Simplify ReftableCompactor

The ReftableCompactor supported a byteLimit, but this is currently
unused. The FileReftableStack has a more sophisticated strategy that
amortizes compaction costs.

Rename min/maxUpdateIndex to reflogExpire{Min,Max}UpdateIndex to
reflect their purpose  more accurately.

Since reflogs are generally pruned chronologically (oldest entries are
expired first), one can only prune entries on full compaction, so they
should not be set by default.

Rephrase the function Reader#minUpdateIndex and maxUpdateIndex. These
vars are documented to affect log entries, but semantically, they are
about ref entries. Since ref entries have their timestamps
delta-compressed, it is important for the min/maxUpdateIndex values to
be coherent between different tables.

The logical timestamps for log entries do not have to be coherent in
different tables, as the timestamps of a log entry is part of the key.
For example, a table written at update index 20 may contain a tombstone
log entry at timestamp 1.

Therefore, we set ReftableWriter's min/maxUpdateIndex from the merged
tables we are compacting, rather than from the compaction settings
(which should only control reflog expiry.)

The previous behavior could drop log entries erroneously, especially
in the presence of tombstone log entries. Unfortunately, testing this
properly requires both an API for adding log tombstones, and a more
refined API for controlling automatic compaction. Hence, no test.

Change-Id: I2f4eb7866f607fddd0629809e8e61f0b9097717f
Signed-off-by: Han-Wen Nienhuys <hanwen@google.com>
6 files changed
tree: 0cf00bdb35cac120e15ad5f7e0f205580d17893e
  1. .mvn/
  2. Documentation/
  3. lib/
  4. org.eclipse.jgit/
  5. org.eclipse.jgit.ant/
  6. org.eclipse.jgit.ant.test/
  7. org.eclipse.jgit.archive/
  8. org.eclipse.jgit.benchmarks/
  9. org.eclipse.jgit.coverage/
  10. org.eclipse.jgit.http.apache/
  11. org.eclipse.jgit.http.server/
  12. org.eclipse.jgit.http.test/
  13. org.eclipse.jgit.junit/
  14. org.eclipse.jgit.junit.http/
  15. org.eclipse.jgit.junit.ssh/
  16. org.eclipse.jgit.lfs/
  17. org.eclipse.jgit.lfs.server/
  18. org.eclipse.jgit.lfs.server.test/
  19. org.eclipse.jgit.lfs.test/
  20. org.eclipse.jgit.packaging/
  21. org.eclipse.jgit.pgm/
  22. org.eclipse.jgit.pgm.test/
  23. org.eclipse.jgit.ssh.apache/
  24. org.eclipse.jgit.ssh.apache.test/
  25. org.eclipse.jgit.test/
  26. org.eclipse.jgit.ui/
  27. tools/
  28. .bazelrc
  29. .bazelversion
  30. .gitattributes
  31. .gitignore
  32. .mailmap
  33. BUILD
  34. CONTRIBUTING.md
  35. LICENSE
  36. pom.xml
  37. README.md
  38. 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.