Summary:
This patch adds three test cases for ExpandWhileOverlapping()
to the compaction_picker_test test suite.
ExpandWhileOverlapping() only has an effect if the comparison
function for the internal keys allows for overlapping user
keys in different SST files on the same level. Thus, this
patch adds a comparator based on sequence numbers to
compaction_picker_test for the new test cases.

Test Plan:
- make compaction_picker_test && ./compaction_picker_test
  -> All tests pass
- Replace body of ExpandWhileOverlapping() with `return true`
  -> Compile and run ./compaction_picker_test as before
  -> New tests fail

Reviewers: sdong, yhchiang, rven, anthony, IslamAbdelRahman, kradhakrishnan, igor

Reviewed By: igor

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D41277

Summary:
Two issues:
* the input keys to the compaction don't include sequence number.
* sequence number is set to max(seq_num), but it should be set to max(seq_num)+1, because the condition here is strictly-larger (i.e. we will only zero-out sequence number if the DB's sequence number is strictly greater than the key's sequence number): https://github.com/facebook/rocksdb/blob/master/db/compaction_job.cc#L830

Test Plan: make compaction_job_test && ./compaction_job_test

Reviewers: sdong, lovro

Reviewed By: lovro

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D41247

Summary:
This fixes the following scenario we've hit:
 - we reached max_total_wal_size, created a new wal and scheduled flushing all memtables corresponding to the old one,
 - before the last of these flushes started its column family was dropped; the last background flush call was a no-op; no one removed the old wal from alive_logs_,
 - hours have passed and no flushes happened even though lots of data was written; data is written to different column families, compactions are disabled; old column families are dropped before memtable grows big enough to trigger a flush; the old wal still sits in alive_logs_ preventing max_total_wal_size limit from kicking in,
 - a few more hours pass and we run out disk space because of one huge .log file.

Test Plan: `make check`; backported the new test, checked that it fails without this diff

Reviewers: igor

Reviewed By: igor

Subscribers: dhruba

Differential Revision: https://reviews.facebook.net/D40893

Summary: Try to allocate LevelFileIteratorState and LevelFileNumIterator from DB iterator's arena, instead of calling malloc and free.

Test Plan: valgrind check

Reviewers: rven, yhchiang, anthony, kradhakrishnan, igor

Reviewed By: igor

Subscribers: leveldb, dhruba

Differential Revision: https://reviews.facebook.net/D40929

Summary: We have a race in the way test works. We avoided the race by adding the
wait to the counter. I thought 1s was eternity, but that is not true in some
scenarios. Increasing the timeout to 10s and adding warnings.

Also, adding nosleep to avoid the case where the wakeup thread is waiting behind
the sleeping thread for scheduling.

Test Plan: Run make check

Reviewers: siying igorcanadi

CC: leveldb@

Task ID: #7312624

Blame Rev:

Summary:
When seek target is a merge key (`kTypeMerge`), `DBIter::FindNextUserEntry()`
advances the underlying iterator _past_ the current key (`saved_key_`); see
`MergeValuesNewToOld()`. However, `FindPrevUserKey()` assumes that `iter_`
points to an entry with the same user key as `saved_key_`. As a result,
`it->Seek(key) && it->Prev()` can cause the iterator to be positioned at the
_next_, instead of the previous, entry (new test, written by @lovro, reproduces
the bug).

This diff changes `FindPrevUserKey()` to also skip keys that are _greater_ than
`saved_key_`.

Test Plan: db_test

Reviewers: igor, sdong

Reviewed By: sdong

Subscribers: leveldb, dhruba, lovro

Differential Revision: https://reviews.facebook.net/D40791

Summary: Make column_family_test runnable in ROCKSDB_LITE.

Test Plan: column_family_test

Reviewers: sdong, igor

Reviewed By: igor

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D40251

Summary: Avoid falling victim to race condition.

Test Plan: Run the unit test

Reviewers: sdong igor

CC: leveldb@

Task ID: #7312624

Blame Rev:

Summary: It's not really nice to call user's API with garbage data in new_value. This diff makes sure that new_value is empty before calling the merge operator.

Test Plan: Added assert to Merge operator in merge_test

Reviewers: sdong, yhchiang

Reviewed By: yhchiang

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D40773

Summary:
Fixes task 7156865 where a compaction causes a hang in flush
memtable if CancelAllBackgroundWork was called prior to it.
Stack trace is in : https://phabricator.fb.com/P19848829
We end up waiting for a flush which will never happen because there are no background threads.

