Summary:
Issue https://github.com/facebook/rocksdb/issues/7133 reported that using `system_clock` in `FileOperationInfo::TimePoint` causes the duration of file flush operation (which can be a noop on MacOS in some scenarios) appears to be 0 and fail an assertion in listener_test. Using `steady_clock` supposedly fixed the problem.
`steady_clock` actually fits better into the use cases of `FileOperationInfo::TimePoint` as all usages care about durations but not wall clock time.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7153

Test Plan: make check.

Reviewed By: riversand963

Differential Revision: D22654136

Pulled By: roghnin

fbshipit-source-id: 5980b1080734bdae496a18071a2c2b5887c67d85

Summary:
BackupEngine requires computing table checksums twice when backing up table files to the `shared_checksum` directory.

The repeated computation can be avoided by utilizing the db session id stored as a part of the table properties.

Filenames of table files in the `shared_checksum` directory depend on the following conditions:
1. the naming scheme is `kOptionalChecksumAndDbSessionId`,
2. `db_session_id` is not empty,
3. checksum is available in the DB manifest.

If 1,2,3 are satisfied, then the filenames will be of the form `<file_number>_<checksum>_<db_session_id>.sst`.
If 1,2 are satisfied, then the filenames will be of the form `<file_number>_<db_session_id>.sst`.
In all other cases, the filenames are of the form `<file_number>_<checksum>_<size>.sst`.

Additionally, if `kOptionalChecksumAndDbSessionId` is used (and not falling back to `kChecksumAndFileSize`), the `<checksum>` appeared in the filenames is hexadecimally encoded, instead of being plain `uint32_t` value.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7110

Test Plan: backupable_db_test and manual tests.

Reviewed By: ajkr

Differential Revision: D22508992

Pulled By: gg814

fbshipit-source-id: 5669f0ea9ad5a097f69f6d87aca4abba15032389

Summary:
Two TSAN tests occaionaly fail. Exclude them for now:

[ RUN      ] DeleteFileTest.BackgroundPurgeCFDropTest
db/deletefile_test.cc:122: Failure
Expected equality of these values:
  required_manifest
    Which is: 1
  manifest_cnt
    Which is: 2

[ RUN      ] FormatLatest/ColumnFamilyTest.FlushCloseWALFiles/0
db/column_family_test.cc:3004: Failure
Expected equality of these values:
  2
  env.num_open_wal_file_.load()
    Which is: 1

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7152

Test Plan: Watch CircleCI restuls

Reviewed By: ajkr

Differential Revision: D22632285

fbshipit-source-id: 29fa348e8be917be0237c74812a8b0b04978e84e

Summary:
TSAN reports warning in one column_family_test:

WARNING: ThreadSanitizer: data race (pid=16352)
  Write of size 8 at 0x7ffcdf042158 by main thread:
    #0 pthread_cond_destroy <null> (column_family_test+0x471f65)
    https://github.com/facebook/rocksdb/issues/1 rocksdb::port::CondVar::~CondVar() /home/circleci/project/port/port_posix.cc:101:49 (column_family_test+0x8a627a)
    https://github.com/facebook/rocksdb/issues/2 rocksdb::test::SleepingBackgroundTask::~SleepingBackgroundTask() /home/circleci/project/./test_util/testutil.h:397:7 (column_family_test+0x54b6e2)
    https://github.com/facebook/rocksdb/issues/3 rocksdb::ColumnFamilyTest_FlushCloseWALFiles_Test::TestBody() /home/circleci/project/db/column_family_test.cc:3008:1 (column_family_test+0x54b6e2)
......
  Previous read of size 8 at 0x7ffcdf042158 by thread T2 (mutexes: write M0):
    #0 pthread_cond_broadcast <null> (column_family_test+0x471dd2)
    https://github.com/facebook/rocksdb/issues/1 rocksdb::port::CondVar::SignalAll() /home/circleci/project/port/port_posix.cc:139:28 (column_family_test+0x8a651a)
    https://github.com/facebook/rocksdb/issues/2 rocksdb::test::SleepingBackgroundTask::DoSleep() /home/circleci/project/./test_util/testutil.h:412:12 (column_family_test+0x58574b)
......

Likely, SleepingBackgroundTask::DoSleep() started to execute after the main thread has finished everything, cancelled and waited for sleeping tasks to finish. At this time, although DoSlee() will not sleep, but it also accesses the mutex, creating a data race with destructor of the test. Fix this bug by waiting for the sleeping task to start sleeping after it is scheduled.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7150

Test Plan: Run these modified tests and make sure it doesn't break.

