Summary: Add a utility function that trigger necessary full compaction and put output to the correct level by looking at new options and old options.

Test Plan: Add unit tests for it.

Reviewers: andrewkr, igor, IslamAbdelRahman

Reviewed By: IslamAbdelRahman

Subscribers: muthu, sumeet, leveldb, andrewkr, dhruba

Differential Revision: https://reviews.facebook.net/D60783

Summary:
parallel tests are broken because gnu_parallel is reading deprecated options from `/etc/parallel/config`
Fix this by passing `--plain` to ignore `/etc/parallel/config`

Test Plan: make check -j64

Reviewers: kradhakrishnan, sdong, andrewkr, yiwu, arahut

Reviewed By: arahut

Subscribers: andrewkr, dhruba

Differential Revision: https://reviews.facebook.net/D61359

Summary:
Experiments on column-aware encodings. Supported features: 1) extract data blocks from SST file and encode with specified encodings; 2) Decode encoded data back into row format; 3) Directly extract data blocks and write in row format (without prefix encoding); 4) Get column distribution statistics for column format; 5) Dump data blocks separated by columns in human-readable format.

There is still on-going work on this diff. More refactoring is necessary.

Test Plan: Wrote tests in `column_aware_encoding_test.cc`. More tests should be added.

Reviewers: sdong

Reviewed By: sdong

Subscribers: arahut, andrewkr, dhruba

Differential Revision: https://reviews.facebook.net/D60027

More granular steps in the Makefile, can help with running all or single Java tests (and with ASAN build - https://github.com/facebook/rocksdb/wiki/JNI-Debugging) (#1237)

Summary:
Removing moreutils from sandcastle and adding gnu parallel.
Then passing in J= nproc command

Test Plan: Testing on sandcastle

Reviewers: sdong, kradhakrishnan

Reviewed By: kradhakrishnan

Subscribers: andrewkr, dhruba

Differential Revision: https://reviews.facebook.net/D61017

Summary:
TickersNameMap is not consistent with Tickers enum.
this cause us to report wrong statistics and sometimes to access TickersNameMap outside it's boundary causing crashes (in Fb303 statistics)

Test Plan: added new unit test

Reviewers: sdong, kradhakrishnan

Reviewed By: kradhakrishnan

Subscribers: andrewkr, dhruba

Differential Revision: https://reviews.facebook.net/D61083

Summary:
Tsan crash white-box test was disabled because it never ends. Re-enable it with reduced killing odds.
Add a parameter in crash test script to allow we pass it through an environment variable.

Test Plan: Run it manually.

Reviewers: IslamAbdelRahman

Reviewed By: IslamAbdelRahman

Subscribers: leveldb, andrewkr, dhruba

Differential Revision: https://reviews.facebook.net/D61053

This reverts commit 08ab1d83.

Summary: Multiput atomiciy is broken across multiple column families if we don't sync WAL before flushing one column family. The WAL file may contain a write batch containing writes to a key to the CF to be flushed and a key to other CF. If we don't sync WAL before flushing, if machine crashes after flushing, the write batch will only be partial recovered. Data to other CFs are lost.

Test Plan: Add a new unit test which will fail without the diff.

Reviewers: yhchiang, IslamAbdelRahman, igor, yiwu

Reviewed By: yiwu

Subscribers: yiwu, leveldb, andrewkr, dhruba

Differential Revision: https://reviews.facebook.net/D60915

Summary: RocksDB behavior is slightly different between data on tmpfs and normal file systems. Add a test case to run RocksDB on normal file system.

Test Plan: See the tests launched by Phabricator

Reviewers: kradhakrishnan, IslamAbdelRahman, gunnarku

Reviewed By: gunnarku

Subscribers: leveldb, andrewkr, dhruba

Differential Revision: https://reviews.facebook.net/D60963

EnvLibrados is a customized RocksDB Env to use RADOS as the backend file system of RocksDB. It overrides all file system related API of default Env. The easiest way to use it is just like following:

	std::string db_name = "test_db";
	std::string config_path = "path/to/ceph/config";
	DB* db;
	Options options;
	options.env = EnvLibrados(db_name, config_path);
	Status s = DB::Open(options, kDBPath, &db);

Then EnvLibrados will forward all file read/write operation to the RADOS cluster assigned by config_path. Default pool is db_name+"_pool".

