Summary:
Add a threshold timestamp, full_history_ts_low_ of type `std::string*` to
`CompactionIterator`, so that RocksDB can also perform garbage collection during
compaction.
* If full_history_ts_low_ is nullptr, then compaction iterator does not perform
  GC, preserving all timestamp history for all keys. Compaction iterator will
treat user key with different timestamps as different user keys.
* If full_history_ts_low_ is not nullptr, then compaction iterator performs
  GC. GC will look at keys older than `*full_history_ts_low_` and determine their
  eligibility based on factors including snapshots.

Current rules of GC:
 * If an internal key is in the same snapshot as a previous counterpart
    with the same user key, and this key is eligible for GC, and the key is
    not single-delete or merge operand, then this key can be dropped. Note
    that the previous internal key cannot be a merge operand either.
 * If a tombstone is the most recent one in the earliest snapshot and it
    is eligible for GC, and keyNotExistsBeyondLevel() is true, then this
    tombstone can be dropped.
 * If a tombstone is the most recent one in a snapshot and it is eligible
    for GC, and the compaction is at bottommost level, then all other older
    internal keys of the same user key must also be eligible for GC, thus
    can be dropped
* Single-delete, delete-range and merge are not currently supported.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7556

Test Plan: make check

Reviewed By: ltamasi

Differential Revision: D24507728

Pulled By: riversand963

fbshipit-source-id: 3c09c7301f41eed76dfcf4d1527e68cf6e0a8bb3

Summary:
When `ASSERT_STATUS_CHECKED` is enabled, `transaction_test` does not pass without this PR.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7572

Test Plan: `ASSERT_STATUS_CHECKED=1 make   -j32 transaction_test && ./transaction_test`

Reviewed By: zhichao-cao

Differential Revision: D24404319

Pulled By: cheng-chang

fbshipit-source-id: 13689035995366ab06d8eada3ea404e45fef8bc5

Summary:
This option determines whether WALs will be tracked in MANIFEST and verified on recovery.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7275

Test Plan:
db_options_test
options_test

Reviewed By: pdillinger

Differential Revision: D23181418

Pulled By: cheng-chang

fbshipit-source-id: 5dd1cdc166f3dfc1c93c094df4a2f7734e3b4547

Summary:
(a) own copy of kMicrosInSecond
(b) out-of-line sync point code

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7426

Test Plan: FB internal

Reviewed By: ajkr

Differential Revision: D23861363

Pulled By: pdillinger

fbshipit-source-id: de6b1621dca2f7391c5ff72bad04a7613dc27527

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:
(1) Skip check on specific key if restoring an old backup
(small minority of cases) because it can fail in those cases. (2) Remove
an old assertion about number of column families and number of keys
passed in, which is broken by atomic flush (cf_consistency) test. Like
other code (for better or worse) assume a single key and iterate over
column families. (3) Apply mock_direct_io to NewSequentialFile so that
db_stress backup works on /dev/shm.

Also add more context to output in case of backup/restore db_stress
failure.

Also a minor fix to BackupEngine to report first failure status in
creating new backup, and drop another clue about the potential
source of a "Backup failed" status.

Reverts "Disable backup/restore stress test (https://github.com/facebook/rocksdb/issues/7350)"

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7357

Test Plan:
Using backup_one_in=10000,
"USE_CLANG=1 make crash_test_with_atomic_flush" for 30+ minutes
"USE_CLANG=1 make blackbox_crash_test" for 30+ minutes
And with use_direct_reads with TEST_TMPDIR=/dev/shm/rocksdb

Reviewed By: riversand963

Differential Revision: D23567244

Pulled By: pdillinger

fbshipit-source-id: e77171c2e8394d173917e36898c02dead1c40b77

Summary:
And change the internal time value from seconds to microseconds.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7293

Reviewed By: pdillinger

Differential Revision: D23253751

Pulled By: jay-zhuang

fbshipit-source-id: 36aa9376b8801b85bd10163173590a17cf4f3a3a

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: Pull Request resolved: https://github.com/facebook/rocksdb/pull/7280

Test Plan: `make check`

Reviewed By: riversand963

Differential Revision: D23195192

Pulled By: ltamasi

fbshipit-source-id: 743b382de391963e62ba86119e9fbd0233ea3b3a

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:
Make (most of) the env*_test pass when ASSERT_STATUS_CHECKED is enabled.

