Commit Graph

35 Commits

Author SHA1 Message Date
Levi Tamasi
9f21d08660 Move kNoExpiration to blob_db.h (#7018)
Summary:
The constant `kNoExpiration` is currently defined in an
internal/implementation header (`blob_log_format.h`); the patch moves it
to the public header `blob_db.h` so it is accessible to users.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/7018

Test Plan: `make check`

Reviewed By: riversand963

Differential Revision: D22191354

Pulled By: ltamasi

fbshipit-source-id: 98c8012a83b999a3f1a30e955ce6bb71ba29dc5c
2020-06-23 13:45:06 -07:00
Levi Tamasi
06c3b85b9a Disallow using the base DB's storage directory as blob_dir in BlobDB (#6810)
Summary:
https://github.com/facebook/rocksdb/pull/6807 extends the logic that
identifies and purges obsolete files to blob files handled by RocksDB
itself. In order to prevent that from interfering with the current BlobDB code,
we need to make sure that `BlobDBOptions::blob_dir` is different from
the storage directories used by the base DB. (Note: this is true by default.)
The patch adds a check that explicitly disallows this configuration and
returns `Status::NotSupported` from `BlobDB::Open` in such cases.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6810

Test Plan: Tested using the BlobDB mode of `db_bench`.

Reviewed By: riversand963

Differential Revision: D21412676

Pulled By: ltamasi

fbshipit-source-id: 6630cc7481e48c8bf55d59423b25f14d52ffe681
2020-05-06 14:00:46 -07:00
sdong
fdf882ded2 Replace namespace name "rocksdb" with ROCKSDB_NAMESPACE (#6433)
Summary:
When dynamically linking two binaries together, different builds of RocksDB from two sources might cause errors. To provide a tool for user to solve the problem, the RocksDB namespace is changed to a flag which can be overridden in build time.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6433

Test Plan: Build release, all and jtest. Try to build with ROCKSDB_NAMESPACE with another flag.

Differential Revision: D19977691

fbshipit-source-id: aa7f2d0972e1c31d75339ac48478f34f6cfcfb3e
2020-02-20 12:09:57 -08:00
Levi Tamasi
1dd7873e08 Remove earlier partial BlobDB GC implementation (#6278)
Summary:
In addition to removing the earlier partially implemented garbage collection
logic from the BlobDB codebase, the patch also removes the test cases (as well as
the related sync points, as appropriate) that were only relevant for the old
implementation, and reworks the remaining ones so they use the new GC logic.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6278

Test Plan: `make check`

Differential Revision: D19335226

Pulled By: ltamasi

fbshipit-source-id: 0cc1794bc9892feda1426ed5522a318f3cb1b692
2020-01-14 15:08:44 -08:00
Levi Tamasi
7a7ca8eb5b BlobDB: only compare CF IDs when checking whether an API call is for the default CF (#6226)
Summary:
BlobDB currently only supports using the default column family. The earlier
code enforces this by comparing the `ColumnFamilyHandle` passed to the
`Get`/`Put`/etc. call with the handle returned by `DefaultColumnFamily`
(which, at the end of the day, comes from `DBImpl::default_cf_handle_`).
Since other `ColumnFamilyHandle`s can also point to the default column
family, this can reject legitimate requests as well. (As an example,
with the earlier code, the handle returned by `BlobDB::Open` cannot
actually be used in API calls.) The patch fixes this by comparing only
the IDs of the column family handles instead of the pointers themselves.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6226

Test Plan: `make check`

Differential Revision: D19187461

Pulled By: ltamasi

fbshipit-source-id: 54ce2e12ebb1f07e6d1e70e3b1e0213dfa94bda2
2019-12-19 18:05:49 -08:00
Levi Tamasi
583c6953d8 Move out valid blobs from the oldest blob files during compaction (#6121)
Summary:
The patch adds logic that relocates live blobs from the oldest N non-TTL
blob files as they are encountered during compaction (assuming the BlobDB
configuration option `enable_garbage_collection` is `true`), where N is defined
as the number of immutable non-TTL blob files multiplied by the value of
a new BlobDB configuration option called `garbage_collection_cutoff`.
(The default value of this parameter is 0.25, that is, by default the valid blobs
residing in the oldest 25% of immutable non-TTL blob files are relocated.)
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6121

Test Plan: Added unit test and tested using the BlobDB mode of `db_bench`.

