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96a1d8d34c
prepare_to_write_split_index() does the major work, classifying deleted, updated and added entries. write_link_extension() then just writes it down. An observation is, deleting an entry, then adding it back is recorded as "entry X is deleted, entry X is added", not "entry X is replaced". This is simpler, with small overhead: a replaced entry is stored without its path, a new entry is store with its path. A note about unpack_trees() and the deduplication code inside prepare_to_write_split_index(). Usually tracking updated/removed entries via read-cache API is enough. unpack_trees() manipulates the index in a different way: it throws the entire source index out, builds up a new one, copying/duplicating entries (using dup_entry) from the source index over if necessary, then returns the new index. A naive solution would be marking the entire source index "deleted" and add their duplicates as new. That could bring $GIT_DIR/index back to the original size. So we try harder and memcmp() between the original and the duplicate to see if it needs updating. We could avoid memcmp() too, by avoiding duplicating the original entry in dup_entry(). The performance gain this way is within noise level and it complicates unpack-trees.c. So memcmp() is the preferred way to deal with deduplication. Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Git - the stupid content tracker
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"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/everyday.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.