Summary:
MurmurHash becomes expensive when we do millions Get() a second in one
thread. Add this option to allow the first hash function to use identity
function as hash function. It results in QPS increase from 3.7M/s to
~4.3M/s. I did not observe improvement for end to end RocksDB
performance. This may be caused by other bottlenecks that I will address
in a separate diff.

Test Plan:
```
[ljin@dev1964 rocksdb] ./cuckoo_table_reader_test --enable_perf --file_dir=/dev/shm --write --identity_as_first_hash=0
==== Test CuckooReaderTest.WhenKeyExists
==== Test CuckooReaderTest.WhenKeyExistsWithUint64Comparator
==== Test CuckooReaderTest.CheckIterator
==== Test CuckooReaderTest.CheckIteratorUint64
==== Test CuckooReaderTest.WhenKeyNotFound
==== Test CuckooReaderTest.TestReadPerformance
With 125829120 items, utilization is 93.75%, number of hash functions: 2.
Time taken per op is 0.272us (3.7 Mqps) with batch size of 0, # of found keys 125829120
With 125829120 items, utilization is 93.75%, number of hash functions: 2.
Time taken per op is 0.138us (7.2 Mqps) with batch size of 10, # of found keys 125829120
With 125829120 items, utilization is 93.75%, number of hash functions: 2.
Time taken per op is 0.142us (7.1 Mqps) with batch size of 25, # of found keys 125829120
With 125829120 items, utilization is 93.75%, number of hash functions: 2.
Time taken per op is 0.142us (7.0 Mqps) with batch size of 50, # of found keys 125829120
With 125829120 items, utilization is 93.75%, number of hash functions: 2.
Time taken per op is 0.144us (6.9 Mqps) with batch size of 100, # of found keys 125829120

With 104857600 items, utilization is 78.12%, number of hash functions: 2.
Time taken per op is 0.201us (5.0 Mqps) with batch size of 0, # of found keys 104857600
With 104857600 items, utilization is 78.12%, number of hash functions: 2.
Time taken per op is 0.121us (8.3 Mqps) with batch size of 10, # of found keys 104857600
With 104857600 items, utilization is 78.12%, number of hash functions: 2.
Time taken per op is 0.123us (8.1 Mqps) with batch size of 25, # of found keys 104857600
With 104857600 items, utilization is 78.12%, number of hash functions: 2.
Time taken per op is 0.121us (8.3 Mqps) with batch size of 50, # of found keys 104857600
With 104857600 items, utilization is 78.12%, number of hash functions: 2.
Time taken per op is 0.112us (8.9 Mqps) with batch size of 100, # of found keys 104857600

With 83886080 items, utilization is 62.50%, number of hash functions: 2.
Time taken per op is 0.251us (4.0 Mqps) with batch size of 0, # of found keys 83886080
With 83886080 items, utilization is 62.50%, number of hash functions: 2.
Time taken per op is 0.107us (9.4 Mqps) with batch size of 10, # of found keys 83886080
With 83886080 items, utilization is 62.50%, number of hash functions: 2.
Time taken per op is 0.099us (10.1 Mqps) with batch size of 25, # of found keys 83886080
With 83886080 items, utilization is 62.50%, number of hash functions: 2.
Time taken per op is 0.100us (10.0 Mqps) with batch size of 50, # of found keys 83886080
With 83886080 items, utilization is 62.50%, number of hash functions: 2.
Time taken per op is 0.116us (8.6 Mqps) with batch size of 100, # of found keys 83886080

With 73400320 items, utilization is 54.69%, number of hash functions: 2.
Time taken per op is 0.189us (5.3 Mqps) with batch size of 0, # of found keys 73400320
With 73400320 items, utilization is 54.69%, number of hash functions: 2.
Time taken per op is 0.095us (10.5 Mqps) with batch size of 10, # of found keys 73400320
With 73400320 items, utilization is 54.69%, number of hash functions: 2.
Time taken per op is 0.096us (10.4 Mqps) with batch size of 25, # of found keys 73400320
With 73400320 items, utilization is 54.69%, number of hash functions: 2.
Time taken per op is 0.098us (10.2 Mqps) with batch size of 50, # of found keys 73400320
