Summary: Make RocksDb build and run on Windows to be functionally
 complete and performant. All existing test cases run with no
 regressions. Performance numbers are in the pull-request.

 Test plan: make all of the existing unit tests pass, obtain perf numbers.

 Co-authored-by: Praveen Rao praveensinghrao@outlook.com
 Co-authored-by: Sherlock Huang baihan.huang@gmail.com
 Co-authored-by: Alex Zinoviev alexander.zinoviev@me.com
 Co-authored-by: Dmitri Smirnov dmitrism@microsoft.com

Summary:
This diff update DB::CompactRange to use RangeCompactionOptions instead of using multiple parameters
Old CompactRange is still available but deprecated

Test Plan:
make all check
make rocksdbjava
USE_CLANG=1 make all
OPT=-DROCKSDB_LITE make release

Reviewers: sdong, yhchiang, igor

Reviewed By: igor

Subscribers: dhruba

Differential Revision: https://reviews.facebook.net/D40209

Summary:
We go to great lengths to make sure MaybeScheduleFlushOrCompaction() is called outside of write thread. But anyway, it's still called in the mutex, so it's not that much cheaper.

This diff removes the "optimization" and cleans up the code a bit.

Test Plan: make check

Reviewers: rven, sdong

Reviewed By: sdong

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D40113

Summary:
Add an option in GetApproximateSize() so that the result will include estimated sizes in mem tables.
To implement it, implement an estimated count from the beginning to a key in skip list. The approach is to count to find the entry, how many Next() is issued from each level, and sum them with a weight that is <branching factor> ^ <level>.

Test Plan: Add a test case

Subscribers: leveldb, dhruba

Differential Revision: https://reviews.facebook.net/D40119

Summary:
We slow down data into the database to the rate of options.delayed_write_rate (a new option) with this patch.

The thread synchronization approach I take is to still synchronize write controller by DB mutex and GetDelay() is inside DB mutex. Try to minimize the frequency of getting time in GetDelay(). I verified it through db_bench and it seems to work

hard_rate_limit is deprecated.

options.delayed_write_rate is still not dynamically changeable. Need to work on it as a follow-up.

Test Plan: Add new unit tests in db_test

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

Reviewed By: igor

Subscribers: ikabiljo, leveldb, dhruba

Differential Revision: https://reviews.facebook.net/D36351

Summary:
Adding largest sequence number to FlushJobInfo
and passing flushed file metadata to NotifyOnFlushCompleted which include alot of other values that we may want to expose in FlushJobInfo

Test Plan: make check

Reviewers: igor, sdong

Reviewed By: sdong

Subscribers: dhruba

Differential Revision: https://reviews.facebook.net/D39927

Summary:
EventListener::OnFlushCompleted() now passes a structure instead
of a list of parameters.  This minimizes the API change in the
future.

Test Plan:
listener_test
compact_files_test
example/compact_files_example

Reviewers: kradhakrishnan, sdong, IslamAbdelRahman, rven, igor

Reviewed By: rven, igor

Subscribers: IslamAbdelRahman, rven, dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D39543

Summary:
This diff updates the logic of how we do trivial move, now trivial move can run on any number of files in input level as long as they are not overlapping

The conditions for trivial move have been updated

Introduced conditions:
  - Trivial move cannot happen if we have a compaction filter (except if the compaction is not manual)
  - Input level files cannot be overlapping

Removed conditions:
  - Trivial move only run when the compaction is not manual
  - Input level should can contain only 1 file

More context on what tests failed because of Trivial move
```
DBTest.CompactionsGenerateMultipleFiles
This test is expecting compaction on a file in L0 to generate multiple files in L1, this test will fail with trivial move because we end up with one file in L1
```

```
DBTest.NoSpaceCompactRange
This test expect compaction to fail when we force environment to report running out of space, of course this is not valid in trivial move situation
because trivial move does not need any extra space, and did not check for that
```

```
DBTest.DropWrites
Similar to DBTest.NoSpaceCompactRange
```

```
DBTest.DeleteObsoleteFilesPendingOutputs
This test expect that a file in L2 is deleted after it's moved to L3, this is not valid with trivial move because although the file was moved it is now used by L3
```

```
CuckooTableDBTest.CompactionIntoMultipleFiles
Same as DBTest.CompactionsGenerateMultipleFiles
```

