Commit Graph

40 Commits

Author SHA1 Message Date
sdong
cb19e7411f Fix bugs in DBWALTest.kTolerateCorruptedTailRecords triggered by #5520 (#5550)
Summary:
https://github.com/facebook/rocksdb/pull/5520 caused a buffer overflow bug in DBWALTest.kTolerateCorruptedTailRecords. Fix it.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5550

Test Plan: Run the test in UBSAN. It used to fail. Not it succeeds.

Differential Revision: D16165516

fbshipit-source-id: 42c56a6bc64eb091f054b87757fcbef60da825f7
2019-07-09 11:18:32 -07:00
haoyuhuang
bb4178066d Integrate block cache tracer into db_impl (#5433)
Summary:
This PR integrates the block cache tracer class into db_impl.cc.
db_impl.cc contains a member variable of AtomicBlockCacheTraceWriter class and passes its reference to the block_based_table_reader.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5433

Differential Revision: D15728016

Pulled By: HaoyuHuang

fbshipit-source-id: 23d5659e8c82d556833dcc1a5558aac8c1f7db71
2019-06-13 15:43:10 -07:00
Siying Dong
e9e0101ca4 Move test related files under util/ to test_util/ (#5377)
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
2019-05-30 11:25:51 -07:00
Siying Dong
f0dda35d7d Preload some files even if options.max_open_files (#3340)
Summary:
Choose to preload some files if options.max_open_files != -1. This can slightly narrow the gap of performance between options.max_open_files is -1 and a large number. To avoid a significant regression to DB reopen speed if options.max_open_files != -1. Limit the files to preload in DB open time to 16.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/3340

Differential Revision: D6686945

Pulled By: siying

fbshipit-source-id: 8ec11bbdb46e3d0cdee7b6ad5897a09c5a07869f
2018-12-28 18:02:28 -08:00
Soli
a478682260 Fix #3840: only SyncClosedLogs for multiple CFs (#4460)
Summary:
Call `SyncClosedLogs()` only if there are more than one column families.

Update several unit tests (in `fault_injection_test` and `db_flush_test`) correspondingly.

See #3840 for more info.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4460

Differential Revision: D12896377

Pulled By: riversand963

fbshipit-source-id: f49afdaec32568f12f001219a3aec1dfde3b32bf
2018-11-13 11:32:16 -08:00
Sagar Vemuri
dc3528077a Update all unique/shared_ptr instances to be qualified with namespace std (#4638)
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
2018-11-09 11:19:58 -08:00
Yi Wu
dc813e4b85 Improve log handling when recover without flush (#4405)
Summary:
Improve log handling when avoid_flush_during_recovery=true.
1. restore total_log_size_ after recovery, by summing up existing log sizes. Fixes #4253.
2. truncate the last existing log, since this log can contain preallocated space and it will be a waste to keep the space. It avoids a crash loop of user application cause a lot of log with non-trivial size being created and ultimately take up all disk space.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4405

Differential Revision: D9953933

Pulled By: yiwu-arbug

fbshipit-source-id: 967780fee8acec7f358b6eb65190fb4684f82e56
2018-09-26 10:37:48 -07:00
Yanqin Jin
bb5dcea98e Add path to WritableFileWriter. (#4039)
Summary:
We want to sample the file I/O issued by RocksDB and report the function calls. This requires us to include the file paths otherwise it's hard to tell what has been going on.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4039

Differential Revision: D8670178

Pulled By: riversand963

fbshipit-source-id: 97ee806d1c583a2983e28e213ee764dc6ac28f7a
2018-08-23 10:12:58 -07:00
Siying Dong
d59549298f Skip deleted WALs during recovery
Summary:
This patch record min log number to keep to the manifest while flushing SST files to ignore them and any WAL older than them during recovery. This is to avoid scenarios when we have a gap between the WAL files are fed to the recovery procedure. The gap could happen by for example out-of-order WAL deletion. Such gap could cause problems in 2PC recovery where the prepared and commit entry are placed into two separate WAL and gap in the WALs could result into not processing the WAL with the commit entry and hence breaking the 2PC recovery logic.

