Summary: Use a better way to map from a key with locality to a random location. Now with the same -read_random_exp_range setting, hit rate drops, which it is expected.

Test Plan: ./db_bench --benchmarks=readrandom -statistics -use_existing_db -cache_size=5000000 --read_random_exp_range=<multiple_values>

Reviewers: MarkCallaghan, kradhakrishnan, igor

Reviewed By: igor

Subscribers: leveldb, dhruba

Differential Revision: https://reviews.facebook.net/D34761

Summary:
Provide an API which enables users to infor Rocksdb that it is
shutting down.

Test Plan: db_test

Reviewers: sdong, igor

Reviewed By: igor

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D34617

Summary: Got it working by some voodoo programming

Test Plan: works!

Reviewers: sdong

Reviewed By: sdong

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D34611

Summary: Allow GetThreadList() to report the start time of the current operation.

Test Plan:
./db_bench --benchmarks=fillrandom --num=100000 --threads=40 \
  --max_background_compactions=10 --max_background_flushes=3 \
  --thread_status_per_interval=1000 --key_size=16 --value_size=1000 \
  --num_column_families=10

Sample output:
          ThreadID ThreadType                    cfName    Operation        OP_StartTime         State
   140338840797248   High Pri column_family_name_000003        Flush 2015/03/09-17:49:59
   140338844991552   High Pri column_family_name_000004        Flush 2015/03/09-17:49:59
   140338849185856    Low Pri
   140338983403584    Low Pri
   140339008569408    Low Pri
   140338861768768    Low Pri
   140338924683328    Low Pri
   140338899517504    Low Pri
   140338853380160    Low Pri
   140338882740288    Low Pri
   140338865963072   High Pri column_family_name_000006        Flush 2015/03/09-17:49:59
   140338954043456    Low Pri
   140338857574464    Low Pri

Reviewers: igor, rven, sdong

Reviewed By: sdong

Subscribers: lgalanis, dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D34689

Summary: Introduce parameter -read_random_exp_range in db_bench to provide some key skewness in readrandom and multireadrandom benchmarks. It will helpful to cover block cache better.

Test Plan:
Run benchmarks with this new parameter. I can clearly see block cache hit rate change while I increase this value (DB size is about 66MB):

./db_bench --benchmarks=readrandom -statistics -use_existing_db -cache_size=5000000 --read_random_exp_range=0.0
rocksdb.block.cache.data.miss COUNT : 958418
rocksdb.block.cache.data.hit COUNT : 41582

./db_bench --benchmarks=readrandom -statistics -use_existing_db -cache_size=5000000 --read_random_exp_range=5.0
rocksdb.block.cache.data.miss COUNT : 819518
rocksdb.block.cache.data.hit COUNT : 180482

./db_bench --benchmarks=readrandom -statistics -use_existing_db -cache_size=5000000 --read_random_exp_range=10.0
rocksdb.block.cache.data.miss COUNT : 450479
rocksdb.block.cache.data.hit COUNT : 549521

./db_bench --benchmarks=readrandom -statistics -use_existing_db -cache_size=5000000 --read_random_exp_range=20.0
rocksdb.block.cache.data.miss COUNT : 223192
rocksdb.block.cache.data.hit COUNT : 776808

Reviewers: MarkCallaghan, kradhakrishnan, yhchiang, rven, igor

Reviewed By: igor

Subscribers: leveldb, dhruba

Differential Revision: https://reviews.facebook.net/D34629

Summary: I want to be able to set this through mongo config.

Test Plan: added unit test

Reviewers: sdong

Reviewed By: sdong

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D34599

Summary:
Add --thread_status_per_interval to db_bench, which allows
db_bench to optionally enable print the current thread status
periodically.