Differential Revision: D18785357

Pulled By: ltamasi

fbshipit-source-id: 8c21c512a18fba777ec28765c88682bb1a5e694e
2019-12-13 10:13:05 -08:00
Levi Tamasi
8e7aa62813 BlobDB: Maintain mapping between blob files and SSTs (#6020)
Summary:
The patch adds logic to BlobDB to maintain the mapping between blob files
and SSTs for which the blob file in question is the oldest blob file referenced
by the SST file. The mapping is initialized during database open based on the
information retrieved using `GetLiveFilesMetaData`, and updated after
flushes/compactions based on the information received through the `EventListener`
interface (or, in the case of manual compactions issued through the `CompactFiles`
API, the `CompactionJobInfo` object).
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6020

Test Plan: Added a unit test; also tested using the BlobDB mode of `db_bench`.

Differential Revision: D18410508

Pulled By: ltamasi

fbshipit-source-id: dd9e778af781cfdb0d7056298c54ba9cebdd54a5
2019-11-11 14:01:34 -08:00
anand76
fefd4b98c5 Introduce a new MultiGet batching implementation (#5011)
Summary:
This PR introduces a new MultiGet() API, with the underlying implementation grouping keys based on SST file and batching lookups in a file. The reason for the new API is twofold - the definition allows callers to allocate storage for status and values on stack instead of std::vector, as well as return values as PinnableSlices in order to avoid copying, and it keeps the original MultiGet() implementation intact while we experiment with batching.

Batching is useful when there is some spatial locality to the keys being queries, as well as larger batch sizes. The main benefits are due to -
1. Fewer function calls, especially to BlockBasedTableReader::MultiGet() and FullFilterBlockReader::KeysMayMatch()
2. Bloom filter cachelines can be prefetched, hiding the cache miss latency

The next step is to optimize the binary searches in the level_storage_info, index blocks and data blocks, since we could reduce the number of key comparisons if the keys are relatively close to each other. The batching optimizations also need to be extended to other formats, such as PlainTable and filter formats. This also needs to be added to db_stress.

Benchmark results from db_bench for various batch size/locality of reference combinations are given below. Locality was simulated by offsetting the keys in a batch by a stride length. Each SST file is about 8.6MB uncompressed and key/value size is 16/100 uncompressed. To focus on the cpu benefit of batching, the runs were single threaded and bound to the same cpu to eliminate interference from other system events. The results show a 10-25% improvement in micros/op from smaller to larger batch sizes (4 - 32).

Batch   Sizes

1        | 2        | 4         | 8      | 16  | 32

Random pattern (Stride length 0)
4.158 | 4.109 | 4.026 | 4.05 | 4.1 | 4.074        - Get
4.438 | 4.302 | 4.165 | 4.122 | 4.096 | 4.075 - MultiGet (no batching)
4.461 | 4.256 | 4.277 | 4.11 | 4.182 | 4.14        - MultiGet (w/ batching)

Good locality (Stride length 16)
4.048 | 3.659 | 3.248 | 2.99 | 2.84 | 2.753
4.429 | 3.728 | 3.406 | 3.053 | 2.911 | 2.781
4.452 | 3.45 | 2.833 | 2.451 | 2.233 | 2.135

Good locality (Stride length 256)
4.066 | 3.786 | 3.581 | 3.447 | 3.415 | 3.232
4.406 | 4.005 | 3.644 | 3.49 | 3.381 | 3.268
4.393 | 3.649 | 3.186 | 2.882 | 2.676 | 2.62

Medium locality (Stride length 4096)
4.012 | 3.922 | 3.768 | 3.61 | 3.582 | 3.555
4.364 | 4.057 | 3.791 | 3.65 | 3.57 | 3.465
4.479 | 3.758 | 3.316 | 3.077 | 2.959 | 2.891

dbbench command used (on a DB with 4 levels, 12 million keys)-
TEST_TMPDIR=/dev/shm numactl -C 10  ./db_bench.tmp -use_existing_db=true -benchmarks="readseq,multireadrandom" -write_buffer_size=4194304 -target_file_size_base=4194304 -max_bytes_for_level_base=16777216 -num=12000000 -reads=12000000 -duration=90 -threads=1 -compression_type=none -cache_size=4194304000 -batch_size=32 -disable_auto_compactions=true -bloom_bits=10 -cache_index_and_filter_blocks=true -pin_l0_filter_and_index_blocks_in_cache=true -multiread_batched=true -multiread_stride=4
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5011

