dbe4e8b3fd
The priority queue is used by the merged iterator to iterate over
reftable records from multiple tables in the correct order. The queue
ends up having one record for each table that is being iterated over,
with the record that is supposed to be shown next at the top. For
example, the key of a ref record is equal to its name so that we end up
sorting the priority queue lexicographically by ref name.
To figure out the order we need to compare the reftable record keys with
each other. This comparison is done by formatting them into a `struct
strbuf` and then doing `strbuf_strcmp()` on the result. We then discard
the buffers immediately after the comparison.
This ends up being very expensive. Because the priority queue usually
contains as many records as we have tables, we call the comparison
function `O(log($tablecount))` many times for every record we insert.
Furthermore, when iterating over many refs, we will insert at least one
record for every ref we are iterating over. So ultimately, this ends up
being called `O($refcount * log($tablecount))` many times.
Refactor the code to use the new `refatble_record_cmp()` function that
has been implemented in a preceding commit. This function does not need
to allocate memory and is thus significantly more efficient.
The following benchmark prints a single ref matching a specific pattern
out of 1 million refs via git-show-ref(1), where the reftable stack
consists of three tables:
Benchmark 1: show-ref: single matching ref (revision = HEAD~)
Time (mean ± σ): 224.4 ms ± 6.5 ms [User: 220.6 ms, System: 3.6 ms]
Range (min … max): 216.5 ms … 261.1 ms 1000 runs
Benchmark 2: show-ref: single matching ref (revision = HEAD)
Time (mean ± σ): 172.9 ms ± 4.4 ms [User: 169.2 ms, System: 3.6 ms]
Range (min … max): 166.5 ms … 204.6 ms 1000 runs
Summary
show-ref: single matching ref (revision = HEAD) ran
1.30 ± 0.05 times faster than show-ref: single matching ref (revision = HEAD~)
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
|
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|---|---|---|
| .github | ||
| Documentation | ||
| block-sha1 | ||
| builtin | ||
| ci | ||
| compat | ||
| contrib | ||
| ewah | ||
| git-gui | ||
| gitk-git | ||
| gitweb | ||
| mergetools | ||
| negotiator | ||
| oss-fuzz | ||
| perl | ||
| po | ||
| refs | ||
| reftable | ||
| sha1 | ||
| sha1collisiondetection@855827c583 | ||
| sha1dc | ||
| sha256 | ||
| t | ||
| templates | ||
| trace2 | ||
| xdiff | ||
| .cirrus.yml | ||
| .clang-format | ||
| .editorconfig | ||
| .gitattributes | ||
| .gitignore | ||
| .gitlab-ci.yml | ||
| .gitmodules | ||
| .mailmap | ||
| .tsan-suppressions | ||
| CODE_OF_CONDUCT.md | ||
| COPYING | ||
| GIT-VERSION-GEN | ||
| INSTALL | ||
| LGPL-2.1 | ||
| Makefile | ||
| README.md | ||
| RelNotes | ||
| SECURITY.md | ||
| abspath.c | ||
| abspath.h | ||
| 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 | ||
| attr.c | ||
| attr.h | ||
| banned.h | ||
| base85.c | ||
| base85.h | ||
| 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-uri.c | ||
| bundle-uri.h | ||
| bundle.c | ||
| bundle.h | ||
| cache-tree.c | ||
| cache-tree.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 | ||