Reviewed By: riversand963

Differential Revision: D22630716

fbshipit-source-id: cc5781cf69083685de406490438898238bdfc2d3

Summary:
PR https://github.com/facebook/rocksdb/issues/6944 transitioned `BlockIter` from using `Comparator*` to using
concrete `UserComparatorWrapper` and `InternalKeyComparator`. However,
adding them as instance variables to `BlockIter` was not optimal.
Bloating `BlockIter` caused the `ArenaWrappedDBIter`'s arena allocator to do more heap
allocations (in certain cases) which harmed performance of `DB::NewIterator()`. This PR
pushes down the concrete comparator objects to the point of usage, which
forces them to be on the stack. As a result, the `BlockIter` is back to
its original size prior to https://github.com/facebook/rocksdb/issues/6944 (actually a bit smaller since there
were two `Comparator*` before).

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7149

Test Plan:
verified our internal `DB::NewIterator()`-heavy regression
test no longer reports regression.

Reviewed By: riversand963

Differential Revision: D22623189

Pulled By: ajkr

fbshipit-source-id: f6d69accfe5de51e0bd9874a480b32b29909bab6

Summary:
https://github.com/facebook/rocksdb/pull/7145 creates a minor data race against the stat creation counter. Turn it to atomic.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7151

Test Plan: Run the test.

Reviewed By: ajkr

Differential Revision: D22631014

fbshipit-source-id: c6fb69ac5b9df7139795dacea5ce9fb9fd3278d7

Summary:
To have test report.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7137

Reviewed By: siying

Differential Revision: D22630798

Pulled By: jay-zhuang

fbshipit-source-id: bc07ba673c0bceed5a4829b4af2d9a74435379c7

Summary:
Remove the 3 testing cases that cause the time out in linux build by https://github.com/facebook/rocksdb/issues/6765 . Will fix them later.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7141

Test Plan: make asan_check, buck run

Reviewed By: ajkr

Differential Revision: D22593831

Pulled By: zhichao-cao

fbshipit-source-id: 14956c36476ecc3393f613178c22e13df843126e

Summary:
In CircleCI tests, we failed to fail tests properly if parallel doesn't return an error code. It's probably would happen when unit tests fail with signals, rather than return values. Fix them.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7147

Test Plan: Manually ingest a failure and see it to fail.

Reviewed By: jay-zhuang

Differential Revision: D22611594

fbshipit-source-id: 88a42425a41d1213d29bd2e7c80731d2bdd5644b

fbshipit-source-id: 798decc90db4f13770e97cdce3c0df7d5421b2a3

fbshipit-source-id: 5113fe0c527595e4227ff827253b7414abbdf7ac

Summary:
Previously when running `db_bench` with large value for `num_multi_dbs` and enabled `Options::dump_malloc_stats`, we would see most CPU spent in jemalloc locking. After this PR that no longer shows up at the top of the profile.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7145

Reviewed By: riversand963

Differential Revision: D22593031

Pulled By: ajkr

fbshipit-source-id: 3b3fc91f93249c6afee53f59f34c487c3fc5add6

Summary:
This PR does a few things:
- The "compression_opts" and "bottom_compression_opts" can now be read/written as name/value pairs of options (instead of only a colon-separated list;
- These options can now be read/written to the Options file;
- The parallel_threads value can now be set (either in the colon or name-value format).

The compression options are now stored and treated as a OptionTypeInfo::Struct by the options system, meaning they can be read and written like the other structs.  This change allows them to be read/written easily to the options file.

Additionally, the colon-format was extended to allow support for setting parallel threads.  Tests were added to test all of the option settings via the optional parameters in the colon format.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/6817

Reviewed By: ajkr

Differential Revision: D22396004

Pulled By: zhichao-cao

fbshipit-source-id: 38bcf74b7e9cd5bc2a84540fac2e9ba4f765b2c8

Summary:
Periodic syncing of blob files is handled by a lower layer, namely by
`WritableFileWriter`; the `NeedsFsync` method of `BlobFile` and the
`last_fsync_` member variable are actually unused and thus can be
removed. See also https://github.com/facebook/rocksdb/pull/7125 .

