Summary:
Previously `DBOptions::use_direct_io_for_flush_and_compaction=true` combined with `DBOptions::use_direct_reads=false` could cause RocksDB to simultaneously read from two file descriptors for the same file, where background reads used direct I/O and foreground reads used buffered I/O. Our measurements found this mixed-mode I/O negatively impacted foreground read perf, compared to when only buffered I/O was used.

This PR makes the mixed-mode I/O situation impossible by repurposing `DBOptions::use_direct_io_for_flush_and_compaction` to only apply to background writes, and `DBOptions::use_direct_reads` to apply to all reads. There is no risk of direct background direct writes happening simultaneously with buffered reads since we never read from and write to the same file simultaneously.
Closes https://github.com/facebook/rocksdb/pull/3829

Differential Revision: D7915443

Pulled By: ajkr

fbshipit-source-id: 78bcbf276449b7e7766ab6b0db246f789fb1b279

Summary:
The only use of RandomRW is to change seqno when bulkloading, and in this use case, the file should exist. We should fail the file opening in this case.
Closes https://github.com/facebook/rocksdb/pull/3827

Differential Revision: D7913719

Pulled By: siying

fbshipit-source-id: 62cf6734f1a6acb9e14f715b927da388131c3492

Summary:
sync parent directory after deleting a file in delete scheduler. Otherwise, trim speed may not be as smooth as what we want.
Closes https://github.com/facebook/rocksdb/pull/3767

Differential Revision: D7760136

Pulled By: siying

fbshipit-source-id: ec131d53b61953f09c60d67e901e5eeb2716b05f

Summary:
Background activities like compaction can negatively affect
latency of higher-priority tasks like request processing. To avoid this,
rocksdb already lowers the IO priority of background threads on Linux
systems. While this takes care of typical IO-bound systems, it does not
help much when CPU (temporarily) becomes the bottleneck. This is
especially likely when using more expensive compression settings.

This patch adds an API to allow for lowering the CPU priority of
background threads, modeled on the IO priority API. Benchmarks (see
below) show significant latency and throughput improvements when CPU
bound. As a result, workloads with some CPU usage bursts should benefit
from lower latencies at a given utilization, or should be able to push
utilization higher at a given request latency target.

A useful side effect is that compaction CPU usage is now easily visible
in common tools, allowing for an easier estimation of the contribution
of compaction vs. request processing threads.

As with IO priority, the implementation is limited to Linux, degrading
to a no-op on other systems.
Closes https://github.com/facebook/rocksdb/pull/3763

Differential Revision: D7740096

Pulled By: gwicke

fbshipit-source-id: e5d32373e8dc403a7b0c2227023f9ce4f22b413c

Summary:
There's a group of stats in PerfContext for profiling the write path. They break down the write time into WAL write, memtable insert, throttling, and everything else. We use these stats a lot for figuring out the cause of slow writes.

These stats got a bit out of date and are now categorizing some interesting things as "everything else", and also do some double counting. This PR fixes it and adds two new stats: time spent waiting for other threads of the batch group, and time spent waiting for scheduling flushes/compactions. Probably these will be enough to explain all the occasional abnormally slow (multiple seconds) writes that we're seeing.
Closes https://github.com/facebook/rocksdb/pull/3602

Differential Revision: D7251562

Pulled By: al13n321

fbshipit-source-id: 0a2d0f5a4fa5677455e1f566da931cb46efe2a0d

Summary:
1. Add a new ticker stat rocksdb.number.multiget.keys.found to track the
number of keys successfully read
2. Update rocksdb.memtable.hit/miss in DBImpl::MultiGet(). It was being done in
DBImpl::GetImpl(), but not MultiGet
Closes https://github.com/facebook/rocksdb/pull/3730

Differential Revision: D7677364

Pulled By: anand1976

fbshipit-source-id: af22bd0ef8ddc5cf2b4244b0a024e539fe48bca5

Summary:
Add DB properties "rocksdb.block-cache-capacity", "rocksdb.block-cache-usage", "rocksdb.block-cache-pinned-usage" to show block cache usage.
Closes https://github.com/facebook/rocksdb/pull/3734

