Summary:
Add java bindings for Options.block_cache and allow DbBenchmark to
set cache_size.

Test Plan:
make rocksdbjava
make jtest
make jdb_Bench

Reviewers: haobo, sdong, ankgup87

Reviewed By: ankgup87

CC: leveldb, dhruba

Differential Revision: https://reviews.facebook.net/D17481

Summary:
* Add a benchmark for java binding for rocksdb.  The java benchmark
  is a complete rewrite based on the c++ db/db_bench.cc and the
  DbBenchmark in dain's java leveldb.
* Support multithreading.
* 'readseq' is currently not supported as it requires RocksDB Iterator.

* usage:

  --benchmarks
    Comma-separated list of operations to run in the specified order
        Actual benchmarks:
                fillseq    -- write N values in sequential key order in async mode
                fillrandom -- write N values in random key order in async mode
                fillbatch  -- write N/1000 batch where each batch has 1000 values
                              in random key order in sync mode
                fillsync   -- write N/100 values in random key order in sync mode
                fill100K   -- write N/1000 100K values in random order in async mode
                readseq    -- read N times sequentially
                readrandom -- read N times in random order
                readhot    -- read N times in random order from 1% section of DB
        Meta Operations:
                delete     -- delete DB
    DEFAULT: [fillseq, readrandom, fillrandom]

  --compression_ratio
    Arrange to generate values that shrink to this fraction of
        their original size after compression
    DEFAULT: 0.5

  --use_existing_db
    If true, do not destroy the existing database.  If you set this
        flag and also specify a benchmark that wants a fresh database,  that benchmark will fail.
    DEFAULT: false

  --num
    Number of key/values to place in database.
    DEFAULT: 1000000

  --threads
    Number of concurrent threads to run.
    DEFAULT: 1

  --reads
    Number of read operations to do.  If negative, do --nums reads.

  --key_size
    The size of each key in bytes.
    DEFAULT: 16

  --value_size
    The size of each value in bytes.
    DEFAULT: 100

  --write_buffer_size
    Number of bytes to buffer in memtable before compacting
        (initialized to default value by 'main'.)
    DEFAULT: 4194304

  --cache_size
    Number of bytes to use as a cache of uncompressed data.
        Negative means use default settings.
    DEFAULT: -1

  --seed
    Seed base for random number generators.
    DEFAULT: 0

  --db
    Use the db with the following name.
    DEFAULT: /tmp/rocksdbjni-bench

* Add RocksDB.write().

Test Plan: make jbench

Reviewers: haobo, sdong, dhruba, ankgup87

Reviewed By: haobo

CC: leveldb

Differential Revision: https://reviews.facebook.net/D17433

Summary: Avoid a JNI call to GetByteArrayElements, which may introduce a byte-array-copy.

Test Plan: make jtest

Reviewers: haobo, sdong, dhruba

CC: leveldb

Differential Revision: https://reviews.facebook.net/D17451

Summary:
Improve the internal interface between java and c++ for basic db operations
by including the RocksDB native handle (i.e., c++ pointer of rocksdb::DB)
as a input parameter of the internal interface.

This improvement reduces one JNI call per db operation from c++.

Test Plan: make test

Reviewers: haobo, sdong, dhruba

Reviewed By: sdong

CC: leveldb

Differential Revision: https://reviews.facebook.net/D17445

[JNI] Add java api and java tests for WriteBatch and WriteOptions, add put() and remove() to RocksDB.

Summary:
* Add java api for rocksdb::WriteBatch and rocksdb::WriteOptions, which are necessary components
  for running benchmark.
* Add java test for org.rocksdb.WriteBatch and org.rocksdb.WriteOptions.
* Add remove() to org.rocksdb.RocksDB, and add put() and remove() to RocksDB which take
  org.rocksdb.WriteOptions.

Test Plan: make jtest

Reviewers: haobo, sdong, dhruba

Reviewed By: sdong

CC: leveldb

Differential Revision: https://reviews.facebook.net/D17373

Summary:
* [java] Add a java api for rocksdb::Options, currently only supports create_if_missing.
* [java] Add a test for RocksDBException in RocksDBSample.

Test Plan: make jtest

Reviewers: haobo, sdong

Reviewed By: haobo

CC: leveldb, dhruba

Differential Revision: https://reviews.facebook.net/D17385

Summary:
* [java] RocksDB now does not implement Closeable.
* [java] RocksDB.close() is now synchronized.
* [c++] Fix a bug in rocksjni.cc that does not release a java reference before
        throwing an exception.

Test Plan:
make jni
make jtest

Reviewers: haobo, sdong

Reviewed By: haobo

CC: leveldb

Differential Revision: https://reviews.facebook.net/D17355

Summary: Fix a bug in RocksDBSample.java and minor code improvement in rocksjni.cc.

Test Plan:
make jni
make jtest

Reviewers: haobo, sdong

Reviewed By: haobo

CC: leveldb

Differential Revision: https://reviews.facebook.net/D17325

Summary:
This diff contains a simple jni library for rocksdb which supports open, get,
put and closeusing default options (including Options, ReadOptions, and
WriteOptions.)  In the usual case, Java developers can use the c++ rocksdb
library in the way similar to the following:

    RocksDB db = RocksDB.open(path_to_db);
    ...
    db.put("hello".getBytes(), "world".getBytes();
    byte[] value = db.get("hello".getBytes());
    ...
    db.close();

Specifically, this diff has the following major classes:

* RocksDB: a Java wrapper class which forwards the operations
  from the java side to c++ rocksdb library.
* RocksDBException: ncapsulates the error of an operation.
  This exception type is used to describe an internal error from
  the c++ rocksdb library.

This diff also include a simple java sample code calling c++ rocksdb library.

To build the rocksdb jni library, simply run make jni, and make jtest will try to
build and run the sample code.

Note that if the rocksdb is not built with the default glibc that Java uses,
java will try to load the wrong glibc during the run time.  As a result,
the sample code might not work properly during the run time.

Test Plan:
* make jni
* make jtest

Reviewers: haobo, dhruba, sdong, igor, ljin

Reviewed By: dhruba

CC: leveldb, xjin

Differential Revision: https://reviews.facebook.net/D17109