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Colby Ranger 3b325917a5 Added read/write support for pack bitmap index. 
A pack bitmap index is an additional index of compressed
bitmaps of the object graph. Furthermore, a logical API of the index
functionality is included, as it is expected to be used by the
PackWriter.

Compressed bitmaps are created using the javaewah library, which is a
word-aligned compressed variant of the Java bitset class based on
run-length encoding. The library only works with positive integer
values. Thus, the maximum number of ObjectIds in a pack file that
this index can currently support is limited to Integer.MAX_VALUE.

Every ObjectId is given an integer mapping. The integer is the
position of the ObjectId in the complete ObjectId list, sorted
by offset, for the pack file. That integer is what the bitmaps
use to reference the ObjectId. Currently, the new index format can
only be used with pack files that contain a complete closure of the
object graph e.g. the result of a garbage collection.

The index file includes four bitmaps for the Git object types i.e.
commits, trees, blobs, and tags. In addition, a collection of
bitmaps keyed by an ObjectId is also included. The bitmap for each entry
in the collection represents the full closure of ObjectIds reachable
from the keyed ObjectId (including the keyed ObjectId itself). The
bitmaps are further compressed by XORing the current bitmaps against
prior bitmaps in the index, and selecting the smallest representation.
The XOR'd bitmap and offset from the current entry to the position
of the bitmap to XOR against is the actual representation of the entry
in the index file. Each entry contains one byte, which is currently
used to note whether the bitmap should be blindly reused.

Change-Id: Id328724bf6b4c8366a088233098c18643edcf40f
 		2013-03-05 11:09:44 -08:00
org.eclipse.jgit Added read/write support for pack bitmap index. 2013-03-05 11:09:44 -08:00
org.eclipse.jgit.ant Prepare 2.4.0-SNAPSHOT builds 2013-02-14 00:59:25 +01:00
org.eclipse.jgit.ant.test Prepare 2.4.0-SNAPSHOT builds 2013-02-14 00:59:25 +01:00
org.eclipse.jgit.console Prepare 2.4.0-SNAPSHOT builds 2013-02-14 00:59:25 +01:00
org.eclipse.jgit.http.server Prepare 2.4.0-SNAPSHOT builds 2013-02-14 00:59:25 +01:00
org.eclipse.jgit.http.test Prepare 2.4.0-SNAPSHOT builds 2013-02-14 00:59:25 +01:00
org.eclipse.jgit.junit Prepare 2.4.0-SNAPSHOT builds 2013-02-14 00:59:25 +01:00
org.eclipse.jgit.junit.http Prepare 2.4.0-SNAPSHOT builds 2013-02-14 00:59:25 +01:00
org.eclipse.jgit.packaging Deploy Maven artifacts to Eclipse Nexus repository 2013-02-23 14:30:57 +01:00
org.eclipse.jgit.pgm Break the dependency on RevObject when creating a newObjectToPack(). 2013-03-04 14:43:22 -08:00
org.eclipse.jgit.pgm.test Prepare 2.4.0-SNAPSHOT builds 2013-02-14 00:59:25 +01:00
org.eclipse.jgit.test Added read/write support for pack bitmap index. 2013-03-05 11:09:44 -08:00
org.eclipse.jgit.ui Prepare 2.4.0-SNAPSHOT builds 2013-02-14 00:59:25 +01:00
tools Fix version.sh 2011-12-10 01:03:33 +01:00
.eclipse_iplog Update Eclipse IP log for 1.0 2011-05-25 20:14:35 +02:00
.gitattributes Initial JGit contribution to eclipse.org 2009-09-29 16:47:03 -07:00
.gitignore Ignore /target 2012-03-05 21:11:57 -08:00
LICENSE Clean up LICENSE file 2010-07-02 14:52:49 -07:00
README.md Implement recursive merge strategy 2013-02-22 23:51:50 +01:00
SUBMITTING_PATCHES Correcting explanation of EDL 2009-10-28 14:12:07 +01:00
pom.xml Added read/write support for pack bitmap index. 2013-03-05 11:09:44 -08:00

README.md

Java Git

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

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

  • 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.http.server

    Server for the smart and dumb Git HTTP protocol.

  • org.eclipse.jgit.pgm

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

  • org.eclipse.jgit.test

    Unit tests for org.eclipse.jgit and the same licensing rules.

Warnings/Caveats

  • Symbolic links are not supported because java does not support it. Such links could be damaged.

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

  • Don't try the library with a JDK other than 1.6 (Java 6) unless you are prepared to investigate problems yourself. JDK 1.5.0_11 and later Java 5 versions may work. Earlier versions do not. JDK 1.4 is not supported. Apple's Java 1.5.0_07 is reported to work acceptably. We have no information about other vendors. Please report your findings if you try.

  • 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 the jgit.gitprefix system propety or 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 same value as the user.home system property.

Package 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.

  • org.eclipse.jgit.pgm/

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

Missing Features

There are some missing features:

  • gitattributes support

Support

Post question, comments or patches to the jgit-dev@eclipse.org mailing list. You need to be subscribed to post, see here:

https://dev.eclipse.org/mailman/listinfo/jgit-dev

Contributing

See the EGit Contributor Guide:

http://wiki.eclipse.org/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:

http://git-scm.com/