Test Plan:
./db_bench --benchmarks=fillrandom --num=100000 --threads=40 --max_background_compactions=10 --max_background_flushes=3 --thread_status_per_interval=1000 --key_size=16 --value_size=1000 --num_column_families=10

Sample output:
          ThreadID ThreadType                         dbName                     cfName       Operation           State
   140281571770432    Low Pri
   140281575964736   High Pri  /tmp/rocksdbtest-5297/dbbench  column_family_name_000001           Flush
   140281710182464    Low Pri  /tmp/rocksdbtest-5297/dbbench  column_family_name_000008      Compaction
   140281638879296    Low Pri  /tmp/rocksdbtest-5297/dbbench  column_family_name_000007      Compaction
   140281592741952    Low Pri
   140281580159040   High Pri  /tmp/rocksdbtest-5297/dbbench  column_family_name_000002           Flush
   140281676628032    Low Pri  /tmp/rocksdbtest-5297/dbbench  column_family_name_000006      Compaction
   140281584353344    Low Pri
   140281622102080    Low Pri  /tmp/rocksdbtest-5297/dbbench  column_family_name_000009      Compaction
   140281605324864    Low Pri  /tmp/rocksdbtest-5297/dbbench  column_family_name_000004      Compaction
   140281601130560   High Pri  /tmp/rocksdbtest-5297/dbbench                    default           Flush
   140281596936256    Low Pri
   140281588547648    Low Pri

Reviewers: igor, rven, sdong

Reviewed By: rven

Subscribers: dhruba

Differential Revision: https://reviews.facebook.net/D34515

Summary: Fix a bug in stall time counter.  Improve its output format.

Test Plan:
export ROCKSDB_TESTS=Timeout
./db_test

./db_bench --benchmarks=fillrandom --stats_interval=10000 --statistics=true --stats_per_interval=1 --num=1000000 --threads=4 --level0_stop_writes_trigger=3 --level0_slowdown_writes_trigger=2

sample output:
    Uptime(secs): 35.8 total, 0.0 interval
    Cumulative writes: 359590 writes, 359589 keys, 183047 batches, 2.0 writes per batch, 0.04 GB user ingest, stall seconds: 1786.008 ms
    Cumulative WAL: 359591 writes, 183046 syncs, 1.96 writes per sync, 0.04 GB written
    Interval writes: 253 writes, 253 keys, 128 batches, 2.0 writes per batch, 0.0 MB user ingest, stall time: 0 us
    Interval WAL: 253 writes, 128 syncs, 1.96 writes per sync, 0.00 MB written

Reviewers: MarkCallaghan, igor, sdong

Reviewed By: sdong

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D34275

options.level_compaction_dynamic_level_bytes to allow RocksDB to pick size bases of levels dynamically.

Summary:
When having fixed max_bytes_for_level_base, the ratio of size of largest level and the second one can range from 0 to the multiplier. This makes LSM tree frequently irregular and unpredictable. It can also cause poor space amplification in some cases.

In this improvement (proposed by Igor Kabiljo), we introduce a parameter option.level_compaction_use_dynamic_max_bytes. When turning it on, RocksDB is free to pick a level base in the range of (options.max_bytes_for_level_base/options.max_bytes_for_level_multiplier, options.max_bytes_for_level_base] so that real level ratios are close to options.max_bytes_for_level_multiplier.

Test Plan: New unit tests and pass tests suites including valgrind.

Reviewers: MarkCallaghan, rven, yhchiang, igor, ikabiljo

Reviewed By: ikabiljo

Subscribers: yoshinorim, ikabiljo, dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D31437

Summary:
fix typo

Task ID: #

Blame Rev:

Test Plan:
Revert Plan:

Database Impact:

Memcache Impact:

Other Notes:

EImportant:

- begin *PUBLIC* platform impact section -
Bugzilla: #
- end platform impact -

Reviewers: igor

Reviewed By: igor

Subscribers: dhruba

Differential Revision: https://reviews.facebook.net/D34251

Summary: As title

Test Plan: compiles

Reviewers: sdong

Reviewed By: sdong

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D34191

Summary:
    Summary:
    Added a new option to ColumnFamllyOptions  - optimize_filters_for_hits. This option can be used in the case where most
    accesses to the store are key hits and we dont need to optimize performance for key misses.
    This is useful when you have a very large database and most of your lookups succeed.  The option allows the store to
     not store and use filters in the last level (the largest level which contains data). These filters can take a large amount of
     space for large databases (in memory and on-disk). For the last level, these filters are only useful for key misses and not
     for key hits. If we are not optimizing for key misses, we can choose to not store these filters for that level.