Differential Revision: D7657180

Pulled By: yiwu-arbug

fbshipit-source-id: dd34a019d5878dab539c51ee82669e97b2b745fd

Summary:
Previously threads were named "rocksdb:bg\<index in thread pool\>", so the first thread in all thread pools would be named "rocksdb:bg0". Users want to be able to distinguish threads used for flush (high-pri) vs regular compaction (low-pri) vs compaction to bottom-level (bottom-pri). So I changed the thread naming convention to include the thread-pool priority.
Closes https://github.com/facebook/rocksdb/pull/3702

Differential Revision: D7581415

Pulled By: ajkr

fbshipit-source-id: ce04482b6acd956a401ef22dc168b84f76f7d7c1

Summary:
This is a hack as temporary fix of MyRocks with rollbacking  the merge operands. The way MyRocks uses merge operands is without protection of locks, which violates the assumption behind the rollback algorithm. They are ok with not being rolled back as it would just create a gap in the autoincrement column. The hack add an option to disable the rollback of merge operands by default and only enables it to let the unit test pass.
Closes https://github.com/facebook/rocksdb/pull/3711

Differential Revision: D7597177

Pulled By: maysamyabandeh

fbshipit-source-id: 544be0f666c7e7abb7f651ec8b23124e05056728

Summary:
The existing unit test did not set the level so the check for pinned partitioned filter/index being properly released from the block cache was not properly exercised as they only take effect in level 0. As a result a memory leak in pinned partitioned filters was hidden. The patch fix the test as well as the bug.
Closes https://github.com/facebook/rocksdb/pull/3692

Differential Revision: D7559763

Pulled By: maysamyabandeh

fbshipit-source-id: 55eff274945838af983c764a7d71e8daff092e4a

Summary: Closes https://github.com/facebook/rocksdb/pull/3666

Differential Revision: D7457634

Pulled By: sagar0

fbshipit-source-id: 47741e2ee66e9255c580f4e38cfb86b284c27c2f

Summary:
When `max_valid_backups_to_open` is set, the `BackupEngine` doesn't know about the files referenced by existing backups. This PR prevents us from deleting valid files when that option is set, in cases where we are unable to accurately determine refcount. There are warnings logged when we may miss deleting unreferenced files, and a recommendation in the header for users to periodically unset this option and run a full `GarbageCollect`.
Closes https://github.com/facebook/rocksdb/pull/3518

Differential Revision: D7008331

Pulled By: ajkr

fbshipit-source-id: 87907f964dc9716e229d08636a895d2fc7b72305

Summary:
Level Compaction with TTL.

As of today, a file could exist in the LSM tree without going through the compaction process for a really long time if there are no updates to the data in the file's key range. For example, in certain use cases, the keys are not actually "deleted"; instead they are just set to empty values. There might not be any more writes to this "deleted" key range, and if so, such data could remain in the LSM for a really long time resulting in wasted space.

Introducing a TTL could solve this problem. Files (and, in turn, data) older than TTL will be scheduled for compaction when there is no other background work. This will make the data go through the regular compaction process and get rid of old unwanted data.
This also has the (good) side-effect of all the data in the non-bottommost level being newer than ttl, and all data in the bottommost level older than ttl. It could lead to more writes while reducing space.

This functionality can be controlled by the newly introduced column family option -- ttl.

TODO for later:
- Make ttl mutable
- Extend TTL to Universal compaction as well? (TTL is already supported in FIFO)
- Maybe deprecate CompactionOptionsFIFO.ttl in favor of this new ttl option.
Closes https://github.com/facebook/rocksdb/pull/3591

Differential Revision: D7275442

Pulled By: sagar0

fbshipit-source-id: dcba484717341200d419b0953dafcdf9eb2f0267

Summary:
Provide a block_align option in BlockBasedTableOptions to allow
alignment of SST file data blocks. This will avoid higher
IOPS/throughput load due to < 4KB data blocks spanning 2 4KB pages.
When this option is set to true, the block alignment is set to lower of
block size and 4KB.
Closes https://github.com/facebook/rocksdb/pull/3502

Differential Revision: D7400897

Pulled By: anand1976

fbshipit-source-id: 04cc3bd144e88e3431a4f97604e63ad7a0f06d44

Summary:
Currently log_writer->AddRecord in WriteImpl is protected from concurrent calls via FlushWAL only if two_write_queues_ option is set. The patch fixes the problem by i) skip log_writer->AddRecord in FlushWAL if manual_wal_flush is not set, ii) protects log_writer->AddRecord in WriteImpl via log_write_mutex_ if manual_wal_flush_ is set but two_write_queues_ is not.