With 73400320 items, utilization is 54.69%, number of hash functions: 2.
Time taken per op is 0.105us (9.5 Mqps) with batch size of 100, # of found keys 73400320

[ljin@dev1964 rocksdb] ./cuckoo_table_reader_test --enable_perf --file_dir=/dev/shm --write --identity_as_first_hash=1
==== Test CuckooReaderTest.WhenKeyExists
==== Test CuckooReaderTest.WhenKeyExistsWithUint64Comparator
==== Test CuckooReaderTest.CheckIterator
==== Test CuckooReaderTest.CheckIteratorUint64
==== Test CuckooReaderTest.WhenKeyNotFound
==== Test CuckooReaderTest.TestReadPerformance
With 125829120 items, utilization is 93.75%, number of hash functions: 2.
Time taken per op is 0.230us (4.3 Mqps) with batch size of 0, # of found keys 125829120
With 125829120 items, utilization is 93.75%, number of hash functions: 2.
Time taken per op is 0.086us (11.7 Mqps) with batch size of 10, # of found keys 125829120
With 125829120 items, utilization is 93.75%, number of hash functions: 2.
Time taken per op is 0.088us (11.3 Mqps) with batch size of 25, # of found keys 125829120
With 125829120 items, utilization is 93.75%, number of hash functions: 2.
Time taken per op is 0.083us (12.1 Mqps) with batch size of 50, # of found keys 125829120
With 125829120 items, utilization is 93.75%, number of hash functions: 2.
Time taken per op is 0.083us (12.1 Mqps) with batch size of 100, # of found keys 125829120

With 104857600 items, utilization is 78.12%, number of hash functions: 2.
Time taken per op is 0.159us (6.3 Mqps) with batch size of 0, # of found keys 104857600
With 104857600 items, utilization is 78.12%, number of hash functions: 2.
Time taken per op is 0.078us (12.8 Mqps) with batch size of 10, # of found keys 104857600
With 104857600 items, utilization is 78.12%, number of hash functions: 2.
Time taken per op is 0.080us (12.6 Mqps) with batch size of 25, # of found keys 104857600
With 104857600 items, utilization is 78.12%, number of hash functions: 2.
Time taken per op is 0.080us (12.5 Mqps) with batch size of 50, # of found keys 104857600
With 104857600 items, utilization is 78.12%, number of hash functions: 2.
Time taken per op is 0.082us (12.2 Mqps) with batch size of 100, # of found keys 104857600

With 83886080 items, utilization is 62.50%, number of hash functions: 2.
Time taken per op is 0.154us (6.5 Mqps) with batch size of 0, # of found keys 83886080
With 83886080 items, utilization is 62.50%, number of hash functions: 2.
Time taken per op is 0.077us (13.0 Mqps) with batch size of 10, # of found keys 83886080
With 83886080 items, utilization is 62.50%, number of hash functions: 2.
Time taken per op is 0.077us (12.9 Mqps) with batch size of 25, # of found keys 83886080
With 83886080 items, utilization is 62.50%, number of hash functions: 2.
Time taken per op is 0.078us (12.8 Mqps) with batch size of 50, # of found keys 83886080
With 83886080 items, utilization is 62.50%, number of hash functions: 2.
Time taken per op is 0.079us (12.6 Mqps) with batch size of 100, # of found keys 83886080

With 73400320 items, utilization is 54.69%, number of hash functions: 2.
Time taken per op is 0.218us (4.6 Mqps) with batch size of 0, # of found keys 73400320
With 73400320 items, utilization is 54.69%, number of hash functions: 2.
Time taken per op is 0.083us (12.0 Mqps) with batch size of 10, # of found keys 73400320
With 73400320 items, utilization is 54.69%, number of hash functions: 2.
Time taken per op is 0.085us (11.7 Mqps) with batch size of 25, # of found keys 73400320
With 73400320 items, utilization is 54.69%, number of hash functions: 2.
Time taken per op is 0.086us (11.6 Mqps) with batch size of 50, # of found keys 73400320
With 73400320 items, utilization is 54.69%, number of hash functions: 2.
Time taken per op is 0.078us (12.8 Mqps) with batch size of 100, # of found keys 73400320
```