This diff is based on a work by @sdong https://reviews.facebook.net/D34149

Test Plan: make -j64 check

Reviewers: rven, sdong, igor

Reviewed By: igor

Subscribers: yhchiang, ott, march, dhruba, sdong

Differential Revision: https://reviews.facebook.net/D34797

Summary:
Fix the following compile warning in db/db_impl

  db/db_impl.cc:1603:19: error: implicit conversion loses integer precision: 'const uint64_t' (aka 'const unsigned long') to 'int' [-Werror,-Wshorten-64-to-32]
     info.job_id = job_id;
                 ~ ^~~~~~

Test Plan: db_test

Reviewers: sdong

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D39423

Summary:
Allow EventListener::OnCompactionCompleted to return CompactionJobStats,
which contains useful information about a compaction.

Example CompactionJobStats returned by OnCompactionCompleted():
    smallest_output_key_prefix 05000000
    largest_output_key_prefix 06990000
    elapsed_time 42419
    num_input_records 300
    num_input_files 3
    num_input_files_at_output_level 2
    num_output_records 200
    num_output_files 1
    actual_bytes_input 167200
    actual_bytes_output 110688
    total_input_raw_key_bytes 5400
    total_input_raw_value_bytes 300000
    num_records_replaced 100
    is_manual_compaction 1

Test Plan: Developed a mega test in db_test which covers 20 variables in CompactionJobStats.

Reviewers: rven, igor, anthony, sdong

Reviewed By: sdong

Subscribers: tnovak, dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D38463

Summary:
Add EventListener::OnTableFileCreated(), which will be called
when a table file is created.  This patch is part of the
EventLogger and EventListener integration.

Test Plan: Augment existing test in db/listener_test.cc

Reviewers: anthony, kradhakrishnan, rven, igor, sdong

Reviewed By: sdong

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D38865

Summary: In DB::CompactRange(), change parameter "reduce_level" to "change_level". Users can compact all data to the last level if needed. By doing it, users can migrate the DB to options.level_compaction_dynamic_level_bytes=true.

Test Plan: Add a unit test for it.

Reviewers: yhchiang, anthony, kradhakrishnan, igor, rven

Reviewed By: rven

Subscribers: leveldb, dhruba

Differential Revision: https://reviews.facebook.net/D39099

Summary:
DBImpl::notifying_events_ is a internal counter in DBImpl which is
used to prevent DB close when DB is notifying events.  However, as
the current events all rely on either compaction or flush which
already have similar counters to prevent DB close, it is safe to
remove notifying_events_.

Test Plan:
listener_test
examples/compact_files_example

Reviewers: igor, anthony, kradhakrishnan, rven, sdong

Reviewed By: sdong

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D39315

Summary: Optimistic transactions supporting begin/commit/rollback semantics.  Currently relies on checking the memtable to determine if there are any collisions at commit time.  Not yet implemented would be a way of enuring the memtable has some minimum amount of history so that we won't fail to commit when the memtable is empty.  You should probably start with transaction.h to get an overview of what is currently supported.

Test Plan: Added a new test, but still need to look into stress testing.

Reviewers: yhchiang, igor, rven, sdong

Reviewed By: sdong

Subscribers: adamretter, MarkCallaghan, leveldb, dhruba

Differential Revision: https://reviews.facebook.net/D33435

Summary: Removed an unused private variable in db_impl.h

Test Plan: make db_test

Reviewers: sdong, anthony, igor

Reviewed By: igor

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D38925

Summary: Make DB::GetDbIdentity() be const function.

Test Plan: make db_test

Reviewers: igor, rven, sdong

Reviewed By: sdong

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D38745

Summary:
Added a couple functions to WriteBatchWithIndex to make it easier to query the value of a key including reading pending writes from a batch.  (This is needed for transactions).

I created write_batch_with_index_internal.h to use to store an internal-only helper function since there wasn't a good place in the existing class hierarchy to store this function (and it didn't seem right to stick this function inside WriteBatchInternal::Rep).

Since I needed to access the WriteBatchEntryComparator, I moved some helper classes from write_batch_with_index.cc into write_batch_with_index_internal.h/.cc.  WriteBatchIndexEntry, ReadableWriteBatch, and WriteBatchEntryComparator are all unchanged (just moved to a different file(s)).

Test Plan: Added new unit tests.