Fixes #3599
Closes https://github.com/facebook/rocksdb/pull/3656

Differential Revision: D7405608

Pulled By: maysamyabandeh

fbshipit-source-id: d6cc265051c77ae49c7c6df4f427350baaf46934

Summary:
We have not been updating our HISTORY.md change log with the RocksJava changes. Going forward, lets add Java changes also to HISTORY.md.
There is an old java/HISTORY-JAVA.md, but it hasn't been updated in years. It is much easier to remember to update the change log in a single file, HISTORY.md.

I added information about shared block cache here, which was introduced in #3623.
Closes https://github.com/facebook/rocksdb/pull/3647

Differential Revision: D7384448

Pulled By: sagar0

fbshipit-source-id: 9b6e569f44e6df5cb7ba06413d9975df0b517d20

Summary:
Fsync after writing global sequence number to the ingestion file in ExternalSstFileIngestionJob. Otherwise the file metadata could be incorrect.
Closes https://github.com/facebook/rocksdb/pull/3644

Differential Revision: D7373813

Pulled By: sagar0

fbshipit-source-id: 4da2c9e71a8beb5c08b4ac955f288ee1576358b8

Summary:
Add `bytes_max_delete_chunk` in SstFileManager so that we can drop a large file in multiple batches.
Closes https://github.com/facebook/rocksdb/pull/3640

Differential Revision: D7358679

Pulled By: siying

fbshipit-source-id: ef17f0da2f5723dbece2669485a9b91b3edc0bb7

Summary: Closes https://github.com/facebook/rocksdb/pull/3631

Differential Revision: D7367519

Pulled By: gfosco

fbshipit-source-id: 57826cc1c9ffc9f2b351075567b8ad929809cb74

Summary:
`Writer::WriteBuffer` was always called at the beginning of checkpoint/backup. But that log writer has no internal synchronization, which meant the same buffer could be flushed twice in a race condition case, causing a WAL entry to be duplicated. Then subsequent WAL entries would be at unexpected offsets, causing the 32KB block boundaries to be overlapped and manifesting as a corruption.

This PR fixes the behavior to only use `WriteBuffer` (via `FlushWAL`) in checkpoint/backup when manual WAL flush is enabled. In that case, users are responsible for providing synchronization between WAL flushes. We can also consider removing the call entirely.
Closes https://github.com/facebook/rocksdb/pull/3603

Differential Revision: D7277447

Pulled By: ajkr

fbshipit-source-id: 1b15bd7fd930511222b075418c10de0aaa70a35a

Summary: Closes https://github.com/facebook/rocksdb/pull/3568

Differential Revision: D7170953

Pulled By: siying

fbshipit-source-id: 9cfb8dd88b7266da920c0e0c1e10fb2c5af0641c

Summary:
This diff handles cases where compaction causes an ENOSPC error.
This does not handle corner cases where another background job is started while compaction is running, and the other background job triggers ENOSPC, although we do allow the user to provision for these background jobs with SstFileManager::SetCompactionBufferSize.
It also does not handle the case where compaction has finished and some other background job independently triggers ENOSPC.

Usage: Functionality is inside SstFileManager. In particular, users should set SstFileManager::SetMaxAllowedSpaceUsage, which is the reference highwatermark for determining whether to cancel compactions.
Closes https://github.com/facebook/rocksdb/pull/3449

Differential Revision: D7016941

Pulled By: amytai

fbshipit-source-id: 8965ab8dd8b00972e771637a41b4e6c645450445

Summary:
This is the simplest way I could think of to speed up `CompactRange`. It works but isn't that optimal because it relies on the same `max_compaction_bytes` and `max_subcompactions` options that are used in other places. If it turns out to be useful we can allow overriding these in `CompactRangeOptions` in the future.
Closes https://github.com/facebook/rocksdb/pull/3549

Differential Revision: D7117634

Pulled By: ajkr

fbshipit-source-id: d0cd03d6bd0d2fd7ea3fb13cd3b8bf7c47d11e42

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

Summary:
The zeroed entries were not removed from prepared_section_completed_ map. This patch adds a unit test to show the problem and fixes that by refactoring the code. The new code is more efficient since i) it uses two separate mutex to avoid contention between commit and prepare threads, ii) it uses a sorted vector for maintaining uniq log entires with prepare which avoids a very large heap with many duplicate entries.
Closes https://github.com/facebook/rocksdb/pull/3545

