[Java] Optimize statistics collector, improve object dependency in RocksObjects

Summary:
This diff merges pull request #208.  Contributor: ankgup87

[Java] Optimize statistics collector
* Optimize statistics collector by collecting statistics of multiple DBs in a single thread rather than starting up a new thread for each DB.
* Also, fix packaging of jnilib file on OS_X platform.
* Diff review: https://reviews.facebook.net/D20265

[Java] Add documentation on interdependency of dispose call of RocksObjects
* Remove transferCppRawPointersOwnershipFrom function.
  - This function was setting opt.filter_ and thus filter_ to be null. This way there is no
    one holding reference for filter object and can thus be GC'd which is not the intention.
    Replaced it with storeOptionsInstace which stores options instance. Options class
    internally holds Filter instance. Thus when Options is GC'd, filter reference
    will be GC'd automatically.
* Added documentation explaining interdependency of Filter, Options and DB.
* Diff review: https://reviews.facebook.net/D20379

Test Plan:
described in their diff reviews

Reviewers:  haobo sdong swapnilghike zzbennett rsumbaly yhchiang

Reviewed by: yhchiang
[Java] Optimize statistics collector, improve object dependency in RocksObjects

Summary:
This diff merges pull request 208.  Contributor: ankgup87

[Java] Optimize statistics collector
* Optimize statistics collector by collecting statistics of multiple DBs in a single thread rather than starting up a new thread for each DB.
* Also, fix packaging of jnilib file on OS_X platform.
* Diff review: https://reviews.facebook.net/D20265

[Java] Add documentation on interdependency of dispose call of RocksObjects
* Remove transferCppRawPointersOwnershipFrom function.
  - This function was setting opt.filter_ and thus filter_ to be null. This way there is no
    one holding reference for filter object and can thus be GC'd which is not the intention.
    Replaced it with storeOptionsInstace which stores options instance. Options class
    internally holds Filter instance. Thus when Options is GC'd, filter reference
    will be GC'd automatically.
* Added documentation explaining interdependency of Filter, Options and DB.
* Diff review: https://reviews.facebook.net/D20379

Test Plan:
described in their diff reviews

Reviewers:  haobo sdong swapnilghike zzbennett rsumbaly yhchiang

Reviewed by: yhchiang
Add a utility function to guess optimized options based on constraints

Summary:
Add a function GetOptions(), where based on four parameters users give: read/write amplification threshold, memory budget for mem tables and target DB size, it picks up a compaction style and parameters for them. Background threads are not touched yet.

One limit of this algorithm: since compression rate and key/value size are hard to predict, it's hard to predict level 0 file size from write buffer size. Simply make 1:1 ratio here.

Sample results: https://reviews.facebook.net/P477

Test Plan: Will add some a unit test where some sample scenarios are given and see they pick the results that make sense

Reviewers: yhchiang, dhruba, haobo, igor, ljin

Reviewed By: ljin

Subscribers: leveldb

Differential Revision: https://reviews.facebook.net/D18741
Move include/utilities/*.h to include/rocksdb/utilities/*.h

Summary:
All public headers need to be under `include/rocksdb` directory. Otherwise, clients include our header files like this:

    #include <rocksdb/db.h>
    #include <utilities/backupable_db.h> // still our public header!

Also, internally, we include:

    #include "utilities/backupable/backupable_db.h" // internal header
    #include "utilities/backupable_db.h" // public header

which is confusing.

This way, when we install rocksdb as a system library, we can just copy `include/rocksdb` directory to system's header files. We can't really copy `utilities` directory to system's header files.

Test Plan: compiles

Reviewers: dhruba, ljin, yhchiang, sdong

Reviewed By: sdong

Subscribers: leveldb

Differential Revision: https://reviews.facebook.net/D20409
Bump the version
Also bump version in Makefile
Fixed a bug in Compaction.cc where input_levels_ was not properly resized.

Summary:
Fixed a bug in Compaction.cc where input_levels_ was not properly resized.
Without this fix, there would be invalid access in input_levels_ when more
than two levels are involved in one compaction run.

This fix will go to master instead of compaction branch.

Test Plan: tested in compaction branch.