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7138

Test Plan: `make check`

Reviewed By: zhichao-cao

Differential Revision: D22562981

Pulled By: ltamasi

fbshipit-source-id: c235aad94a7c27120528c9ec270a7a5b9154e49f

Summary:
Add "examples" build (which build examples folder in rocksdb) in TravisCI to CircleCI. This is helpful before pull request.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7136

Test Plan: Watch for CircleCI results to succeed

Reviewed By: jay-zhuang

Differential Revision: D22555528

Pulled By: akankshamahajan15

fbshipit-source-id: 6bca16647760d5f0131f064765fe9e88e034c578

Summary:
TSAN shows warning with clang with warning similar to this:

WARNING: ThreadSanitizer: data race (pid=10159)
  Atomic write of size 8 at 0x7b5000002890 by thread T33:
    #0 __tsan_atomic64_store <null> (db_test+0x4ca2b5)
    https://github.com/facebook/rocksdb/issues/1 std::__atomic_base<unsigned long>::store(unsigned long, std::memory_order) /usr/bin/../lib/gcc/x86_64-linux-gnu/5.4.0/../../../../include/c++/5.4.0/bits/atomic_base.h:374:2 (db_test+0x774fde)
    https://github.com/facebook/rocksdb/issues/2 rocksdb::VersionSet::SetLastSequence(unsigned long) /home/circleci/project/./db/version_set.h:1057:20 (db_test+0x774fde)
    https://github.com/facebook/rocksdb/issues/3 rocksdb::DBImpl::WriteImpl(rocksdb::WriteOptions const&, rocksdb::WriteBatch*, rocksdb::WriteCallback*, unsigned long*, unsigned long, bool, unsigned long*, unsigned long, rocksdb::PreReleaseCallback*) /home/circleci/project/db/db_impl/db_impl_write.cc:449:18 (db_test+0x774fde)
......
  Previous read of size 8 at 0x7b5000002890 by thread T5 (mutexes: write M1044689462619020832):
    #0 rocksdb::DBImpl::ReleaseSnapshot(rocksdb::Snapshot const*) /home/circleci/project/db/db_impl/db_impl.cc (db_test+0x6f4ae7)
    https://github.com/facebook/rocksdb/issues/1 rocksdb::(anonymous namespace)::MTThreadBody(void*) /home/circleci/project/db/db_test.cc:2514:13 (db_test+0x56ac59)
    https://github.com/facebook/rocksdb/issues/2 rocksdb::(anonymous namespace)::StartThreadWrapper(void*) /home/circleci/project/env/env_posix.cc:443:3 (db_test+0x88c4cd)

It is not limited to ReleaseSnapshot() and rocksdb::DBImpl::MultiCFSnapshot().

While we are not 100% sure it doesn't indicate any correctness violation, we suppress them for now to keep TSAN clean with more tests so that we can cover more bugs with CI.

In the gcc runs we have been running, this warning rarely shows up.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7126

Test Plan: See the mini-TSAN test to pass with reasonable run time.

Reviewed By: ajkr

Differential Revision: D22552375

fbshipit-source-id: ebdd3854cb3becec3403970326a1ca961db2ab00

Summary:
In both cases where `BlobDBImpl::DecompressSlice` is called,
`compression_type` is already checked at the call site; thus, the check
inside the method is redundant and can be turned into an assertion.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7127

Test Plan: `make check`

Reviewed By: zhichao-cao

Differential Revision: D22533454

Pulled By: ltamasi

fbshipit-source-id: ae524443fc6abe0a5fb12327a3fe761a9cd2c831

Summary: Pull Request resolved: https://github.com/facebook/rocksdb/pull/7135

Reviewed By: siying

Differential Revision: D22553594

Pulled By: jay-zhuang

fbshipit-source-id: 5b40621ffad05c4fffe3ac536a11d6c87e7ef512

Summary:
In current codebase, in write path, if Retryable IO Error happens, SetBGError is called. The retryable IO Error is converted to hard error and DB is in read only mode. User or application needs to resume it. In this PR, if Retryable IO Error happens in one DB, SetBGError will create a new thread to call Resume (auto resume). otpions.max_bgerror_resume_count controls if auto resume is enabled or not (if max_bgerror_resume_count<=0, auto resume will not be enabled). options.bgerror_resume_retry_interval controls the time interval to call Resume again if the previous resume fails due to the Retryable IO Error. If non-retryable error happens during resume, auto resume will terminate.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/6765

Test Plan: Added the unit test cases in error_handler_fs_test and pass make asan_check

Reviewed By: anand1976

Differential Revision: D21916789

Pulled By: zhichao-cao

fbshipit-source-id: acb8b5e5dc3167adfa9425a5b7fc104f6b95cb0b

Summary:
Fix typo in ThreadData comment

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7131

Reviewed By: riversand963

Differential Revision: D22543135

Pulled By: jay-zhuang

fbshipit-source-id: 39c9d0e8cd5a364af9a2f05fd3783e8482dea976

Summary:
Currently, RocksDB lets compaction to go through even in case of
corrupted keys, the number of which is reported in CompactionJobStats.
However, RocksDB does not check this value. We should let compaction run
in a stricter mode.