There are some options that users could set for EnvLibrados.
- write_buffer_size. This variable is the max buffer size for WritableFile. After reaching the buffer_max_size, EnvLibrados will sync buffer content to RADOS, then clear buffer.
- db_pool. Rather than using default pool, users could set their own db pool name
- wal_dir. The dir for WAL files. Because RocksDB only has 2-level structure (dir_name/file_name), the format of wal_dir is "/dir_name"(CAN'T be "/dir1/dir2"). Default wal_dir is "/wal".
- wal_pool. Corresponding pool name for WAL files. Default value is db_name+"_wal_pool"

The example of setting options looks like following:

	db_name = "test_db";
	db_pool = db_name+"_pool";
	wal_dir = "/wal";
	wal_pool = db_name+"_wal_pool";
	write_buffer_size = 1 << 20;
	env_ = new EnvLibrados(db_name, config, db_pool, wal_dir, wal_pool, write_buffer_size);

	DB* db;
	Options options;
	options.env = env_;
	// The last level dir name should match the dir name in prefix_pool_map
	options.wal_dir = "/tmp/wal";

	// open DB
	Status s = DB::Open(options, kDBPath, &db);

Librados is required to compile EnvLibrados. Then use "$make LIBRADOS=1" to compile RocksDB. If you want to only compile EnvLibrados test, just run "$ make env_librados_test LIBRADOS=1". To run env_librados_test, you need to have a running RADOS cluster with the configure file located in "../ceph/src/ceph.conf" related to "rocksdb/".

Summary:
Fix flush not being commit while writing manifest, which is a recent bug introduced by D60075.

The issue:
# Options.max_background_flushes > 1
# Background thread A pick up a flush job, flush, then commit to manifest. (Note that mutex is released before writing manifest.)
# Background thread B pick up another flush job, flush. When it gets to `MemTableList::InstallMemtableFlushResults`, it notices another thread is commiting, so it quit.
# After the first commit, thread A doesn't double check if there are more flush result need to commit, leaving the second flush uncommitted.

Test Plan: run the test. Also verify the new test hit deadlock without the fix.

Reviewers: sdong, igor, lightmark

Reviewed By: lightmark

Subscribers: andrewkr, omegaga, dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D60969

The tests run by `make check` require Bash. On Debian you'd need to run
the test as `make SHELL=/bin/bash check`. This commit makes it work on
all POSIX compatible shells (tested on Debian with `dash`).

Summary: As Title.

Test Plan: See how the diff works.

Reviewers: kradhakrishnan, andrewkr, gunnarku

Reviewed By: gunnarku

Subscribers: leveldb, andrewkr, dhruba

Differential Revision: https://reviews.facebook.net/D60933

Summary:
When write stalls because of auto compaction is disabled, or stop write trigger is reached,
user may change these two options to unblock writes. Unfortunately we had issue where the write
thread will block the attempt to persist the options, thus creating a deadlock. This diff
fix the issue and add two test cases to detect such deadlock.

Test Plan:
Run unit tests.

Also, revert db_impl.cc to master (but don't revert `DBImpl::BackgroundCompaction:Finish` sync point) and run db_options_test. Both tests should hit deadlock.

Reviewers: sdong

Reviewed By: sdong

Subscribers: andrewkr, dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D60627

Summary: In D33849 we updated Makefile to generate .d files for all .cc sources. Since we have more types of source files now, this needs to be updated so that this mechanism can work for new files.

Test Plan: change a dependent .h file, re-make and see if .o file is recompiled.

Reviewers: sdong, andrewkr

Reviewed By: andrewkr

Subscribers: andrewkr, dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D60591

Summary:
Update Makefile to show warnings when we have invalid paths in our make_config.mk file

sample output

```
$ make static_lib -j64
Makefile:150: Warning: /mnt/gvfs/third-party2/libgcc/53e0eac8911888a105aa98b9a35fe61cf1d8b278/4.9.x/gcc-4.9-glibc-2.20/024dbc3/libs dont exist
Makefile:150: Warning: /mnt/gvfs/third-party2/llvm-fb/b91de48a4974ec839946d824402b098d43454cef/stable/centos6-native/7aaccbe/../../src/clang/tools/scan-build/scan-build dont exist
  GEN      util/build_version.cc
```

Test Plan: check that warning is printed visually

Reviewers: sdong, yiwu, andrewkr

Reviewed By: andrewkr

Subscribers: andrewkr, dhruba

Differential Revision: https://reviews.facebook.net/D59523

Summary:
This provides provides an implementation of PersistentCacheTier that is
specialized for RAM. This tier does not persist data though.