Reviewers: sdong, igor, yhchiang

Reviewed By: igor

Subscribers: leveldb

Differential Revision: https://reviews.facebook.net/D23451

Summary:
Fixed a signed-unsigned comparison in spatial_db.cc

utilities/spatialdb/spatial_db.cc:542:38: error: comparison between signed and unsigned integer expressions [-Werror=sign-compare]
cc1plus: all warnings being treated as errors
make: *** [utilities/spatialdb/spatial_db.o] Error 1

Test Plan:
make spatial_db_test
./spatial_db_test

Reviewers: ljin, sdong, reddragon, igor

Reviewed By: reddragon

Subscribers: reddragon, leveldb

Differential Revision: https://reviews.facebook.net/D23565

Summary:
This is continuing the work done by https://github.com/facebook/rocksdb/commit/27b22f13a300c00c72de7fc826fdae21a734eb49

It's just cleaning up some unnecessary constructors. The most important change is removing Block::Block(const BlockContents& contents) constructor. It was only used from the unit test.

Test Plan: compiles

Reviewers: sdong, yhchiang, ljin

Reviewed By: ljin

Subscribers: leveldb

Differential Revision: https://reviews.facebook.net/D23547

Summary:
as title

Test Plan:
./cuckoo_table_builder_test

Reviewers:igor

CC:leveldb

Task ID: #

Blame Rev:

Decompression refactoring

This replaces a mishmash of pointers in the Block and BlockContents classes with
std::unique_ptr. It also changes the semantics of BlockContents to be limited to
use as a constructor parameter for Block objects, as it owns any block buffers
handed to it.

Summary:
This is to avoid cutting file prematurely and resulting file size to be
half of specified.

Test Plan: db_bench

Reviewers: sdong, yhchiang, igor

Reviewed By: igor

Subscribers: leveldb

Differential Revision: https://reviews.facebook.net/D23541

Summary: as title

Test Plan:
make all check
I will think a way to set up stress test for this

Reviewers: sdong, yhchiang, igor

Reviewed By: igor

Subscribers: leveldb

Differential Revision: https://reviews.facebook.net/D23055

Summary: as title

Test Plan: options_test

Reviewers: sdong, yhchiang, igor

Reviewed By: igor

Subscribers: leveldb

Differential Revision: https://reviews.facebook.net/D23283

util/cache_bench.cc needs to include inttypes.h

Summary: We currently don't test mmap reads as part of db_test. Piggyback it on kWalDir test config.

Test Plan: make check

Reviewers: ljin, sdong, yhchiang

Reviewed By: yhchiang

Subscribers: leveldb

Differential Revision: https://reviews.facebook.net/D23337

Summary:
Fixed 32-bit overflowing issue when converting jlong to size_t by
capping jlong to std::numeric_limits<size_t>::max().

Test Plan:
make rocksdbjava
make jtest

Reviewers: ankgup87, ljin, sdong, igor

Reviewed By: igor

Subscribers: leveldb

Differential Revision: https://reviews.facebook.net/D23511

Summary: This work on my compiler, but it turns out some compilers don't implicitly add constness, see: https://github.com/facebook/rocksdb/issues/284. This diff adds constness explicitly.

Test Plan: still compiles

Reviewers: sdong

Reviewed By: sdong

Subscribers: leveldb

Differential Revision: https://reviews.facebook.net/D23409

Summary: See https://github.com/facebook/rocksdb/issues/283

Test Plan: make install/uninstall

Reviewers: ljin, sdong, yhchiang

Reviewed By: yhchiang

Subscribers: leveldb

Differential Revision: https://reviews.facebook.net/D23373

Summary:
Include WriteBatch into RocksDBSample.java, fix how DbBenchmark.java handles WriteBatch.
Previously DbBenchmark.java does not use WriteBatch when benchmarks is set to fillbatch.

Test Plan:
make rocksdbjava -j32
make jtest
make jdb_bench
cd java
./jdb_bench.sh --benchmarks=fillbatch

Reviewers: naveenatceg, ljin, sdong, ankgup87

Reviewed By: ankgup87

Subscribers: leveldb

Differential Revision: https://reviews.facebook.net/D22983

Summary: As we discussed offline

Test Plan: compiles

Reviewers: yhchiang, sdong, ljin, dhruba

Reviewed By: sdong

Subscribers: leveldb

Differential Revision: https://reviews.facebook.net/D22989

fix rate limiter crash #286

Summary:
Hope these scripts will allow people to run/repro benchmark easily
I think it is time to re-run flash benchmarks and report results
Please comment if any other benchmark runs are needed

Test Plan: ran it

Reviewers: yhchiang, igor, sdong

Reviewed By: igor

Subscribers: dhruba, MarkCallaghan, leveldb

Differential Revision: https://reviews.facebook.net/D23139

Summary: This diff just moves the write thread control out of the DBImpl. I will need this as I will control column family data concurrency by only accessing some data in the write thread. That way, we won't have to lock our accesses to column family hash table (mappings from IDs to CFDs).

Test Plan: make check

Reviewers: sdong, yhchiang, ljin

Reviewed By: ljin

Subscribers: leveldb

Differential Revision: https://reviews.facebook.net/D23301

Summary: Uhm...

