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Nicolas Pitre c553ca25bd pack-objects: learn about pack index version 2
Pack index version 2 goes as follows:

 - 8 bytes of header with signature and version.

 - 256 entries of 4-byte first-level fan-out table.

 - Table of sorted 20-byte SHA1 records for each object in pack.

 - Table of 4-byte CRC32 entries for raw pack object data.

 - Table of 4-byte offset entries for objects in the pack if offset is
   representable with 31 bits or less, otherwise it is an index in the next
   table with top bit set.

 - Table of 8-byte offset entries indexed from previous table for offsets
   which are 32 bits or more (optional).

 - 20-byte SHA1 checksum of sorted object names.

 - 20-byte SHA1 checksum of the above.

The object SHA1 table is all contiguous so future pack format that would
contain this table directly won't require big changes to the code. It is
also tighter for slightly better cache locality when looking up entries.

Support for large packs exceeding 31 bits in size won't impose an index
size bloat for packs within that range that don't need a 64-bit offset.
And because newer objects which are likely to be the most frequently used
are located at the beginning of the pack, they won't pay the 64-bit offset
lookup at run time either even if the pack is large.

Right now an index version 2 is created only when the biggest offset in a
pack reaches 31 bits.  It might be a good idea to always use index version
2 eventually to benefit from the CRC32 it contains when reusing pack data
while repacking.

[jc: with the "oops" fix to keep track of the last offset correctly]