    This option is only provided for BlockBasedTable. We skip the filters when we are compacting

Test Plan:
1. Modified db_test toalso run tests with an additonal option (skip_filters_on_last_level)
 2. Added another unit test to db_test which specifically tests that filters are being skipped

Reviewers: rven, igor, sdong

Reviewed By: sdong

Subscribers: lgalanis, yoshinorim, MarkCallaghan, rven, dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D33717

Summary:
When using latest clang (3.6 or 3.7/trunck) rocksdb is failing with many errors. Almost all of them are missing override errors. This diff adds missing override keyword. No manual changes.

Prerequisites: bear and clang 3.5 build with extra tools

```lang=bash
% USE_CLANG=1 bear make all # generate a compilation database http://clang.llvm.org/docs/JSONCompilationDatabase.html
% clang-modernize -p . -include . -add-override
% make format
```

Test Plan:
Make sure all tests are passing.
```lang=bash
% #Use default fb code clang.
% make check
```
Verify less error and no missing override errors.
```lang=bash
% # Have trunk clang present in path.
% ROCKSDB_NO_FBCODE=1 CC=clang CXX=clang++ make
```

Reviewers: igor, kradhakrishnan, rven, meyering, sdong

Reviewed By: sdong

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D34077

Summary:
An old commit (482401) changed DoWrite to use the value of --writes rather
than --num to determine the range for keys. This restores the old and correct
behavior which is to limit it using --num.

Task ID: #6353043

Blame Rev:

Test Plan:
run db_bench

Revert Plan:

Database Impact:

Memcache Impact:

Other Notes:

EImportant:

- begin *PUBLIC* platform impact section -
Bugzilla: #
- end platform impact -

Reviewers: igor

Reviewed By: igor

Subscribers: dhruba

Differential Revision: https://reviews.facebook.net/D34065

Summary:
In a release build, a member was not being accessed. This
member was only being accessed in a debug build. We now add an accessor
function for this member and the buid succeeds.

Test Plan: build release/unity/debug on linux/mac

Reviewers: sdong, igor

Reviewed By: igor

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D34035

This reverts commit bd339a97.

Conflicts:
	db/managed_iterator.cc

Summary: This causes warnings on OS X

Test Plan: compiles

Reviewers: rven, sdong

Reviewed By: sdong

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D33969

Test Plan: Run "make clean && make all check"

Reviewers: rven, igor, yhchiang, kradhakrishnan, MarkCallaghan, sdong

Reviewed By: sdong

Subscribers: dhruba

Differential Revision: https://reviews.facebook.net/D33627

Summary:
This diff contains trivial fixes for 6 scan-build warnings:

**db/c_test.c**
`db` variable is never read. Removed assignment.
scan-build report:
http://home.fburl.com/~sugak/latest20/report-9b77d2.html#EndPath

**db/db_iter.cc**
`skipping` local variable is assigned to false. Then in the next switch block the only "non return" case assign `skipping` to true, the rest cases don't use it and all do return.
scan-build report:
http://home.fburl.com/~sugak/latest20/report-13fca7.html#EndPath

**db/log_reader.cc**
In `bool Reader::SkipToInitialBlock()` `offset_in_block` local variable is assigned to 0 `if (offset_in_block > kBlockSize - 6)` and then never used. Removed the assignment and renamed it to `initial_offset_in_block` to avoid confusion.
scan-build report:
http://home.fburl.com/~sugak/latest20/report-a618dd.html#EndPath

In `bool Reader::ReadRecord(Slice* record, std::string* scratch)` local variable `in_fragmented_record` in switch case `kFullType` block is assigned to false and then does `return` without use. In the other switch case `kFirstType` block the same `in_fragmented_record` is assigned to false, but later assigned to true without prior use. Removed assignment for both cases.
scan-build reprots:
http://home.fburl.com/~sugak/latest20/report-bb86b0.html#EndPath
http://home.fburl.com/~sugak/latest20/report-a975be.html#EndPath

**table/plain_table_key_coding.cc**
Local variable `user_key_size` is assigned when declared. But then in both places where it is used assigned to `static_cast<uint32_t>(key.size() - 8)`. Changed to initialize the variable to the proper value in declaration.
scan-build report:
http://home.fburl.com/~sugak/latest20/report-9e6b86.html#EndPath

**tools/db_stress.cc**
Missing `break` in switch case block. This seems to be a bug. Added missing `break`.

Test Plan:
Make sure all tests are passing and scan-build does not report 'Dead assignment' and 'Dead initialization' bugs.
```lang=bash
% make check
% make analyze
```

Reviewers: meyering, igor, kradhakrishnan, sdong

Reviewed By: sdong

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D33795

Summary:
The "const" attribute applies to the type, and placing it
before that return type retains the desired semantics,
yet avoids the compiler error/warning.