Test Plan: nope

Reviewers: sdong, yhchiang, tnovak, ljin

Reviewed By: ljin

Subscribers: leveldb

Differential Revision: https://reviews.facebook.net/D23343

Fix build issue under macosx

Summary:
Add make install.  If INSTALL_PATH is not set, then rocksdb will be
installed under "/usr/local" directory (/usr/local/include for headers
and /usr/local/lib for library file(s).)

Test Plan:
Develop a simple rocksdb app, called test.cc, and do the followings.

make clean
make static_lib -j32
sudo make install
g++ -std=c++11 test.cc -lrocksdb -lbz2 -lz -o test
./test

sudo make uninstall
make clean
make shared_lib -j32
sudo make install
g++ -std=c++11 test.cc -lrocksdb -lbz2 -lz -o test
./test

make INSTALL_PATH=/tmp/path install
make INSTALL_PATH=/tmp/path uninstall
and make sure things are installed / uninstalled in the specified path.

Reviewers: ljin, sdong, igor

Reviewed By: igor

Subscribers: leveldb

Differential Revision: https://reviews.facebook.net/D23211

Summary:
1. wrap a filter policy like what fbcode/multifeed/rocksdb/MultifeedRocksDbKey.h
   to ensure that rocksdb works fine after filterpolicy interface change

Test Plan: 1. valgrind ./bloom_test

Reviewers: ljin, igor, yhchiang, dhruba, sdong

Reviewed By: sdong

Subscribers: leveldb

Differential Revision: https://reviews.facebook.net/D23229

Summary:
If bg_error_ is set, that means that we mark DB read only. However, current behavior still continues the flushes and compactions, even though bg_error_ is set.

On the other hand, if bg_error_ is set, we will return Status::OK() from CompactRange(), although the compaction didn't actually succeed.

This is clearly not desired behavior. I found this when I was debugging t5132159, although I'm pretty sure these aren't related.

Also, when we're shutting down, it's dangerous to exit RunManualCompaction(), since that will destruct ManualCompaction object. Background compaction job might still hold a reference to manual_compaction_ and this will lead to undefined behavior. I changed the behavior so that we only exit RunManualCompaction when manual compaction job is marked done.

Test Plan: make check

Reviewers: sdong, ljin, yhchiang

Reviewed By: yhchiang

Subscribers: leveldb

Differential Revision: https://reviews.facebook.net/D23223

Summary: Get valgrind to stop complaining about uninitialized value

Test Plan: valgrind not complaining anymore

Reviewers: sdong, yhchiang, ljin

Reviewed By: ljin

Subscribers: leveldb

Differential Revision: https://reviews.facebook.net/D23289

Summary: The test makes sure that we don't call flush too often. For that, it's ok to check if we have less than 10 table files. Otherwise, the test is flaky because it's hard to estimate number of entries in the memtable before it gets flushed (any ideas?)

Test Plan: Still works, but hopefully less flaky.

Reviewers: ljin, sdong, yhchiang

Reviewed by: yhchiang

Subscribers: leveldb

Differential Revision: https://reviews.facebook.net/D23241

Summary:
When memtable is full it calls the registered callback. That callback then registers column family as needing the flush. Every write checks if there are some column families that need to be flushed. This completely eliminates the need for MakeRoomForWrite() function and simplifies our Write code-path.

There is some complexity with the concurrency when the column family is dropped. I made it a bit less complex by dropping the column family from the write thread in https://reviews.facebook.net/D22965. Let me know if you want to discuss this.

Test Plan: make check works. I'll also run db_stress with creating and dropping column families for a while.

Reviewers: yhchiang, sdong, ljin

Reviewed By: ljin

Subscribers: leveldb

Differential Revision: https://reviews.facebook.net/D23067

Summary:
See t5106397.

Also, few more changes:
1. in unit tests, the assumption is that writes will be dropped when there is no space left on device. I changed the wording around it.
2. InvalidArgument() errors are only when user-provided arguments are invalid. When the file is corrupted, we need to return Status::Corruption

Test Plan: make check

Reviewers: sdong, ljin

Reviewed By: ljin

Subscribers: leveldb

Differential Revision: https://reviews.facebook.net/D23145

Summary: as title

Test Plan: make rocksdbjava

Reviewers: sdong, yhchiang, igor

Reviewed By: igor

Subscribers: leveldb

Differential Revision: https://reviews.facebook.net/D23193

Summary: print qps in summary

Test Plan: ./cache_bench

Reviewers: yhchiang, ljin, sdong, igor

Reviewed By: igor

Subscribers: leveldb

Differential Revision: https://reviews.facebook.net/D23079