Summary: Add Java binding and test for rocksdb::ReadOptions.

Test Plan:
make rocksdbjava
make jtest

Reviewers: haobo, dhruba, sdong, ankgup87, rsumbaly, swapnilghike, zzbennett

Reviewed By: haobo

CC: leveldb

Differential Revision: https://reviews.facebook.net/D18129

Summary:
Add Java bindings for memtables and sst format.  Specifically,
add two abstract Java classses --- MemTableConfig and SstFormatConfig.
Each MemTable / SST implementation should has its own config class
extends MemTableConfig / SstFormatConfig respectively and pass it
to Options via setMemTableConfig / setSstConfig.

Test Plan:
make rocksdbjava
make jdb_test
make jdb_bench
java/jdb_bench.sh \
  --benchmarks=fillseq,readrandom,readwhilewriting \
  --memtablerep=hash_skiplist \
  --use_plain_table=1 \
  --key_size=20 \
  --prefix_size=12 \
  --value_size=100 \
  --cache_size=17179869184 \
  --disable_wal=0 \
  --sync=0 \

Reviewers: haobo, ankgup87, sdong

Reviewed By: haobo

CC: leveldb, dhruba

Differential Revision: https://reviews.facebook.net/D17997

Summary:
* Add a class SizeUnit to store frequently used consts.  Currently
  it has KB, MB, GB, TB, and PB.

* Change the parameter type of Options.writeBufferSize and Options.blockSize
  from int to long.

Test Plan:
make rocksdbjava
make jtest

Reviewers: haobo, ankgup87, sdong, dhruba

Reviewed By: haobo

CC: leveldb

Differential Revision: https://reviews.facebook.net/D17703

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:
Make each set function of Options / WriteOptions return its option instance.
Java developers can now easier specify each option like the following:

    options.setCreateIfMissing(true)
        .setWriteBufferSize(8 * 1024)
        .setMaxWriteBufferNumber(3)
        .setDisableSeekCompaction(true)
        .setBlockSize(64 * 1024)
        .setMaxBackgroundCompactions(10);

Test Plan:
make rocksdbjava
make jtest

Reviewers: haobo, ankgup87, sdong, dhruba

Reviewed By: haobo

CC: leveldb

Differential Revision: https://reviews.facebook.net/D17661

Expose JNI layer for these options: block_size, max_write_buffer_number, write_buffer_size, disable_seek_compaction, max_background_compactions.

[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