No description
Find a file
Jeff King c8d521faf7 Add delta-islands.{c,h}
Hosting providers that allow users to "fork" existing
repos want those forks to share as much disk space as
possible.

Alternates are an existing solution to keep all the
objects from all the forks into a unique central repo,
but this can have some drawbacks. Especially when
packing the central repo, deltas will be created
between objects from different forks.

This can make cloning or fetching a fork much slower
and much more CPU intensive as Git might have to
compute new deltas for many objects to avoid sending
objects from a different fork.

Because the inefficiency primarily arises when an
object is deltified against another object that does
not exist in the same fork, we partition objects into
sets that appear in the same fork, and define
"delta islands". When finding delta base, we do not
allow an object outside the same island to be
considered as its base.

So "delta islands" is a way to store objects from
different forks in the same repo and packfile without
having deltas between objects from different forks.

This patch implements the delta islands mechanism in
"delta-islands.{c,h}", but does not yet make use of it.

A few new fields are added in 'struct object_entry'
in "pack-objects.h" though.

The documentation will follow in a patch that actually
uses delta islands in "builtin/pack-objects.c".

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-08-16 10:51:17 -07:00
.github
block-sha1
builtin Merge branch 'jt/commit-graph-per-object-store' 2018-08-02 15:30:47 -07:00
ci
compat
contrib
Documentation Fifth batch for 2.19 cycle 2018-08-02 15:38:09 -07:00
ewah
git-gui
gitk-git
gitweb
mergetools
negotiator Merge branch 'jt/fetch-negotiator-skipping' 2018-08-02 15:30:46 -07:00
perl
po
ppc
refs Merge branch 'sb/object-store-lookup' 2018-08-02 15:30:42 -07:00
sha1collisiondetection@19d97bf5af
sha1dc
t Merge branch 'jt/commit-graph-per-object-store' 2018-08-02 15:30:47 -07:00
templates
vcs-svn
xdiff
.clang-format
.gitattributes
.gitignore
.gitmodules
.mailmap
.travis.yml
.tsan-suppressions
abspath.c
aclocal.m4
advice.c Merge branch 'ab/checkout-default-remote' 2018-08-02 15:30:41 -07:00
advice.h Merge branch 'ab/checkout-default-remote' 2018-08-02 15:30:41 -07:00
alias.c
alias.h
alloc.c
alloc.h
apply.c Merge branch 'jm/cache-entry-from-mem-pool' 2018-08-02 15:30:43 -07:00
apply.h
archive-tar.c
archive-zip.c
archive.c
archive.h
argv-array.c
argv-array.h
attr.c
attr.h
base85.c
bisect.c
bisect.h
blame.c Merge branch 'jm/cache-entry-from-mem-pool' 2018-08-02 15:30:43 -07:00
blame.h
blob.c
blob.h
branch.c
branch.h
builtin.h
bulk-checkin.c
bulk-checkin.h
bundle.c
bundle.h
cache-tree.c
cache-tree.h
cache.h Merge branch 'jt/commit-graph-per-object-store' 2018-08-02 15:30:47 -07:00
chdir-notify.c
chdir-notify.h
check-builtins.sh
check-racy.c
check_bindir
checkout.c
checkout.h
color.c
color.h
column.c
column.h
combine-diff.c
command-list.txt
commit-graph.c Merge branch 'sb/object-store-lookup' 2018-08-02 15:30:42 -07:00
commit-graph.h
commit-slab-decl.h
commit-slab-impl.h
commit-slab.h
commit.c Merge branch 'jt/commit-graph-per-object-store' 2018-08-02 15:30:47 -07:00
commit.h Merge branch 'sb/object-store-lookup' 2018-08-02 15:30:42 -07:00
common-main.c
config.c Merge branch 'jt/commit-graph-per-object-store' 2018-08-02 15:30:47 -07:00
config.h
config.mak.dev
config.mak.in
config.mak.uname
configure.ac
connect.c
connect.h
connected.c
connected.h
convert.c
convert.h
copy.c
COPYING
