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Derrick Stolee 7903efb717 bundle-uri: download in creationToken order
The creationToken heuristic provides an ordering on the bundles
advertised by a bundle list. Teach the Git client to download bundles
differently when this heuristic is advertised.

The bundles in the list are sorted by their advertised creationToken
values, then downloaded in decreasing order. This avoids the previous
strategy of downloading bundles in an arbitrary order and attempting
to apply them (likely failing in the case of required commits) until
discovering the order through attempted unbundling.

During a fresh 'git clone', it may make sense to download the bundles in
increasing order, since that would prevent the need to attempt
unbundling a bundle with required commits that do not exist in our empty
object store. The cost of testing an unbundle is quite low, and instead
the chosen order is optimizing for a future bundle download during a
'git fetch' operation with a non-empty object store.

Since the Git client continues fetching from the Git remote after
downloading and unbundling bundles, the client's object store can be
ahead of the bundle provider's object store. The next time it attempts
to download from the bundle list, it makes most sense to download only
the most-recent bundles until all tips successfully unbundle. The
strategy implemented here provides that short-circuit where the client
downloads a minimal set of bundles.

However, we are not satisfied by the naive approach of downloading
bundles until one successfully unbundles, expecting the earlier bundles
to successfully unbundle now. The example repository in t5558
demonstrates this well:

 ---------------- bundle-4

       4
      / \
 ----|---|------- bundle-3
     |   |
     |   3
     |   |
 ----|---|------- bundle-2
     |   |
     2   |
     |   |
 ----|---|------- bundle-1
      \ /
       1
       |
 (previous commits)

In this repository, if we already have the objects for bundle-1 and then
try to fetch from this list, the naive approach will fail. bundle-4
requires both bundle-3 and bundle-2, though bundle-3 will successfully
unbundle without bundle-2. Thus, the algorithm needs to keep this in
mind.

A later implementation detail will store the maximum creationToken seen
during such a bundle download, and the client will avoid downloading a
bundle unless its creationToken is strictly greater than that stored
value. For now, if the client seeks to download from an identical
bundle list since its previous download, it will download the
most-recent bundle then stop since its required commits are already in
the object store.

Add tests that exercise this behavior, but we will expand upon these
tests when incremental downloads during 'git fetch' make use of
creationToken values.

