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The function `refs_for_each_glob_ref_in()` can be used to iterate
through all refs in a specific prefix with globbing. The logic to handle
this is currently hosted by `refs_for_each_glob_ref_in()`, which sets up
a callback function that knows to filter out refs that _don't_ match the
given globbing pattern.
The way we do this is somewhat inefficient though: even though the
function is expected to only yield refs in the given prefix, we still
end up iterating through _all_ references, regardless of whether or not
their name matches the given prefix.
Extend `refs_for_each_ref_ext()` so that it can handle patterns and
adapt `refs_for_each_glob_ref_in()` to use it. This means we continue to
use the same callback-based infrastructure to filter individual refs via
the globbing pattern, but we can now also use the other functionality of
the `_ext()` variant.
Most importantly, this means that we now properly handle the prefix.
This results in a performance improvement when using a prefix where a
significant majority of refs exists outside of the prefix. The following
benchmark is an extreme case, with 1 million refs that exist outside the
prefix and a single ref that exists inside it:
Benchmark 1: git rev-parse --branches=refs/heads/* (rev = HEAD~)
Time (mean ± σ): 115.9 ms ± 0.7 ms [User: 113.0 ms, System: 2.4 ms]
Range (min … max): 114.9 ms … 117.8 ms 25 runs
Benchmark 2: git rev-parse --branches=refs/heads/* (rev = HEAD)
Time (mean ± σ): 1.1 ms ± 0.1 ms [User: 0.3 ms, System: 0.7 ms]
Range (min … max): 1.0 ms … 2.3 ms 2092 runs
Summary
git rev-parse --branches=refs/heads/* (rev = HEAD) ran
107.01 ± 6.49 times faster than git rev-parse --branches=refs/heads/* (rev = HEAD~)
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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.adoc to get started, then see
Documentation/giteveryday.adoc for a useful minimum set of commands, and
Documentation/git-<commandname>.adoc 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.adoc
(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