Differential Revision: D7106071

Pulled By: maysamyabandeh

fbshipit-source-id: b3ae17cb6cd37ef10b6b35e0086c15c758768a48

Summary:
Add "rocksdb.live-sst-files-size" DB property which only include files of latest version. Existing "rocksdb.total-sst-files-size" include files from all versions and thus include files that's obsolete but not yet deleted. I'm going to use this new property to cap blob db sst + blob files size.
Closes https://github.com/facebook/rocksdb/pull/3548

Differential Revision: D7116939

Pulled By: yiwu-arbug

fbshipit-source-id: c6a52e45ce0f24ef78708156e1a923c1dd6bc79a

Summary:
CompactRange has a call to Flush because we guarantee that, at the time it's called, all existing keys in the range will be pushed through the user's compaction filter. However, previously the flush was done blindly, so it'd happen even if the memtable does not contain keys in the range specified by the user. This caused unnecessarily many L0 files to be created, leading to write stalls in some cases. This PR checks the memtable's contents, and decides to flush only if it overlaps with `CompactRange`'s range.

- Move the memtable overlap check logic from `ExternalSstFileIngestionJob` to `ColumnFamilyData::RangesOverlapWithMemtables`
- Reuse the above logic in `CompactRange` and skip flushing if no overlap
Closes https://github.com/facebook/rocksdb/pull/3520

Differential Revision: D7018897

Pulled By: ajkr

fbshipit-source-id: a3c6b1cfae56687b49dd89ccac7c948e53545934

Summary: Closes https://github.com/facebook/rocksdb/pull/3532

Differential Revision: D7062828

Pulled By: miasantreble

fbshipit-source-id: d36967a1cfbcaeeeb33b9f0e09e15dea85b08b70

RocksDBOptionsParser::Parse()'s `ignore_unknown_options` argument only ingores options from higher version.

Summary:
RocksDB should always be able to parse an option file generated using the same or lower version. Unknown option should only happen if it is from a higher version. Change the behavior of RocksDBOptionsParser::Parse()'s behavior with ignore_unknown_options=true so that unknown option from a lower or the same version will never be skipped.
Closes https://github.com/facebook/rocksdb/pull/3527

Differential Revision: D7048851

Pulled By: siying

fbshipit-source-id: e261caea12f6515611a4a29f39acf2b619df2361

Summary:
- made `CreateCheckpoint` properly return `InvalidArgument` when called with an empty directory. Previously it triggered an assertion failure due to a bug in the logic.
- made `ldb` set empty `checkpoint_dir` if that's what the user specifies, so that we can use it to properly test `CreateCheckpoint` in the future.

Differential Revision: D6874562

fbshipit-source-id: dcc1bd41768261d9338987fa7711444289707ed7

Summary:
- Refactored logic for checking write stall condition to a helper function: `GetWriteStallConditionAndCause`. Now it is decoupled from the logic for updating WriteController / stats in `RecalculateWriteStallConditions`, so we can reuse it for predicting whether write stall will occur.
- Updated `CompactRange` to first check whether the one additional immutable memtable / L0 file would cause stalling before it flushes. If so, it waits until that is no longer true.
- Updated `bg_cv_` to be signaled on `SetOptions` calls. The stall conditions `CompactRange` cares about can change when (1) flush finishes, (2) compaction finishes, or (3) options dynamically change. The cv was already signaled for (1) and (2) but not yet for (3).
Closes https://github.com/facebook/rocksdb/pull/3381

Differential Revision: D6754983

Pulled By: ajkr

fbshipit-source-id: 5613e03f1524df7192dc6ae885d40fd8f091d972

Summary:
There are a couple of places where we swallow any error from
WriteBuffer() - in SwitchMemtable() and DBImpl::CloseImpl(). Propagate
the error up in those cases rather than ignoring it.
Closes https://github.com/facebook/rocksdb/pull/3404

Differential Revision: D6879954

Pulled By: anand1976

fbshipit-source-id: 2ef88b554be5286b0a8bad7384ba17a105395bdb

Summary:
Using `DeleteFilesInRange` to delete files in a lot of ranges can be slow, because
`VersionSet::LogAndApply` is expensive.