Signed-off-by: Nicolas Pitre <nico@cam.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>
2007-04-10 12:48:14 -07:00
arm
compat
contrib Merge branch 'maint' 2007-04-05 16:34:51 -07:00
Documentation git-archive: make tar the default format 2007-04-09 18:51:40 -07:00
git-gui
gitweb Merge branch 'maint' 2007-04-05 16:34:51 -07:00
mozilla-sha1
perl
ppc
t git-archive: make tar the default format 2007-04-09 18:51:40 -07:00
templates Reimplement emailing part of hooks--update in contrib/hooks/post-receive-email 2007-03-31 01:21:18 -07:00
xdiff
.gitignore A new merge stragety 'subtree'. 2007-04-07 02:29:40 -07:00
.mailmap
alloc.c
archive-tar.c
archive-zip.c
archive.h
base85.c
blob.c
blob.h
builtin-add.c Merge branch 'jc/index-output' 2007-04-07 02:26:24 -07:00
builtin-annotate.c
builtin-apply.c Merge branch 'jc/index-output' 2007-04-07 02:26:24 -07:00
builtin-archive.c git-archive: make tar the default format 2007-04-09 18:51:40 -07:00
builtin-blame.c
builtin-branch.c Make builtin-branch.c handle the git config file 2007-04-06 16:54:39 -07:00
builtin-bundle.c Rename warn() to warning() to fix symbol conflicts on BSD and Mac OS 2007-03-31 01:11:11 -07:00
builtin-cat-file.c
builtin-check-ref-format.c
builtin-checkout-index.c _GIT_INDEX_OUTPUT: allow plumbing to output to an alternative index file. 2007-04-03 23:44:32 -07:00
builtin-commit-tree.c
builtin-config.c
builtin-count-objects.c get rid of num_packed_objects() 2007-04-10 12:48:14 -07:00
builtin-describe.c
builtin-diff-files.c
builtin-diff-index.c
builtin-diff-tree.c
builtin-diff.c
builtin-fetch--tool.c
builtin-fmt-merge-msg.c
builtin-for-each-ref.c
builtin-fsck.c get rid of num_packed_objects() 2007-04-10 12:48:14 -07:00
builtin-gc.c
builtin-grep.c Initialize tree descriptors with a helper function rather than by hand. 2007-03-21 10:21:57 -07:00
builtin-init-db.c
builtin-log.c
builtin-ls-files.c Optimize directory listing with pathspec limiter. 2007-03-31 17:41:32 -07:00
builtin-ls-tree.c
builtin-mailinfo.c git-mailinfo fixes for patch munging 2007-03-31 00:59:19 -07:00
builtin-mailsplit.c
builtin-merge-base.c
builtin-merge-file.c
builtin-mv.c Merge branch 'jc/index-output' 2007-04-07 02:26:24 -07:00
builtin-name-rev.c
builtin-pack-objects.c pack-objects: learn about pack index version 2 2007-04-10 12:48:14 -07:00
builtin-pack-refs.c
builtin-prune-packed.c
builtin-prune.c
builtin-push.c git-push to multiple locations does not stop at the first failure 2007-04-07 02:27:31 -07:00
builtin-read-tree.c Merge branch 'jc/read-tree-df' (early part) 2007-04-07 23:52:40 -07:00
builtin-reflog.c Initialize tree descriptors with a helper function rather than by hand. 2007-03-21 10:21:57 -07:00
builtin-rerere.c rerere: make sorting really stable. 2007-04-04 14:12:03 -07:00
builtin-rev-list.c Merge branch 'maint' 2007-04-05 16:34:51 -07:00
builtin-rev-parse.c
builtin-revert.c git-revert: Revert revert message to old behaviour 2007-03-24 02:50:22 -07:00
builtin-rm.c _GIT_INDEX_OUTPUT: allow plumbing to output to an alternative index file. 2007-04-03 23:44:32 -07:00
builtin-runstatus.c
builtin-shortlog.c
builtin-show-branch.c
builtin-show-ref.c
builtin-stripspace.c
builtin-symbolic-ref.c
builtin-tar-tree.c
builtin-unpack-objects.c add overflow tests on pack offset variables 2007-04-10 12:48:14 -07:00
builtin-update-index.c Merge branch 'jc/index-output' 2007-04-07 02:26:24 -07:00
builtin-update-ref.c
builtin-upload-archive.c
builtin-verify-pack.c
builtin-write-tree.c _GIT_INDEX_OUTPUT: allow plumbing to output to an alternative index file. 2007-04-03 23:44:32 -07:00
builtin.h
cache-tree.c
cache-tree.h
cache.h get rid of num_packed_objects() 2007-04-10 12:48:14 -07:00
check-builtins.sh
check-racy.c
color.c
color.h
combine-diff.c
commit.c Merge branch 'maint' to synchronize with 1.5.0.6 2007-03-28 15:39:57 -07:00
commit.h
config.c Fix renaming branch without config file 2007-04-05 14:53:22 -07:00
config.mak.in Add --with-tcltk and --without-tcltk to configure. 2007-03-31 23:59:47 -07:00