Differential Revision: D14348703

Pulled By: anand1976

fbshipit-source-id: 774406dab3776d979c809522a67bedac6c17f84b
2019-04-11 14:28:26 -07:00
Levi Tamasi
79b6ab43ce BlobDB: Remove GC interval option (#5044)
Summary:
Remove BlobDBOptions.garbage_collection_interval_secs for now, since
garbage collection is not yet implemented in BlobDB.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5044

Differential Revision: D14354046

Pulled By: ltamasi

fbshipit-source-id: 2b966b6d1e088ba9462f3ea73e115013562fbc04
2019-03-07 10:19:05 -08:00
Sagar Vemuri
3cfc7515fc Remove an unused option (#4888)
Summary:
Remove `garbage_collection_deletion_size_threshold` as it is not used anywhere.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4888

Differential Revision: D13685982

Pulled By: sagar0

fbshipit-source-id: e08d3017b9a0c8fa99bc332b595ee4ed9db70c87
2019-01-16 11:48:43 -08:00
Sagar Vemuri
55e03b67df Correct the comment about inlined blob option (#4887)
Summary:
- Corrected a comment asserting that the values "smaller" than a min_blob_size will be inlined in the base db.
- Also fixed the type of ttl_range_secs while dumping blobdb options.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4887

Differential Revision: D13680163

Pulled By: sagar0

fbshipit-source-id: 306c8cf2daa52210ffc334a6924ef44ffdedf887
2019-01-15 16:36:49 -08:00
Yi Wu
c970358574 BlobDB: Can return expiration together with Get() (#4227)
Summary:
Add API to allow fetching expiration of a key with `Get()`.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4227

Differential Revision: D9169897

Pulled By: yiwu-arbug

fbshipit-source-id: 2a6f216c493dc75731ddcef1daa689b517fab31b
2018-08-06 17:43:14 -07:00
Yi Wu
140f256da2 BlobDB: Cleanup TTLExtractor interface (#4229)
Summary:
Cleanup TTLExtractor interface. The original purpose of it is to allow our users keep using existing `Write()` interface but allow it to accept TTL via `TTLExtractor`. However the interface is confusing. Will replace it with something like `WriteWithTTL(batch, ttl)` in the future.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4229

Differential Revision: D9174390

Pulled By: yiwu-arbug

fbshipit-source-id: 68201703d784408b851336ab4dd9b84188245b2d
2018-08-06 11:58:05 -07:00
Yi Wu
6d454d7376 BlobDB: is_fifo=true also evict non-TTL blob files (#4049)
Summary:
Previously with is_fifo=true we only evict TTL file. Changing it to also evict non-TTL files from oldest to newest, after exhausted TTL files.
Closes https://github.com/facebook/rocksdb/pull/4049

Differential Revision: D8604597

Pulled By: yiwu-arbug

fbshipit-source-id: bc4209ee27c1528ce4b72833e6f1e1bff80082c1
2018-06-25 22:43:05 -07:00
Yi Wu
b864bc9b5b Blob DB: Improve FIFO eviction
Summary:
Improving blob db FIFO eviction with the following changes,
* Change blob_dir_size to max_db_size. Take into account SST file size when computing DB size.
* FIFO now only take into account live sst files and live blob files. It is normal for disk usage to go over max_db_size because there are obsolete sst files and blob files pending deletion.
* FIFO eviction now also evict TTL blob files that's still open. It doesn't evict non-TTL blob files.
* If FIFO is triggered, it will pass an expiration and the current sequence number to compaction filter. Compaction filter will then filter inlined keys to evict those with an earlier expiration and smaller sequence number. So call LSM FIFO.
* Compaction filter also filter those blob indexes where corresponding blob file is gone.
* Add an event listener to listen compaction/flush event and update sst file size.
* Implement DB::Close() to make sure base db, as well as event listener and compaction filter, destruct before blob db.
* More blob db statistics around FIFO.
* Fix some locking issue when accessing a blob file.
Closes https://github.com/facebook/rocksdb/pull/3556