Before the commit, for 2PC case, we determined which log number to keep in FindObsoleteFiles(). We looked at the earliest logs with outstanding prepare entries, or prepare entries whose respective commit or abort are in memtable. With the commit, the same calculation is done while we apply the SST flush. Just before installing the flush file, we precompute the earliest log file to keep after the flush finishes using the same logic (but skipping the memtables just flushed), record this information to the manifest entry for this new flushed SST file. This pre-computed value is also remembered in memory, and will later be used to determine whether a log file can be deleted. This value is unlikely to change until next flush because the commit entry will stay in memtable. (In WritePrepared, we could have removed the older log files as soon as all prepared entries are committed. It's not yet done anyway. Even if we do it, the only thing we loss with this new approach is earlier log deletion between two flushes, which does not guarantee to happen anyway because the obsolete file clean-up function is only executed after flush or compaction)

This min log number to keep is stored in the manifest using the safely-ignore customized field of AddFile entry, in order to guarantee that the DB generated using newer release can be opened by previous releases no older than 4.2.
Closes https://github.com/facebook/rocksdb/pull/3765

Differential Revision: D7747618

Pulled By: siying

fbshipit-source-id: d00c92105b4f83852e9754a1b70d6b64cb590729
2018-05-03 15:43:09 -07:00
Siying Dong
d5afa73789 Revert "Skip deleted WALs during recovery"
Summary:
This reverts commit 73f21a7b21.

It breaks compatibility. When created a DB using a build with this new change, opening the DB and reading the data will fail with this error:

"Corruption: Can't access /000000.sst: IO error: while stat a file for size: /tmp/xxxx/000000.sst: No such file or directory"

This is because the dummy AddFile4 entry generated by the new code will be treated as a real entry by an older build. The older build will think there is a real file with number 0, but there isn't such a file.
Closes https://github.com/facebook/rocksdb/pull/3762

Differential Revision: D7730035

Pulled By: siying

fbshipit-source-id: f2051859eff20ef1837575ecb1e1bb96b3751e77
2018-04-23 12:01:26 -07:00
Maysam Yabandeh
73f21a7b21 Skip deleted WALs during recovery
Summary:
This patch record the deleted WAL numbers in the manifest to ignore them and any WAL older than them during recovery. This is to avoid scenarios when we have a gap between the WAL files are fed to the recovery procedure. The gap could happen by for example out-of-order WAL deletion. Such gap could cause problems in 2PC recovery where the prepared and commit entry are placed into two separate WAL and gap in the WALs could result into not processing the WAL with the commit entry and hence breaking the 2PC recovery logic.
Closes https://github.com/facebook/rocksdb/pull/3488

Differential Revision: D6967893

Pulled By: maysamyabandeh

fbshipit-source-id: 13119feb155a08ab6d4909f437c7a750480dc8a1
2018-03-30 11:28:05 -07:00
Maysam Yabandeh
18dcf7f98d WritePrepared Txn: PreReleaseCallback
Summary:
Add PreReleaseCallback to be called at the end of WriteImpl but before publishing the sequence number. The callback is used in WritePrepareTxn to i) update the commit map, ii) update the last published sequence number in the 2nd write queue. It also ensures that all the commits will go to the 2nd queue.
These changes will ensure that the commit map is updated before the sequence number is published and used by reading snapshots. If we use two write queues, the snapshots will use the seq number published by the 2nd queue. If we use one write queue (the default, the snapshots will use the last seq number in the memtable, which also indicates the last published seq number.
Closes https://github.com/facebook/rocksdb/pull/3205

Differential Revision: D6438959

Pulled By: maysamyabandeh

fbshipit-source-id: f8b6c434e94bc5f5ab9cb696879d4c23e2577ab9
2017-11-30 23:50:45 -08:00
Maysam Yabandeh
857adf388f WritePrepared Txn: Refactor conf params
Summary:
Summary of changes:
- Move seq_per_batch out of Options
- Rename concurrent_prepare to two_write_queues
- Add allocate_seq_only_for_data_
Closes https://github.com/facebook/rocksdb/pull/3136