Signed-off-by: Derrick Stolee <derrickstolee@github.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2023-01-31 08:57:48 -08:00
.github ci: use a newer `github-script` version 2022-11-08 15:35:13 -05:00
Documentation bundle-uri: parse bundle.heuristic=creationToken 2023-01-31 08:57:48 -08:00
block-sha1
builtin clone: unbundle the advertised bundles 2022-12-25 16:24:24 +09:00
ci
compat Merge branch 'rs/no-more-run-command-v' 2022-11-08 17:15:12 -05:00
contrib Merge branch 'pb/subtree-split-and-merge-after-squashing-tag-fix' 2022-10-30 21:04:43 -04:00
ewah
git-gui
gitk-git
gitweb
mergetools
negotiator
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perl
po
refs
reftable
sha1collisiondetection@855827c583
sha1dc
sha256
t bundle-uri: download in creationToken order 2023-01-31 08:57:48 -08:00
templates
trace2
xdiff
.cirrus.yml
.clang-format
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.gitattributes
.gitignore Merge branch 'js/cmake-updates' 2022-10-27 14:51:53 -07:00
.gitmodules
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CODE_OF_CONDUCT.md
COPYING
GIT-VERSION-GEN
INSTALL
LGPL-2.1
Makefile Merge branch 'ds/bundle-uri-3' 2022-10-30 21:04:44 -04:00
README.md
RelNotes
SECURITY.md
abspath.c
aclocal.m4
add-interactive.c use child_process members "args" and "env" directly 2022-10-30 14:04:40 -04:00
add-interactive.h
add-patch.c
advice.c
advice.h
alias.c
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alloc.c
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apply.c Merge branch 'tb/cap-patch-at-1gb' 2022-10-30 21:04:43 -04:00
apply.h
archive-tar.c archive-tar: report filter start error only once 2022-10-30 19:50:43 -04:00
archive-zip.c
archive.c Merge branch 'rs/archive-dedup-printf' into maint-2.38 2022-10-27 15:24:14 -07:00
archive.h
attr.c
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banned.h
base85.c
bisect.c replace and remove run_command_v_opt() 2022-10-30 14:04:51 -04:00
bisect.h
blame.c
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blob.c
blob.h
bloom.c
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branch.c
branch.h
builtin.h
bulk-checkin.c
bulk-checkin.h
bundle-uri.c bundle-uri: download in creationToken order 2023-01-31 08:57:48 -08:00
bundle-uri.h bundle-uri: parse bundle.<id>.creationToken values 2023-01-31 08:57:48 -08:00
bundle.c bundle: verify using check_connected() 2023-01-31 08:57:47 -08:00
bundle.h Merge branch 'ds/bundle-uri-3' 2022-10-30 21:04:44 -04:00
cache-tree.c
cache-tree.h
cache.h
cbtree.c
cbtree.h
chdir-notify.c
chdir-notify.h
check-builtins.sh
checkout.c
checkout.h
chunk-format.c
chunk-format.h
color.c
color.h
column.c
column.h
combine-diff.c
command-list.txt
commit-graph.c
commit-graph.h
commit-reach.c
commit-reach.h
commit-slab-decl.h
commit-slab-impl.h
commit-slab.h
commit.c Merge branch 'pw/rebase-keep-base-fixes' 2022-10-30 21:04:42 -04:00
commit.h
common-main.c
config.c Merge branch 'ds/bundle-uri-3' 2022-10-30 21:04:44 -04:00
config.h
config.mak.dev
config.mak.in
config.mak.uname
configure.ac
connect.c clone: request the 'bundle-uri' command when available 2022-12-25 16:24:23 +09:00
connect.h
connected.c
connected.h
convert.c
convert.h
copy.c
credential.c
credential.h
csum-file.c
csum-file.h
ctype.c
daemon.c
date.c
date.h
decorate.c
decorate.h
delta-islands.c
delta-islands.h
delta.h
detect-compiler
diagnose.c
diagnose.h
diff-delta.c
diff-lib.c
diff-merges.c
diff-merges.h
diff-no-index.c
diff.c Merge branch 'rs/no-more-run-command-v' 2022-11-08 17:15:12 -05:00
diff.h
diffcore-break.c
diffcore-delta.c
diffcore-order.c
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diffcore.h
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dir.c Merge branch 'rs/use-fspathncmp' into maint-2.38 2022-10-27 15:24:13 -07:00
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editor.c
entry.c
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environment.c
environment.h
exec-cmd.c
exec-cmd.h
fetch-negotiator.c
fetch-negotiator.h
fetch-pack.c
fetch-pack.h
fmt-merge-msg.c
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fsck.c
fsck.h
fsmonitor--daemon.h
fsmonitor-ipc.c replace and remove run_command_v_opt_tr2() 2022-10-30 14:04:48 -04:00
fsmonitor-ipc.h
fsmonitor-path-utils.h
fsmonitor-settings.c
fsmonitor-settings.h
fsmonitor.c
fsmonitor.h
generate-cmdlist.sh
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generate-hooklist.sh
gettext.c
gettext.h
git-add--interactive.perl
git-archimport.perl
git-bisect.sh
git-compat-util.h Merge branch 'ab/unused-annotation' into maint-2.38 2022-10-27 15:24:12 -07:00
git-curl-compat.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-quiltimport.sh
git-request-pull.sh
git-send-email.perl
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git-submodule.sh
git-svn.perl
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git.c use child_process members "args" and "env" directly 2022-10-30 14:04:40 -04:00
git.rc
gpg-interface.c
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graph.c
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grep.c
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help.c Merge branch 'ab/doc-synopsis-and-cmd-usage' 2022-10-28 11:26:54 -07:00
help.h
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lockfile.c
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ls-refs.c
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mailinfo.c
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match-trees.c
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merge-ort.h
merge-recursive.c
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merge.c use child_process members "args" and "env" directly 2022-10-30 14:04:40 -04:00