Reviewers: rven, yhchiang, sdong, igor

Reviewed By: igor

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D38037

Summary: fix crashes in stats and compaction filter for db_ttl_impl

Test Plan:
Ran build with lots of debugging
https://reviews.facebook.net/differential/diff/194175/

Reviewers: yhchiang, igor, rven

Reviewed By: igor

Subscribers: rven, dhruba

Differential Revision: https://reviews.facebook.net/D38001

Summary:
Added these events:
* Recovery start, finish and also when recovery creates a file
* Trivial move
* Compaction start, finish and when compaction creates a file
* Flush start, finish

Also includes small fix to EventLogger

Also added option ROCKSDB_PRINT_EVENTS_TO_STDOUT which is useful when we debug things. I've spent far too much time chasing LOG files.

Still didn't get sst table properties in JSON. They are written very deeply into the stack. I'll address in separate diff.

TODO:
* Write specification. Let's first use this for a while and figure out what's good data to put here, too. After that we'll write spec
* Write tools that parse and analyze LOGs. This can be in python or go. Good intern task.

Test Plan: Ran db_bench with ROCKSDB_PRINT_EVENTS_TO_STDOUT. Here's the output: https://phabricator.fb.com/P19811976

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

Reviewed By: anthony

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D37521

Summary:
This diff implements a new `DB` method `PromoteL0` which moves all files in L0
to a given level skipping compaction, provided that the files have disjoint
ranges and all levels up to the target level are empty.

This method provides finer-grain control for trivial compactions, and it is
useful for bulk-loading pre-sorted keys. Compared to D34797, it does not change
the semantics of an existing operation, which can impact existing code.

PromoteL0 is designed to work well in combination with the proposed
`GetSstFileWriter`/`AddFile` interface, enabling to "design" the level structure
by populating one level at a time. Such fine-grained control can be very useful
for static or mostly-static databases.

Test Plan: `make check`

Reviewers: IslamAbdelRahman, philipp, MarkCallaghan, yhchiang, igor, sdong

Reviewed By: sdong

Subscribers: dhruba

Differential Revision: https://reviews.facebook.net/D37107

Summary:
Some Mongo+Rocks datasets in Parse's environment are not doing compactions very frequently. During the quiet period (with no IO), we'd like to schedule compactions so that our reads become faster. Also, aggressively compacting during quiet periods helps when write bursts happen. In addition, we also want to compact files that are containing deleted key ranges (like old oplog keys).

All of this is currently not possible with CompactRange() because it's single-threaded and blocks all other compactions from happening. Running CompactRange() risks an issue of blocking writes because we generate too much Level 0 files before the compaction is over. Stopping writes is very dangerous because they hold transaction locks. We tried running manual compaction once on Mongo+Rocks and everything fell apart.

MarkForCompaction() solves all of those problems. This is very light-weight manual compaction. It is lower priority than automatic compactions, which means it shouldn't interfere with background process keeping the LSM tree clean. However, if no automatic compactions need to be run (or we have extra background threads available), we will start compacting files that are marked for compaction.

Test Plan: added a new unit test

Reviewers: yhchiang, rven, MarkCallaghan, sdong

Reviewed By: sdong

Subscribers: yoshinorim, dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D37083

Summary:
Cleaning up log files can do heavy IO, since we call ftruncate() in the destructor. We don't want to call ftruncate() in user threads.

This diff moves cleaning to background threads (flush and compaction)

Test Plan: make check, will also run valgrind

Reviewers: yhchiang, rven, MarkCallaghan, sdong

Reviewed By: sdong

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D36177

Summary: Some suggestions for cleanup from Igor.

Test Plan: Regression tests.

Reviewers: igor

Reviewed By: igor

Subscribers: dhruba

Differential Revision: https://reviews.facebook.net/D35169

Summary:
Here's my proposal for making our LOGs easier to read by machines.

The idea is to dump all events as JSON objects. JSON is easy to read by humans, but more importantly, it's easy to read by machines. That way, we can parse this, load into SQLite/mongo and then query or visualize.

I started with table_create and table_delete events, but if everybody agrees, I'll continue by adding more events (flush/compaction/etc etc)

Test Plan:
Ran db_bench. Observed:
2015/01/15-14:13:25.788019 1105ef000 EVENT_LOG_v1 {"time_micros": 1421360005788015, "event": "table_file_creation", "file_number": 12, "file_size": 1909699}
2015/01/15-14:13:25.956500 110740000 EVENT_LOG_v1 {"time_micros": 1421360005956498, "event": "table_file_deletion", "file_number": 12}

Reviewers: yhchiang, rven, dhruba, MarkCallaghan, lgalanis, sdong

Reviewed By: sdong

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D31647

Summary: Fixed a bug where CompactFiles won't delete obsolete files until flush.

