c08589efdc
Teach index-pack to, when processing the objects in a pack with --promisor specified on the CLI, repack local objects (and the local objects that they refer to, recursively) referenced by these objects into promisor packs. This prevents the situation in which, when fetching from a promisor remote, we end up with promisor objects (newly fetched) referring to non-promisor objects (locally created prior to the fetch). This situation may arise if the client had previously pushed objects to the remote, for example. One issue that arises in this situation is that, if the non-promisor objects become inaccessible except through promisor objects (for example, if the branch pointing to them has moved to point to the promisor object that refers to them), then GC will garbage collect them. There are other ways to solve this, but the simplest seems to be to enforce the invariant that we don't have promisor objects referring to non-promisor objects. This repacking is done from index-pack to minimize the performance impact. During a fetch, the only time most objects are fully inflated in memory is when their object ID is computed, so we also scan the objects (to see which objects they refer to) during this time. Also to minimize the performance impact, an object is calculated to be local if it's a loose object or present in a non-promisor pack. (If it's also in a promisor pack or referred to by an object in a promisor pack, it is technically already a promisor object. But a misidentification of a promisor object as a non-promisor object is relatively benign here - we will thus repack that promisor object into a promisor pack, duplicating it in the object store, but there is no correctness issue, just an issue of inefficiency.) Signed-off-by: Jonathan Tan <jonathantanmy@google.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 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