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Git's clean/smudge mechanism invokes an external filter process for every single blob that is affected by a filter. If Git filters a lot of blobs then the startup time of the external filter processes can become a significant part of the overall Git execution time. In a preliminary performance test this developer used a clean/smudge filter written in golang to filter 12,000 files. This process took 364s with the existing filter mechanism and 5s with the new mechanism. See details here: https://github.com/github/git-lfs/pull/1382 This patch adds the `filter.<driver>.process` string option which, if used, keeps the external filter process running and processes all blobs with the packet format (pkt-line) based protocol over standard input and standard output. The full protocol is explained in detail in `Documentation/gitattributes.txt`. A few key decisions: * The long running filter process is referred to as filter protocol version 2 because the existing single shot filter invocation is considered version 1. * Git sends a welcome message and expects a response right after the external filter process has started. This ensures that Git will not hang if a version 1 filter is incorrectly used with the filter.<driver>.process option for version 2 filters. In addition, Git can detect this kind of error and warn the user. * The status of a filter operation (e.g. "success" or "error) is set before the actual response and (if necessary!) re-set after the response. The advantage of this two step status response is that if the filter detects an error early, then the filter can communicate this and Git does not even need to create structures to read the response. * All status responses are pkt-line lists terminated with a flush packet. This allows us to send other status fields with the same protocol in the future. Helped-by: Martin-Louis Bright <mlbright@gmail.com> Reviewed-by: Jakub Narebski <jnareb@gmail.com> Signed-off-by: Lars Schneider <larsxschneider@gmail.com> 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 http://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-.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 http://news.gmane.org/gmane.comp.version-control.git/, http://marc.info/?l=git and other archival sites.
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