Differential Revision: D7139328

Pulled By: yiwu-arbug

fbshipit-source-id: ea5edb07b33dfceacb2682f4789bea61de28bbfa
2018-03-06 11:57:42 -08:00
Yi Wu
1209b6db5c Blob DB: remove existing garbage collection implementation
Summary:
Red diff to remove existing implementation of garbage collection. The current approach is reference counting kind of approach and require a lot of effort to get the size counter right on compaction and deletion. I'm going to go with a simple mark-sweep kind of approach and will send another PR for that.

CompactionEventListener was added solely for blob db and it adds complexity and overhead to compaction iterator. Removing it as well.
Closes https://github.com/facebook/rocksdb/pull/3551

Differential Revision: D7130190

Pulled By: yiwu-arbug

fbshipit-source-id: c3a375ad2639a3f6ed179df6eda602372cc5b8df
2018-03-02 12:57:23 -08:00
Yi Wu
e62a763752 Blob DB: miscellaneous changes
Summary:
* Expose garbage collection related options
* Minor logging and counter name update
* Remove unused constants.
Closes https://github.com/facebook/rocksdb/pull/3451

Differential Revision: D6867077

Pulled By: yiwu-arbug

fbshipit-source-id: 6c3272a9c9d78b125a0bd6b2e56d00d087cdd6c8
2018-01-31 18:13:23 -08:00
Yi Wu
48cf8da2bb BlobDB: update blob_db_options.bytes_per_sync behavior
Summary:
Previously, if blob_db_options.bytes_per_sync, there is a background job to call fsync() for every bytes_per_sync bytes written to a blob file. With the change we simply pass bytes_per_sync as env_options_ to blob files so that sync_file_range() will be used instead.
Closes https://github.com/facebook/rocksdb/pull/3297

Differential Revision: D6606994

Pulled By: yiwu-arbug

fbshipit-source-id: 452424be52e32ba92f5ea603b564e9b88929af47
2017-12-19 16:41:41 -08:00
Yi Wu
250a51a3f9 BlobDB: refactor DB open logic
Summary:
Refactor BlobDB open logic. List of changes:

Major:
* On reopen, mark blob files found as immutable, do not use them for writing new keys.
* Not to scan the whole file to find file footer. Instead just seek to the end of the file and try to read footer.

Minor:
* Move most of the real logic from blob_db.cc to blob_db_impl.cc.
* Not to hold shared_ptr of event listeners in global maps in blob_db.cc
* Some changes to BlobFile interface.
* Improve logging and error handling.
Closes https://github.com/facebook/rocksdb/pull/3246

Differential Revision: D6526147

Pulled By: yiwu-arbug

fbshipit-source-id: 9dc4cdd63359a2f9b696af817086949da8d06952
2017-12-11 12:12:38 -08:00
Yi Wu
f662f8f0b6 Blob DB: option to enable garbage collection
Summary:
Add an option to enable/disable auto garbage collection, where we keep counting how many keys have been evicted by either deletion or compaction and decide whether to garbage collect a blob file.

Default disable auto garbage collection for now since the whole logic is not fully tested and we plan to make major change to it.
Closes https://github.com/facebook/rocksdb/pull/3117

Differential Revision: D6224756

Pulled By: yiwu-arbug

fbshipit-source-id: cdf53bdccec96a4580a2b3a342110ad9e8864dfe
2017-11-02 15:58:27 -07:00
Yi Wu
f6082d1944 Blob DB: cleanup unused options
Summary:
* cleanup num_concurrent_simple_blobs. We don't do concurrent writes (by taking write_mutex_) so it doesn't make sense to have multiple non TTL files open. We can revisit later when we want to improve writes.
* cleanup eviction callback. we don't have plan to use it now.
* rename s/open_simple_blob_files_/open_non_ttl_file_/ and s/open_blob_files_/open_ttl_files_/ to avoid confusion.
Closes https://github.com/facebook/rocksdb/pull/3088

Differential Revision: D6182598

Pulled By: yiwu-arbug

fbshipit-source-id: 99e6f5e01fa66d31309cdb06ce48502464bac6ad
2017-10-31 16:42:08 -07:00
Yi Wu
5a2a6483dc Blob DB: Inline small values in base DB
Summary:
Adding the `min_blob_size` option to allow storing small values in base db (in LSM tree) together with the key. The goal is to improve performance for small values, while taking advantage of blob db's low write amplification for large values.

