Summary:
Extend support to track blob files in SST File manager.
 This PR notifies SstFileManager whenever a new blob file is created,
 via OnAddFile and  an obsolete blob file deleted via OnDeleteFile
 and delete file via ScheduleFileDeletion.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/8037

Test Plan: Add new unit tests

Reviewed By: ltamasi

Differential Revision: D26891237

Pulled By: akankshamahajan15

fbshipit-source-id: 04c69ccfda2a73782fd5c51982dae58dd11979b6

Summary:
Introduces and uses a SystemClock class to RocksDB.  This class contains the time-related functions of an Env and these functions can be redirected from the Env to the SystemClock.

Many of the places that used an Env (Timer, PerfStepTimer, RepeatableThread, RateLimiter, WriteController) for time-related functions have been changed to use SystemClock instead.  There are likely more places that can be changed, but this is a start to show what can/should be done.  Over time it would be nice to migrate most (if not all) of the uses of the time functions from the Env to the SystemClock.

There are several Env classes that implement these functions.  Most of these have not been converted yet to SystemClock implementations; that will come in a subsequent PR.  It would be good to unify many of the Mock Timer implementations, so that they behave similarly and be tested similarly (some override Sleep, some use a MockSleep, etc).

Additionally, this change will allow new methods to be introduced to the SystemClock (like https://github.com/facebook/rocksdb/issues/7101 WaitFor) in a consistent manner across a smaller number of classes.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7858

Reviewed By: pdillinger

Differential Revision: D26006406

Pulled By: mrambacher

fbshipit-source-id: ed10a8abbdab7ff2e23d69d85bd25b3e7e899e90

Summary:
Third batch of adding more tests to ASSERT_STATUS_CHECKED.

* db_compaction_filter_test
* db_compaction_test
* db_dynamic_level_test
* db_inplace_update_test
* db_sst_test
* db_tailing_iter_test
* db_io_failure_test

Also update GetApproximateSizes APIs to all return Status.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7715

Reviewed By: jay-zhuang

Differential Revision: D25806896

Pulled By: pdillinger

fbshipit-source-id: 6cb9d62ba5a756c645812754c596ad3995d7c262

Summary:
This PR does a few things:

1.  The MockFileSystem class was split out from the MockEnv.  This change would theoretically allow a MockFileSystem to be used by other Environments as well (if we created a means of constructing one).  The MockFileSystem implements a FileSystem in its entirety and does not rely on any Wrapper implementation.

2.  Make the RocksDB test suite work when MOCK_ENV=1 and ENCRYPTED_ENV=1 are set.  To accomplish this, a few things were needed:
- The tests that tried to use the "wrong" environment (Env::Default() instead of env_) were updated
- The MockFileSystem was changed to support the features it was missing or mishandled (such as recursively deleting files in a directory or supporting renaming of a directory).

3.  Updated the test framework to have a ROCKSDB_GTEST_SKIP macro.  This can be used to flag tests that are skipped.  Currently, this defaults to doing nothing (marks the test as SUCCESS) but will mark the tests as SKIPPED when RocksDB is upgraded to a version of gtest that supports this (gtest-1.10).

I have run a full "make check" with MEM_ENV, ENCRYPTED_ENV,  both, and neither under both MacOS and RedHat.  A few tests were disabled/skipped for the MEM/ENCRYPTED cases.  The error_handler_fs_test fails/hangs for MEM_ENV (presumably a timing problem) and I will introduce another PR/issue to track that problem.  (I will also push a change to disable those tests soon).  There is one more test in DBTest2 that also fails which I need to investigate or skip before this PR is merged.

Theoretically, this PR should also allow the test suite to run against an Env loaded from the registry, though I do not have one to try it with currently.

