Summary:
After https://github.com/facebook/rocksdb/issues/6949 , VersionSet::io_status_ can be concurrently accessed by multiple
threads without lock, causing tsan test to fail. For example, a bg flush thread
resets io_status_ before calling LogAndApply(), while another thread already in
the process of LogAndApply() reads io_status_. This is a bug.

We do not have to reset io_status_ each time we call LogAndApply(). io_status_
is part of the state of VersionSet, and it indicates the outcome of preceding
MANIFEST/CURRENT files IO operations. Its value should be updated only when:

1. MANIFEST/CURRENT files IO fail for the first time.
2. MANIFEST/CURRENT files IO succeed as part of recovering from a prior
   failure without process restart, e.g. calling Resume().

Test Plan (devserver):
COMPILE_WITH_TSAN=1 make check
COMPILE_WITH_TSAN=1 make db_test2
./db_test2 --gtest_filter=DBTest2.CompactionStall
Pull Request resolved: https://github.com/facebook/rocksdb/pull/7034

Reviewed By: zhichao-cao

Differential Revision: D22247137

Pulled By: riversand963

fbshipit-source-id: 77b83e05390f3ee3cd2d96d3fdd6fe4f225e3216

Summary:
This PR provides preliminary support for handling IO error during MANIFEST write.
File write/sync is not guaranteed to be atomic. If we encounter an IOError while writing/syncing to the MANIFEST file, we cannot be sure about the state of the MANIFEST file. The version edits may or may not have reached the file. During cleanup, if we delete the newly-generated SST files referenced by the pending version edit(s), but the version edit(s) actually are persistent in the MANIFEST, then next recovery attempt will process the version edits(s) and then fail since the SST files have already been deleted.
One approach is to truncate the MANIFEST after write/sync error, so that it is safe to delete the SST files. However, file truncation may not be supported on certain file systems. Therefore, we take the following approach.
If an IOError is detected during MANIFEST write/sync, we disable file deletions for the faulty database. Depending on whether the IOError is retryable (set by underlying file system), either RocksDB or application can call `DB::Resume()`, or simply shutdown and restart. During `Resume()`, RocksDB will try to switch to a new MANIFEST and write all existing in-memory version storage in the new file. If this succeeds, then RocksDB may proceed. If all recovery is completed, then file deletions will be re-enabled.
Note that multiple threads can call `LogAndApply()` at the same time, though only one of them will be going through the process MANIFEST write, possibly batching the version edits of other threads. When the leading MANIFEST writer finishes, all of the MANIFEST writing threads in this batch will have the same IOError. They will all call `ErrorHandler::SetBGError()` in which file deletion will be disabled.

Possible future directions:
- Add an `ErrorContext` structure so that it is easier to pass more info to `ErrorHandler`. Currently, as in this example, a new `BackgroundErrorReason` has to be added.

Test plan (dev server):
make check
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6949

Reviewed By: anand1976

Differential Revision: D22026020

Pulled By: riversand963

fbshipit-source-id: f3c68a2ef45d9b505d0d625c7c5e0c88495b91c8

Update Flush policy in PartitionedIndexBuilder on switching from user-key to internal-key mode (#7096)

Summary:
When format_version is high enough to support user-key and
there are index entries for same user key that spans multiple data
blocks then it changes from user-key mode to internal-key mode. But the
flush policy is not reset to point to Block Builder of internal-keys.
After this switch, no entries are added to user key index partition
result, thus it never triggers flushing the block.

Fix: 1. After adding the entry in sub_builder_index_, if there is a switch
from user-key to internal-key, then flush policy is updated to point to
Block Builder of internal-keys index partition.
2. Set sub_builder_index_->seperator_is_key_plus_seq_ = true if
seperator_is_key_plus_seq_  is set to true so that subsequent partitions
can also use internal key mode.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7096

Test Plan: make check -j64

Reviewed By: ajkr

Differential Revision: D22416598

Pulled By: akankshamahajan15

fbshipit-source-id: 01fc2dc07ea1b32f8fb803995ebe6e9a3fbe67ac

Summary: Fix a Facebook internal build

Test Plan: buck build @mode/opt :c_test :c_test_bin (was compilation
failure, now "not found")
buck build @mode/dev :c_test :c_test_bin (still passes)