This PR adds a new `DeleteFilesInRange` function to delete files in multiple
ranges at once.

Close https://github.com/facebook/rocksdb/issues/2951
Closes https://github.com/facebook/rocksdb/pull/3431

Differential Revision: D6849228

Pulled By: ajkr

fbshipit-source-id: daeedcabd8def4b1d9ee95a58266dee77b5d68cb

Summary:
This change improves the performance of iterators doing long range scans (e.g. big/full table scans in MyRocks) by using readahead and prefetching additional data on each disk IO. This prefetching is automatically enabled on noticing more than 2 IOs for the same table file during iteration. The readahead size starts with 8KB and is exponentially increased on each additional sequential IO, up to a max of 256 KB. This helps in cutting down the number of IOs needed to complete the range scan.

Constraints:
- The prefetched data is stored by the OS in page cache. So this currently works only for non direct-reads use-cases i.e applications which use page cache. (Direct-I/O support will be enabled in a later PR).
- This gets currently enabled only when ReadOptions.readahead_size = 0 (which is the default value).

Thanks to siying for the original idea and implementation.

**Benchmarks:**
Data fill:
```
TEST_TMPDIR=/data/users/$USER/benchmarks/iter ./db_bench -benchmarks=fillrandom -num=1000000000 -compression_type="none" -level_compaction_dynamic_level_bytes
```
Do a long range scan: Seekrandom with large number of nexts
```
TEST_TMPDIR=/data/users/$USER/benchmarks/iter ./db_bench -benchmarks=seekrandom -duration=60 -num=1000000000 -use_existing_db -seek_nexts=10000 -statistics -histogram
```

Page cache was cleared before each experiment with the command:
```
sudo sh -c "echo 3 > /proc/sys/vm/drop_caches"
```
```
Before:
seekrandom   :   34020.945 micros/op 29 ops/sec;   32.5 MB/s (1636 of 1999 found)
With this change:
seekrandom   :    8726.912 micros/op 114 ops/sec;  126.8 MB/s (5702 of 6999 found)
```
~3.9X performance improvement.

Also verified with strace and gdb that the readahead size is increasing as expected.
```
strace -e readahead -f -T -t -p <db_bench process pid>
```
Closes https://github.com/facebook/rocksdb/pull/3282

Differential Revision: D6586477

Pulled By: sagar0

fbshipit-source-id: 8a118a0ed4594fbb7f5b1cafb242d7a4033cb58c

Summary:
To prevent user who implement the Iterator interface fail to implement SeekForPrev by mistake.
Closes https://github.com/facebook/rocksdb/pull/3402

Differential Revision: D6790681

Pulled By: yiwu-arbug

fbshipit-source-id: bd75b8ced30208982e0a1414d34384d93496827a

Summary:
Flush() call could be waiting indefinitely if min_write_buffer_number_to_merge is used. Consider the sequence:
1. User call Flush() with flush_options.wait = true
2. The manual flush started in the background
3. New memtable become immutable because of writes. The new memtable will not trigger flush if min_write_buffer_number_to_merge is not reached.
4. The manual flush finish.

Because of the new memtable created at step 3 not being flush, previous logic of WaitForFlushMemTable() keep waiting, despite the memtables it intent to flush has been flushed.

Here instead of checking if there are any more memtables to flush, WaitForFlushMemTable() also check the id of the earliest memtable. If the id is larger than that of latest memtable at the time flush was initiated, it means all the memtable at the time of flush start has all been flush.
Closes https://github.com/facebook/rocksdb/pull/3378

Differential Revision: D6746789

Pulled By: yiwu-arbug

fbshipit-source-id: 35e698f71c7f90b06337a93e6825f4ea3b619bfa

Summary:
When calling `DisableFileDeletions` followed by `GetSortedWalFiles`, we guarantee the files returned by the latter call won't be deleted until after file deletions are re-enabled. However, `GetSortedWalFiles` didn't omit files already planned for deletion via `PurgeObsoleteFiles`, so the guarantee could be broken.

