![]() The current line-level log implementation performs a preprocessing step in prepare_revision_walk(), during which the line_log_filter() function filters and rewrites history to keep only commits modifying the given line range. This preprocessing affects both responsiveness and correctness: - Git doesn't produce any output during this preprocessing step. Checking whether a commit modified the given line range is somewhat expensive, so depending on the size of the given revision range this preprocessing can result in a significant delay before the first commit is shown. - Limiting the number of displayed commits (e.g. 'git log -3 -L...') doesn't limit the amount of work during preprocessing, because that limit is applied during history traversal. Alas, by that point this expensive preprocessing step has already churned through the whole revision range to find all commits modifying the revision range, even though only a few of them need to be shown. - It rewrites parents, with no way to turn it off. Without the user explicitly requesting parent rewriting any parent object ID shown should be that of the immediate parent, just like in case of a pathspec-limited history traversal without parent rewriting. However, after that preprocessing step rewrote history, the subsequent "regular" history traversal (i.e. get_revision() in a loop) only sees commits modifying the given line range. Consequently, it can only show the object ID of the last ancestor that modified the given line range (which might happen to be the immediate parent, but many-many times it isn't). This patch addresses both the correctness and, at least for the common case, the responsiveness issues by integrating line-level log filtering into the regular revision walking machinery: - Make process_ranges_arbitrary_commit(), the static function in 'line-log.c' deciding whether a commit modifies the given line range, public by removing the static keyword and adding the 'line_log_' prefix, so it can be called from other parts of the revision walking machinery. - If the user didn't explicitly ask for parent rewriting (which, I believe, is the most common case): - Call this now-public function during regular history traversal, namely from get_commit_action() to ignore any commits not modifying the given line range. Note that while this check is relatively expensive, it must be performed before other, much cheaper conditions, because the tracked line range must be adjusted even when the commit will end up being ignored by other conditions. - Skip the line_log_filter() call, i.e. the expensive preprocessing step, in prepare_revision_walk(), because, thanks to the above points, the revision walking machinery is now able to filter out commits not modifying the given line range while traversing history. This way the regular history traversal sees the unmodified history, and is therefore able to print the object ids of the immediate parents of the listed commits. The eliminated preprocessing step can greatly reduce the delay before the first commit is shown, see the numbers below. - However, if the user did explicitly ask for parent rewriting via '--parents' or a similar option, then stick with the current implementation for now, i.e. perform that expensive filtering and history rewriting in the preprocessing step just like we did before, leaving the initial delay as long as it was. I tried to integrate line-level log filtering with parent rewriting into the regular history traversal, but, unfortunately, several subtleties resisted... :) Maybe someday we'll figure out how to do that, but until then at least the simple and common (i.e. without parent rewriting) 'git log -L:func:file' commands can benefit from the reduced delay. This change makes the failing 'parent oids without parent rewriting' test in 't4211-line-log.sh' succeed. The reduced delay is most noticable when there's a commit modifying the line range near the tip of a large-ish revision range: # no parent rewriting requested, no commit-graph present $ time git --no-pager log -L:read_alternate_refs:sha1-file.c -1 v2.23.0 Before: real 0m9.570s user 0m9.494s sys 0m0.076s After: real 0m0.718s user 0m0.674s sys 0m0.044s A significant part of the remaining delay is spent reading and parsing commit objects in limit_list(). With the help of the commit-graph we can eliminate most of that reading and parsing overhead, so here are the timing results of the same command as above, but this time using the commit-graph: Before: real 0m8.874s user 0m8.816s sys 0m0.057s After: real 0m0.107s user 0m0.091s sys 0m0.013s The next patch will further reduce the remaining delay. To be clear: this patch doesn't actually optimize the line-level log, but merely moves most of the work from the preprocessing step to the history traversal, so the commits modifying the line range can be shown as soon as they are processed, and the traversal can be terminated as soon as the given number of commits are shown. Consequently, listing the full history of a line range, potentially all the way to the root commit, will take the same time as before (but at least the user might start reading the output earlier). Furthermore, if the most recent commit modifying the line range is far away from the starting revision, then that initial delay will still be significant. Additional testing by Derrick Stolee: In the Linux kernel repository, the MAINTAINERS file was changed ~3,500 times across the ~915,000 commits. In addition to that edit frequency, the file itself is quite large (~18,700 lines). This means that a significant portion of the computation is taken up by computing the patch-diff of the file. This patch improves the real time it takes to output the first result quite a bit: Command: git log -L 100,200:MAINTAINERS -n 1 >/dev/null Before: 3.88 s After: 0.71 s If we drop the "-n 1" in the command, then there is no change in end-to-end process time. This is because the command still needs to walk the entire commit history, which negates the point of this patch. This is expected. As a note for future reference, the ~4.3 seconds in the old code spends ~2.6 seconds computing the patch-diffs, and the rest of the time is spent walking commits and computing diffs for which paths changed at each commit. The changed-path Bloom filters could improve the end-to-end computation time (i.e. no "-n 1" in the command). Signed-off-by: SZEDER Gábor <szeder.dev@gmail.com> Signed-off-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com> |