Finally, once this is accepted, it would be nice if there was a CircleCI job to run these tests on a checkin so this effort does not become stale.  I do not know how to do that, so if someone could write that job, it would be appreciated :)

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7566

Reviewed By: zhichao-cao

Differential Revision: D24408980

Pulled By: jay-zhuang

fbshipit-source-id: 911b1554a4d0da06fd51feca0c090a4abdcb4a5f

Summary: Pull Request resolved: https://github.com/facebook/rocksdb/pull/7455

Reviewed By: riversand963

Differential Revision: D23985283

Pulled By: ajkr

fbshipit-source-id: 5dd2be62350f6e31d13a1e7821cb848a37699c93

Summary:
This PR merges the functionality of making the ColumnFamilyOptions, TableFactory, and DBOptions into Configurable into a single PR, resolving any merge conflicts

Pull Request resolved: https://github.com/facebook/rocksdb/pull/5753

Reviewed By: ajkr

Differential Revision: D23385030

Pulled By: zhichao-cao

fbshipit-source-id: 8b977a7731556230b9b8c5a081b98e49ee4f160a

Summary:
Right now all I/O failures under PartitionIndexReader::CacheDependencies() is swallowed. This doesn't impact correctness but we've made a decision that any I/O error in read path now should be returned to users for awareness. Return errors in those cases instead.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7297

Test Plan: Add a new unit test that ingest errors in this code path and see Get() fails. Only one I/O path is hit in PartitionIndexReader::CacheDependencies(). Several option changes are attempt but not able to got other pread paths triggered. Not sure whether other failure cases would be even possible. Would rely on continuous stress test to validate it.

Reviewed By: anand1976

Differential Revision: D23257950

fbshipit-source-id: 859dbc92fa239996e1bb378329344d3d54168c03

Summary:
There's a potential deadlock caused by MockTimeEnv time value get to a large number, which causes TimedWait() wait forever. The test misuses the microseconds as seconds, making it more likely to happen.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7277

Reviewed By: pdillinger

Differential Revision: D23183873

Pulled By: jay-zhuang

fbshipit-source-id: 6fc38ebd40b4125a99551204b271f91a27e70086

Summary:
After https://github.com/facebook/rocksdb/pull/7036, we still see extra DBTest that can timeout when running 10 or 20 in parallel. Expand skip-fsync mode in whole DBTest. Still preserve other tests from doing this mode to be conservative.

This commit reinstates https://github.com/facebook/rocksdb/issues/7049, whose un-revert was lost in an automatic
infrastructure mis-merge.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7274

Test Plan: Run all existing files.

Reviewed By: pdillinger

Differential Revision: D23177444

fbshipit-source-id: 1f61690b2ac6333c3b2c87176fef6b2cba086b33

Summary:
Have a global StatsDumpScheduler for all DB instance stats dumping, including `DumpStats()` and `PersistStats()`. Before this, there're 2 dedicate threads for every DB instance, one for DumpStats() one for PersistStats(), which could create lots of threads if there're hundreds DB instances.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7223

Reviewed By: riversand963

Differential Revision: D23056737

Pulled By: jay-zhuang

fbshipit-source-id: 0faa2311142a73433ebb3317361db7cbf43faeba

Summary:
We have a number of tests hanging on MacOS and windows due to
mishandling of code for mock sleeps. In addition, the code was in
terrible shape because the same variable (addon_time_) would sometimes
refer to microseconds and sometimes to seconds. One test even assumed it
was nanoseconds but was written to pass anyway.

This has been cleaned up so that DB tests generally use a SpecialEnv
function to mock sleep, for either some number of microseconds or seconds
depending on the function called. But to call one of these, the test must first
call SetMockSleep (precondition enforced with assertion), which also turns
sleeps in RocksDB into mock sleeps. To also removes accounting for actual
clock time, call SetTimeElapseOnlySleepOnReopen, which implies
SetMockSleep (on DB re-open). This latter setting only works by applying
on DB re-open, otherwise havoc can ensue if Env goes back in time with
DB open.

More specifics:

Removed some unused test classes, and updated comments on the general
problem.

Fixed DBSSTTest.GetTotalSstFilesSize using a sync point callback instead
of mock time. For this we have the only modification to production code,
inserting a sync point callback in flush_job.cc, which is not a change to
production behavior.