One test that opens a database is currently disabled in this mode, as there are many errors that need revisited for DB tests and status checks.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7176

Reviewed By: cheng-chang

Differential Revision: D22799278

Pulled By: ajkr

fbshipit-source-id: 16d8a02eaeecd6df1060249b6a5811292801f2ed

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:
Delicious copy-pasta from https://github.com/facebook/rocksdb/issues/7039

Also fixing DestroyDir to allow files to go missing while it is operating. This seems to fix failures I got with test plan reproducer.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7103

Test Plan:
make blackbox_crash_test_with_atomic_flush for a while with
checkpoint_one_in=100

Reviewed By: siying

Differential Revision: D22435315

Pulled By: pdillinger

fbshipit-source-id: 0ec0538402493887aeda43ecc03f32979cb84ced

Summary:
We don't need them.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/7008

Test Plan: "make check" and ensure "make crash_test" starts

Reviewed By: ajkr

Differential Revision: D22143838

Pulled By: pdillinger

fbshipit-source-id: 72c8e16603abc59f4954e304466bc4dc1f58f94e

Summary:
The ```for``` loop in ```VerifyChecksumInBlocks``` only checks ```index_iter->Valid()``` which could be ```false``` either due to reaching the end of the index or, in case of partitioned index, it could be due to a checksum mismatch error when reading a 2nd level index block. Instead of throwing away the index iterator status, we need to return any errors back to the caller.

Tests:
Add a test in block_based_table_reader_test.cc.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6909

Reviewed By: pdillinger

Differential Revision: D21833922

Pulled By: anand1976

fbshipit-source-id: bc778ebf1121dbbdd768689de5183f07a9f0beae

Summary:
Currently, `DeleteDir` only deletes the directory if there are no other directories under the target dir. This PR makes it delete directories recursively.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6934

Test Plan:
Added a new unit test in testutil_test.cc.
`make testutil_test`

Reviewed By: zhichao-cao

Differential Revision: D21884211

Pulled By: cheng-chang

fbshipit-source-id: 0b9a48a200f494ee007aef5d1763b4aa331f8b5a

Summary:
Release code now depends on gtest, indirectly through including "test_util/testharness.h". This creates multiple problems. One important reason is the definition of IGNORE_STATUS_IF_ERROR() in test_util/testharness.h. Move it to sync_point.h instead.
Note that utilities/cassandra/format.h still depends on "test_util/testharness.h". This will be resolved in a separate diff.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6907

Test Plan: Run all existing tests.

Reviewed By: ajkr

Differential Revision: D21829884

fbshipit-source-id: 9253c19ffde2936f3ae68998210f8e54f645a6e6

Summary:
Currently, in direct IO mode, `MultiGet` retrieves the data blocks one by one instead of in parallel, see `BlockBasedTable::RetrieveMultipleBlocks`.

Since direct IO is supported in `RandomAccessFileReader::MultiRead` in https://github.com/facebook/rocksdb/pull/6446, this PR applies `MultiRead` to `MultiGet` so that the data blocks can be retrieved in parallel.

Also, in direct IO mode and when data blocks are compressed and need to uncompressed, this PR only allocates one continuous aligned buffer to hold the data blocks, and then directly uncompress the blocks to insert into block cache, there is no longer intermediate copies to scratch buffers.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6815

Test Plan:
1. added a new unit test `BlockBasedTableReaderTest::MultiGet`.
2. existing unit tests and stress tests  contain tests against `MultiGet` in direct IO mode.

Reviewed By: anand1976

Differential Revision: D21426347

Pulled By: cheng-chang

fbshipit-source-id: b8446ae0e74152444ef9111e97f8e402ac31b24f

Summary:
Tried making Status object enforce that it is checked in some way. In cases it is not checked, `PermitUncheckedError()` must be called explicitly.

Added a way to run tests (`ASSERT_STATUS_CHECKED=1 make -j48 check`) on a
whitelist. The effort appears significant to get each test to pass with
this assertion, so I only fixed up enough to get one test (`options_test`)
working and added it to the whitelist.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6798

Reviewed By: pdillinger

Differential Revision: D21377404

Pulled By: ajkr

fbshipit-source-id: 73236f9c8df38f01cf24ecac4a6d1661b72d077e

Summary:
Fix the following cases that can cause false alarms in db_stress when read fault injection is
 enabled -
1. Turn off corruption/truncation when direct IO is enabled. Since the actual IO size is larger than block size due to alignment requirements, the corruption may not result in a detectable error.
2. Handle the case when the randomly generated string to overwrite the original block is identical to the original.