Why do we need this tier ?

This is ideal as tier 0. This tier can host data that is too hot.

Why can't we use Cache variants ?

Yes you can use them instead. This tier can potentially outperform BlockCache
in RAW mode by virtue of compression and compressed cache in block cache doesn't
seem very popular. Potentially this tier can be modified to under stand the
disadvantage of the tier below and retain data that the tier below is bad at
handling (for example index and bloom data that is huge in size)

Test Plan: Run unit tests added

Subscribers: andrewkr, dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D57069

Summary:
- Provide env_test as a static library. We will build it for future releases so internal Envs can use env_test by linking against this library.
- Add tests for CustomEnv, which is configurable via ENV_TEST_URI environment variable. It uses the URI-based Env lookup (depends on D58449).
- Refactor env_basic_test cases to use a unique/configurable directory for test files.

Test Plan:
built a test binary against librocksdb_env_test.a. It registered the
default Env with URI prefix "a://".

- verify runs all CustomEnv tests when URI with correct prefix is provided

```
$ ENV_TEST_URI="a://ok" ./tmp --gtest_filter="CustomEnv/*"
...
[  PASSED  ] 12 tests.
```

- verify runs no CustomEnv tests when URI with non-matching prefix is provided

```
$ ENV_TEST_URI="b://ok" ./tmp --gtest_filter="CustomEnv/*"
...
[  PASSED  ] 0 tests.
```

Reviewers: ldemailly, IslamAbdelRahman, lightmark, sdong

Reviewed By: sdong

Subscribers: andrewkr, dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D58485

Summary:
Extracted basic Env-related tests from mock_env_test and memenv_test into a
parameterized test for Envs: env_basic_test.

Depends on D58449. (The dependency is here only so I can keep this series of
diffs in a chain -- there is no dependency on that diff's code.)

Test Plan: ran tests

Reviewers: IslamAbdelRahman, sdong

Reviewed By: sdong

Subscribers: andrewkr, dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D58635

Summary:
This enables configurable Envs without recompiling. For example, my
next diff will make env_test test an Env created by NewEnvFromUri(). Then,
users can determine which Env is tested simply by providing the URI for
NewEnvFromUri() (e.g., through a CLI argument or environment variable).

The registration process allows us to register any Env that is linked with the
RocksDB library, so we can register our internal Envs as well.

The registration code is inspired by our internal InitRegistry.

Test Plan: new unit test

Reviewers: IslamAbdelRahman, lightmark, ldemailly, sdong

Reviewed By: sdong

Subscribers: leveldb, dhruba, andrewkr

Differential Revision: https://reviews.facebook.net/D58449

Summary:
This patch allows db_bench to initialize it's RocksDB Options via a
options file, specified by the --options_file flag.  Note that if
--options_file flag is set, then it has higher priority than the
command-line argument.

Test Plan: db_bench_tool_test

Reviewers: sdong, IslamAbdelRahman, kradhakrishnan, yiwu, andrewkr

Reviewed By: andrewkr

Subscribers: andrewkr, dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D58533

Summary:
Currently all the tools are included in librocksdb.a (db_bench is not). With
this separate library, we can access db_bench functionality from our internal
repo and eventually move tools out of librocksdb.a.

Test Plan: built a simple binary against this library that invokes db_bench_tool().

Reviewers: IslamAbdelRahman, sdong

Reviewed By: sdong

Subscribers: andrewkr, dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D58977

Summary: add class SimCache(base class with instrumentation api) and SimLRUCache(derived class with detailed implementation) which is used as an instrumented block cache that can predict hit rate for different cache size

