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commitb4ec08db341116ced37925fd38e7668625c4af8c[log] [tgz]
authorAntonio Barone <syntonyze@gmail.com>Tue Apr 23 17:51:22 2024 +0200
committerAntonio Barone <syntonyze@gmail.com>Tue Apr 23 18:16:00 2024 +0200
treebfa04e7c794926c8969270a8c2f37fb2300a6099
parent5c1c006307cac302b07d42ed3172a3cb3e630dcc [diff]
Introduce `quickMatchSearchForReuse` config.

During the search for reuse phase jgit attempts to find the best object
representation by scanning all existing packfiles.

This ensures that the best delta representation is selected from all the
available ones, effectively saving space when repacking objects in
packfiles.

In a scenario where the number of packfiles is large however (i.e.
thousands of packfiles), this thorough search to find the best object
representation could be quite time consuming, up to the point where it
becomes unacceptable, leading to a "Search for reuse phase" to last
several minutes.

Introduce the possibility to trade-off between efficiency and the
quality of object representation chosen during the search for reuse
phase, by introducing the `quickMatchSearchForReuse` config.

When enabled, the search stops scanning upon finding the first matching
object representation, potentially sacrificing finding the best
representation for efficiency.

To increase the chance to find the best (or at least a very good) object
representation, when `quickMatchSearchForReuse` is enabled, the
packfiles are scanned from the most recent to the oldest, giving
priority to the ones having a bitmap, so that the most recent repacks
are traversed first.

We tested this on a ~3Gb repository having ~4M objects spanning across
4k packfiles on a Mac M3 with 36 GB ram: The search for reuse phase
during a GC operation goes down from ~3 minutes to ~20 seconds.

Change-Id: Ib44efded20c2e09a44b6234412a2cf94e7cd4b0f
7 files changed
tree: bfa04e7c794926c8969270a8c2f37fb2300a6099
  1. .github/
  2. .mvn/
  3. .settings/
  4. Documentation/
  5. lib/
  6. org.eclipse.jgit/
  7. org.eclipse.jgit.ant/
  8. org.eclipse.jgit.ant.test/
  9. org.eclipse.jgit.archive/
  10. org.eclipse.jgit.benchmarks/
  11. org.eclipse.jgit.coverage/
  12. org.eclipse.jgit.gpg.bc/
  13. org.eclipse.jgit.gpg.bc.test/
  14. org.eclipse.jgit.http.apache/
  15. org.eclipse.jgit.http.server/
  16. org.eclipse.jgit.http.test/
  17. org.eclipse.jgit.junit/
  18. org.eclipse.jgit.junit.http/
  19. org.eclipse.jgit.junit.ssh/
  20. org.eclipse.jgit.lfs/
  21. org.eclipse.jgit.lfs.server/
  22. org.eclipse.jgit.lfs.server.test/
  23. org.eclipse.jgit.lfs.test/
  24. org.eclipse.jgit.packaging/
  25. org.eclipse.jgit.pgm/
  26. org.eclipse.jgit.pgm.test/
  27. org.eclipse.jgit.ssh.apache/
  28. org.eclipse.jgit.ssh.apache.agent/
  29. org.eclipse.jgit.ssh.apache.test/
  30. org.eclipse.jgit.ssh.jsch/
  31. org.eclipse.jgit.ssh.jsch.test/
  32. org.eclipse.jgit.test/
  33. org.eclipse.jgit.ui/
  34. tools/
  35. .bazelrc
  36. .bazelversion
  37. .gitattributes
  38. .gitignore
  39. .mailmap
  40. BUILD
  41. CODE_OF_CONDUCT.md
  42. CONTRIBUTING.md
  43. LICENSE
  44. pom.xml
  45. README.md
  46. SECURITY.md
  47. WORKSPACE
README.md

Java Git

An implementation of the Git version control system in pure Java.

This project is licensed under the EDL (Eclipse Distribution License).

JGit can be imported straight into Eclipse and built and tested from there. It can be built from the command line using Maven or Bazel. The CI builds use Maven and run on Jenkins.

  • org.eclipse.jgit

    A pure Java library capable of being run standalone, with no additional support libraries. It provides classes to read and write a Git repository and operate on a working directory.

    All portions of JGit are covered by the EDL. Absolutely no GPL, LGPL or EPL contributions are accepted within this package.

  • org.eclipse.jgit.ant

    Ant tasks based on JGit.

  • org.eclipse.jgit.archive

    Support for exporting to various archive formats (zip etc).

  • org.eclipse.jgit.http.apache

    Apache httpclient support.