Summary:
This is to fix special logic to run tests inside FB.
Buck test is broken after moving to cpp_unittest(). Move c_test back to the previous approach.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7076

Test Plan: Watch the Sandcastle run

Reviewed By: ajkr

Differential Revision: D22370096

fbshipit-source-id: 4a464d0903f2c76ae2de3a8ad373ffc9bedec64c

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

Test Plan: `make check`

Reviewed By: riversand963

Differential Revision: D22191354

Pulled By: ltamasi

fbshipit-source-id: 98c8012a83b999a3f1a30e955ce6bb71ba29dc5c

Summary:
The bug fixed in https://github.com/facebook/rocksdb/pull/1816/ is now applicable to iterator too. This was not an issue but https://github.com/facebook/rocksdb/pull/2886 caused the regression. If a put and DB flush happens just between iterator to get latest sequence number and getting super version, empty result for the key or an older value can be returned, which is wrong.
Fix it in the same way as the fix in https://github.com/facebook/rocksdb/issues/1816, that is to get the sequence number after referencing the super version.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6973

Test Plan: Will run stress tests for a while to make sure there is no general regression.

Reviewed By: ajkr

Differential Revision: D22029348

fbshipit-source-id: 94390f93630906796d6e2fec321f44a920953fd1

Summary:
https://github.com/facebook/rocksdb/issues/5411 refactored `VersionSet::Recover` but introduced a bug, explained as follows.
Before, once a checksum mismatch happens, `reporter` will set `s` to be non-ok. Therefore, Recover will stop processing the MANIFEST any further.
```
// Correct
// Inside Recover
LogReporter reporter;
reporter.status = &s;
log::Reader reader(..., reporter);
while (reader.ReadRecord() && s.ok()) {
...
}
```
The bug is that, the local variable `s` in `ReadAndRecover` won't be updated by `reporter` while reading the MANIFEST. It is possible that the reader sees a checksum mismatch in a record, but `ReadRecord` retries internally read and finds the next valid record. The mismatched record will be ignored and no error is reported.
```
// Incorrect
// Inside Recover
LogReporter reporter;
reporter.status = &s;
log::Reader reader(..., reporter);
s = ReadAndRecover(reader, ...);

// Inside ReadAndRecover
  Status s;  // Shadows the s in Recover.
  while (reader.ReadRecord() && s.ok()) {
   ...
  }
```
`LogReporter` can use a separate `log_read_status` to track the errors while reading the MANIFEST. RocksDB can process more MANIFEST entries only if `log_read_status.ok()`.
Test plan (devserver):
make check
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6996

Reviewed By: ajkr

Differential Revision: D22105746

Pulled By: riversand963

fbshipit-source-id: b22f717a423457a41ca152a242abbb64cf91fc38

Summary:
Compressed block cache is disabled in https://github.com/facebook/rocksdb/pull/4650 for no good reason. Re-enable it.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6990

Test Plan: Add a unit test to make sure a general function works with read-only DB + compressed block cache.

Reviewed By: ltamasi

Differential Revision: D22072755

fbshipit-source-id: 2a55df6363de23a78979cf6c747526359e5dc7a1

Summary:
The 6.11.fb branch is already cut so I will also backport this PR to
that branch.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6994

Reviewed By: riversand963

Differential Revision: D22084532

Pulled By: ajkr

fbshipit-source-id: 0b025f738cc31c65c673cbf89302359e88a34d19

Summary:
In best-efforts recovery, an error that is not Corruption or IOError::kNotFound or IOError::kPathNotFound will be overwritten silently. Fix this by checking all non-ok cases and return early.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6989

Test Plan: make check

Reviewed By: ajkr

Differential Revision: D22071418

Pulled By: riversand963

fbshipit-source-id: 5a4ea5dfb1a41f41c7a3fdaf62b163007b42f04b

Summary:
Best-efforts recovery does not check the content of CURRENT file to determine which MANIFEST to recover from. However, it still checks the presence of CURRENT file to determine whether to create a new DB during `open()`. Therefore, we can tweak the logic in `open()` a little bit so that best-efforts recovery does not rely on CURRENT file at all.

