////////////////////////////////////////////////////////////
"git" can mean anything, 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
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.
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).
Many Git online resources are accessible from http://git-scm.com/
including full documentation and Git related tools.
The user discussion and development of Git take place on the Git
mailing list -- everyone is welcome to post bug reports, feature
requests, comments and patches to git@vger.kernel.org (read
Documentation/SubmittingPatches for instructions on patch submission).
To subscribe to the list, send an email with just "subscribe git" in
the body to majordomo@vger.kernel.org. The mailing list archives are
available at http://news.gmane.org/gmane.comp.version-control.git/,
http://marc.info/?l=git and other archival sites.
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.