Test Plan:
./compact_files_test
export ROCKSDB_TESTS=CompactFiles
./db_test

Reviewers: rven, sdong, igor

Reviewed By: igor

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D34671

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:
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:
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:
Add a counter for collecting the wait time on db mutex.
Also add MutexWrapper and CondVarWrapper for measuring wait time.

Test Plan:
./db_test
export ROCKSDB_TESTS=MutexWaitStats
./db_test

verify stats output using db_bench
make clean
make release
./db_bench --statistics=1 --benchmarks=fillseq,readwhilewriting --num=10000 --threads=10

Sample output:
    rocksdb.db.mutex.wait.micros COUNT : 7546866

Reviewers: MarkCallaghan, rven, sdong, igor

Reviewed By: igor

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D32787

Summary: This adds a listener for compactions, and gives some useful statistics on each compaction pass.

Test Plan: Unit tests.

Reviewers: sdong, igor, rven, yhchiang

Reviewed By: yhchiang

Subscribers: dhruba

Differential Revision: https://reviews.facebook.net/D31641

Summary: log_dir_unsynced_ is a confusing name. Rename it to log_dir_synced_ and flip the value.

Test Plan: Run ./fault_injection_test

Reviewers: rven, yhchiang, igor

Reviewed By: igor

Subscribers: leveldb, dhruba

Differential Revision: https://reviews.facebook.net/D32235

Summary:
1. If WAL directory is different from db directory. Sync the directory after creating a log file under it.
2. After creating an SST file, sync its parent directory instead of DB directory.
3. change the check of kResetDeleteUnsyncedFiles in fault_injection_test. Since we changed the behavior to sync log files' parent directory after first WAL sync, instead of creating, kResetDeleteUnsyncedFiles will not guarantee to show post sync updates.

Test Plan: make all check

Reviewers: yhchiang, rven, igor

Reviewed By: igor

Subscribers: leveldb, dhruba

Differential Revision: https://reviews.facebook.net/D32067

Summary: Allow GetThreadList() to indicate a thread is doing Compaction.

Test Plan:
export ROCKSDB_TESTS=ThreadStatus
./db_test

Reviewers: ljin, igor, sdong

Reviewed By: sdong

Subscribers: leveldb, dhruba, jonahcohen, rven

Differential Revision: https://reviews.facebook.net/D30105

Summary:
There are two versions of FindObsoleteFiles():
* full scan, which is executed every 6 hours (and it's terribly slow)
* no full scan, which is executed every time a background process finishes and iterator is deleted

This diff is optimizing the second case (no full scan). Here's what we do before the diff:
* Get the list of obsolete files (files with ref==0). Some files in obsolete_files set might actually be live.
* Get the list of live files to avoid deleting files that are live.
* Delete files that are in obsolete_files and not in live_files.

After this diff:
* The only files with ref==0 that are still live are files that have been part of move compaction. Don't include moved files in obsolete_files.
* Get the list of obsolete files (which exclude moved files).
* No need to get the list of live files, since all files in obsolete_files need to be deleted.

I'll post the benchmark results, but you can get the feel of it here: https://reviews.facebook.net/D30123

This depends on D30123.

P.S. We should do full scan only in failure scenarios, not every 6 hours. I'll do this in a follow-up diff.

Test Plan:
One new unit test. Made sure that unit test fails if we don't have a `if (!f->moved)` safeguard in ~Version.

make check

Big number of compactions and flushes:

  ./db_stress --threads=30 --ops_per_thread=20000000 --max_key=10000 --column_families=20 --clear_column_family_one_in=10000000 --verify_before_write=0  --reopen=15 --max_background_compactions=10 --max_background_flushes=10 --db=/fast-rocksdb-tmp/db_stress --prefixpercent=0 --iterpercent=0 --writepercent=75 --db_write_buffer_size=2000000

Reviewers: yhchiang, rven, sdong

Reviewed By: sdong

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D30249

Summary:
When scaling to higher number of column families, the worst bottleneck was MaybeScheduleFlushOrCompaction(), which did a for loop over all column families while holding a mutex. This patch addresses the issue.