Differential Revision: D6304458

Pulled By: maysamyabandeh

fbshipit-source-id: 08e685bfa82bbc41b5b1c5eb7040a8ca6e05e58c
2017-11-10 17:28:12 -08:00
Zhongyi Xie
1d6700f9e6 Add test kPointInTimeRecoveryCFConsistency
Summary:
Context/problem:

- CFs may be flushed at different times
- A WAL can only be deleted after all CFs have flushed beyond end of that WAL.
- Point-in-time recovery might stop upon reaching the first corruption.
- Some CFs may have already flushed beyond that point, while others haven't. We should fail the Open() instead of proceeding with inconsistent CFs.
Closes https://github.com/facebook/rocksdb/pull/2900

Differential Revision: D5863281

Pulled By: miasantreble

fbshipit-source-id: 180dbaf83d96c804cff49b3c406312a4ae61313e
2017-09-22 17:26:36 -07:00
Maysam Yabandeh
c57050b770 Use the default copy constructor in Options
Summary:
Our current implementation of (semi-)copy constructor of DBOptions and ColumnFamilyOptions seems to intend value by value copy, which is what the default copy constructor does anyway. Moreover not using the default constructor has the risk of forgetting to add newly added options.

As an example, allow_2pc seems to be forgotten in the copy constructor which was causing one of the unit tests not seeing its effect.
Closes https://github.com/facebook/rocksdb/pull/2888

Differential Revision: D5846368

Pulled By: maysamyabandeh

fbshipit-source-id: 1ee92a2aeae93886754b7bc039c3411ea2458683
2017-09-15 17:15:10 -07:00
Siying Dong
3c327ac2d0 Change RocksDB License
Summary: Closes https://github.com/facebook/rocksdb/pull/2589

Differential Revision: D5431502

Pulled By: siying

fbshipit-source-id: 8ebf8c87883daa9daa54b2303d11ce01ab1f6f75
2017-07-15 16:11:23 -07:00
Maysam Yabandeh
499ebb3ab5 Optimize for serial commits in 2PC
Summary:
Throughput: 46k tps in our sysbench settings (filling the details later)

The idea is to have the simplest change that gives us a reasonable boost
in 2PC throughput.

Major design changes:
1. The WAL file internal buffer is not flushed after each write. Instead
it is flushed before critical operations (WAL copy via fs) or when
FlushWAL is called by MySQL. Flushing the WAL buffer is also protected
via mutex_.
2. Use two sequence numbers: last seq, and last seq for write. Last seq
is the last visible sequence number for reads. Last seq for write is the
next sequence number that should be used to write to WAL/memtable. This
allows to have a memtable write be in parallel to WAL writes.
3. BatchGroup is not used for writes. This means that we can have
parallel writers which changes a major assumption in the code base. To
accommodate for that i) allow only 1 WriteImpl that intends to write to
memtable via mem_mutex_--which is fine since in 2PC almost all of the memtable writes
come via group commit phase which is serial anyway, ii) make all the
parts in the code base that assumed to be the only writer (via
EnterUnbatched) to also acquire mem_mutex_, iii) stat updates are
protected via a stat_mutex_.

Note: the first commit has the approach figured out but is not clean.
Submitting the PR anyway to get the early feedback on the approach. If
we are ok with the approach I will go ahead with this updates:
0) Rebase with Yi's pipelining changes
1) Currently batching is disabled by default to make sure that it will be
consistent with all unit tests. Will make this optional via a config.
2) A couple of unit tests are disabled. They need to be updated with the
serial commit of 2PC taken into account.
3) Replacing BatchGroup with mem_mutex_ got a bit ugly as it requires
releasing mutex_ beforehand (the same way EnterUnbatched does). This
needs to be cleaned up.
Closes https://github.com/facebook/rocksdb/pull/2345

