ea78edbebe
When 'pack-objects' is invoked with '--path-walk', it prevents us from using reachability bitmaps. This behavior dates back to70664d2865(pack-objects: add --path-walk option, 2025-05-16), which included a comment in the relevant portion of the command-line arguments handling that read as follows: /* * We must disable the bitmaps because we are removing * the --objects / --objects-edge[-aggressive] options. */ Infb2c309b7d(pack-objects: pass --objects with --path-walk, 2026-05-02), path-walk learned to pass '--objects' again, but still kept bitmap traversal disabled. That leaves two useful cases unsupported: * A path-walk repack that writes bitmaps does not give the bitmap selector any commits, because path-walk reveals commits through `add_objects_by_path()` rather than through `show_commit()`, where `index_commit_for_bitmap()` is normally called. * An invocation like "git pack-objects --use-bitmap-index --path-walk" never tries an existing bitmap, even when one is available and could answer the request. Fortunately for us, neither restriction is required. * On the writing side: teach the path-walk object callback to call `index_commit_for_bitmap()` for commits that it adds to the pack. That gives the bitmap selector the commit candidates it would have seen from the regular traversal. * For bitmap reading, keep passing '--objects' to the internal rev_list machinery, but stop clearing `use_bitmap_index`. If an existing bitmap can answer the request, use it; otherwise fall back to path-walk's own enumeration. As a result, we can see significantly reduced pack sizes from p5311 before this commit: Test HEAD^ HEAD ---------------------------------------------------------------------------------- 5311.38: server (1 days, --path-walk) 2.56(2.52+0.03) 0.01(0.01+0.00) -99.6% 5311.39: size (1 days, --path-walk) 123.9K 123.9K +0.0% 5311.40: client (1 days, --path-walk) 0.00(0.01+0.00) 0.00(0.00+0.00) = 5311.42: server (2 days, --path-walk) 2.57(2.52+0.05) 0.01(0.01+0.00) -99.6% 5311.43: size (2 days, --path-walk) 123.9K 123.9K +0.0% 5311.44: client (2 days, --path-walk) 0.00(0.00+0.00) 0.00(0.00+0.00) = 5311.46: server (4 days, --path-walk) 2.58(2.51+0.07) 0.01(0.01+0.00) -99.6% 5311.47: size (4 days, --path-walk) 123.9K 123.9K +0.0% 5311.48: client (4 days, --path-walk) 0.00(0.00+0.00) 0.00(0.00+0.00) = 5311.50: server (8 days, --path-walk) 2.58(2.53+0.04) 0.02(0.02+0.00) -99.2% 5311.51: size (8 days, --path-walk) 152.4K 152.4K +0.0% 5311.52: client (8 days, --path-walk) 0.00(0.01+0.00) 0.00(0.01+0.00) = 5311.54: server (16 days, --path-walk) 2.58(2.52+0.05) 0.03(0.02+0.00) -98.8% 5311.55: size (16 days, --path-walk) 205.3K 205.3K +0.0% 5311.56: client (16 days, --path-walk) 0.01(0.01+0.00) 0.01(0.01+0.00) +0.0% 5311.58: server (32 days, --path-walk) 2.59(2.53+0.06) 0.03(0.03+0.00) -98.8% 5311.59: size (32 days, --path-walk) 209.3K 209.3K +0.0% 5311.60: client (32 days, --path-walk) 0.01(0.02+0.00) 0.01(0.02+0.00) +0.0% 5311.62: server (64 days, --path-walk) 2.70(2.76+0.06) 0.16(0.24+0.04) -94.1% 5311.63: size (64 days, --path-walk) 4.1M 4.1M +0.0% 5311.64: client (64 days, --path-walk) 0.44(0.50+0.02) 0.44(0.51+0.02) +0.0% 5311.66: server (128 days, --path-walk) 2.88(3.20+0.05) 0.34(0.65+0.05) -88.2% 5311.67: size (128 days, --path-walk) 9.0M 9.0M -0.0% 5311.68: client (128 days, --path-walk) 0.93(1.22+0.07) 0.93(1.20+0.08) +0.0% We get the same size of output pack, but this commit allows us to do so in a significantly shorter amount of time. Intuitively, we're generating the same pack (hence the unchanged 'test_size' output from run to run), but varying how we get there. Before this commit, pack-objects prefers '--path-walk' to '--use-bitmap-index', so we generate the output pack by performing a normal '--path-walk' traversal. With this commit, we are operating over a *repacked* state (that itself was done with a '--path-walk' traversal), but are able to perform pack-reuse on that repacked state via bitmaps. There is one wrinkle when it comes to '--boundary', which we must not pass into the bitmap walk in the presence of both '--path-walk' and '--use-bitmap-index'. Path-walk needs boundary commits when it performs its own traversal, in order to discover bases for thin packs, but the bitmap traversal does not expect this. Work around this by setting `revs->boundary` as late as possible within the '--path-walk' traversal, after any bitmap attempt has either succeeded or declined to answer the request. Signed-off-by: Taylor Blau <me@ttaylorr.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