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Every compilation unit in Git is expected to include "git-compat-util.h"
first, either directly or indirectly via "builtin.h". This header papers
over differences between platforms so that we can expect the typical
POSIX functions to exist. Furthermore, it provides functionality that we
end up using everywhere.
This header is thus quite heavy as a consequence. Preprocessing it as a
standalone unit via `clang -E git-compat-util.h` yields over 23,000
lines of code overall. Naturally, it takes quite some time to compile
all of this.
Luckily, this is exactly the kind of use case that precompiled headers
aim to solve: instead of recompiling it every single time, we compile it
once and then link the result into the executable. If include guards are
set up properly it means that the file won't need to be reprocessed.
Set up such a precompiled header for "git-compat-util.h" and wire it up
via Meson. This leads to a significant speedup when performing full
builds:
Benchmark 1: ninja (rev = HEAD~)
Time (mean ± σ): 14.467 s ± 0.126 s [User: 248.133 s, System: 31.298 s]
Range (min … max): 14.195 s … 14.633 s 10 runs
Benchmark 2: ninja (rev = HEAD)
Time (mean ± σ): 10.307 s ± 0.111 s [User: 173.290 s, System: 23.998 s]
Range (min … max): 10.030 s … 10.433 s 10 runs
Summary
ninja (rev = HEAD) ran
1.40 ± 0.02 times faster than ninja (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