e2d003dbed
When an object is not found in a repository's object store, we sometimes call reprepare_packed_git() to see if the object was temporarily moved into a new pack-file (and its old pack-file or loose object was deleted). This process does a scan of each pack directory within each odb, but does not reevaluate if the odb list needs updating. Extend reprepare_packed_git() to also reprepare the alternate odb list by setting loaded_alternates to zero and calling prepare_alt_odb(). This will add newly-discoverd odbs to the linked list, but will not duplicate existing ones nor will it remove existing ones that are no longer listed in the alternates file. Do this under the object read lock to avoid readers from interacting with a potentially incomplete odb being added to the odb list. If the alternates file was edited to _remove_ some alternates during the course of the Git process, Git will continue to see alternates that were ever valid for that repository. ODBs are not removed from the list, the same as the existing behavior before this change. Git already has protections against an alternate directory disappearing from the filesystem during the lifetime of a process, and those are still in effect. This change is specifically for concurrent changes to the repository, so it is difficult to create a test that guarantees this behavior is correct. I manually verified by introducing a reprepare_packed_git() call into get_revision() and stepped into that call in a debugger with a parent 'git log' process. Multiple runs of prepare_alt_odb() kept the_repository->objects->odb as a single-item chain until I added a .git/objects/info/alternates file in a different process. The next run added the new odb to the chain and subsequent runs did not add to the chain. Signed-off-by: Derrick Stolee <derrickstolee@github.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 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 with just "subscribe git" in the body to majordomo@vger.kernel.org (not the Git list). 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