The most important difference is that in Java7 we have symbolic links
and for most operations in the work tree we want to operate on the link
itself rather than the link target, which the old File methods generally
do.
We also add support for the hidden attribute, which only makes sense
on Windows and exists, just since there are claims that Files.exists
is faster the File.exists.
A new bundle is only activated when run with a Java7 execution
environment. It is implemented as a fragment.
Tycho currently has no way to conditionally include optional features
based on the java version used to run the build, this means with this
change the jgit packaging build always needs to be run using java 7.
Change-Id: I3d6580d6fa7b22f60d7e54ab236898ed44954ffd
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
This breaks all existing callers once. Applications are not supposed
to build against the internal storage API unless they can accept API
churn and make necessary updates as versions change.
Change-Id: I2ab1327c202ef2003565e1b0770a583970e432e9
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>
Robin Rosenberg
Shawn Pearce
Matthias Sohn
Tomasz Zarna