Test plan (dev server):
make check
./db_basic_test --gtest_filter=DBBasicTest.RecoverWithNoCurrentFile
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6970

Reviewed By: anand1976

Differential Revision: D22013990

Pulled By: riversand963

fbshipit-source-id: db552a1868c60ed70e1f7cd252a3a076eb8ea58f

Summary: Pull Request resolved: https://github.com/facebook/rocksdb/pull/6972

Reviewed By: zhichao-cao

Differential Revision: D22021953

Pulled By: ajkr

fbshipit-source-id: 4debbafe45b5939fd28549230eebf6006eb43440

Summary:
The `FileMetaData` objects associated with table files already contain the
number of the oldest blob file referenced by the SST in question. This patch
adds the inverse mapping to `BlobFileMetaData`, namely the set of table file
numbers for which the oldest blob file link points to the given blob file (these
are referred to as *linked SSTs*). This mapping will be used by the GC logic.

Implementation-wise, the patch builds on the `BlobFileMetaDataDelta`
functionality introduced in https://github.com/facebook/rocksdb/pull/6835: newly linked/unlinked SSTs are
accumulated in `BlobFileMetaDataDelta`, and the changes to the linked SST set
are applied in one shot when the new `Version` is saved. The patch also reworks
the blob file related consistency checks in `VersionBuilder` so they validate the
consistency of the forward table file -> blob file links and the backward blob file ->
table file links for blob files that are part of the `Version`.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6945

Test Plan: `make check`

Reviewed By: riversand963

Differential Revision: D21912228

Pulled By: ltamasi

fbshipit-source-id: c5bc7acf6e729a8fccbb12672dd5cd00f6f000f8

Summary:
If `options.wal_recovery_mode == WALRecoveryMode::kPointInTimeRecovery`, RocksDB stops replaying WAL once hitting an error and discards the rest of the WAL. This can lead to data loss if the error occurs at an offset smaller than the last sync'ed offset.
Ideally, RocksDB point-in-time recovery should permit recovery if the error occurs after last synced offset while fail recovery if error occurs before the last synced offset. However, RocksDB does not track the synced offset of WALs. Consequently, RocksDB does not know whether an error occurs before or after the last synced offset. An error can be one of the following.
- WAL record checksum mismatch. This can result from both corruption of synced data and dropping of unsynced data during shutdown. We cannot be sure which one. In order not to defeat the original motivation to permit the latter case, we keep the original behavior of point-in-time WAL recovery.
- IOError. This means the WAL can be bad, an indicator of whole file becoming unavailable, not to mention synced part of the WAL. Therefore, we choose to modify the behavior of point-in-time recovery and fail the database recovery.

Test plan (devserver):
make check
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6963

Reviewed By: ajkr

Differential Revision: D22011083

Pulled By: riversand963

fbshipit-source-id: f9cbf29a37dc5cc40d3fa62f89eed1ad67ca1536

Summary:
https://github.com/facebook/rocksdb/pull/6901 subtly changed the handling of the corner case
when a table file is deleted from a level, then re-added to the same level. (Note: this
should be extremely rare; one scenario that comes to mind is a trivial move followed by
a call to `ReFitLevel` that moves the file back to the original level.) Before that change,
a new `FileMetaData` object was created as a result of this sequence; after the change,
the original `FileMetaData` was essentially resurrected (since the deletion and the addition
simply cancel each other out with the change). This patch restores the original behavior,
which is more intuitive considering the interface, and in sync with how trivial moves are handled.
(Also note that `FileMetaData` contains some mutable data members, the values of which
might be different in the resurrected object and the freshly created one.)
The PR also fixes a bug in this area: with the original pre-6901 code, `VersionBuilder`
would add the same file twice to the same level in the scenario described above.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6939

Test Plan: `make check`

Reviewed By: ajkr

Differential Revision: D21905580

Pulled By: ltamasi

fbshipit-source-id: da07ae45384ecf3c6c53506d106432d88a7ec9df

Summary:
`DBTest2.CompressionFailures` currently tests many configurations
sequentially using nested loops, which often leads to timeouts
in our test system. The patch turns it into a parameterized test
instead.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6968

Test Plan: `make check`

Reviewed By: siying

Differential Revision: D22006954

Pulled By: ltamasi

fbshipit-source-id: f71f2f7108086b7651ecfce3d79a7fab24620b2c

Summary:
Application can ingest SST files with file checksum information, such that during ingestion, DB is able to check data integrity and identify of the SST file. The PR introduces generate_and_verify_file_checksum to IngestExternalFileOption to control if the ingested checksum information should be verified with the generated checksum.