| 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 | ||
| copy.h | ||
| 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 | ||
| diff.h | ||
| diffcore-break.c | ||
| diffcore-delta.c | ||
| diffcore-order.c | ||
| diffcore-pickaxe.c | ||
| diffcore-rename.c | ||
| diffcore-rotate.c | ||
| diffcore.h | ||
| dir-iterator.c | ||
| dir-iterator.h | ||
| dir.c | ||
| dir.h | ||
| editor.c | ||
| editor.h | ||
| entry.c | ||
| entry.h | ||
| 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 | ||
| fmt-merge-msg.h | ||
| fsck.c | ||
| fsck.h | ||
| fsmonitor--daemon.h | ||
| fsmonitor-ipc.c | ||
| fsmonitor-ipc.h | ||
| fsmonitor-ll.h | ||
| fsmonitor-path-utils.h | ||
| fsmonitor-settings.c | ||
| fsmonitor-settings.h | ||
| fsmonitor.c | ||
| fsmonitor.h | ||
| generate-cmdlist.sh | ||
| generate-configlist.sh | ||
| generate-hooklist.sh | ||
| gettext.c | ||
| gettext.h | ||
| git-archimport.perl | ||
| git-compat-util.h | ||
| 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 | ||
| git-sh-i18n.sh | ||
| git-sh-setup.sh | ||
| git-submodule.sh | ||
| git-svn.perl | ||
| git-web--browse.sh | ||
| git-zlib.c | ||
| git-zlib.h | ||
| git.c | ||
| git.rc | ||
| gpg-interface.c | ||
| gpg-interface.h | ||
| graph.c | ||
| graph.h | ||
| grep.c | ||
| grep.h | ||
| hash-ll.h | ||
| hash-lookup.c | ||
| hash-lookup.h | ||
| hash.h | ||
| hashmap.c | ||
| hashmap.h | ||
| help.c | ||
| help.h | ||
| hex-ll.c | ||
| hex-ll.h | ||
| hex.c | ||
| hex.h | ||
| hook.c | ||
| hook.h | ||
| http-backend.c | ||
| http-fetch.c | ||
| http-push.c | ||
| http-walker.c | ||
| http.c | ||
| http.h | ||
| ident.c | ||
| ident.h | ||
| imap-send.c | ||
| iterator.h | ||
| json-writer.c | ||
| json-writer.h | ||
| khash.h | ||
| kwset.c | ||
| kwset.h | ||
| levenshtein.c | ||
| levenshtein.h | ||
| 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 | ||
| lockfile.c | ||
| lockfile.h | ||
| log-tree.c | ||
| log-tree.h | ||
| ls-refs.c | ||
| ls-refs.h | ||
| mailinfo.c | ||
| mailinfo.h | ||
| mailmap.c | ||
| mailmap.h | ||
| match-trees.c | ||
| match-trees.h | ||
| mem-pool.c | ||
| mem-pool.h | ||
| merge-blobs.c | ||
| merge-blobs.h | ||
| merge-ll.c | ||
| merge-ll.h | ||
| merge-ort-wrappers.c | ||
| merge-ort-wrappers.h | ||
| merge-ort.c | ||
| merge-ort.h | ||
| merge-recursive.c | ||
| merge-recursive.h | ||
| merge.c | ||
| merge.h | ||
| mergesort.h | ||
| midx.c | ||
| midx.h | ||
| name-hash.c | ||
| name-hash.h | ||
| neue | ||
| notes-cache.c | ||
| notes-cache.h | ||
| notes-merge.c | ||
| notes-merge.h | ||
| notes-utils.c | ||
| notes-utils.h | ||
| notes.c | ||
| notes.h | ||
| object-file.c | ||
| object-file.h | ||
| object-name.c | ||
| object-name.h | ||
| object-store-ll.h | ||
| object-store.h | ||
| object.c | ||
| object.h | ||
| oid-array.c | ||
| oid-array.h | ||
| oidmap.c | ||
| oidmap.h | ||
| oidset.c | ||
| oidset.h | ||
| oidtree.c | ||
| oidtree.h | ||
| pack-bitmap-write.c | ||
| pack-bitmap.c | ||
| pack-bitmap.h | ||
| pack-check.c | ||
| pack-mtimes.c | ||
| pack-mtimes.h | ||
| pack-objects.c | ||
| pack-objects.h | ||
| pack-revindex.c | ||
| pack-revindex.h | ||
| pack-write.c | ||
| pack.h | ||
| packfile.c | ||
| packfile.h | ||
| pager.c | ||