Test Plan:
Add a test case in `db_block_cache_test.cc` called `SimCacheTest` to test basic logic of SimCache.
Also add option `-simcache_size` in db_bench. if set with a value other than -1, then the benchmark will use this value as the size of the simulator cache and finally output the simulation result.
```
[gzh@dev9927.prn1 ~/local/rocksdb] ./db_bench -benchmarks "fillseq,readrandom" -cache_size 1000000 -simcache_size 1000000
RocksDB:    version 4.8
Date:       Tue May 17 16:56:16 2016
CPU:        32 * Intel(R) Xeon(R) CPU E5-2660 0 @ 2.20GHz
CPUCache:   20480 KB
Keys:       16 bytes each
Values:     100 bytes each (50 bytes after compression)
Entries:    1000000
Prefix:    0 bytes
Keys per prefix:    0
RawSize:    110.6 MB (estimated)
FileSize:   62.9 MB (estimated)
Write rate: 0 bytes/second
Compression: Snappy
Memtablerep: skip_list
Perf Level: 0
WARNING: Assertions are enabled; benchmarks unnecessarily slow
------------------------------------------------
DB path: [/tmp/rocksdbtest-112628/dbbench]
fillseq      :       6.809 micros/op 146874 ops/sec;   16.2 MB/s
DB path: [/tmp/rocksdbtest-112628/dbbench]
readrandom   :       6.343 micros/op 157665 ops/sec;   17.4 MB/s (1000000 of 1000000 found)

SIMULATOR CACHE STATISTICS:
SimCache LOOKUPs: 986559
SimCache HITs:    264760
SimCache HITRATE: 26.84%

[gzh@dev9927.prn1 ~/local/rocksdb] ./db_bench -benchmarks "fillseq,readrandom" -cache_size 1000000 -simcache_size 10000000
RocksDB:    version 4.8
Date:       Tue May 17 16:57:10 2016
CPU:        32 * Intel(R) Xeon(R) CPU E5-2660 0 @ 2.20GHz
CPUCache:   20480 KB
Keys:       16 bytes each
Values:     100 bytes each (50 bytes after compression)
Entries:    1000000
Prefix:    0 bytes
Keys per prefix:    0
RawSize:    110.6 MB (estimated)
FileSize:   62.9 MB (estimated)
Write rate: 0 bytes/second
Compression: Snappy
Memtablerep: skip_list
Perf Level: 0
WARNING: Assertions are enabled; benchmarks unnecessarily slow
------------------------------------------------
DB path: [/tmp/rocksdbtest-112628/dbbench]
fillseq      :       5.066 micros/op 197394 ops/sec;   21.8 MB/s
DB path: [/tmp/rocksdbtest-112628/dbbench]
readrandom   :       6.457 micros/op 154870 ops/sec;   17.1 MB/s (1000000 of 1000000 found)

SIMULATOR CACHE STATISTICS:
SimCache LOOKUPs: 1059764
SimCache HITs:    374501
SimCache HITRATE: 35.34%

[gzh@dev9927.prn1 ~/local/rocksdb] ./db_bench -benchmarks "fillseq,readrandom" -cache_size 1000000 -simcache_size 100000000
RocksDB:    version 4.8
Date:       Tue May 17 16:57:32 2016
CPU:        32 * Intel(R) Xeon(R) CPU E5-2660 0 @ 2.20GHz
CPUCache:   20480 KB
Keys:       16 bytes each
Values:     100 bytes each (50 bytes after compression)
Entries:    1000000
Prefix:    0 bytes
Keys per prefix:    0
RawSize:    110.6 MB (estimated)
FileSize:   62.9 MB (estimated)
Write rate: 0 bytes/second
Compression: Snappy
Memtablerep: skip_list
Perf Level: 0
WARNING: Assertions are enabled; benchmarks unnecessarily slow
------------------------------------------------
DB path: [/tmp/rocksdbtest-112628/dbbench]
fillseq      :       5.632 micros/op 177572 ops/sec;   19.6 MB/s
DB path: [/tmp/rocksdbtest-112628/dbbench]
readrandom   :       6.892 micros/op 145094 ops/sec;   16.1 MB/s (1000000 of 1000000 found)

SIMULATOR CACHE STATISTICS:
SimCache LOOKUPs: 1150767
SimCache HITs:    1034535
SimCache HITRATE: 89.90%
```

Reviewers: IslamAbdelRahman, andrewkr, sdong

Reviewed By: sdong

Subscribers: MarkCallaghan, andrewkr, dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D57999

Summary: Deprecate this one option and delete code and tests that are now superfluous.

