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The git replay command currently outputs update commands that can be
piped to update-ref to achieve a rebase, e.g.
git replay --onto main topic1..topic2 | git update-ref --stdin
This separation had advantages for three special cases:
* it made testing easy (when state isn't modified from one step to
the next, you don't need to make temporary branches or have undo
commands, or try to track the changes)
* it provided a natural can-it-rebase-cleanly (and what would it
rebase to) capability without automatically updating refs, similar
to a --dry-run
* it provided a natural low-level tool for the suite of hash-object,
mktree, commit-tree, mktag, merge-tree, and update-ref, allowing
users to have another building block for experimentation and making
new tools
However, it should be noted that all three of these are somewhat
special cases; users, whether on the client or server side, would
almost certainly find it more ergonomic to simply have the updating
of refs be the default.
For server-side operations in particular, the pipeline architecture
creates process coordination overhead. Server implementations that need
to perform rebases atomically must maintain additional code to:
1. Spawn and manage a pipeline between git-replay and git-update-ref
2. Coordinate stdout/stderr streams across the pipe boundary
3. Handle partial failure states if the pipeline breaks mid-execution
4. Parse and validate the update-ref command output
Change the default behavior to update refs directly, and atomically (at
least to the extent supported by the refs backend in use). This
eliminates the process coordination overhead for the common case.
For users needing the traditional pipeline workflow, add a new
--ref-action=<mode> option that preserves the original behavior:
git replay --ref-action=print --onto main topic1..topic2 | git update-ref --stdin
The mode can be:
* update (default): Update refs directly using an atomic transaction
* print: Output update-ref commands for pipeline use
Test suite changes:
All existing tests that expected command output now use
--ref-action=print to preserve their original behavior. This keeps
the tests valid while allowing them to verify that the pipeline workflow
still works correctly.
New tests were added to verify:
- Default atomic behavior (no output, refs updated directly)
- Bare repository support (server-side use case)
- Equivalence between traditional pipeline and atomic updates
- Real atomicity using a lock file to verify all-or-nothing guarantee
- Test isolation using test_when_finished to clean up state
- Reflog messages include replay mode and target
A following commit will add a replay.refAction configuration
option for users who prefer the traditional pipeline output as their
default behavior.
Helped-by: Elijah Newren <newren@gmail.com>
Helped-by: Patrick Steinhardt <ps@pks.im>
Helped-by: Christian Couder <christian.couder@gmail.com>
Helped-by: Phillip Wood <phillip.wood123@gmail.com>
Signed-off-by: Siddharth Asthana <siddharthasthana31@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 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