| pager.h | ||
| parallel-checkout.c | ||
| parallel-checkout.h | ||
| parse-options-cb.c | ||
| parse-options.c | ||
| parse-options.h | ||
| parse.c | ||
| parse.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 | ||
| preload-index.h | ||
| 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-caps.c | ||
| protocol-caps.h | ||
| protocol.c | ||
| protocol.h | ||
| prune-packed.c | ||
| prune-packed.h | ||
| quote.c | ||
| quote.h | ||
| range-diff.c | ||
| range-diff.h | ||
| reachable.c | ||
| reachable.h | ||
| read-cache-ll.h | ||
| read-cache.c | ||
| read-cache.h | ||
| rebase-interactive.c | ||
| rebase-interactive.h | ||
| rebase.c | ||
| rebase.h | ||
| ref-filter.c | ||
| ref-filter.h | ||
| reflog-walk.c | ||
| reflog-walk.h | ||
| reflog.c | ||
| reflog.h | ||
| refs.c | ||
| refs.h | ||
| refspec.c | ||
| refspec.h | ||
| remote-curl.c | ||
| remote.c | ||
| remote.h | ||
| replace-object.c | ||
| replace-object.h | ||
| repo-settings.c | ||
| repository.c | ||
| repository.h | ||
| rerere.c | ||
| rerere.h | ||
| reset.c | ||
| reset.h | ||
| resolve-undo.c | ||
| resolve-undo.h | ||
| revision.c | ||
| revision.h | ||
| run-command.c | ||
| run-command.h | ||
| sane-ctype.h | ||
| scalar.c | ||
| send-pack.c | ||
| send-pack.h | ||
| sequencer.c | ||
| sequencer.h | ||
| serve.c | ||
| serve.h | ||
| server-info.c | ||
| server-info.h | ||
| setup.c | ||
| setup.h | ||
| sh-i18n--envsubst.c | ||
| sha1dc_git.c | ||
| sha1dc_git.h | ||
| shallow.c | ||
| shallow.h | ||
| shared.mak | ||
| shell.c | ||
| shortlog.h | ||
| sideband.c | ||
| sideband.h | ||
| sigchain.c | ||
| sigchain.h | ||
| simple-ipc.h | ||
| sparse-index.c | ||
| sparse-index.h | ||
| split-index.c | ||
| split-index.h | ||
| stable-qsort.c | ||
| statinfo.c | ||
| statinfo.h | ||
| strbuf.c | ||
| strbuf.h | ||
| streaming.c | ||
| streaming.h | ||
| string-list.c | ||
| string-list.h | ||
| strmap.c | ||
| strmap.h | ||
| strvec.c | ||
| strvec.h | ||
| sub-process.c | ||
| sub-process.h | ||
| submodule-config.c | ||
| submodule-config.h | ||
| submodule.c | ||
| submodule.h | ||
| symlinks.c | ||
| symlinks.h | ||
| 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 | ||
| unix-stream-server.c | ||
| unix-stream-server.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 | ||
| versioncmp.h | ||
| walker.c | ||
| walker.h | ||
| wildmatch.c | ||
| wildmatch.h | ||
| worktree.c | ||
| worktree.h | ||
| wrap-for-bin.sh | ||
| wrapper.c | ||
| wrapper.h | ||
| write-or-die.c | ||
| write-or-die.h | ||
| ws.c | ||
| ws.h | ||
| wt-status.c | ||
| wt-status.h | ||
| xdiff-interface.c | ||
| xdiff-interface.h | ||
README.md
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 and Documentation/CodingGuidelines).
Those wishing to help with error message, usage and informational message
string translations (localization l10) should see po/README.md
(a po file is a Portable Object file that holds the translations).
To subscribe to the list, send an email to git+subscribe@vger.kernel.org (see https://subspace.kernel.org/subscribing.html for details). The mailing list archives are available at https://lore.kernel.org/git/, https://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