Removed unnecessary resetting of mock times to 0 in many tests. RocksDB
deals in relative time. Any behaviors relying on absolute date/time are likely
a bug. (The above test DBSSTTest.GetTotalSstFilesSize was the only one
clearly injecting a specific absolute time for actual testing convenience.) Just
in case I misunderstood some test, I put this note in each replacement:
// NOTE: Presumed unnecessary and removed: resetting mock time in env

Strengthened some tests like MergeTestTime, MergeCompactionTimeTest, and
FilterCompactionTimeTest in db_test.cc

stats_history_test and blob_db_test are each their own beast, rather deeply
dependent on MockTimeEnv. Each gets its own variant of a work-around for
TimedWait in a mock time environment. (Reduces redundancy and
inconsistency in stats_history_test.)

Intended follow-up:

Remove TimedWait from the public API of InstrumentedCondVar, and only
make that accessible through Env by passing in an InstrumentedCondVar and
a deadline. Then the Env implementations mocking time can fix this problem
without using sync points. (Test infrastructure using sync points interferes
with individual tests' control over sync points.)

With that change, we can simplify/consolidate the scattered work-arounds.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7101

Test Plan: make check on Linux and MacOS

Reviewed By: zhichao-cao

Differential Revision: D23032815

Pulled By: pdillinger

fbshipit-source-id: 7f33967ada8b83011fb54e8279365c008bd6610b

Summary:
Cleans up some of the dependencies on test code in the Makefile while building tools:
- Moves the test::RandomString, DBBaseTest::RandomString into Random
- Moves the test::RandomHumanReadableString into Random
- Moves the DestroyDir method into file_utils
- Moves the SetupSyncPointsToMockDirectIO into sync_point.
- Moves the FaultInjection Env and FS classes under env

These changes allow all of the tools to build without dependencies on test_util, thereby simplifying the build dependencies.  By moving the FaultInjection code, the dependency in db_stress on different libraries for debug vs release was eliminated.

Tested both release and debug builds via Make and CMake for both static and shared libraries.

More work remains to clean up how the tools are built and remove some unnecessary dependencies.  There is also more work that should be done to get the Makefile and CMake to align in their builds -- what is in the libraries and the sizes of the executables are different.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7097

Reviewed By: riversand963

Differential Revision: D22463160

Pulled By: pdillinger

fbshipit-source-id: e19462b53324ab3f0b7c72459dbc73165cc382b2

Summary:
Replace `reinterpret_cast` with `static_cast_with_check` for `DBImpl` and `ColumnFamilyHandleImpl`.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/7067

Reviewed By: siying

Differential Revision: D22361587

Pulled By: jay-zhuang

fbshipit-source-id: dfe9e8f3af39c3d27cc372c55ab9ad905eb0a5a1

Summary:
This reverts commit 4f1534bd.

This commit caused failures and deadlocks in
MultiThreadedDBTest.MultiThreaded/69 and others.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/7070

Reviewed By: riversand963

Differential Revision: D22358778

Pulled By: pdillinger

fbshipit-source-id: faf8f2cb469a7063a113921c8e9c64a9f7610dac

Summary:
After https://github.com/facebook/rocksdb/pull/7036, we still see extra DBTest that can timeout when running 10 or 20 in parallel. Expand skip-fsync mode in whole DBTest. Still preserve other tests from doing this mode to be conservative.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/7049

Test Plan: Run all existing files.

Reviewed By: pdillinger

Differential Revision: D22301700

fbshipit-source-id: f9a9e3b3b26ce640665a47cb8bff33ba0c89b565

Summary:
Fsyncing files is not providing more test coverage in many tests. Provide an option in SpecialEnv to turn it off to speed it up and enable this option in some tests with relatively long run time.
Most of those tests can be divided as parameterized gtest too. This two speed up approaches are orthogonal and we can do both if needed.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/7036

Test Plan: Run all tests and make sure they pass.