Tests:
Run db_stress w/ and wo/ direct IO and fault injection turned on
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6777

Reviewed By: zhichao-cao

Differential Revision: D21316734

Pulled By: anand1976

fbshipit-source-id: bf0e6468043063ca81ff877d4bf71d3f296c77aa

Summary:
In crash test, the db directory might be set to /dev/shm or /tmp, in certain environments such as internal testing infrastructure, neither of these directories support direct IO, so direct IO is never enabled in crash test.

This PR sets up SyncPoints in direct IO related code paths to disable O_DIRECT flag in calls to `open`, so the direct IO code paths will be executed, all direct IO related assertions will be checked, but no real direct IO request will be issued to the file system.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6727

Test Plan:
export CRASH_TEST_EXT_ARGS="--use_direct_reads=1 --mmap_read=0"
make -j24 crash_test

Reviewed By: zhichao-cao

Differential Revision: D21139250

Pulled By: cheng-chang

fbshipit-source-id: db9adfe78d91aa4759835b1af91c5db7b27b62ee

Summary:
In https://github.com/facebook/rocksdb/pull/6455, we modified the interface of `RandomAccessFileReader::Read` to be able to get rid of memcpy in direct IO mode.
This PR applies the new interface to `BlockFetcher` when reading blocks from SST files in direct IO mode.

Without this PR, in direct IO mode, when fetching and uncompressing compressed blocks, `BlockFetcher` will first copy the raw compressed block into `BlockFetcher::compressed_buf_` or `BlockFetcher::stack_buf_` inside `RandomAccessFileReader::Read` depending on the block size. then during uncompressing, it will copy the uncompressed block into `BlockFetcher::heap_buf_`.

In this PR, we get rid of the first memcpy and directly uncompress the block from `direct_io_buf_` to `heap_buf_`.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6689

Test Plan: A new unit test `block_fetcher_test` is added.

Reviewed By: anand1976

Differential Revision: D21006729

Pulled By: cheng-chang

fbshipit-source-id: 2370b92c24075692423b81277415feb2aed5d980

Summary:
False alarms are caused by codepaths that intentionally swallow IO
errors.

Tests:
make crash_test
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6741

Reviewed By: ltamasi

Differential Revision: D21181138

Pulled By: anand1976

fbshipit-source-id: 5ccfbc68eb192033488de6269e59c00f2c65ce00

Summary:
This PR fixes some typos in code comments.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6733

Reviewed By: siying

Differential Revision: D21209037

Pulled By: zhichao-cao

fbshipit-source-id: d9274611fab1f5e992998c8c4117b8078c4cbc69

Summary:
Based on https://github.com/facebook/rocksdb/issues/6648 (CLA Signed), but heavily modified / extended:

* Implicit capture of this via [=] deprecated in C++20, and [=,this] not standard before C++20 -> now using explicit capture lists
* Implicit copy operator deprecated in gcc 9 -> add explicit '= default' definition
* std::random_shuffle deprecated in C++17 and removed in C++20 -> migrated to a replacement in RocksDB random.h API
* Add the ability to build with different std version though -DCMAKE_CXX_STANDARD=11/14/17/20 on the cmake command line
* Minimal rebuild flag of MSVC is deprecated and is forbidden with /std:c++latest (C++20)
* Added MSVC 2019 C++11 & MSVC 2019 C++20 in AppVeyor
* Added GCC 9 C++11 & GCC9 C++20 in Travis
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6697

Test Plan: make check and CI

Reviewed By: cheng-chang

Differential Revision: D21020318

Pulled By: pdillinger

fbshipit-source-id: 12311be5dbd8675a0e2c817f7ec50fa11c18ab91

Summary:
IsDirectory() is a common API to check whether a path is a regular file or
directory.
POSIX: call stat() and use S_ISDIR(st_mode)
Windows: PathIsDirectoryA() and PathIsDirectoryW()
HDFS: FileSystem.IsDirectory()
Java: File.IsDirectory()
...
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6711

Test Plan: make check

Reviewed By: anand1976

Differential Revision: D21053520

Pulled By: riversand963

fbshipit-source-id: 680aadfd8ce982b63689190cf31b3145d5a89e27

Summary:
Add env_fault_injection argument to db_stress.  When enabled,
FaultInjectionTestEnv will be used instead.  Currently this
option does not support running with other env setting.