We fix it by making `GetSortedWalFiles` wait for the number of pending purges to hit zero if file deletions are disabled. This condition is eventually met since `PurgeObsoleteFiles` is guaranteed to be called for the existing pending purges, and new purges cannot be scheduled while file deletions are disabled. Once the condition is met, `GetSortedWalFiles` simply returns the content of DB and archive directories, which nobody can delete (except for deletion scheduler, for which I plan to fix this bug later) until deletions are re-enabled.
Closes https://github.com/facebook/rocksdb/pull/3341

Differential Revision: D6681131

Pulled By: ajkr

fbshipit-source-id: 90b1e2f2362ea9ef715623841c0826611a817634

Summary:
**# Summary**

RocksDB uses SSE crc32 intrinsics to calculate the crc32 values but it does it in single way fashion (not pipelined on single CPU core). Intel's whitepaper () published an algorithm that uses 3-way pipelining for the crc32 intrinsics, then use pclmulqdq intrinsic to combine the values. Because pclmulqdq has overhead on its own, this algorithm will show perf gains on buffers larger than 216 bytes, which makes RocksDB a perfect user, since most of the buffers RocksDB call crc32c on is over 4KB. Initial db_bench show tremendous CPU gain.

This change uses the 3-way SSE algorithm by default. The old SSE algorithm is now behind a compiler tag NO_THREEWAY_CRC32C. If user compiles the code with NO_THREEWAY_CRC32C=1 then the old SSE Crc32c algorithm would be used. If the server does not have SSE4.2 at the run time the slow way (Non SSE) will be used.

**# Performance Test Results**
We ran the FillRandom and ReadRandom benchmarks in db_bench. ReadRandom is the point of interest here since it calculates the CRC32 for the in-mem buffers. We did 3 runs for each algorithm.

Before this change the CRC32 value computation takes about 11.5% of total CPU cost, and with the new 3-way algorithm it reduced to around 4.5%. The overall throughput also improved from 25.53MB/s to 27.63MB/s.

1) ReadRandom in db_bench overall metrics

    PER RUN
    Algorithm | run | micros/op | ops/sec |Throughput (MB/s)
    3-way      |  1   | 4.143   | 241387 | 26.7
    3-way      |  2   | 3.775   | 264872 | 29.3
    3-way      | 3    | 4.116   | 242929 | 26.9
    FastCrc32c|1  | 4.037   | 247727 | 27.4
    FastCrc32c|2  | 4.648   | 215166 | 23.8
    FastCrc32c|3  | 4.352   | 229799 | 25.4

     AVG
    Algorithm     |    Average of micros/op |   Average of ops/sec |    Average of Throughput (MB/s)
    3-way           |     4.01                               |      249,729                 |      27.63
    FastCrc32c  |     4.35                              |     230,897                  |      25.53

 2)   Crc32c computation CPU cost (inclusive samples percentage)
    PER RUN
    Implementation | run |  TotalSamples   | Crc32c percentage
    3-way                 |  1    |  4,572,250,000 | 4.37%
    3-way                 |  2    |  3,779,250,000 | 4.62%
    3-way                 |  3    |  4,129,500,000 | 4.48%
    FastCrc32c       |  1    |  4,663,500,000 | 11.24%
    FastCrc32c       |  2    |  4,047,500,000 | 12.34%
    FastCrc32c       |  3    |  4,366,750,000 | 11.68%

 **# Test Plan**
     make -j64 corruption_test && ./corruption_test
      By default it uses 3-way SSE algorithm

     NO_THREEWAY_CRC32C=1 make -j64 corruption_test && ./corruption_test

    make clean && DEBUG_LEVEL=0 make -j64 db_bench
    make clean && DEBUG_LEVEL=0 NO_THREEWAY_CRC32C=1 make -j64 db_bench
Closes https://github.com/facebook/rocksdb/pull/3173

Differential Revision: D6330882

Pulled By: yingsu00

fbshipit-source-id: 8ec3d89719533b63b536a736663ca6f0dd4482e9

Summary: Closes https://github.com/facebook/rocksdb/pull/3252

Differential Revision: D6539373

Pulled By: siying

fbshipit-source-id: ce7c3d3fe625852179055295da9cf7bc80755025

Summary: Closes https://github.com/facebook/rocksdb/pull/3242

Differential Revision: D6514255

Pulled By: ajkr

fbshipit-source-id: c39fa8e745866b052649d02bf339e794d77e96a3