Differential Revision: D5210732

Pulled By: maysamyabandeh

fbshipit-source-id: 78653bd95a35cd1e831e555e0e57bdfd695355a4
2017-06-24 14:11:29 -07:00
Siying Dong
d616ebea23 Add GPLv2 as an alternative license.
Summary: Closes https://github.com/facebook/rocksdb/pull/2226

Differential Revision: D4967547

Pulled By: siying

fbshipit-source-id: dd3b58ae1e7a106ab6bb6f37ab5c88575b125ab4
2017-04-27 18:06:12 -07:00
Siying Dong
d2dce5611a Move some files under util/ to separate dirs
Summary:
Move some files under util/ to new directories env/, monitoring/ options/ and cache/
Closes https://github.com/facebook/rocksdb/pull/2090

Differential Revision: D4833681

Pulled By: siying

fbshipit-source-id: 2fd8bef
2017-04-05 19:09:16 -07:00
Siying Dong
d5b607a43f Make db_wal_test slightly faster
Summary:
Avoid to run db_wal_test in all the DB test options, and some small changes.
Closes https://github.com/facebook/rocksdb/pull/1921

Differential Revision: D4622054

Pulled By: siying

fbshipit-source-id: 890fd64
2017-02-28 17:39:10 -08:00
Dmitri Smirnov
0a4cdde50a Windows thread
Summary:
introduce new methods into a public threadpool interface,
- allow submission of std::functions as they allow greater flexibility.
- add Joining methods to the implementation to join scheduled and submitted jobs with
  an option to cancel jobs that did not start executing.
- Remove ugly `#ifdefs` between pthread and std implementation, make it uniform.
- introduce pimpl for a drop in replacement of the implementation
- Introduce rocksdb::port::Thread typedef which is a replacement for std::thread.  On Posix Thread defaults as before std::thread.
- Implement WindowsThread that allocates memory in a more controllable manner than windows std::thread with a replaceable implementation.
- should be no functionality changes.
Closes https://github.com/facebook/rocksdb/pull/1823

Differential Revision: D4492902

Pulled By: siying

fbshipit-source-id: c74cb11
2017-02-06 14:54:18 -08:00
Reid Horuff
1ca5f6d132 Fix 2PC Recovery SeqId Miscount
Summary:
Originally sequence ids were calculated, in recovery, based off of the first seqid found if the first log recovered. The working seqid was then incremented from that value based on every insertion that took place. This was faulty because of the potential for missing log files or inserts that skipped the WAL. The current recovery scheme grabs sequence from current recovering batch and increments using memtableinserter to track how many actual inserts take place. This works for 2PC batches as well scenarios where some logs are missing or inserts that skip the WAL.
Closes https://github.com/facebook/rocksdb/pull/1486

Differential Revision: D4156064

Pulled By: reidHoruff

fbshipit-source-id: a6da8d9
2016-11-10 11:09:22 -08:00
Andrew Kryczka
f47054015d Handle WAL deletion when using avoid_flush_during_recovery
Summary:
Previously the WAL files that were avoided during recovery would never
be considered for deletion. That was because alive_log_files_ was only
populated when log files are created. This diff further populates
alive_log_files_ with existing log files that aren't flushed during recovery,
such that FindObsoleteFiles() can find them later.

Depends on D64053.

Test Plan: new unit test, verifies it fails before this change and passes after

Reviewers: sdong, IslamAbdelRahman, yiwu

Reviewed By: yiwu

Subscribers: leveldb, dhruba, andrewkr

Differential Revision: https://reviews.facebook.net/D64059
2016-10-14 12:59:51 -07:00
Andrew Kryczka
1b7af5fb1a Redo handling of recycled logs in full purge
Summary:
This reverts commit 9e4aa798c3,
which doesn't handle all cases (see inline comment).

I reimplemented the logic as suggested in the initial PR: https://github.com/facebook/rocksdb/pull/1313.

This approach has two benefits:

- All the parsing/filtering of full_scan_candidate_files is kept together in PurgeObsoleteFiles.
- We only need to check whether log file is recycled in one place where we've already determined it's a log file

Test Plan:
new unit test, verified fails before the original fix, still passes
now.

