Do not create reflog for remote tracking branches during clone

When using JGit on a non-bare repository, the CloneCommand
it previously created local reflogs for all branches including remote
tracking ones, causing the generation of a potentially large
number of files on the local filesystem.

The creation of the remote-tracking branches (refs/remotes/*) during
clone is not an issue for the local filesystem because all of them are
stored in a single packed-refs file. However, the creation of a large
number of ref logs on a local filesystem IS an issue because it
may not be tuned or initialised in term of inodes to contain a very
large number of files.

When a user (or a CI system) performs the CloneCommand against
a potentially large repository (e.g., millions of branches), it is
interested in working or validating a single branch or tag and is
unlikely to work with all the remote-tracking branches.
The eager creation of a reflogs for all the remote-tracking branches is
not just a performance issue but may also compromise the ability to
use JGit for cloning a large repository.

The behaviour implemented in this change is also consistent with the
optimisation done in the C code-base [1].

We differentiate between clone and fetch commands using --branch
<initialBranch> option, that is only available in clone command,
and is set as HEAD per default.

[1] https://github.com/git/git/commit/58f233ce1ed67bbc31a429fde5c65d5050fdbd7d

Bug: 579805
Change-Id: I58d0d36a8a4ce42e0f59b8bf063747c4b81bd859
Signed-off-by: Luca Milanesio <luca.milanesio@gmail.com>
3 files changed
tree: f9421b46d8b1dadb7695adbf181166849435f676
  1. .mvn/
  2. .settings/
  3. Documentation/
  4. lib/
  5. org.eclipse.jgit/
  6. org.eclipse.jgit.ant/
  7. org.eclipse.jgit.ant.test/
  8. org.eclipse.jgit.archive/
  9. org.eclipse.jgit.benchmarks/
  10. org.eclipse.jgit.coverage/
  11. org.eclipse.jgit.gpg.bc/
  12. org.eclipse.jgit.gpg.bc.test/
  13. org.eclipse.jgit.http.apache/
  14. org.eclipse.jgit.http.server/
  15. org.eclipse.jgit.http.test/
  16. org.eclipse.jgit.junit/
  17. org.eclipse.jgit.junit.http/
  18. org.eclipse.jgit.junit.ssh/
  19. org.eclipse.jgit.lfs/
  20. org.eclipse.jgit.lfs.server/
  21. org.eclipse.jgit.lfs.server.test/
  22. org.eclipse.jgit.lfs.test/
  23. org.eclipse.jgit.packaging/
  24. org.eclipse.jgit.pgm/
  25. org.eclipse.jgit.pgm.test/
  26. org.eclipse.jgit.ssh.apache/
  27. org.eclipse.jgit.ssh.apache.test/
  28. org.eclipse.jgit.ssh.jsch/
  29. org.eclipse.jgit.ssh.jsch.test/
  30. org.eclipse.jgit.test/
  31. org.eclipse.jgit.ui/
  32. tools/
  33. .bazelrc
  34. .bazelversion
  35. .gitattributes
  36. .gitignore
  37. .mailmap
  38. BUILD
  39. CODE_OF_CONDUCT.md
  40. CONTRIBUTING.md
  41. DEPENDENCIES
  42. LICENSE
  43. pom.xml
  44. README.md
  45. SECURITY.md
  46. 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.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 requires at least a Java 8 JDK.

  • 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 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:

  • verifying signed commits
  • signing tags
  • signing push

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.