The approach is similar to our earlier efforts: instead of a pull-model, where we do something for every column family, we can do a push-based model -- when we detect that column family is ready to be flushed/compacted, we add it to the flush_queue_/compaction_queue_. That way we don't need to loop over every column family in MaybeScheduleFlushOrCompaction.

Here are the performance results:

Command:

    ./db_bench --write_buffer_size=268435456 --db_write_buffer_size=268435456 --db=/fast-rocksdb-tmp/rocks_lots_of_cf --use_existing_db=0 --open_files=55000 --statistics=1 --histogram=1 --disable_data_sync=1 --max_write_buffer_number=2 --sync=0 --benchmarks=fillrandom --threads=16 --num_column_families=5000  --disable_wal=1 --max_background_flushes=16 --max_background_compactions=16 --level0_file_num_compaction_trigger=2 --level0_slowdown_writes_trigger=2 --level0_stop_writes_trigger=3 --hard_rate_limit=1 --num=33333333 --writes=33333333

Before the patch:

     fillrandom   :      26.950 micros/op 37105 ops/sec;    4.1 MB/s

After the patch:

      fillrandom   :      17.404 micros/op 57456 ops/sec;    6.4 MB/s

Next bottleneck is VersionSet::AddLiveFiles, which is painfully slow when we have a lot of files. This is coming in the next patch, but when I removed that code, here's what I got:

      fillrandom   :       7.590 micros/op 131758 ops/sec;   14.6 MB/s

Test Plan:
make check

two stress tests:

Big number of compactions and flushes:

    ./db_stress --threads=30 --ops_per_thread=20000000 --max_key=10000 --column_families=20 --clear_column_family_one_in=10000000 --verify_before_write=0  --reopen=15 --max_background_compactions=10 --max_background_flushes=10 --db=/fast-rocksdb-tmp/db_stress --prefixpercent=0 --iterpercent=0 --writepercent=75 --db_write_buffer_size=2000000

max_background_flushes=0, to verify that this case also works correctly

    ./db_stress --threads=30 --ops_per_thread=2000000 --max_key=10000 --column_families=20 --clear_column_family_one_in=10000000 --verify_before_write=0  --reopen=3 --max_background_compactions=3 --max_background_flushes=0 --db=/fast-rocksdb-tmp/db_stress --prefixpercent=0 --iterpercent=0 --writepercent=75 --db_write_buffer_size=2000000

Reviewers: ljin, rven, yhchiang, sdong

Reviewed By: sdong

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D30123

Summary: Now DB::GetSnapshot() doesn't scale to more column families, as it needs to go through all the column families to find whether snapshot is supported. This patch optimizes it.

Test Plan:
Add unit tests to cover negative cases.
make all check

Reviewers: yhchiang, rven, igor

Reviewed By: igor

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D30093

Summary: This is a regression bug introduced by https://reviews.facebook.net/D24729 . max_total_wal_size would be off the target it should be more and more in the case that the a user holds the current super version after flush or compaction. This patch fixes it

Test Plan: make all check

Reviewers: yhchiang, rven, igor

Reviewed By: igor

Subscribers: ljin, yoshinorim, MarkCallaghan, hermanlee4, dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D29961

Summary:
Add a counter in SnapshotList to show number of snapshots. Also a unix timestamp in every snapshot.
Add two DB Properties to return number of snapshots and timestamp of the oldest one.

Test Plan: Add unit test checking

Reviewers: yhchiang, rven, igor

Reviewed By: igor

Subscribers: leveldb, dhruba, MarkCallaghan

Differential Revision: https://reviews.facebook.net/D29919

Summary:
Introduces a new class for managing write buffer memory across column
families.  We supplement ColumnFamilyOptions::write_buffer_size with
ColumnFamilyOptions::write_buffer, a shared pointer to a WriteBuffer
instance that enforces memory limits before flushing out to disk.

Test Plan: Added SharedWriteBuffer unit test to db_test.cc

Reviewers: sdong, rven, ljin, igor

Reviewed By: igor

Subscribers: tnovak, yhchiang, dhruba, xjin, MarkCallaghan, yoshinorim

Differential Revision: https://reviews.facebook.net/D22581

Summary:
Moved checkpoint to utilities.
Addressed comments by Igor, Siying, Dhruba

Test Plan: db_test/SnapshotLink

Reviewers: dhruba, igor, sdong

Reviewed By: igor

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D29079