Reviewed By: ltamasi

Differential Revision: D22268084

fbshipit-source-id: 6d4a838a1b7328c13931a2a5d93de57aa02afaab

Summary:
This very old test code bug was causing a new valgrind failure
in MultiGetDeadlineExceeded

Also fix hang in MultiGetDeadlineExceeded by unifying with some logic from another test.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6803

Test Plan: run that unit test under valgrind, make check

Reviewed By: siying

Differential Revision: D21388470

Pulled By: pdillinger

fbshipit-source-id: 0ce99d6d5eb8cd3195b17406892c8c5cff5fa5dd

Summary:
Since read threads do not coordinate on loading data into block
cache, two threads between Lookup and Insert can end up loading and
inserting the same data. This is particularly concerning with
cache_index_and_filter_blocks since those are hot and more likely to
be race targets if ejected from (or not pre-populated in) the cache.

Particularly with moves toward disaggregated / network storage, the cost
of redundant retrieval might be high, and we should at least have some
hard statistics from which we can estimate impact.

Example with full filter thrashing "cliff":

    $ ./db_bench --benchmarks=fillrandom --num=15000000 --cache_index_and_filter_blocks -bloom_bits=10
    ...
    $ ./db_bench --db=/tmp/rocksdbtest-172704/dbbench --use_existing_db --benchmarks=readrandom,stats --num=200000 --cache_index_and_filter_blocks --cache_size=$((130 * 1024 * 1024)) --bloom_bits=10 --threads=16 -statistics 2>&1 | egrep '^rocksdb.block.cache.(.*add|.*redundant)' | grep -v compress | sort
    rocksdb.block.cache.add COUNT : 14181
    rocksdb.block.cache.add.failures COUNT : 0
    rocksdb.block.cache.add.redundant COUNT : 476
    rocksdb.block.cache.data.add COUNT : 12749
    rocksdb.block.cache.data.add.redundant COUNT : 18
    rocksdb.block.cache.filter.add COUNT : 1003
    rocksdb.block.cache.filter.add.redundant COUNT : 217
    rocksdb.block.cache.index.add COUNT : 429
    rocksdb.block.cache.index.add.redundant COUNT : 241
    $ ./db_bench --db=/tmp/rocksdbtest-172704/dbbench --use_existing_db --benchmarks=readrandom,stats --num=200000 --cache_index_and_filter_blocks --cache_size=$((120 * 1024 * 1024)) --bloom_bits=10 --threads=16 -statistics 2>&1 | egrep '^rocksdb.block.cache.(.*add|.*redundant)' | grep -v compress | sort
    rocksdb.block.cache.add COUNT : 1182223
    rocksdb.block.cache.add.failures COUNT : 0
    rocksdb.block.cache.add.redundant COUNT : 302728
    rocksdb.block.cache.data.add COUNT : 31425
    rocksdb.block.cache.data.add.redundant COUNT : 12
    rocksdb.block.cache.filter.add COUNT : 795455
    rocksdb.block.cache.filter.add.redundant COUNT : 130238
    rocksdb.block.cache.index.add COUNT : 355343
    rocksdb.block.cache.index.add.redundant COUNT : 172478
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6681

Test Plan: Some manual testing (above) and unit test covering key metrics is included

Reviewed By: ltamasi

Differential Revision: D21134113

Pulled By: pdillinger

fbshipit-source-id: c11497b5f00f4ffdfe919823904e52d0a1a91d87

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

Summary:
Add oldest snapshot sequence property, so we can use `db.GetProperty("rocksdb.oldest-snapshot-sequence")` to get the sequence number of the oldest snapshot.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6228

Differential Revision: D19264145

Pulled By: maysamyabandeh

fbshipit-source-id: 67fbe5304d89cbc475bd404e30d1299f7b11c010

Summary:
This change enables custom implementations of FilterPolicy to
wrap a variety of NewBloomFilterPolicy and select among them based on
contextual information such as table level and compaction style.