credential-cache--daemon.c
credential-cache.c
credential-store.c
credential.c
credential.h
csum-file.c
csum-file.h
ctype.c
daemon.c
date.c
decorate.c
decorate.h
delta-islands.c Add delta-islands.{c,h} 2018-08-16 10:51:17 -07:00
delta-islands.h Add delta-islands.{c,h} 2018-08-16 10:51:17 -07:00
delta.h
detect-compiler
diff-delta.c
diff-lib.c
diff-no-index.c
diff.c Merge branch 'sb/diff-color-move-more' 2018-08-02 15:30:40 -07:00
diff.h Merge branch 'sb/diff-color-move-more' 2018-08-02 15:30:40 -07:00
diffcore-break.c
diffcore-delta.c
diffcore-order.c
diffcore-pickaxe.c
diffcore-rename.c
diffcore.h
dir-iterator.c
dir-iterator.h
dir.c
dir.h
editor.c
entry.c
environment.c
exec-cmd.c
exec-cmd.h
fast-import.c Merge branch 'sb/object-store-lookup' 2018-08-02 15:30:42 -07:00
fetch-negotiator.c
fetch-negotiator.h
fetch-object.c
fetch-object.h
fetch-pack.c Merge branch 'jt/fetch-negotiator-skipping' 2018-08-02 15:30:46 -07:00
fetch-pack.h Merge branch 'jt/fetch-nego-tip' 2018-08-02 15:30:43 -07:00
fmt-merge-msg.h
fsck.c Merge branch 'sb/object-store-lookup' 2018-08-02 15:30:42 -07:00
fsck.h
fsmonitor.c
fsmonitor.h
generate-cmdlist.sh
gettext.c
gettext.h
git-add--interactive.perl
git-archimport.perl
git-bisect.sh
git-compat-util.h
git-cvsexportcommit.perl
git-cvsimport.perl
git-cvsserver.perl
git-difftool--helper.sh
git-filter-branch.sh
git-instaweb.sh
git-merge-octopus.sh
git-merge-one-file.sh
git-merge-resolve.sh
git-mergetool--lib.sh
git-mergetool.sh
git-p4.py
git-parse-remote.sh
git-quiltimport.sh
git-rebase--am.sh
git-rebase--interactive.sh
git-rebase--merge.sh
git-rebase--preserve-merges.sh
git-rebase.sh
git-remote-testgit.sh
git-request-pull.sh
git-send-email.perl Merge branch 'jm/send-email-tls-auth-on-batch' 2018-08-02 15:30:46 -07:00
git-sh-i18n.sh
git-sh-setup.sh
git-stash.sh
git-submodule.sh
git-svn.perl
GIT-VERSION-GEN
git-web--browse.sh
git.c Merge branch 'jm/cache-entry-from-mem-pool' 2018-08-02 15:30:43 -07:00
git.rc
gpg-interface.c
gpg-interface.h
graph.c
graph.h
grep.c Merge branch 'tb/grep-only-matching' 2018-08-02 15:30:44 -07:00
grep.h Merge branch 'tb/grep-only-matching' 2018-08-02 15:30:44 -07:00
hash.h
hashmap.c
hashmap.h
help.c
help.h
hex.c
http-backend.c
http-fetch.c
http-push.c
http-walker.c
http.c
http.h
ident.c
imap-send.c
INSTALL
iterator.h
khash.h
kwset.c
kwset.h
levenshtein.c
levenshtein.h
LGPL-2.1
line-log.c Merge branch 'sb/object-store-lookup' 2018-08-02 15:30:42 -07:00
line-log.h
line-range.c
line-range.h
list-objects-filter-options.c
list-objects-filter-options.h
list-objects-filter.c
list-objects-filter.h
list-objects.c Merge branch 'sb/object-store-lookup' 2018-08-02 15:30:42 -07:00
list-objects.h
list.h
ll-merge.c
ll-merge.h
lockfile.c
lockfile.h
log-tree.c Merge branch 'sb/object-store-lookup' 2018-08-02 15:30:42 -07:00
log-tree.h
ls-refs.c
ls-refs.h
mailinfo.c
mailinfo.h
mailmap.c
mailmap.h
Makefile Add delta-islands.{c,h} 2018-08-16 10:51:17 -07:00
match-trees.c
mem-pool.c
mem-pool.h
merge-blobs.c
merge-blobs.h
merge-recursive.c Merge branch 'en/dirty-merge-fixes' 2018-08-02 15:30:45 -07:00
merge-recursive.h
merge.c Merge branch 'en/dirty-merge-fixes' 2018-08-02 15:30:45 -07:00
mergesort.c
mergesort.h
name-hash.c
notes-cache.c
notes-cache.h
notes-merge.c
notes-merge.h
notes-utils.c
notes-utils.h
notes.c
notes.h
object-store.h
object.c
object.h Merge branch 'sb/object-store-lookup' 2018-08-02 15:30:42 -07:00
oidmap.c
oidmap.h
oidset.c
oidset.h
pack-bitmap-write.c
pack-bitmap.c
pack-bitmap.h
pack-check.c
pack-objects.c
