Bug: 500967
Change-Id: I7fabc2654af97011c62f46d5c30ee992341e45e2
Signed-off-by: Andrey Loskutov <loskutov@gmx.de>

JGit style is to import exactly the classes required, and never
to use "import foo.*" as the foo package could add new classes
in the future which are conflicting/confusing with the imports
already used by a source file.

Change-Id: I5693408c777e5843ec65fff1163d5d717849fa34

The current IgnoreRule/FileNameMatcher implementation scales not well
with huge repositories - it is both slow and memory expensive while
parsing glob expressions (bug 440732). Addtitionally, the "double star"
pattern (/**/) is not understood by the old parser (bug 416348).

The proposed implementation is a complete clean room rewrite of the
gitignore parser, aiming to add missing double star pattern support and
improve the performance and memory consumption.

The glob expressions from .gitignore rules are converted to Java regular
expressions (java.util.regex.Pattern). java.util.regex.Pattern code can
evaluate expression from gitignore rules considerable faster (and with
less memory consumption) as the old FileNameMatcher implementation.

CQ: 8828
Bug: 416348
Bug: 440732
Change-Id: Ibefb930381f2f16eddb9947e592752f8ae2b76e1
Signed-off-by: Andrey Loskutov <loskutov@gmx.de>
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>

The test checks if an error is thrown when trying to create the same tag
for the second time.

Change-Id: I4ed2f6c997587f0ea23bd26a32fb64a2d48a980e
Signed-off-by: Chris Aniszczyk <zx@twitter.com>

Change-Id: I3d257666c6fbed7b238c575808f73ec518e811b9
Signed-off-by: Chris Aniszczyk <zx@twitter.com>

Change-Id: I9829950b686ce3b8c70b8f7a1774d5e2b55cd00a
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>

CQ: 6385
Bug: 365444
Change-Id: I2d5164cd92429673fe3c37e9f5f9bc565192cc12
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>

jgit.storage.dht is a storage provider implementation for JGit that
permits storing the Git repository in a distributed hashtable, NoSQL
system, or other database.  The actual underlying storage system is
undefined, and can be plugged in by implementing 7 small interfaces:

  *  Database
  *  RepositoryIndexTable
  *  RepositoryTable
  *  RefTable
  *  ChunkTable
  *  ObjectIndexTable
  *  WriteBuffer

The storage provider interface tries to assume very little about the
underlying storage system, and requires only three key features:

  *  key -> value lookup (a hashtable is suitable)
  *  atomic updates on single rows
  *  asynchronous operations (Java's ExecutorService is easy to use)

Most NoSQL database products offer all 3 of these features in their
clients, and so does any decent network based cache system like the
open source memcache product.  Relying only on key equality for data
retrevial makes it simple for the storage engine to distribute across
multiple machines.  Traditional SQL systems could also be used with a
JDBC based spi implementation.

Before submitting this change I have implemented six storage systems
for the spi layer:

  * Apache HBase[1]
  * Apache Cassandra[2]
  * Google Bigtable[3]
  * an in-memory implementation for unit testing
  * a JDBC implementation for SQL
  * a generic cache provider that can ride on top of memcache

All six systems came in with an spi layer around 1000 lines of code to
implement the above 7 interfaces.  This is a huge reduction in size
compared to prior attempts to implement a new JGit storage layer.  As
this package shows, a complete JGit storage implementation is more
than 17,000 lines of fairly complex code.

A simple cache is provided in storage.dht.spi.cache.  Implementers can
use CacheDatabase to wrap any other type of Database and perform fast
reads against a network based cache service, such as the open source
memcached[4].  An implementation of CacheService must be provided to
glue this spi onto the network cache.

[1] https://github.com/spearce/jgit_hbase
[2] https://github.com/spearce/jgit_cassandra
[3] http://labs.google.com/papers/bigtable.html
[4] http://memcached.org/

Change-Id: I0aa4072781f5ccc019ca421c036adff2c40c4295
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>

Per CQ 3448 this is the initial contribution of the JGit project
to eclipse.org.  It is derived from the historical JGit repository
at commit 3a2dd9921c.

Signed-off-by: Shawn O. Pearce <spearce@spearce.org>