* Moves FilterBuildingContext to public API and elaborates it with more
useful data. (It would be nice to put more general options-like data,
but at the time this object is constructed, we are using internal APIs
ImmutableCFOptions and MutableCFOptions and don't have easy access to
ColumnFamilyOptions that I can tell.)

* Renames BloomFilterPolicy::GetFilterBitsBuilderInternal to
GetBuilderWithContext, because it's now public.

* Plumbs through the table's "level_at_creation" for filter building
context.

* Simplified some tests by adding GetBuilder() to
MockBlockBasedTableTester.

* Adds test as DBBloomFilterTest.ContextCustomFilterPolicy, including
sample wrapper class LevelAndStyleCustomFilterPolicy.

* Fixes a cross-test bug in DBBloomFilterTest.OptimizeFiltersForHits
where it does not reset perf context.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6088

Test Plan: make check, valgrind on db_bloom_filter_test

Differential Revision: D18697817

Pulled By: pdillinger

fbshipit-source-id: 5f987a2d7b07cc7a33670bc08ca6b4ca698c1cf4

Summary:
Add a new API that allows a user to call MultiGet specifying multiple keys belonging to different column families. This is mainly useful for users who want to do a consistent read of keys across column families, with the added performance benefits of batching and returning values using PinnableSlice.

As part of this change, the code in the original multi-column family MultiGet for acquiring the super versions has been refactored into a separate function that can be used by both, the batching and the non-batching versions of MultiGet.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5816

Test Plan:
make check
make asan_check
asan_crash_test

Differential Revision: D18408676

Pulled By: anand1976

fbshipit-source-id: 933e7bec91dd70e7b633be4ff623a1116cc28c8d

Summary:
Most existing RocksDB unit tests run on `Env::Default()`. It will be useful to port the unit tests to non-default environments, e.g. `HdfsEnv`, etc.
This pull request is one step towards this goal. If RocksDB unit tests are built with a static library exposing a function `RegisterCustomObjects()`, then it is possible to implement custom object registrar logic in the library. RocksDB unit test can call `RegisterCustomObjects()` at the beginning.
By default, `ROCKSDB_UNITTESTS_WITH_CUSTOM_OBJECTS_FROM_STATIC_LIBS` is not defined, thus this PR has no impact on existing RocksDB because `RegisterCustomObjects()` is a noop.
Test plan (on devserver):
```
$make clean && COMPILE_WITH_ASAN=1 make -j32 all
$make check
```
All unit tests must pass.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5676

Differential Revision: D16679157

Pulled By: riversand963

fbshipit-source-id: aca571af3fd0525277cdc674248d0fe06e060f9d

Summary:
When using `PRIu64` type of printf specifier, current code base does the following:
```
#ifndef __STDC_FORMAT_MACROS
#define __STDC_FORMAT_MACROS
#endif
#include <inttypes.h>
```
However, this can be simplified to
```
#include <cinttypes>
```
as long as flag `-std=c++11` is used.
This should solve issues like https://github.com/facebook/rocksdb/issues/5159
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5402

Differential Revision: D15701195

Pulled By: miasantreble

fbshipit-source-id: 6dac0a05f52aadb55e9728038599d3d2e4b59d03

Summary: Pull Request resolved: https://github.com/facebook/rocksdb/pull/5390

Differential Revision: D15579388

Pulled By: vjnadimpalli

fbshipit-source-id: 5bfc95e31554b8ff05b97b76d6534113f527f366

Summary:
Move arena, allocator, and memory tools under util to a separate memory/ directory.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5382

Differential Revision: D15564655

Pulled By: siying

fbshipit-source-id: 9cd6b5d0d3d52b39606e19221fa154596e5852a5

Summary: Pull Request resolved: https://github.com/facebook/rocksdb/pull/5373

Differential Revision: D15559425

Pulled By: vjnadimpalli

fbshipit-source-id: 5d6d6d615582bedd96a4b879bb25d429a6de8b55

Summary:
There are too many types of files under util/. Some test related files don't belong to there or just are just loosely related. Mo
ve them to a new directory test_util/, so that util/ is cleaner.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5377

