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2012-09-05Delete storage.dht packageShawn O. Pearce1-34/+0
This experiment proved to be not very useful. I had originally planned to use this on top of Google Bigtable, Apache HBase or Apache Cassandra. Unfortunately the schema is very complex and does not perform well. The storage.dfs package has much better performance and has been in production at Google for many months now, proving it is a viable storage backend for Git. As there are no users of the storage.dht schema, either at Google or any other company, nor any valid open source implementations of the storage system, drop the entire package and API from the JGit project. There is no point in trying to maintain code that is simply not used. Change-Id: Ia8d32f27426d2bcc12e7dc9cc4524c59f4fe4df9 Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
2011-12-15Enforce the use of Java5 API:s only (with a few exceptions)Robin Rosenberg1-0/+6
This only works with Eclipse 3.6 and newer and requires installation of new package. Documentation is not very good, but there is a blog about it here: http://eclipseandjazz.blogspot.com/2011/10/of-invalid-references-to-system.html API checking is especially useful on OS X where Java5 is not readily available. Change-Id: I3c0ad460874a21c073f5ac047146cbf5d31992b4 Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
2011-05-05Store Git on any DHTShawn O. Pearce1-0/+28
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>

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