    1. If generate_and_verify_file_checksum options is *FALSE*: *1)* if DB does not enable SST file checksum, the checksum information ingested will be ignored; *2)* if DB enables the SST file checksum and the checksum function name matches the checksum function name in DB, we trust the ingested checksum, store it in Manifest. If the checksum function name does not match, we treat that as an error and fail the IngestExternalFile() call.
    2. If generate_and_verify_file_checksum options is *TRUE*: *1)* if DB does not enable SST file checksum, the checksum information ingested will be ignored; *2)* if DB enable the SST file checksum, we will use the checksum generator from DB to calculate the checksum for each ingested SST files after they are copied or moved. Then, compare the checksum results with the ingested checksum information: _A)_ if the checksum function name does not match, _verification always report true_ and we store the DB generated checksum information in Manifest. _B)_ if the checksum function name mach, and checksum match, ingestion continues and stores the checksum information in the Manifest. Otherwise, terminate file ingestion and report file corruption.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6891

Test Plan: added unit test, pass make asan_check

Reviewed By: pdillinger

Differential Revision: D21935988

Pulled By: zhichao-cao

fbshipit-source-id: 7b55f486632db467e76d72602218d0658aa7f6ed

Summary:
This is required so that the test cases can safely be run in parallel.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6962

Test Plan: `make check`

Reviewed By: zhichao-cao

Differential Revision: D21980060

Pulled By: ltamasi

fbshipit-source-id: 616b7a0b686155d3874848b9098c67ad3f47efcc

Summary:
This saves up to two key comparisons in block seeks. The first key
comparison saved is a redundant key comparison against the restart key
where the linear scan starts. This comparison is saved in all cases
except when the found key is in the first restart interval. The
second key comparison saved is a redundant key comparison against the
restart key where the linear scan ends. This is only saved in cases
where all keys in the restart interval are less than the target
(probability roughly `1/restart_interval`).
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6646

Test Plan:
ran a benchmark with mostly default settings and counted key comparisons

before: `user_key_comparison_count = 19399529`
after: `user_key_comparison_count = 18431498`

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: pdillinger

Differential Revision: D20849707

Pulled By: ajkr

fbshipit-source-id: 1f01c5cd99ea771fd27974046e37b194f1cdcfac

Summary:
Memory pinned by `pin_l0_filter_and_index_blocks_in_cache` needs to be predictable based on user config. This PR makes sure
we do not pin extra memory for large files generated by intra-L0 (see https://github.com/facebook/rocksdb/issues/6889).
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6911

Test Plan: unit test

Reviewed By: siying

Differential Revision: D21835818

Pulled By: ajkr

fbshipit-source-id: a11a088549d06bed8aacc2548d266e5983f0ead4

Summary: Pull Request resolved: https://github.com/facebook/rocksdb/pull/6960

Test Plan: `make check`

Reviewed By: zhichao-cao

Differential Revision: D21958416

Pulled By: ltamasi

fbshipit-source-id: 97cf05027b7363014b07836e7f158c23827bd661

Summary:
as title
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6951

Test Plan: tests included + manual

Reviewed By: ajkr

Differential Revision: D21918540

Pulled By: pdillinger

fbshipit-source-id: 79d4991f2a831214fc7e477a839ec19dbbace6c5

Summary:
Moving towards the long term goal of moving most CI build to CircleCI when possible, add some Linux tests in CircleCI. This is not all what we can include to CircleCI. For example, Java builds are not includ
ed.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6937

Test Plan: Watch CI build results.

Reviewed By: pdillinger

Differential Revision: D21941605

fbshipit-source-id: db6aead3c45f523386d4fb30d224cfde573cccad

Summary:
When MultiGet is called with duplicate keys, and the key matches the
largest key in an SST file and the value type is merge, only the first
instance of the duplicate key is returned with correct results. This is
due to the incorrect assumption that if a key in a batch is equal to the
largest key in the file, the next key cannot be present in that file.