Test Plan: all tests pass

Reviewers: igor, yhchiang, IslamAbdelRahman

Reviewed By: IslamAbdelRahman

Subscribers: msalib, leveldb, andrewkr, dhruba

Differential Revision: https://reviews.facebook.net/D55317

Summary:
Introduce MaxOperator a simple merge operator that return the max of all operands.
This merge operand help me in benchmarking

Test Plan: Add new unitttests

Reviewers: sdong, andrewkr, yhchiang

Reviewed By: yhchiang

Subscribers: andrewkr, dhruba

Differential Revision: https://reviews.facebook.net/D57873

Summary:
This is a part of effort to reduce the size of db_test.cc. We move the following tests to a separate file `db_io_failure_test.cc`:

* DropWrites
* DropWritesFlush
* NoSpaceCompactRange
* NonWritableFileSystem
* ManifestWriteError
* PutFailsParanoid

Test Plan: Run `make check` to see if the tests are working properly.

Reviewers: sdong, IslamAbdelRahman

Reviewed By: IslamAbdelRahman

Subscribers: andrewkr, dhruba

Differential Revision: https://reviews.facebook.net/D58341

Summary:
We expect the persistent read cache to perform at speeds upto 8 GB/s. In order
to accomplish that, we need build a index mechanism which operate in the order
of multiple millions per sec rate.

This patch provide the basic data structure to accomplish that:

(1) Hash table implementation with lock contention spread
    It is based on the StripedHashSet<T> implementation in
    The Art of multiprocessor programming by Maurice Henry & Nir Shavit
(2) LRU implementation
    Place holder algorithm for further optimizing
(3) Evictable Hash Table implementation
    Building block for building index data structure that evicts data like files
    etc

TODO:
(1) Figure if the sharded hash table and LRU can be used instead
(2) Figure if we need to support configurable eviction algorithm for
EvictableHashTable

Test Plan: Run unit tests

Subscribers: andrewkr, dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D55785

Summary:
Introduced option to dump malloc statistics using new option flag.
    Added new command line option to db_bench tool to enable this
    funtionality.
    Also extended build to support environments with/without jemalloc.

Test Plan:
1) Build rocksdb using `make` command. Launch the following command
    `./db_bench --benchmarks=fillrandom --dump_malloc_stats=true
    --num=10000000` end verified that jemalloc dump is present in LOG file.
    2) Build rocksdb using `DISABLE_JEMALLOC=1  make db_bench -j32` and ran
    the same db_bench tool and found the following message in LOG file:
    "Please compile with jemalloc to enable malloc dump".
    3) Also built rocksdb using `make` command on MacOS to verify behavior
    in non-FB environment.
    Also to debug build configuration change temporary changed
    AM_DEFAULT_VERBOSITY = 1 in Makefile to see compiler and build
    tools output. For case 1) -DROCKSDB_JEMALLOC was present in compiler
    command line. For both 2) and 3) this flag was not present.

Reviewers: sdong

Reviewed By: sdong

Subscribers: andrewkr, dhruba

Differential Revision: https://reviews.facebook.net/D57321

* Musl libc does not provide adaptive mutex. Added feature test for PTHREAD_MUTEX_ADAPTIVE_NP.

* Musl libc does not provide backtrace(3). Added a feature check for backtrace(3).

* Fixed compiler error.

* Musl libc does not implement backtrace(3). Added platform check for libexecinfo.

* Alpine does not appear to support gcc -pg option. By default (gcc has PIE option enabled) it fails with:

gcc: error: -pie and -pg|p|profile are incompatible when linking

When -fno-PIE and -nopie are used it fails with:

/usr/lib/gcc/x86_64-alpine-linux-musl/5.3.0/../../../../x86_64-alpine-linux-musl/bin/ld: cannot find gcrt1.o: No such file or directory

Added gcc -pg platform test and output PROFILING_FLAGS accordingly. Replaced pg var in Makefile with PROFILING_FLAGS.

* fix segfault when TEST_IOCTL_FRIENDLY_TMPDIR is undefined and default candidates are not suitable

* use ASSERT_DOUBLE_EQ instead of ASSERT_EQ

* When compiled with ROCKSDB_MALLOC_USABLE_SIZE UniversalCompactionFourPaths and UniversalCompactionSecondPathRatio tests fail due to premature memtable flushes on systems with 16-byte alignment. Arena runs out of block space before GenerateNewFile() completes.

Increased options.write_buffer_size.

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

Summary:
Generate t/run-* scripts to run tests in $PARALLEL_TEST separately, then make check_0 rule execute all of them.

Run `time make check` after running `make all`.
master: 71 sec
with this diff: 63 sec.

It seems moving more tests to $PARALLEL_TEST doesn't help improve test time though.