Also adding expiration timestamp to blob index. It will be useful to evict stale blob indexes in base db by adding a compaction filter. I'll work on the compaction filter in future patches.

See blob_index.h for the new blob index format. There are 4 cases when writing a new key:
* small value w/o TTL: put in base db as normal value (i.e. ValueType::kTypeValue)
* small value w/ TTL: put (type, expiration, value) to base db.
* large value w/o TTL: write value to blob log and put (type, file, offset, size, compression) to base db.
* large value w/TTL: write value to blob log and put (type, expiration, file, offset, size, compression) to base db.
Closes https://github.com/facebook/rocksdb/pull/3066

Differential Revision: D6142115

Pulled By: yiwu-arbug

fbshipit-source-id: 9526e76e19f0839310a3f5f2a43772a4ad182cd0
2017-10-26 12:30:54 -07:00
Yi Wu
dcd36a6aee Make it explicit blob db doesn't support CF
Summary:
Blob db doesn't currently support column families. Return NotSupported status explicitly.
Closes https://github.com/facebook/rocksdb/pull/2825

Differential Revision: D5757438

Pulled By: yiwu-arbug

fbshipit-source-id: 44de9408fd032c98e8ae337d4db4ed37169bd9fa
2017-09-08 11:11:04 -07:00
Yi Wu
92afe830f9 Update all blob db TTL and timestamps to uint64_t
Summary:
The current blob db implementation use mix of int32_t, uint32_t and uint64_t for TTL and expiration. Update all timestamps to uint64_t for consistency.
Closes https://github.com/facebook/rocksdb/pull/2683

Differential Revision: D5557103

Pulled By: yiwu-arbug

fbshipit-source-id: e4eab2691629a755e614e8cf1eed9c3a681d0c42
2017-08-03 17:57:30 -07:00
Yi Wu
1900771bd2 Dump Blob DB options to info log
Summary:
* Dump blob db options to info log
* Remove BlobDBOptionsImpl to disallow dynamic cast *BlobDBOptions into *BlobDBOptionsImpl. Move options there to be constants or into BlobDBOptions. The dynamic cast is broken after #2645
* Change some of the default options
* Remove blob_db_options.min_blob_size, which is unimplemented. Will implement it soon.
Closes https://github.com/facebook/rocksdb/pull/2671

Differential Revision: D5529912

Pulled By: yiwu-arbug

fbshipit-source-id: dcd58ca981db5bcc7f123b65a0d6f6ae0dc703c7
2017-08-01 13:01:47 -07:00
Yi Wu
aaf42fe775 Move blob_db/ttl_extractor.h into blob_db/blob_db.h
Summary:
Move blob_db/ttl_extractor.h into blob_db/blob_db.h
Also exclude TTLExtractor from LITE build.
Closes https://github.com/facebook/rocksdb/pull/2665

Differential Revision: D5520009

Pulled By: yiwu-arbug

fbshipit-source-id: 4813dcc272c7cc4bf2cdac285256d9a17d78c7b7
2017-07-28 14:28:21 -07:00
Yi Wu
6083bc79f8 Blob DB TTL extractor
Summary:
Introducing blob_db::TTLExtractor to replace extract_ttl_fn. The TTL
extractor can be use to extract TTL from keys insert with Put or
WriteBatch. Change over existing extract_ttl_fn are:
* If value is changed, it will be return via std::string* (rather than Slice*). With Slice* the new value has to be part of the existing value. With std::string* the limitation is removed.
* It can optionally return TTL or expiration.