configure.ac Eliminate checks of user-specified Tcl/Tk interpreter. 2007-03-31 23:59:47 -07:00
connect.c Fix "getaddrinfo()" buglet 2007-03-27 13:00:13 -07:00
convert-objects.c
convert.c
copy.c
COPYING
csum-file.c compute a CRC32 for each object as stored in a pack 2007-04-10 12:48:14 -07:00
csum-file.h compute a CRC32 for each object as stored in a pack 2007-04-10 12:48:14 -07:00
ctype.c
daemon.c
date.c
delta.h
diff-delta.c
diff-lib.c
diff.c Show binary file size change in diff --stat 2007-04-05 15:07:16 -07:00
diff.h
diffcore-break.c
diffcore-delta.c
diffcore-order.c
diffcore-pickaxe.c
diffcore-rename.c
diffcore.h
dir.c Optimize directory listing with pathspec limiter. 2007-03-31 17:41:32 -07:00
dir.h Optimize directory listing with pathspec limiter. 2007-03-31 17:41:32 -07:00
dump-cache-tree.c
entry.c
environment.c
exec_cmd.c
exec_cmd.h
fast-import.c Rename warn() to warning() to fix symbol conflicts on BSD and Mac OS 2007-03-31 01:11:11 -07:00
fetch-pack.c
fetch.c Initialize tree descriptors with a helper function rather than by hand. 2007-03-21 10:21:57 -07:00
fetch.h
generate-cmdlist.sh
git-add--interactive.perl
git-am.sh Use diff* with --exit-code in git-am, git-rebase and git-merge-ours 2007-03-24 23:01:36 -07:00
git-applymbox.sh
git-applypatch.sh
git-archimport.perl
git-bisect.sh git-bisect: allow bisecting with only one bad commit. 2007-04-06 17:55:57 -07:00
git-checkout.sh checkout: allow detaching to HEAD even when switching to the tip of a branch 2007-04-03 23:43:59 -07:00
git-clean.sh
git-clone.sh http-fetch: don't use double-slash as directory separator in URLs 2007-03-28 04:44:16 -07:00
git-commit.sh git-read-tree --index-output=<file> 2007-04-03 23:44:32 -07:00
git-compat-util.h make overflow test on delta base offset work regardless of variable size 2007-04-10 12:48:14 -07:00
git-cvsexportcommit.perl
git-cvsimport.perl cvsimport: Improve usage error reporting 2007-04-06 16:46:11 -07:00
git-cvsserver.perl
git-fetch.sh Merge branch 'js/fetch-progress' 2007-04-08 23:27:22 -07:00
git-instaweb.sh
git-lost-found.sh Fix lost-found to show commits only referenced by reflogs 2007-04-05 15:00:03 -07:00
git-ls-remote.sh
git-merge-octopus.sh
git-merge-one-file.sh
git-merge-ours.sh Use diff* with --exit-code in git-am, git-rebase and git-merge-ours 2007-03-24 23:01:36 -07:00
git-merge-resolve.sh
git-merge-stupid.sh
git-merge.sh A new merge stragety 'subtree'. 2007-04-07 02:29:40 -07:00
git-mergetool.sh mergetool: Clean up description of files and prompts for merge resolutions 2007-03-29 22:46:16 -04:00
git-p4import.py
git-parse-remote.sh
git-pull.sh
git-quiltimport.sh git-quiltimport /bin/sh-ism fix 2007-03-29 23:11:33 -07:00
git-rebase.sh Use diff* with --exit-code in git-am, git-rebase and git-merge-ours 2007-03-24 23:01:36 -07:00
git-relink.perl
git-remote.perl
git-repack.sh
git-request-pull.sh
git-reset.sh
git-send-email.perl Avoid composing too long "References" header. 2007-04-06 16:49:44 -07:00
git-sh-setup.sh
git-svn.perl git-svn: fix log command to avoid infinite loop on long commit messages 2007-04-08 19:54:07 -07:00
git-svnimport.perl
git-tag.sh
git-verify-tag.sh
GIT-VERSION-GEN GIT 1.5.1 2007-04-03 22:47:01 -07:00
git.c Revert "builtin-archive: use RUN_SETUP" 2007-04-05 14:10:10 -07:00
git.spec.in RPM spec: include git-p4 in the list of all packages. 2007-04-04 16:01:49 -07:00
gitk [PATCH] prefer "git COMMAND" over "git-COMMAND" in gitk 2007-03-21 22:02:19 +11:00
grep.c
grep.h
hash-object.c
help.c use xrealloc in help.c 2007-03-27 16:57:57 -07:00
http-fetch.c Fix lseek(2) calls with args 2 and 3 swapped 2007-04-05 15:39:12 -07:00
http-push.c Fix lseek(2) calls with args 2 and 3 swapped 2007-04-05 15:39:12 -07:00
http.c
http.h
ident.c
imap-send.c
index-pack.c compute object CRC32 with index-pack 2007-04-10 12:48:14 -07:00
INSTALL
interpolate.c
interpolate.h
list-objects.c Initialize tree descriptors with a helper function rather than by hand. 2007-03-21 10:21:57 -07:00