This will allow
us to later manually produce error when running db_crashtest.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6687

Test Plan:
make db_stress -j32
./db_stress --env_fault_injection
./db_stress --env_fault_injection --hdfs   // expect error message

Reviewed By: ajkr

Differential Revision: D21014683

Pulled By: yhchiang

fbshipit-source-id: 0724aeac37efd57adb72a37defe6dbd3bfa8106a

Summary:
1. Fix a memory leak in FaultInjectionTestFS in the stack trace related
code
2. Check status of all MultiGet keys before deciding whether an error
was swallowed, instead of assuming an ok status for any key means an
undetected error
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6700

Test Plan: Run db_stress with asan and fault injection

Reviewed By: cheng-chang

Differential Revision: D21021498

Pulled By: anand1976

fbshipit-source-id: 489191efd1ab0fa834923a1e1d57253a7a315465

Summary:
The error message is causing problems in the crash tests due to the
error parsing logic in db_crashtest.py.

This is a follow up PR for https://github.com/facebook/rocksdb/pull/6694.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6696

Test Plan: make check

Reviewed By: zhichao-cao

Differential Revision: D21021875

Pulled By: cheng-chang

fbshipit-source-id: 11e3f536df16941a89949ebcd2147cd8dfa3fbe0

Summary:
The error message is causing problems in the crash tests due to the
error parsing logic in db_crashtest.py.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6694

Reviewed By: siying

Differential Revision: D20998531

Pulled By: anand1976

fbshipit-source-id: 89cb54a5f5bb664ae6d239c37559f10e14c5ea07

Summary:
Fix the following issues -
1. Output parsing error in db_crashtest.py
2. Memory leak on exit
3. False alarm on filter block read error
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6693

Test Plan: asan_crash

Reviewed By: cheng-chang

Differential Revision: D20990399

Pulled By: anand1976

fbshipit-source-id: 178ee0dd7c69a4bc5db698379db0dedb29281699

Summary:
Fix release build caused by variable defined but unused.

Test plan (devserver)
```
make release
```
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6690

Reviewed By: cheng-chang

Differential Revision: D20980571

Pulled By: riversand963

fbshipit-source-id: c3f3b13f81dce4bdb19876dc2e710d5902ff8a02

Summary:
This PR implements a fault injection mechanism for injecting errors in reads in db_stress. The FaultInjectionTestFS is used for this purpose. A thread local structure is used to track the errors, so that each db_stress thread can independently enable/disable error injection and verify observed errors against expected errors. This is initially enabled only for Get and MultiGet, but can be extended to iterator as well once its proven stable.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6538

Test Plan:
crash_test
make check

Reviewed By: riversand963

Differential Revision: D20714347

Pulled By: anand1976

fbshipit-source-id: d7598321d4a2d72bda0ced57411a337a91d87dc7

Summary:
Towards making compaction logic compatible with user timestamp.
When computing boundaries and overlapping ranges for inputs of compaction, We need to compare SSTs by user key without timestamp.

Test plan (devserver):
```
make check
```
Several individual tests:
```
./version_set_test --gtest_filter=VersionStorageInfoTimestampTest.GetOverlappingInputs
./db_with_timestamp_compaction_test
./db_with_timestamp_basic_test
```
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6645

Reviewed By: ltamasi

Differential Revision: D20960012

Pulled By: riversand963

fbshipit-source-id: ad377fa9eb481bf7a8a3e1824aaade48cdc653a4

Summary:
The current Env/FileSystem API separation has a couple of issues -
1. It requires the user to specify 2 options - ```Options::env``` and ```Options::file_system``` - which means they have to make code changes to benefit from the new APIs. Furthermore, there is a risk of accessing the same APIs in two different ways, through Env in the old way and through FileSystem in the new way. The two may not always match, for example, if env is ```PosixEnv``` and FileSystem is a custom implementation. Any stray RocksDB calls to env will use the ```PosixEnv``` implementation rather than the file_system implementation.
2. There needs to be a simple way for the FileSystem developer to instantiate an Env for backward compatibility purposes.