  • org.eclipse.jgit.http.server

    Server for the smart and dumb Git HTTP protocol.

  • org.eclipse.jgit.lfs

    Support for LFS (Large File Storage).

  • org.eclipse.jgit.lfs.server

    Basic LFS server support.

  • org.eclipse.jgit.packaging

    Production of Eclipse features and p2 repository for JGit. See the JGit Wiki on why and how to use this module.

  • org.eclipse.jgit.pgm

    Command-line interface Git commands implemented using JGit (“pgm” stands for program).

  • org.eclipse.jgit.ssh.apache

    Client support for the SSH protocol based on Apache Mina sshd.

  • org.eclipse.jgit.ssh.apache.agent

    Optional support for SSH agents for org.eclipse.jgit.ssh.apache.

  • org.eclipse.jgit.ui

    Simple UI for displaying git log.

Tests

  • org.eclipse.jgit.junit, org.eclipse.jgit.junit.http, org.eclipse.jgit.junit.ssh: Helpers for unit testing
  • org.eclipse.jgit.ant.test: Unit tests for org.eclipse.jgit.ant
  • org.eclipse.jgit.http.test: Unit tests for org.eclipse.jgit.http.server
  • org.eclipse.jgit.lfs.server.test: Unit tests for org.eclipse.jgit.lfs.server
  • org.eclipse.jgit.lfs.test: Unit tests for org.eclipse.jgit.lfs
  • org.eclipse.jgit.pgm.test: Unit tests for org.eclipse.jgit.pgm
  • org.eclipse.jgit.ssh.apache.test: Unit tests for org.eclipse.jgit.ssh.apache
  • org.eclipse.jgit.test: Unit tests for org.eclipse.jgit

Warnings/Caveats

  • Native symbolic links are supported, provided the file system supports them. For Windows you must use a non-administrator account and have the SeCreateSymbolicLinkPrivilege.

  • Only the timestamp of the index is used by JGit if the index is dirty.

  • JGit 6.0 and newer requires at least Java 11. Older versions require at least Java 1.8.

  • CRLF conversion is performed depending on the core.autocrlf setting, however Git for Windows by default stores that setting during installation in the “system wide” configuration file. If Git is not installed, use the global or repository configuration for the core.autocrlf setting.

  • The system wide configuration file is located relative to where C Git is installed. Make sure Git can be found via the PATH environment variable. When installing Git for Windows check the “Run Git from the Windows Command Prompt” option. There are other options like Eclipse settings that can be used for pointing out where C Git is installed. Modifying PATH is the recommended option if C Git is installed.

  • We try to use the same notation of $HOME as C Git does. On Windows this is often not the same value as the user.home system property.

Features

  • org.eclipse.jgit

    • Read loose and packed commits, trees, blobs, including deltafied objects.

    • Read objects from shared repositories

    • Write loose commits, trees, blobs.

    • Write blobs from local files or Java InputStreams.

    • Read blobs as Java InputStreams.

    • Copy trees to local directory, or local directory to a tree.

    • Lazily loads objects as necessary.

    • Read and write .git/config files.

    • Create a new repository.

    • Read and write refs, including walking through symrefs.

    • Read, update and write the Git index.

    • Checkout in dirty working directory if trivial.

    • Walk the history from a given set of commits looking for commits introducing changes in files under a specified path.

    • Object transport

      Fetch via ssh, git, http, Amazon S3 and bundles. Push via ssh, git, http, and Amazon S3. JGit does not yet deltify the pushed packs so they may be a lot larger than C Git packs.

    • Garbage collection

    • Merge

    • Rebase

    • And much more

  • org.eclipse.jgit.pgm

    • Assorted set of command line utilities. Mostly for ad-hoc testing of jgit log, glog, fetch etc.

  • org.eclipse.jgit.ant

    • Ant tasks

  • org.eclipse.jgit.archive

    • Support for Zip/Tar and other formats

  • org.eclipse.http

    • HTTP client and server support

Missing Features

There are some missing features:

  • signing push
  • shallow and partial cloning
  • support for remote helpers
  • support for credential helpers
  • support for multiple working trees (git-worktree)
  • using external diff tools
  • support for HTTPS client certificates
  • SHA-256 object IDs
  • git protocol V2 (client side): packfile-uris
  • multi-pack index
  • split index

Support

Post questions, comments or discussions to the jgit-dev@eclipse.org mailing list. You need to be subscribed to post. File bugs and enhancement requests in Bugzilla.

Contributing

See the EGit Contributor Guide.

About Git

More information about Git, its repository format, and the canonical C based implementation can be obtained from the Git website.