Test Plan:
Run the following
  make check
  J=16 make check
  J=1 make check
  make valgrind_check
  J=1 make valgrind_check
  J=16 make_valgrind_check

Reviewers: IslamAbdelRahman, sdong

Reviewed By: sdong

Subscribers: leveldb, kradhakrishnan, dhruba, andrewkr, yhchiang

Differential Revision: https://reviews.facebook.net/D56805

Summary:
Before
{F1131675}

After
{F1131681}

This will have no effect on normal make check

Test Plan: make watch-log

Reviewers: sdong

Reviewed By: sdong

Subscribers: andrewkr, dhruba

Differential Revision: https://reviews.facebook.net/D56847

Summary:
Extend "J=<parallel>" to valgrind_check.
For DBTest, modify the script to run valgrind. For other tests, prefix launch command with valgrind.

Test Plan: Run valgrind_check with J=1 and J>1 and make sure tests run under valgrind. Manually change codes to introduce memory leak and make sure "make watch-log" correctly report it.

Reviewers: yhchiang, yiwu, andrewkr, kradhakrishnan, IslamAbdelRahman

Reviewed By: kradhakrishnan, IslamAbdelRahman

Subscribers: leveldb, andrewkr, dhruba

Differential Revision: https://reviews.facebook.net/D56727

Summary:
  - Update Makefile check_some command to run a subset of the tests
  - Update travis config to split the unittests job into 2 jobs
     -- job testing db_test, db_test2
     -- job testing the rest of the unittests

Test Plan:
Run the new travis.yml on my own branch
https://travis-ci.org/facebook/rocksdb/builds/122691453

Reviewers: kradhakrishnan, yhchiang, sdong, andrewkr

Reviewed By: andrewkr

Subscribers: andrewkr, dhruba

Differential Revision: https://reviews.facebook.net/D56673

Summary: Test DBOptionsAllFieldsSettable sometimes fails under valgrind. Move option settable tests to a separate test file and disable it in valgrind..

Test Plan: Run valgrind test and make sure the test doesn't run.

Reviewers: andrewkr, IslamAbdelRahman

Reviewed By: IslamAbdelRahman

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

Differential Revision: https://reviews.facebook.net/D56529

Summary:
Undefined Behavior Sanitizer (ubsan) is //a good thing// which will help us to find sneaky bugs with low cost. Please see http://developerblog.redhat.com/2014/10/16/gcc-undefined-behavior-sanitizer-ubsan/ for more details and official GCC documentation for more context: https://gcc.gnu.org/onlinedocs/gcc/Instrumentation-Options.html.

Changes itself are quite simple and pretty much imitating whatever is implemented for ASan.

Hooking the UBsan validation build to Sandcastle is a separate step and will be dealt as separate diff because code is in internal repository.

Test Plan: Make sure that that there no regressions when it comes to builds and test pass rate.

Reviewers: leveldb, sdong, IslamAbdelRahman, yhchiang

Reviewed By: yhchiang

Subscribers: andrewkr, dhruba

Differential Revision: https://reviews.facebook.net/D56049

Summary:
Basic test cases:

- Manifest is lost or corrupt
- Manifest refers to too many or too few SST files
- SST file is corrupt
- Unflushed data is present when RepairDB is called

Depends on D55065 for its CreateFile() function in file_utils

Test Plan: Ran the tests.

Reviewers: IslamAbdelRahman, yhchiang, yoshinorim, sdong

Reviewed By: sdong

Subscribers: leveldb, andrewkr, dhruba

Differential Revision: https://reviews.facebook.net/D55485

Summary:
Cache to have an option to fail Cache::Insert() when full. Update call sites to check status and handle error.

I totally have no idea what's correct behavior of all the call sites when they encounter error. Please let me know if you see something wrong or more unit test is needed.

Test Plan: make check -j32, see tests pass.

Reviewers: anthony, yhchiang, andrewkr, IslamAbdelRahman, kradhakrishnan, sdong

Reviewed By: sdong

Subscribers: andrewkr, dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D54705

Summary: We want to provide a way to detect whether an iterator is stale and needs to be recreated. Add a iterator property to return version number.

Test Plan: Add two unit tests for it.

Reviewers: IslamAbdelRahman, yhchiang, anthony, kradhakrishnan, andrewkr

Reviewed By: andrewkr

Subscribers: leveldb, dhruba

Differential Revision: https://reviews.facebook.net/D54921