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block-sha1 | ||
builtin | ||
ci | ||
compat | ||
contrib | ||
Documentation | ||
ewah | ||
git-gui | ||
gitk-git | ||
gitweb | ||
mergetools | ||
negotiator | ||
perl | ||
po | ||
ppc | ||
refs | ||
sha1collisiondetection@855827c583 | ||
sha1dc | ||
sha256 | ||
t | ||
templates | ||
trace2 | ||
vcs-svn | ||
xdiff | ||
.cirrus.yml | ||
.clang-format | ||
.editorconfig | ||
.gitattributes | ||
.gitignore | ||
.gitmodules | ||
.mailmap | ||
.travis.yml | ||
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abspath.c | ||
aclocal.m4 | ||
add-interactive.c | ||
add-interactive.h | ||
add-patch.c | ||
advice.c | ||
advice.h | ||
alias.c | ||
alias.h | ||
alloc.c | ||
alloc.h | ||
apply.c | ||
apply.h | ||
archive-tar.c | ||
archive-zip.c | ||
archive.c | ||
archive.h | ||
argv-array.c | ||
argv-array.h | ||
attr.c | ||
attr.h | ||
azure-pipelines.yml | ||
banned.h | ||
base85.c | ||
bisect.c | ||
bisect.h | ||
blame.c | ||
blame.h | ||
blob.c | ||
blob.h | ||
bloom.c | ||
bloom.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 | ||
chdir-notify.c | ||
chdir-notify.h | ||
check-builtins.sh | ||
check_bindir | ||
checkout.c | ||
checkout.h | ||
CODE_OF_CONDUCT.md | ||
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 | ||
commit.h | ||
common-main.c | ||
config.c | ||
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 | ||
delta-islands.h | ||
delta.h | ||
detect-compiler | ||
diff-delta.c | ||
diff-lib.c | ||
diff-no-index.c | ||
diff.c | ||
diff.h | ||
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 | ||
fetch-negotiator.c | ||
fetch-negotiator.h | ||
fetch-pack.c | ||
fetch-pack.h | ||
fmt-merge-msg.h | ||
fsck.c | ||
fsck.h | ||
fsmonitor.c | ||
fsmonitor.h | ||
fuzz-commit-graph.c | ||
fuzz-pack-headers.c | ||
fuzz-pack-idx.c | ||
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--preserve-merges.sh | ||
git-request-pull.sh | ||
git-send-email.perl | ||
git-sh-i18n.sh | ||
git-sh-setup.sh | ||
git-submodule.sh | ||
git-svn.perl | ||
GIT-VERSION-GEN | ||
git-web--browse.sh | ||
git.c | ||
git.rc | ||
gpg-interface.c | ||
gpg-interface.h | ||
graph.c | ||
graph.h | ||
grep.c | ||
grep.h | ||
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 | ||
interdiff.c | ||
interdiff.h | ||
iterator.h | ||
json-writer.c | ||
json-writer.h | ||
khash.h | ||
kwset.c | ||
kwset.h | ||
levenshtein.c | ||
levenshtein.h | ||
LGPL-2.1 | ||
line-log.c | ||
line-log.h | ||
line-range.c | ||
line-range.h | ||
linear-assignment.c | ||
linear-assignment.h | ||
list-objects-filter-options.c | ||
list-objects-filter-options.h | ||
list-objects-filter.c | ||
list-objects-filter.h | ||
list-objects.c | ||
list-objects.h | ||
list.h | ||
ll-merge.c | ||
ll-merge.h | ||
lockfile.c | ||
lockfile.h | ||
log-tree.c | ||
log-tree.h | ||
ls-refs.c | ||
ls-refs.h | ||
mailinfo.c | ||
mailinfo.h | ||
mailmap.c | ||
mailmap.h | ||
Makefile | ||
match-trees.c | ||
mem-pool.c | ||
mem-pool.h | ||
merge-blobs.c | ||
merge-blobs.h | ||
merge-recursive.c | ||
merge-recursive.h | ||
merge.c | ||
mergesort.c | ||
mergesort.h | ||
midx.c | ||
midx.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 | ||
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 | ||
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 | ||
pretty.h | ||
prio-queue.c | ||
prio-queue.h | ||
progress.c | ||
progress.h | ||
promisor-remote.c | ||
promisor-remote.h | ||
prompt.c | ||
prompt.h | ||
protocol.c | ||
protocol.h | ||
quote.c | ||
quote.h | ||
range-diff.c | ||
range-diff.h | ||
reachable.c | ||
reachable.h | ||
read-cache.c | ||
README.md | ||
rebase-interactive.c | ||
rebase-interactive.h | ||
rebase.c | ||
rebase.h | ||
ref-filter.c | ||
ref-filter.h | ||
reflog-walk.c | ||
reflog-walk.h | ||
refs.c | ||
refs.h | ||
refspec.c | ||
refspec.h | ||
RelNotes | ||
remote-curl.c | ||
remote-testsvn.c | ||
remote.c | ||
remote.h | ||
replace-object.c | ||
replace-object.h | ||
repo-settings.c | ||
repository.c | ||
repository.h | ||
rerere.c | ||
rerere.h | ||
resolve-undo.c | ||
resolve-undo.h | ||
revision.c | ||
revision.h | ||
run-command.c | ||
run-command.h | ||
send-pack.c | ||
send-pack.h | ||
sequencer.c | ||
sequencer.h | ||
serve.c | ||
serve.h | ||
server-info.c | ||
setup.c | ||
sh-i18n--envsubst.c | ||
sha1-array.c | ||
sha1-array.h | ||
sha1-file.c | ||
sha1-lookup.c | ||
sha1-lookup.h | ||
sha1-name.c | ||
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 | ||
stable-qsort.c | ||
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 | ||
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 | ||
trace.c | ||
trace.h | ||
trace2.c | ||
trace2.h | ||
trailer.c | ||
trailer.h | ||
transport-helper.c | ||
transport-internal.h | ||
transport.c | ||
transport.h | ||
tree-diff.c | ||
tree-walk.c | ||
tree-walk.h | ||
tree.c | ||
tree.h | ||
unicode-width.h | ||
unimplemented.sh | ||
unix-socket.c | ||
unix-socket.h | ||
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 | ||
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 | ||
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-<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).
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://lore.kernel.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