Test Plan: Run make

Reviewers: ljin, sdong, igor.sugak, igor

Reviewed By: igor

Subscribers: dhruba

Differential Revision: https://reviews.facebook.net/D33789

Summary:
Otherwise, we would assert that an unsigned expression is always >= 0.
The intent was to form a possibly negative number, and to assert that
that value is always >= 0, but since one variable in the computation
was unsigned, the result was guaranteed to be unsigned, too, rendering
the assertion useless.

Cast that unsigned variable to "int", so that all operands
are signed, and thus so that the result can be negative.

Test Plan:
  Run "make EXTRA_CXXFLAGS='-W -Wextra'" and see fewer errors.

Reviewers: ljin, sdong, igor.sugak, igor

Reviewed By: igor

Subscribers: dhruba

Differential Revision: https://reviews.facebook.net/D33771

Summary:
The "const" attribute does not make sense on a return type,
and provokes a warning/error from gcc -W -Wextra.

Test Plan:
  Run "make EXTRA_CXXFLAGS='-W -Wextra'" and see fewer errors.

Reviewers: ljin, sdong, igor.sugak, igor

Reviewed By: igor

Subscribers: dhruba

Differential Revision: https://reviews.facebook.net/D33759

Summary:
Remove some always-true assertions.
They provoke these compilation failures:

  table/plain_table_key_coding.cc:279:20: error: comparison of unsigned expression >= 0 is always true [-Werror=type-limits]
  db/version_set.cc:336:15: error: comparison of unsigned expression >= 0 is always true [-Werror=type-limits]

* table/plain_table_key_coding.cc (rocksdb): Remove assertion that
unsigned type variable is >= 0.
* db/version_set.cc (DoGenerateLevelFilesBrief): Likewise.

Test Plan:
  Run "make EXTRA_CXXFLAGS='-W -Wextra'" and see fewer errors.

Reviewers: ljin, sdong, igor.sugak, igor

Reviewed By: igor

Subscribers: dhruba

Differential Revision: https://reviews.facebook.net/D33747

Summary:
The bug is detected by scan-build.

In `void WriteSeqSeekSeq(ThreadState* thread)` memory is allocated in line 3118 `Slice key = AllocateKey();` but `Slice` is not responsible deleting `Slice::data()`.

Added `std::unique_ptr<const char[]>*` parameter to ` AllocateKey()`, so that it requires caller to not forget about Slice::data() management.

scan-build bug report: http://home.fburl.com/~sugak/latest6/report-6e9754.html#EndPath

Test Plan:
Make sure scan-build does not report 'Memory leak' in db/db_bench.cc and all tests are passing.
```lang=bash
% make analyze
% make check
```

Reviewers: lgalanis, igor, meyering, sdong

Reviewed By: meyering, sdong

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D33501

Summary:
Prior to this change, "make check" would always waste a lot of
time relinking 60+ binaries. With this change, it does that
only when the generated file, util/build_version.cc, changes,
and that happens only when the date changes or when the
current git SHA changes.

This change makes some other improvements: before, there was no
rule to build a deleted util/build_version.cc. If it was somehow
removed, any attempt to link a program would fail.
There is no longer any need for the separate file,
build_tools/build_detect_version.  Its functionality is
now in the Makefile.

* Makefile (DEPFILES): Don't filter-out util/build_version.cc.
No need, and besides, removing that dependency was wrong.
(date, git_sha, gen_build_version): New helper variables.
(util/build_version.cc): New rule, to create this file
and update it only if it would contain new information.
* build_tools/build_detect_platform: Remove file.
* db/db_impl.cc: Now, print only date (not the time).
* util/build_version.h (rocksdb_build_compile_time): Remove
declaration.  No longer used.