Tests:
Add a new unit test
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6953

Reviewed By: cheng-chang

Differential Revision: D21935898

Pulled By: anand1976

fbshipit-source-id: a2cc327a15150e23fd997546ca64d1c33021cb4c

Summary:
The patch adds a convenience method `GetFileMetaDataByNumber` that
builds on the `FileLocation` functionality introduced recently (see
https://github.com/facebook/rocksdb/pull/6862). This method makes it possible to
retrieve the `FileMetaData` directly as opposed to having to go through
`LevelFiles` and friends.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6940

Test Plan: `make check`

Reviewed By: cheng-chang

Differential Revision: D21905946

Pulled By: ltamasi

fbshipit-source-id: af99e19de21242b2b4a87594a535c6028d16ee72

Summary:
Implemented a subcommand of sst_dump called identify, which determines whether a file is an SST file or identifies and lists all the SST files in a directory;

This update also fixes the problem that sst_dump exits with a success state even if target file/directory does not exist/is not an SST file/is empty/is corrupted.

One test is added to sst_dump_test.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6943

Test Plan: Passed make check and a few manual tests

Reviewed By: pdillinger

Differential Revision: D21928985

Pulled By: gg814

fbshipit-source-id: 9a8b48e0cf1a0e96b13f42b690aba8ad981afad3

Summary:
Since gflags use the global variable to store the flags passed in. In the unit test, if we git one flag per unit test, the result is that all the flags are combined together in the following tests. Therefore, it has the dependency. In this PR, we pass the full arguments each time to ensure that the old arguments will be overwritten by the new one such that the dependency is removed.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6941

Test Plan: make asan_check. run each unit test in trace_analyzer_test independently and in arbitrary orders.

Reviewed By: pdillinger

Differential Revision: D21909176

Pulled By: zhichao-cao

fbshipit-source-id: dca550a0a4a205c30faa620e258a020a3b5b4e13

Summary:
In db_options.c, we should avoid including header files in the `db` directory to avoid introducing unnecessary dependency. The reason why `version_edit.h` has been included in `db_options.cc` is because we need two constants, `kUnknownChecksum` and `kUnknownChecksumFuncName`. We can put these two constants as `constexpr` in the public header `file_checksum.h`.

Test plan (devserver):
make check
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6952

Reviewed By: zhichao-cao

Differential Revision: D21925341

Pulled By: riversand963

fbshipit-source-id: 2902f3b74c97f0cf16c58ad24c095c787c3a40e2

Summary:
RocksDB is an embedded library; we should not write to the application's
console. Note: in each case, the same information is returned in the form of a
`Status::Corruption` object.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6948

Test Plan: `make check`

Reviewed By: ajkr

Differential Revision: D21914965

Pulled By: ltamasi

fbshipit-source-id: ae4b66789aa6b659eb8cc2ed4a048187962c86cc

Summary:
We currently do not have any validation that would ensure that the `FileMetaData`
objects are equivalent when a file gets deleted from the LSM tree and then re-added
(think trivial moves); however, if we did, this test case would be in violation. The patch
changes the values used in the test case so they are consistent.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6942

Test Plan: `make check`

Reviewed By: zhichao-cao

Differential Revision: D21911366

Pulled By: ltamasi

fbshipit-source-id: 2f0486f8337373a6a111b6f28433d70507857104

Summary:
Remove the dead code in table test.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6946

Test Plan: run table_test

Reviewed By: riversand963

Differential Revision: D21913563

Pulled By: zhichao-cao

fbshipit-source-id: c0aa9f3b95dfe87dd7fb2cd4823784f08cb3ddd3

Summary:
Disable two OpenForReadOnly tests in the LITE mode
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6947

Test Plan: passed db_test2

Reviewed By: cheng-chang

Differential Revision: D21914345

Pulled By: gg814

fbshipit-source-id: 58e81baf5d8cf8adcedaef3966aa3a427bbdf7c2

Summary:
Make RocksDB run a predefined unit test so that it can be integrated with better tools.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6926

Test Plan: Watch tests

Reviewed By: pdillinger

Differential Revision: D21866216

fbshipit-source-id: cafca82efdf0b72671be8d30b665e88a75ae6000

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