mergesort.h
midx.c
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name-hash.c
notes-cache.c
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object-file.c
object-name.c
object-store.h
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pack-bitmap-write.c
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pack-write.c
pack.h
packfile.c
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pager.c
parallel-checkout.c
parallel-checkout.h
parse-options-cb.c
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parse-options.h
patch-delta.c
patch-ids.c Merge branch 'jz/patch-id' 2022-10-30 21:04:41 -04:00
patch-ids.h
path.c adjust_shared_perm(): leave g+s alone when the group does not matter 2022-10-28 14:55:27 -07:00
path.h
pathspec.c
pathspec.h
pkt-line.c
pkt-line.h
preload-index.c
pretty.c
pretty.h
prio-queue.c
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progress.c
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promisor-remote.c
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prompt.c
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protocol-caps.c
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protocol.c
protocol.h
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range-diff.c
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reachable.c
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read-cache.c
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ref-filter.c ref-filter: fix parsing of signatures with CRLF and no body 2022-11-02 21:36:04 -04:00
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reflog-walk.c
reflog-walk.h
reflog.c
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refs.c
refs.h
refspec.c
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remote-curl.c
remote.c
remote.h clone: request the 'bundle-uri' command when available 2022-12-25 16:24:23 +09:00
replace-object.c
replace-object.h
repo-settings.c Merge branch 'es/mark-gc-cruft-as-experimental' 2022-11-08 17:14:48 -05:00
repository.c
repository.h Merge branch 'es/mark-gc-cruft-as-experimental' 2022-11-08 17:14:48 -05:00
rerere.c
rerere.h
reset.c
reset.h
resolve-undo.c
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revision.c revisions API: extend the nascent REV_INFO_INIT macro 2022-11-08 16:34:01 -05:00
revision.h revisions API: extend the nascent REV_INFO_INIT macro 2022-11-08 16:34:01 -05:00
run-command.c Merge branch 'rs/no-more-run-command-v' 2022-11-08 17:15:12 -05:00
run-command.h Merge branch 'rs/no-more-run-command-v' 2022-11-08 17:15:12 -05:00
scalar.c use child_process members "args" and "env" directly 2022-10-30 14:04:40 -04:00
send-pack.c
send-pack.h
sequencer.c Merge branch 'rs/no-more-run-command-v' 2022-11-08 17:15:12 -05:00
sequencer.h
serve.c protocol v2: add server-side "bundle-uri" skeleton 2022-12-25 16:24:23 +09:00
serve.h
server-info.c
setup.c
sh-i18n--envsubst.c
sha1dc_git.c
sha1dc_git.h
shallow.c
shallow.h
shared.mak
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shortlog.h
sideband.c
sideband.h
sigchain.c
sigchain.h
simple-ipc.h
sparse-index.c index: raise a bug if the index is materialised more than once 2022-11-04 20:28:28 -04:00
sparse-index.h
split-index.c
split-index.h
stable-qsort.c
strbuf.c strbuf: introduce strbuf_strip_file_from_path() 2022-12-25 16:24:24 +09:00
strbuf.h strbuf: introduce strbuf_strip_file_from_path() 2022-12-25 16:24:24 +09:00
streaming.c
streaming.h
string-list.c
string-list.h
strmap.c
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strvec.c
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sub-process.c
sub-process.h
submodule-config.c
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submodule.c Merge branch 'rs/absorb-git-dir-simplify' 2022-10-30 21:04:42 -04:00
submodule.h
symlinks.c
tag.c
tag.h
tar.h
tempfile.c
tempfile.h
thread-utils.c
thread-utils.h
tmp-objdir.c
tmp-objdir.h replace and remove run_command_v_opt_cd_env() 2022-10-30 14:04:47 -04:00
trace.c
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trailer.c
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transport-helper.c clone: request the 'bundle-uri' command when available 2022-12-25 16:24:23 +09:00
transport-internal.h clone: request the 'bundle-uri' command when available 2022-12-25 16:24:23 +09:00
transport.c bundle-uri: allow relative URLs in bundle lists 2022-12-25 16:24:24 +09:00
transport.h clone: request the 'bundle-uri' command when available 2022-12-25 16:24:23 +09:00
tree-diff.c
tree-walk.c
tree-walk.h
tree.c
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unicode-width.h
unimplemented.sh
unix-socket.c
unix-socket.h
unix-stream-server.c
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unpack-trees.c
unpack-trees.h
upload-pack.c
upload-pack.h
url.c
url.h
urlmatch.c
urlmatch.h
usage.c
userdiff.c
userdiff.h
utf8.c
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varint.c
varint.h
version.c
version.h
versioncmp.c
walker.c
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wildmatch.h
worktree.c
worktree.h
wrap-for-bin.sh
wrapper.c
write-or-die.c
ws.c
wt-status.c
wt-status.h
xdiff-interface.c
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zlib.c

README.md

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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>.

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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 and Documentation/CodingGuidelines).

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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.
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