pack-objects.h Add delta-islands.{c,h} 2018-08-16 10:51:17 -07:00
pack-revindex.c
pack-revindex.h
pack-write.c
pack.h
packfile.c
packfile.h
pager.c
parse-options-cb.c
parse-options.c
parse-options.h
patch-delta.c
patch-ids.c
patch-ids.h
path.c
path.h
pathspec.c
pathspec.h
pkt-line.c
pkt-line.h
preload-index.c
pretty.c Merge branch 'sb/object-store-lookup' 2018-08-02 15:30:42 -07:00
pretty.h
prio-queue.c
prio-queue.h
progress.c
progress.h
prompt.c
prompt.h
protocol.c
protocol.h
quote.c
quote.h
reachable.c
reachable.h
read-cache.c Merge branch 'en/dirty-merge-fixes' 2018-08-02 15:30:45 -07:00
README.md
ref-filter.c Merge branch 'jt/commit-graph-per-object-store' 2018-08-02 15:30:47 -07:00
ref-filter.h
reflog-walk.c
reflog-walk.h
refs.c Merge branch 'sb/object-store-lookup' 2018-08-02 15:30:42 -07:00
refs.h
refspec.c
refspec.h
RelNotes
remote-curl.c
remote-testsvn.c
remote.c Merge branch 'sb/object-store-lookup' 2018-08-02 15:30:42 -07:00
remote.h
replace-object.c
replace-object.h
repository.c
repository.h
rerere.c
rerere.h
resolve-undo.c
resolve-undo.h
revision.c Merge branch 'jt/tags-to-promised-blobs-fix' 2018-08-02 15:30:46 -07:00
revision.h
run-command.c
run-command.h
send-pack.c
send-pack.h
sequencer.c Merge branch 'bc/sequencer-export-work-tree-as-well' 2018-08-02 15:30:45 -07:00
sequencer.h
serve.c
serve.h
server-info.c
setup.c
sh-i18n--envsubst.c
sha1-array.c
sha1-array.h
sha1-file.c Merge branch 'sb/object-store-lookup' 2018-08-02 15:30:42 -07:00
sha1-lookup.c
sha1-lookup.h
sha1-name.c Merge branch 'sb/object-store-lookup' 2018-08-02 15:30:42 -07:00
sha1dc_git.c
sha1dc_git.h
shallow.c
shell.c
shortlog.h
sideband.c
sideband.h
sigchain.c
sigchain.h
split-index.c
split-index.h
strbuf.c
strbuf.h
streaming.c
streaming.h
string-list.c
string-list.h
sub-process.c
sub-process.h
submodule-config.c
submodule-config.h
submodule.c Merge branch 'sb/object-store-lookup' 2018-08-02 15:30:42 -07:00
submodule.h
symlinks.c symlinks: remove PATH_MAX limitation 2014-07-07 11:22:42 -07:00
tag.c Merge branch 'jt/tags-to-promised-blobs-fix' 2018-08-02 15:30:46 -07:00
tag.h
tar.h
tempfile.c
tempfile.h
thread-utils.c
thread-utils.h
tmp-objdir.c
tmp-objdir.h
trace.c
trace.h
trailer.c
trailer.h
transport-helper.c Merge branch 'jt/fetch-nego-tip' 2018-08-02 15:30:43 -07:00
transport-internal.h
transport.c Merge branch 'jt/fetch-nego-tip' 2018-08-02 15:30:43 -07:00
transport.h Merge branch 'jt/fetch-nego-tip' 2018-08-02 15:30:43 -07:00
tree-diff.c
tree-walk.c
tree-walk.h
tree.c Merge branch 'jm/cache-entry-from-mem-pool' 2018-08-02 15:30:43 -07:00
tree.h
unicode-width.h
unimplemented.sh
unix-socket.c
unix-socket.h
unpack-trees.c Merge branch 'jm/cache-entry-from-mem-pool' 2018-08-02 15:30:43 -07:00
unpack-trees.h
upload-pack.c Merge branch 'sb/object-store-lookup' 2018-08-02 15:30:42 -07:00
upload-pack.h
url.c
url.h
urlmatch.c
urlmatch.h
usage.c
userdiff.c
userdiff.h
utf8.c
utf8.h
varint.c
varint.h
version.c
version.h
versioncmp.c
walker.c
walker.h
wildmatch.c
wildmatch.h
worktree.c
worktree.h
wrap-for-bin.sh
wrapper.c
write-or-die.c
ws.c
wt-status.c Merge branch 'sb/object-store-lookup' 2018-08-02 15:30:42 -07:00
wt-status.h
xdiff-interface.c
xdiff-interface.h
zlib.c

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-.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).

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 https://public-inbox.org/git/, http://marc.info/?l=git and other archival sites.

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