Reviewers: ljin, sdong, igor

Reviewed By: igor

Subscribers: leveldb

Differential Revision: https://reviews.facebook.net/D20481
Fixed a compile error in util/options_builder.cc

Summary:
Fixed the following compile error by replacing pow by shift, as it computes
power of 2.

util/options_builder.cc:133:14: error: no member named 'pow' in namespace 'std'
        std::pow(2, std::max(0, std::min(3, level0_stop_writes_trigger -
        ~~~~~^
1 error generated.
make: *** [util/options_builder.o] Error 1

Test Plan: make success in mac and linux

Reviewers: ljin, igor, sdong

Reviewed By: sdong

Subscribers: leveldb

Differential Revision: https://reviews.facebook.net/D20475
[Java] Update header inclusion of utilities files

Summary:
Update header inclusion as include/utilities/*.h has been moved to
include/rocksdb/utilities/*.h

Test Plan: make rocksdbjava

Reviewers: ljin, sdong, igor

Reviewed By: igor

Subscribers: leveldb

Differential Revision: https://reviews.facebook.net/D20517
[Java] Add the missing ROCKSDB_JAR variable in Makefile

Summary:
Add the missing ROCKSDB_JAR variable in Makefile, which is mistakenly
removed in https://reviews.facebook.net/D20289.

Test Plan:
export ROCKSDB_JAR=
make rocksdbjava
SpatialDB

Summary:
This diff is adding spatial index support to RocksDB.

When creating the DB user specifies a list of spatial indexes. Spatial indexes can cover different areas and have different resolution (i.e. number of tiles). This is useful for supporting different zoom levels.

Each element inserted into SpatialDB has:
* a bounding box, which determines how will the element be indexed
* string blob, which will usually be WKB representation of the polygon (http://en.wikipedia.org/wiki/Well-known_text)
* feature set, which is a map of key-value pairs, where value can be int, double, bool, null or a string. FeatureSet will be a set of tags associated with geo elements (for example, 'road': 'highway' and similar)
* a list of indexes to insert the element in. For example, small river element will be inserted in index for high zoom level, while country border will be inserted in all indexes (including the index for low zoom level).

Each query is executed on single spatial index. Query guarantees that it will return all elements intersecting the specified bounding box, but it might also return some extra non-intersecting elements.

Test Plan: Added bunch of unit tests in spatial_db_test

Reviewers: dhruba, yinwang

Reviewed By: yinwang

Subscribers: leveldb

Differential Revision: https://reviews.facebook.net/D20361
Use IterKey instead of string in Block::Iter to reduce malloc

Summary:
  Modify a functioin TrimAppend in dbformat.h: IterKey. Write a test for it in dbformat_test
  Use IterKey in block::Iter to replace std::string to reduce malloc.

  Evaluate it using perf record.
  malloc: 4.26% -> 2.91%
  free: 3.61% -> 3.08%

Test Plan:
  make all check
  ./valgrind db_test dbformat_test

Reviewers: ljin, haobo, yhchiang, dhruba, igor, sdong

Reviewed By: sdong

Differential Revision: https://reviews.facebook.net/D20433
Fix release compile error
NewIterators in read-only mode

Summary: As title.

Test Plan: Added test to column_family_test

Reviewers: ljin, yhchiang, sdong

Reviewed By: sdong

Subscribers: leveldb

Differential Revision: https://reviews.facebook.net/D20523
Merge branch 'master' of github.com:facebook/rocksdb into rocks-compaction
Improve the logic of RocksUniversalCompaction

Summary:
RocksUniversalCompaction now proceeds as follows:
1. Find the first level which has files
2. Compute the estimated output size.
3. If the output size exceed the size limit of the current level,
   then include files in the current level; level++ and repeat
   step 2 and 3 until the current level can fit the output.

Size limit of each level is determined by the following equation, which is
the same as level compaction.
    max_bytes_for_level_base * max_bytes_for_level_multiplier^level

When max_bytes_for_level_multiplier is set to 2, then it is equivalent to
universal compaction.

This patch also fixed the errors where number of compaction input is hard
coded to 2 (while D20577 is waiting for approval in the master)

Next Step: fix the doubling-in-space issue of universal compaction.

Test Plan: Now all test passed!!

Reviewers: igor, ljin, sdong

Subscribers: leveldb

Differential Revision: https://reviews.facebook.net/D20583