Reviewers: IslamAbdelRahman, yiwu, sdong

Reviewed By: yiwu, sdong

Subscribers: leveldb, dhruba, andrewkr

Differential Revision: https://reviews.facebook.net/D64053
2016-10-12 23:13:09 -07:00
Reid Horuff
2c1f95291d Add facility to write only a portion of WriteBatch to WAL
Summary:
When constructing a write batch a client may now call MarkWalTerminationPoint() on that batch. No batch operations after this call will be added written to the WAL but will still be inserted into the Memtable. This facility is used to remove one of the three WriteImpl calls in 2PC transactions. This produces a ~1% perf improvement.

```
RocksDB - unoptimized 2pc, sync_binlog=1, disable_2pc=off
INFO 2016-08-31 14:30:38,814 [main]: REQUEST PHASE COMPLETED. 75000000 requests done in 2619 seconds. Requests/second = 28628

RocksDB - optimized 2pc , sync_binlog=1, disable_2pc=off
INFO 2016-08-31 16:26:59,442 [main]: REQUEST PHASE COMPLETED. 75000000 requests done in 2581 seconds. Requests/second = 29054
```

Test Plan: Two unit tests added.

Reviewers: sdong, yiwu, IslamAbdelRahman

Reviewed By: yiwu

Subscribers: hermanlee4, dhruba, andrewkr

Differential Revision: https://reviews.facebook.net/D64599
2016-10-07 11:32:10 -07:00
Yi Wu
9ed928e7a9 Split DBOptions into ImmutableDBOptions and MutableDBOptions
Summary: Use ImmutableDBOptions/MutableDBOptions internally and DBOptions only for user-facing APIs. MutableDBOptions is barely a placeholder for now. I'll start to move options to MutableDBOptions in following diffs.

Test Plan:
  make all check

Reviewers: yhchiang, IslamAbdelRahman, sdong

Reviewed By: sdong

Subscribers: andrewkr, dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D64065
2016-09-23 16:34:04 -07:00
yiwu-arbug
4bc8c88e6b Recover same sequence id from WAL (#1350)
Summary:
Revert the behavior where we don't read sequence id from WAL, but increase it as we replay the log. We still keep the behave for 2PC for now but will fix later.

This change fixes github issue 1339, where some writes come with WAL disabled and we may recover records with wrong sequence id.

Test Plan: Added unit test.

Subscribers: andrewkr, dhruba

Differential Revision: https://reviews.facebook.net/D64275
2016-09-23 16:15:14 -07:00
sdong
b666f85445 Consider more factors when determining preallocation size of WAL files
Summary: Currently the WAL file preallocation size is 1.1 * write_buffer_size. This, however, will be over-estimated if options.db_write_buffer_size or options.max_total_wal_size is set and is much smaller.

Test Plan: Add a unit test.

Reviewers: andrewkr, yiwu

Reviewed By: yiwu

Subscribers: leveldb, andrewkr, dhruba

Differential Revision: https://reviews.facebook.net/D63957
2016-09-19 12:04:35 -07:00
Yi Wu
40cfa3e021 Fix DBWALTest.RecoveryWithLogDataForSomeCFs with mac
Summary: Seems there's no std::array on mac+clang. Use raw array instead.

Test Plan: run ./db_wal_test on mac.

Reviewers: andrewkr

Reviewed By: andrewkr

Subscribers: andrewkr, dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D64005
2016-09-15 13:44:33 -07:00
Andrew Kryczka
06b4785fec Fix recovery for WALs without data for all CFs
Summary:
if one or more CFs had no data in the WAL, the log number that's used
by FindObsoleteFiles() wasn't updated. We need to treat this case the same as
if the data for that WAL had been flushed.