Other changes in this PR:
* replace `std::chrono::system_clock` with `Env::NowMicros` so that I can mock time in tests.
* add several TTL tests.
* other minor naming change.
Closes https://github.com/facebook/rocksdb/pull/2659

Differential Revision: D5512627

Pulled By: yiwu-arbug

fbshipit-source-id: 0dfcb00d74d060b8534c6130c808e4d5d0a54440
2017-07-27 23:26:04 -07:00
Sagar Vemuri
72502cf227 Revert "comment out unused parameters"
Summary:
This reverts the previous commit 1d7048c598, which broke the build.

Did a `git revert 1d7048c`.
Closes https://github.com/facebook/rocksdb/pull/2627

Differential Revision: D5476473

Pulled By: sagar0

fbshipit-source-id: 4756ff5c0dfc88c17eceb00e02c36176de728d06
2017-07-21 18:26:26 -07:00
Victor Gao
1d7048c598 comment out unused parameters
Summary: This uses `clang-tidy` to comment out unused parameters (in functions, methods and lambdas) in fbcode. Cases that the tool failed to handle are fixed manually.

Reviewed By: igorsugak

Differential Revision: D5454343

fbshipit-source-id: 5dee339b4334e25e963891b519a5aa81fbf627b2
2017-07-21 14:57:44 -07:00
Siying Dong
3c327ac2d0 Change RocksDB License
Summary: Closes https://github.com/facebook/rocksdb/pull/2589

Differential Revision: D5431502

Pulled By: siying

fbshipit-source-id: 8ebf8c87883daa9daa54b2303d11ce01ab1f6f75
2017-07-15 16:11:23 -07:00
foolenough
21b17d7686 Fix BlobDB::Get which only get out the value offset
Summary:
Blob db use StackableDB::get which only get out the
value offset, but not the value.
Fix by making BlobDB::Get override the designated getter.
Closes https://github.com/facebook/rocksdb/pull/2553

Differential Revision: D5396823

Pulled By: yiwu-arbug

fbshipit-source-id: 5a7d1cf77ee44490f836a6537225955382296878
2017-07-12 17:57:40 -07:00
Yi Wu
7a380deff7 Update blob_db_test
Summary:
I'm trying to improve unit test of blob db. I'm rewriting blob db test. In this patch:
* Rewrite tests of basic put/write/delete operations.
* Add disable_background_tasks to BlobDBOptionsImpl to allow me not running any background job for basic unit tests.
* Move DestroyBlobDB out from BlobDBImpl to be a standalone function.
* Remove all garbage collection related tests. Will rewrite them in following patch.
* Disabled compression test since it is failing. Will fix in a followup patch.
Closes https://github.com/facebook/rocksdb/pull/2446

Differential Revision: D5243306

Pulled By: yiwu-arbug

fbshipit-source-id: 157c71ad3b699307cb88baa3830e9b6e74f8e939
2017-06-14 13:12:34 -07:00
Anirban Rahut
d85ff4953c Blob storage pr
Summary:
The final pull request for Blob Storage.
Closes https://github.com/facebook/rocksdb/pull/2269

Differential Revision: D5033189

Pulled By: yiwu-arbug

fbshipit-source-id: 6356b683ccd58cbf38a1dc55e2ea400feecd5d06
2017-05-10 15:14:44 -07:00
Siying Dong
d616ebea23 Add GPLv2 as an alternative license.
Summary: Closes https://github.com/facebook/rocksdb/pull/2226

Differential Revision: D4967547

Pulled By: siying

fbshipit-source-id: dd3b58ae1e7a106ab6bb6f37ab5c88575b125ab4
2017-04-27 18:06:12 -07:00
sdong
8b79422b52 [Proof-Of-Concept] RocksDB Blob Storage with a blob log file.
Summary:
This is a proof of concept of a RocksDB blob log file. The actual value of the Put() is appended to a blob log using normal data block format, and the handle of the block is written as the value of the key in RocksDB.

The prototype only supports Put() and Get(). It doesn't support DB restart, garbage collection, Write() call, iterator, snapshots, etc.

Test Plan: Add unit tests.

Reviewers: arahut

Reviewed By: arahut

Subscribers: kradhakrishnan, leveldb, andrewkr, dhruba

Differential Revision: https://reviews.facebook.net/D61485
2016-08-10 17:05:17 -07:00