Temporarily disable two tests that allow corrupted keys in compaction.
With this PR, the two tests will assert(false) and terminate. Still need
to investigate what is the recommended google-test way of doing it.
Death test (EXPECT_DEATH) in gtest has warnings now.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7124

Test Plan: make check

Reviewed By: ajkr

Differential Revision: D22530722

Pulled By: riversand963

fbshipit-source-id: 6a5a6a992028c6d4f92cb74693c92db462ae4ad6

Summary:
https://github.com/facebook/rocksdb/pull/6850, which added compaction
filter support to BlobDB, reused elements of the BlobDB GC mechanism.
This patch updates some log messages in this logic to account for this
fact; namely, it replaces mentions of "GC" with "compaction/GC" to avoid
confusion in cases when GC is not enabled.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7128

Test Plan: `make check`

Reviewed By: zhichao-cao

Differential Revision: D22535371

Pulled By: ltamasi

fbshipit-source-id: 1f14f3b02ab9983728bbca1cf680420208d9a195

Summary:
This fixes an issue introduced in 0c56fc4d whereby the location of Python is evaluated many times and leads to excessive logging of unknown python locations of CentOS 6.

The location is now only checked once.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7123

Reviewed By: zhichao-cao

Differential Revision: D22532274

Pulled By: ajkr

fbshipit-source-id: cade71b4b46e9a23d63ecb4dd36a4ac8ae217970

Summary:
It is helpful to add some TSAN coverage before a pull request is committed. This diff adds some of them.
Some slow tests are excluded for the running speed. Some are blacklisted because they show warnings. Will investigate these warnings and see whether we can fix or suppress them.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7122

Test Plan: Watch CIrcleCI runs

Reviewed By: riversand963

Differential Revision: D22532133

fbshipit-source-id: 81ddd02d9df19c513a12811979e8ddabae911354

Summary:
Periodic syncing of blob files is performed by `WritableFileWriter`;
`bytes_per_sync_` and `next_sync_offset_` in `BlobLogWriter` are
actually unused (or more precisely, only used by methods that are
themselves unused). The patch removes all this dead code.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7125

Test Plan: `make check`

Reviewed By: riversand963

Differential Revision: D22531021

Pulled By: ltamasi

fbshipit-source-id: 6b293ad5a79d3e6bf15c5c68f7aedd7ce7a15f10

Summary:
Add stress test coverage for `DB::GetProperty()`.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7111

Test Plan:
```
./db_stress -get_property_one_in=1
make crash_test
```

Reviewed By: ajkr

Differential Revision: D22487906

Pulled By: jay-zhuang

fbshipit-source-id: c118d95cc9b4e2fa669a06e6aa531541fa885dc5

Summary:
During memtable lookup, an unrecognized value type should be reported as
Status::Corruption.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7121

Test Plan: make check

Reviewed By: cheng-chang

Differential Revision: D22512124

Pulled By: riversand963

fbshipit-source-id: 9b97be7d9b230c5aae9205f96054420e5ea09066

Summary: Pull Request resolved: https://github.com/facebook/rocksdb/pull/7120

Test Plan: Watch CI results.

Reviewed By: cheng-chang

Differential Revision: D22516995

fbshipit-source-id: ddf7c0482dfac30d9044b833852348eda987cb67

Summary:
1. Add the wrapper classes FileSystemTracingWrapper, FSSequentialFileTracingWrapper, FSRandomAccessFileTracingWrapper, FSWritableFileTracingWrapper, FSRandomRWFileTracingWrapper that forward the calls to underlying storage system and then pass the file operation information to IOTracer. IOTracer dumps the record in binary format for tracing.
2. Add the wrapper classes FileSystemPtr, FSSequentialFilePtr, FSRandomAccessFilePtr, FSWritableFilePtr and FSRandomRWFilePtr that overload operator-> and return ptr to underlying storage system or Tracing wrapper class based on enabling/disabling of IO tracing. These classes are added to bypass Tracing Wrapper classes when we disable tracing.
3. Add enums in trace.h that distinguish which options need to be added for different file operations(Read, close, write etc) as part of tracing record.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7002

Test Plan: make check -j64

Reviewed By: anand1976

Differential Revision: D22127897

Pulled By: akankshamahajan15

fbshipit-source-id: 74cff58ce5661c9a3832dfaa52483f3b2d8565e0

Summary:
Add circleci java build workflow.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7119

Reviewed By: siying

Differential Revision: D22512426

Pulled By: jay-zhuang

fbshipit-source-id: 45a7445c861fee48017bae42cdb7172c8b091475

Summary:
CLANG analyze is useful before pull request. Add it.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7114

Test Plan: Watch the CI results to succeed.