This PR solves the above issues and simplifies the migration in the following ways -
1. Embed a shared_ptr to the ```FileSystem``` in the ```Env```, and remove ```Options::file_system``` as a configurable option. This way, no code changes will be required in application code to benefit from the new API. The default Env constructor uses a ```LegacyFileSystemWrapper``` as the embedded ```FileSystem```.
1a. - This also makes it more robust by ensuring that even if RocksDB
  has some stray calls to Env APIs rather than FileSystem, they will go
  through the same object and thus there is no risk of getting out of
  sync.
2. Provide a ```NewCompositeEnv()``` API that can be used to construct a
PosixEnv with a custom FileSystem implementation. This eliminates an
indirection to call Env APIs, and relieves the FileSystem developer of
the burden of having to implement wrappers for the Env APIs.
3. Add a couple of missing FileSystem APIs - ```SanitizeEnvOptions()``` and
```NewLogger()```

Tests:
1. New unit tests
2. make check and make asan_check
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6552

Reviewed By: riversand963

Differential Revision: D20592038

Pulled By: anand1976

fbshipit-source-id: c3801ad4153f96d21d5a3ae26c92ba454d1bf1f7

Summary:
In the current code base, we can use FaultInjectionTestEnv to simulate the env issue such as file write/read errors, which are used in most of the test. The PR https://github.com/facebook/rocksdb/issues/5761 introduce the File System as a new Env API. This PR implement the FaultInjectionTestFS, which can be used to simulate when File System has issues such as IO error. user can specify any IOStatus error as input, such that FS corresponding actions will return certain error to the caller.

A set of ErrorHandlerFSTests are introduced for testing
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6414

Test Plan: pass make asan_check, pass error_handler_fs_test.

Differential Revision: D20252421

Pulled By: zhichao-cao

fbshipit-source-id: e922038f8ce7e6d1da329fd0bba7283c4b779a21

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:
The DecreaseNumBgThreads test keeps failing on Windows in AppVeyor.
It fails because it depends on a timed wait for the tasks to be dequeued from the threadpool's internal queue, but within the specified time, the task might have not been scheduled onto the newly created threads.
https://github.com/facebook/rocksdb/pull/6232 tries to fix this by waiting for longer time to let the threads scheduled.
This PR tries to fix this by replacing the timed wait with a synchronization on the task's internal conditional variable.
When the number of threads increases, instead of guessing the time needed for the task to be scheduled, it directly blocks on the conditional variable until the task starts running.
But when thread number is reduced, it still does a timed wait, but this does not lead to the flakiness now, will try to remove these timed waits in a future PR.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6393

Test Plan: Wait to see whether AppVeyor tests pass.

Differential Revision: D19890928

Pulled By: cheng-chang

fbshipit-source-id: 4e56e4addf625c98c0876e62d9d57a6f0a156f76

Summary:
Right, when reading from option files, no readahead is used and 8KB buffer is used. It might introduce high latency if the file system provide high latency and doesn't do readahead. Instead, introduce a readahead to the file. When calling inside DB, infer the value from options.log_readahead. Otherwise, a default 512KB readahead size is used.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6372

Test Plan: Add --log_readahead_size in db_bench. Run it with several options and observe read size from option files using strace.

Differential Revision: D19727739

fbshipit-source-id: e6d8053b0a64259abc087f1f388b9cd66fa8a583

Summary:
When paranoid_checks is on, DBImpl::CheckConsistency() iterates over all sst files and calls Env::GetFileSize() for each of them. As far as I could understand, this is pretty arbitrary and doesn't affect correctness - if filesystem doesn't corrupt fsynced files, the file sizes will always match; if it does, it may as well corrupt contents as well as sizes, and rocksdb doesn't check contents on open.

If there are thousands of sst files, getting all their sizes takes a while. If, on top of that, Env is overridden to use some remote storage instead of local filesystem, it can be *really* slow and overload the remote storage service. This PR adds an option to not do GetFileSize(); instead it does GetChildren() for parent directory to check that all the expected sst files are at least present, but doesn't check their sizes.

We can't just disable paranoid_checks instead because paranoid_checks do a few other important things: make the DB read-only on write errors, print error messages on read errors, etc.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6353

Test Plan: ran the added sanity check unit test. Will try it out in a LogDevice test cluster where the GetFileSize() calls are causing a lot of trouble.

Differential Revision: D19656425

Pulled By: al13n321

fbshipit-source-id: c2c421b367633033760d1f56747bad206d1fbf82