Test Plan: new unit test

Reviewers: IslamAbdelRahman, yiwu, sdong

Reviewed By: sdong

Subscribers: andrewkr, dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D63963
2016-09-15 11:40:48 -07:00
Andrew Kryczka
d7242ff4d5 Fix GetSortedWalFiles when log recycling enabled
Summary:
Previously the sequence number was mistakenly passed in an argument
where the log number should go. This caused the reader to assume the old WAL
format was used, which is incompatible with the WAL recycling format.

Test Plan:
new unit test, verified it fails before this change and passes
afterwards.

Reviewers: yiwu, lightmark, IslamAbdelRahman, sdong

Reviewed By: sdong

Subscribers: andrewkr, dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D63987
2016-09-15 09:55:02 -07:00
sdong
32df9733d1 Add options.write_buffer_manager: control total memtable size across DB instances
Summary: Add option write_buffer_manager to help users control total memory spent on memtables across multiple DB instances.

Test Plan: Add a new unit test.

Reviewers: yhchiang, IslamAbdelRahman

Reviewed By: IslamAbdelRahman

Subscribers: adela, benj, sumeet, muthu, leveldb, andrewkr, dhruba

Differential Revision: https://reviews.facebook.net/D59925
2016-07-05 18:11:25 -07:00
charsyam
4f2b0946d1 fix simple typos (#1183) 2016-06-25 08:29:40 +01:00
Yi Wu
bc8af90e8c add option to not flush memtable on open()
Summary:
Add option to not flush memtable on open()
In case the option is enabled, don't delete existing log files by not updating log numbers to MANIFEST.
Will still flush if we need to (e.g. memtable full in the middle). In that case we also flush final memtable.
If wal_recovery_mode = kPointInTimeRecovery, do not halt immediately after encounter corruption. Instead, check if seq id of next log file is last_log_sequence + 1. In that case we continue recovery.

Test Plan: See unit test.

Reviewers: dhruba, horuff, sdong

Reviewed By: sdong

Subscribers: benj, yhchiang, andrewkr, dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D57813
2016-06-13 11:34:16 -07:00
Dmitri Smirnov
ee221d2de0 Introduce XPRESS compresssion on Windows. (#1081)
Comparable with Snappy on comp ratio.
  Implemented using Windows API, does not require external package.
  Avaiable since Windows 8 and server 2012.
  Use -DXPRESS=1 with CMake to enable.
2016-04-19 22:54:24 -07:00
Yi Wu
792762c42c Split db_test.cc
Summary: Split db_test.cc into several files. Moving several helper functions into DBTestBase.

Test Plan: make check

Reviewers: sdong, yhchiang, IslamAbdelRahman

Reviewed By: IslamAbdelRahman

Subscribers: dhruba, andrewkr, kradhakrishnan, yhchiang, leveldb, sdong

Differential Revision: https://reviews.facebook.net/D56715
2016-04-18 09:42:50 -07:00
Baraa Hamodi
21e95811d1 Updated all copyright headers to the new format. 2016-02-09 15:12:00 -08:00
Dmitri Smirnov
3c750b59ae No need to #ifdef test only code on windows 2015-10-22 15:15:37 -07:00
Venkatesh Radhakrishnan
f1fdf5205b Clean up dependency: Move db_test_util.* to db directory
Summary:
As part of tech debt week, we are cleaning up dependencies.
This diff moves db_test_util.[h,cc] from util to db directory.

Test Plan: make check

Reviewers: igor, sdong

Reviewed By: sdong

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D48543
2015-10-12 13:05:42 -07:00
sdong
7ccd1c80a7 Add two unit tests for SyncWAL()
Summary:
Add two unit tests for SyncWAL(). One makes sure SyncWAL() doesn't block writes in the other thread. Another one makes sure SyncWAL() doesn't wait ongoing writes to finish before being executed.

Create a new test file db_wal_test and move two WAL related tests from db_test to here.

Test Plan: Run the new tests

Reviewers: IslamAbdelRahman, rven, kradhakrishnan, kolmike, tnovak, yhchiang

Reviewed By: yhchiang

Subscribers: leveldb, dhruba

Differential Revision: https://reviews.facebook.net/D43605
2015-08-05 14:27:02 -07:00