Reviewed By: riversand963

Differential Revision: D22491942

fbshipit-source-id: 9ccad91c6142fedc3d3dd491cf55054827908f36

Summary:
It is useful to run UBSAN before merging a PR. This commit adds it. We see warning for stl_tree.h, suppress the warning to make it work.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7112

Test Plan: See the CI to succeed. Manually ingest a UBSAN warning and see it got reported.

Reviewed By: pdillinger

Differential Revision: D22490519

fbshipit-source-id: e4495a0c78a3e2dae7dbf294da79585e141cbb66

Summary:
Closes https://github.com/facebook/rocksdb/issues/6729

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7088

Reviewed By: riversand963

Differential Revision: D22481624

Pulled By: pdillinger

fbshipit-source-id: 27c0ebd4168d374ae81f3595e034150c1c97f8b8

Summary:
Along with https://github.com/facebook/rocksdb/issues/6925 and https://github.com/facebook/rocksdb/issues/6998, this should add getters for all Options fields except several ones with non-trivial interface (for example rocksdb_options_set_min_level_to_compress).

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7094

Reviewed By: riversand963

Differential Revision: D22479800

Pulled By: pdillinger

fbshipit-source-id: d14f305e12cfe268d07e0fe229d55cef299c792a

Summary:
Closes https://github.com/facebook/rocksdb/issues/7053

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7090

Reviewed By: riversand963

Differential Revision: D22481199

Pulled By: pdillinger

fbshipit-source-id: 287477db94d57b18bee58189135f44936f1c3ca3

Summary:
There currently exist multiple `GetChildren()` calls in `DBImpl::Recover()`, which can be expensive in cases of distributed file systems.
This pull request try to call `DBImpl::Recover()` of each necessary directory only _once_ and reuse the results in the places of repeated calls in current code.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7044

Test Plan:
Run `make check` and use the default test suite. The modified code should be semantically identical to the current code. As a proof of this solution, we may optionally deploy the system onto a (real or simulated) distributed system and expect reduced latency caused by manifest fetching.

(WIP)

Reviewed By: riversand963

Differential Revision: D22419925

Pulled By: roghnin

fbshipit-source-id: d3774fbfbc246c5527101bc16747eb5c90919886

Summary:
In status.cc, the assert is `assert(sizeof(msgs) > index)`; msgs is a const char* array, sizeof(msgs) is the array size*char* size, which will make the assert pass all the time. Change it to sizeof(msgs)/sizeof(char*) > index.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7045

Test Plan: pass make check

Reviewed By: cheng-chang

Differential Revision: D22291337

Pulled By: zhichao-cao

fbshipit-source-id: 4ba8ebbb8da80ace7ca6adcdb0c66726f993659d

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:
This is a followup to https://github.com/facebook/rocksdb/issues/6646. In that PR, for simplicity I just appended a comparison against the 0th restart key in case `BinarySeek()`'s binary search landed at index 0. As a result there were `2/(N+1) + log_2(N)` key comparisons. This PR does it differently. Now we expand the binary search range by one so it also covers the case where target is at or before the restart key at index 0. As a result, it involves `log_2(N+1)` key comparisons.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7068

Test Plan:
ran readrandom with mostly default settings and counted key comparisons
using `PerfContext`.

before: `user_key_comparison_count = 28881965`
after: `user_key_comparison_count = 27823245`

setup command:

```
$ TEST_TMPDIR=/dev/shm/dbbench ./db_bench -benchmarks=fillrandom,compact -write_buffer_size=1048576 -target_file_size_base=1048576 -max_bytes_for_level_base=4194304 -max_background_jobs=12 -level_compaction_dynamic_level_bytes=true -num=10000000
```

benchmark command:

```
$ TEST_TMPDIR=/dev/shm/dbbench/ ./db_bench -use_existing_db=true -benchmarks=readrandom -disable_auto_compactions=true -num=10000000 -compression_type=none -reads=1000000 -perf_level=3
```

Reviewed By: anand1976

Differential Revision: D22357032

Pulled By: ajkr

fbshipit-source-id: 8b01e9c1c2a4e9d02fc9dfe16c1cc0327f8bdf24

Summary:
As title. The goal is to shorten the execution time of several tests
when they are combined together in a single TEST_F.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7105

Test Plan:
make db_wal_test
./db_wal_test

Reviewed By: ltamasi

Differential Revision: D22442705

Pulled By: riversand963

fbshipit-source-id: 0ad49b8f21fa86dcd5a4d3c9a06af313735ac217