Differential Revision: D15551366

Pulled By: siying

fbshipit-source-id: 0f5c8653832354ef8caa31749c0143815d719e2c

Summary:
util/ means for lower level libraries, so it's a good idea to move the files which requires knowledge to DB out. Create a file/ and move some files there.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5375

Differential Revision: D15550935

Pulled By: siying

fbshipit-source-id: 61a9715dcde5386eebfb43e93f847bba1ae0d3f2

Summary:
Performing unordered writes in rocksdb when unordered_write option is set to true. When enabled the writes to memtable are done without joining any write thread. This offers much higher write throughput since the upcoming writes would not have to wait for the slowest memtable write to finish. The tradeoff is that the writes visible to a snapshot might change over time. If the application cannot tolerate that, it should implement its own mechanisms to work around that. Using TransactionDB with WRITE_PREPARED write policy is one way to achieve that. Doing so increases the max throughput by 2.2x without however compromising the snapshot guarantees.
The patch is prepared based on an original by siying
Existing unit tests are extended to include unordered_write option.

Benchmark Results:
```
TEST_TMPDIR=/dev/shm/ ./db_bench_unordered --benchmarks=fillrandom --threads=32 --num=10000000 -max_write_buffer_number=16 --max_background_jobs=64 --batch_size=8 --writes=3000000 -level0_file_num_compaction_trigger=99999 --level0_slowdown_writes_trigger=99999 --level0_stop_writes_trigger=99999 -enable_pipelined_write=false -disable_auto_compactions  --unordered_write=1
```
With WAL
- Vanilla RocksDB: 78.6 MB/s
- WRITER_PREPARED with unordered_write: 177.8 MB/s (2.2x)
- unordered_write: 368.9 MB/s (4.7x with relaxed snapshot guarantees)

Without WAL
- Vanilla RocksDB: 111.3 MB/s
- WRITER_PREPARED with unordered_write: 259.3 MB/s MB/s (2.3x)
- unordered_write: 645.6 MB/s (5.8x with relaxed snapshot guarantees)

- WRITER_PREPARED with unordered_write disable concurrency control: 185.3 MB/s MB/s (2.35x)

Limitations:
- The feature is not yet extended to `max_successive_merges` > 0. The feature is also incompatible with `enable_pipelined_write` = true as well as with `allow_concurrent_memtable_write` = false.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5218

Differential Revision: D15219029

Pulled By: maysamyabandeh

fbshipit-source-id: 38f2abc4af8780148c6128acdba2b3227bc81759

Summary:
Improve the iterators performance when the user explicitly sets the readahead size via `ReadOptions.readahead_size`.

1. Stop creating new table readers when the user explicitly sets readahead size.
2. Make use of an internal buffer based on `FilePrefetchBuffer` instead of using `ReadaheadRandomAccessFileReader`, to handle the user readahead requests (for both buffered and direct io cases).
3. Add `readahead_size` to db_bench.

**Benchmarks:**
https://gist.github.com/sagar0/53693edc320a18abeaeca94ca32f5737

For 1 MB readahead, Buffered IO performance improves by 28% and Direct IO performance improves by 50%.
For 512KB readahead, Buffered IO performance improves by 30% and Direct IO performance improves by 67%.

**Test Plan:**
Updated `DBIteratorTest.ReadAhead` test to make sure that:
- no new table readers are created for iterators on setting ReadOptions.readahead_size
- At least "readahead" number of bytes are actually getting read on each iterator read.

TODO later:
- Use similar logic for compactions as well.
- This ties in nicely with #4052 and paves the way for removing ReadaheadRandomAcessFile later.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5246

Differential Revision: D15107946

Pulled By: sagar0

fbshipit-source-id: 2c1149729ca7d779e4e8b7710ba6f4e8cbfd3bea

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

Summary:
Cuckoo Hash is less useful than we initially expected. Remove it.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4953

Differential Revision: D13979264

Pulled By: siying

fbshipit-source-id: 2a60afdaa989f045357398b43a1cc5d46f4492ed

Summary:
Avoid locking the DB mutex in order to reference SuperVersions. Instead, we get the thread local cached SuperVersion for each column family in the list. It depends on finding a sequence number that overlaps with all the open memtables. We start with the latest published sequence number, and if any of the memtables is sealed before we can get all the SuperVersions, the process is repeated. After a few times, give up and lock the DB mutex.