Test Plan:
- Run "make check" twice, and note that the second time no linking is performed.
- Remove util/build_version.cc and ensure that any "make"
command regenerates it before doing anything else.
- Run this: strings librocksdb.a|grep _build_.
That prints output including the following:

  rocksdb_build_git_date:2015-02-19
  rocksdb_build_git_sha:2.8.fb-1792-g3cb6cc0

Reviewers: ljin, sdong, igor

Reviewed By: igor

Subscribers: dhruba

Differential Revision: https://reviews.facebook.net/D33591

Summary: Add a DB property about live versions. It can be helpful to figure out whether there are files not live but not yet deleted, in some use cases.

Test Plan: make all check

Reviewers: rven, yhchiang, igor

Reviewed By: igor

Subscribers: yoshinorim, dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D33327

Summary:
This is a diff for managed iterator. A managed iterator
is a wrapper around an iterator which saves the options for that
iterator as well as the current key/value so that the underlying iterator
and its associated memory can be released when it is aged out
automatically or on the request of the user. Will provide the automatic release as a follow-up diff.

Test Plan: Managed* tests in db_test and XF tests for managed iterator

Reviewers: igor, yhchiang, anthony, sdong

Reviewed By: sdong

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D31401

Summary:
Remove ThreadStatusMultiCompaction test as it's currently written
in a way that depends on some randomness, while the flush / compaction
status of a single thread is also covered in ThreadStatusFlush
and ThreadStatusSingleCompaction tests.

Test Plan: ./db_test

Reviewers: igor, sdong

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D33537

Summary: Allow GetThreadList to reflect flush activity.

Test Plan:
Developed ThreadStatusFlush test and updated ThreadStatusMultiCompaction test.

./db_test  ./thread_list_test

Reviewers: sdong, rven, igor

Reviewed By: igor

Subscribers: dhruba

Differential Revision: https://reviews.facebook.net/D32871

Summary:
It would be good to assing background job their IDs. Two benefits:
1) makes LOGs more readable
2) I might use it in my EventLogger, which will try to make our LOG easier to read/query/visualize

Test Plan: ran rocksdb, read the LOG

Reviewers: sdong, rven, yhchiang

Reviewed By: yhchiang

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D31617

Summary: DBTest.DestroyDBMetaDatabase occasionally fails on my dev host, for file not existing. Always create directories to avoid that.

Test Plan: Run the test

Reviewers: rven, yhchiang, igor

Reviewed By: igor

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D33321

Summary: Remember whole key or prefix filtering on/off in SST files. If user opens the DB with a different setting that cannot be satisfied while reading the SST file, ignore the bloom filter.

Test Plan: Add a unit test for it

Reviewers: yhchiang, igor, rven

Reviewed By: rven

Subscribers: leveldb, dhruba

Differential Revision: https://reviews.facebook.net/D32889

Summary: Add counters in perf context to allow users to figure out how time spent on waiting for DB mutex

Test Plan: Add a test and run it.

Reviewers: yhchiang, rven, igor

Reviewed By: igor

Subscribers: leveldb, dhruba

Differential Revision: https://reviews.facebook.net/D33177

Summary: For description of the bug, see comment in db_test. The fix is pretty straight forward.

Test Plan: added unit test. eventually we need better testing of FOF/POF process.

Reviewers: yhchiang, rven, sdong

Reviewed By: sdong

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D33081

Summary:
  - In statistics.h , added tickers.
  - In version_set.cc,
  -- Added a getter method for hit_file_level_ in the class FilePicker
  -- Added a line in the Get() method in case of a found, increment the corresponding counters based on the level of the file respectively.

Corresponding task: https://our.intern.facebook.com/intern/tasks/?s=506100481&t=5952818
Personal fork: https://github.com/sycamlaw43/rocksdb/commit/0c3f2e3600a1e0faad63249c45f3951fd0430b30

Test Plan:
In terminal,
```
make -j32 db_test
ROCKSDB_TESTS=L0L1L2AndUpHitCounter ./db_test
```

Or to use debugger,
```
make -j32 db_test
export ROCKSDB_TESTS=L0L1L2AndUpHitCounter
gdb db_test
```

Reviewers: rven, sdong

Reviewed By: sdong

Subscribers: dhruba

Differential Revision: https://reviews.facebook.net/D32205

Summary: Having a pointer for DB will be helpful to debug when GDB or working on a dump. If the client process doesn't have any thread actively working on RocksDB, it can be hard to find out.

Test Plan: make all check

Reviewers: rven, yhchiang, igor

Reviewed By: igor

Subscribers: yoshinorim, dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D33159