list-objects.h
local-fetch.c
lockfile.c git-read-tree --index-output=<file> 2007-04-03 23:44:32 -07:00
log-tree.c
log-tree.h
Makefile A new merge stragety 'subtree'. 2007-04-07 02:29:40 -07:00
match-trees.c A new merge stragety 'subtree'. 2007-04-07 02:29:40 -07:00
merge-file.c
merge-index.c
merge-recursive.c A new merge stragety 'subtree'. 2007-04-07 02:29:40 -07:00
merge-tree.c Remove "pathlen" from "struct name_entry" 2007-03-21 10:21:56 -07:00
mktag.c
mktree.c
object-refs.c
object.c
object.h
pack-check.c get rid of num_packed_objects() 2007-04-10 12:48:14 -07:00
pack-redundant.c
pack.h
pager.c
patch-delta.c
patch-id.c
path-list.c
path-list.h
path.c
peek-remote.c
pkt-line.c
pkt-line.h
quote.c
quote.h
reachable.c Initialize tree descriptors with a helper function rather than by hand. 2007-03-21 10:21:57 -07:00
reachable.h
read-cache.c Merge branch 'jc/read-tree-df' (early part) 2007-04-07 23:52:40 -07:00
README Update README to point at a few key periodical messages to the list 2007-03-25 17:42:32 -07:00
receive-pack.c
reflog-walk.c
reflog-walk.h
refs.c Make builtin-branch.c handle the git config file 2007-04-06 16:54:39 -07:00
refs.h
RelNotes Start 1.5.2 cycle by prepareing RelNotes for it. 2007-04-07 23:59:32 -07:00
revision.c Rename warn() to warning() to fix symbol conflicts on BSD and Mac OS 2007-03-31 01:11:11 -07:00
revision.h
rsh.c
rsh.h
run-command.c
run-command.h
send-pack.c
server-info.c
setup.c
sha1_file.c make overflow test on delta base offset work regardless of variable size 2007-04-10 12:48:14 -07:00
sha1_name.c get rid of num_packed_objects() 2007-04-10 12:48:14 -07:00
shallow.c
shell.c
show-index.c
sideband.c
sideband.h
ssh-fetch.c
ssh-pull.c
ssh-push.c
ssh-upload.c
strbuf.c
strbuf.h
tag.c
tag.h
tar.h
test-chmtime.c
test-date.c
test-delta.c
test-match-trees.c A new merge stragety 'subtree'. 2007-04-07 02:29:40 -07:00
test-sha1.c
test-sha1.sh
trace.c
tree-diff.c tree_entry_interesting(): allow it to say "everything is interesting" 2007-03-22 00:36:00 -07:00
tree-walk.c Switch over tree descriptors to contain a pre-parsed entry 2007-03-21 11:15:26 -07:00
tree-walk.h Switch over tree descriptors to contain a pre-parsed entry 2007-03-21 11:15:26 -07:00
tree.c Initialize tree descriptors with a helper function rather than by hand. 2007-03-21 10:21:57 -07:00
tree.h
unpack-file.c
unpack-trees.c Fix switching to a branch with D/F when current branch has file D. 2007-04-04 00:25:10 -07:00
unpack-trees.h unpack-trees: get rid of *indpos parameter. 2007-04-04 00:19:28 -07:00
update-server-info.c
upload-pack.c git-upload-pack: make sure we close unused pipe ends 2007-03-29 01:41:23 -07:00
usage.c Rename warn() to warning() to fix symbol conflicts on BSD and Mac OS 2007-03-31 01:11:11 -07:00
utf8.c
utf8.h
var.c
write_or_die.c
wt-status.c Optimize directory listing with pathspec limiter. 2007-03-31 17:41:32 -07:00
wt-status.h
xdiff-interface.c
xdiff-interface.h

////////////////////////////////////////////////////////////////

	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.
It was originally written by Linus Torvalds with help of a group of
hackers around the net. It is currently maintained by Junio C Hamano.

Please read the file INSTALL for installation instructions.
See Documentation/tutorial.txt to get started, then see
Documentation/everyday.txt for a useful minimum set of commands,
and "man git-commandname" for documentation of each command.
CVS users may also want to read Documentation/cvs-migration.txt.

Many Git online resources are accessible from http://git.or.cz/
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. 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://marc.theaimsgroup.com/?l=git and other archival sites.

The messages titled "A note from the maintainer", "What's in
git.git (stable)" and "What's cooking in git.git (topics)" and
the discussion following them on the mailing list give a good
reference for project status, development direction and
remaining tasks.