Tests:
1. Unit tests
2. make check
3. db_bench -

TEST_TMPDIR=/dev/shm ./db_bench -use_existing_db=true -benchmarks=readrandom -write_buffer_size=4194304 -target_file_size_base=4194304 -max_bytes_for_level_base=16777216 -num=5000000 -reads=1000000 -threads=32 -compression_type=none -cache_size=1048576000 -batch_size=1 -bloom_bits=1
readrandom   :       0.167 micros/op 5983920 ops/sec;  426.2 MB/s (1000000 of 1000000 found)

Multireadrandom with batch size 1:
multireadrandom :       0.176 micros/op 5684033 ops/sec; (1000000 of 1000000 found)
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4754

Differential Revision: D13363550

Pulled By: anand1976

fbshipit-source-id: 6243e8de7dbd9c8bb490a8eca385da0c855b1dd4

Summary:
Introduce the first CPU timing counter, perf_context.get_cpu_nanos. This opens a door to more CPU counters in the future.
Only Posix Env has it implemented using clock_gettime() with CLOCK_THREAD_CPUTIME_ID. How accurate the counter is depends on the platform.
Make PerfStepTimer to take an Env as an argument, and sometimes pass it in. The direct reason is to make the unit tests to use SpecialEnv where we can ingest logic there. But in long term, this is a good change.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4741

Differential Revision: D13287798

Pulled By: siying

fbshipit-source-id: 090361049d9d5095d1d1a369fe1338d2e2e1c73f

Summary:
Ran the following commands to recursively change all the files under RocksDB:
```
find . -type f -name "*.cc" -exec sed -i 's/ unique_ptr/ std::unique_ptr/g' {} +
find . -type f -name "*.cc" -exec sed -i 's/<unique_ptr/<std::unique_ptr/g' {} +
find . -type f -name "*.cc" -exec sed -i 's/ shared_ptr/ std::shared_ptr/g' {} +
find . -type f -name "*.cc" -exec sed -i 's/<shared_ptr/<std::shared_ptr/g' {} +
```
Running `make format` updated some formatting on the files touched.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4638

Differential Revision: D12934992

Pulled By: sagar0

fbshipit-source-id: 45a15d23c230cdd64c08f9c0243e5183934338a8

Summary:
The new case is directIO = true, write_global_seqno = false in which we no longer write global_seqno to the external SST file.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4614

Differential Revision: D12885001

Pulled By: riversand963

fbshipit-source-id: 7541bdc608b3a0c93d3c3c435da1b162b36673d4

Summary: Pull Request resolved: https://github.com/facebook/rocksdb/pull/4607

Reviewed By: siying

Differential Revision: D12836696

Pulled By: jsjhoubo

fbshipit-source-id: 7122ccb712d0b0f1cd998aa4477e0da1401bd870

Summary:
Adds a DB option `atomic_flush` to control whether to enable this feature. This PR is a subset of [PR 3752](https://github.com/facebook/rocksdb/pull/3752).
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4023

Differential Revision: D8518381

Pulled By: riversand963

fbshipit-source-id: 1e3bb33e99bb102876a31b378d93b0138ff6634f

Summary:
When `MockTimeEnv` is used in test to mock time methods, we cannot use `CondVar::TimedWait` because it is using real time, not the mocked time for wait timeout. On Mac the method can return immediately without awaking other waiting threads, if the real time is larger than `wait_until` (which is a mocked time). When that happen, the `wait()` method will fall into an infinite loop.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4560

Differential Revision: D10472851

Pulled By: yiwu-arbug

fbshipit-source-id: 898902546ace7db7ac509337dd8677a527209d19