Test Plan: PreShutdownFlush

Reviewers: sdong, igor

Reviewed By: sdong, igor

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D40617

Summary: #7124486: RocksDB's Iterator.SeekToLast should seek to the last key before iterate_upper_bound if presents

Test Plan: ./db_iter_test run successfully with the new testcase

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

Reviewed By: sdong

Subscribers: leveldb, dhruba

Differential Revision: https://reviews.facebook.net/D40425

Summary: Make table_properties_collector_test runnable in ROCKSDB_LITE

Test Plan: table_properties_collector_test

Reviewers: sdong, rven, anthony, kradhakrishnan, IslamAbdelRahman, igor

Reviewed By: igor

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D40581

Summary: Replace force_bottommost_level_compaction in CompactRangeOption with an option that allow the user to (always skip, always compact, compact if compaction filter is present) the bottommost level for level based compaction.

Test Plan: make check

Reviewers: sdong, yhchiang, igor

Reviewed By: igor

Subscribers: dhruba

Differential Revision: https://reviews.facebook.net/D40527

Summary:
Implementation of a table-level row cache.
It only caches point queries done through the `DB::Get` interface, queries done through the `Iterator` interface will completely skip the cache.

Supports snapshots and merge operations.

Test Plan: Ran `make valgrind_check commit-prereq`

Reviewers: igor, philipp, sdong

Reviewed By: sdong

Subscribers: dhruba

Differential Revision: https://reviews.facebook.net/D39849

Summary:
The "one size fits all" approach with WAL recovery will only introduce inconvenience for our varied clients as we go forward. The current recovery is a bit heuristic. We introduce the following levels of consistency while replaying the WAL.

1. RecoverAfterRestart (kTolerateCorruptedTailRecords)

This mocks the current recovery mode.

2. RecoverAfterCleanShutdown (kAbsoluteConsistency)

This is ideal for unit test and cases where the store is shutdown cleanly. We tolerate no corruption or incomplete writes.

3. RecoverPointInTime (kPointInTimeRecovery)

This is ideal when using devices with controller cache or file systems which can loose data on restart. We recover upto the point were is no corruption or incomplete write.

4. RecoverAfterDisaster (kSkipAnyCorruptRecord)

This is ideal mode to recover data. We tolerate corruption and incomplete writes, and we hop over those sections that we cannot make sense of salvaging as many records as possible.

Test Plan:
(1) Run added unit test to cover all levels.
(2) Run make check.

Reviewers: leveldb, sdong, igor

Subscribers: yoshinorim, dhruba

Differential Revision: https://reviews.facebook.net/D38487

Summary: Fixing bad merge

Test Plan: make -j64 check (this is not enough to verify the fix)

Reviewers: igor, sdong

Reviewed By: sdong

Subscribers: dhruba

Differential Revision: https://reviews.facebook.net/D40521

Summary:
When there are multiple column families, the flush in
GetLiveFiles is not atomic, so that there are entries in the wal files
which are needed to get a consisten RocksDB. We now add the log files to
the checkpoint.

Test Plan:
CheckpointCF - This test forces more data to be written to
the other column families after the flush of the first column family but
before the second.

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

Reviewed By: sdong

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D40323

Summary: CompressLevelCompaction() depends on Zlib. We should skip it when zlib is not present.

Test Plan: `make check` without zlib

Reviewers: yhchiang

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D40401

Summary:
Currently RocksDB silently ignores this issue and doesn't compress the data. Based on discussion, we agree that this is pretty bad because it can cause confusion for our users.

This patch fails DB::Open() if we don't support the compression that is specified in the options.

Test Plan: make check with LZ4 not present. If Snappy is not present all tests will just fail because Snappy is our default library. We should make Snappy the requirement, since without it our default DB::Open() fails.

Reviewers: sdong, MarkCallaghan, rven, yhchiang

Reviewed By: yhchiang

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D39687

Summary:
This is https://reviews.facebook.net/D39999 but after introducing an option to force compaction the bottom most level

Changes in this patch
- Introduce force_bottommost_level_compaction to CompactRangeOptions that force compacting bottommost level during compaction
- Skip bottommost level compaction if we dont have a compaction filter and force_bottommost_level_compaction options is not set

Although tests pass on my machine but I suspect that there maybe some tests that I am not aware of that  should use force_bottommost_level_compaction to pass in a deterministic way

Test Plan:
make check
adding new tests

Reviewers: igor, sdong, yhchiang

Reviewed By: yhchiang

Subscribers: dhruba

Differential Revision: https://reviews.facebook.net/D40059

Summary: Currently we dump DBOptions for each column family options we dump. This leads to duplicate lines in our LOG file. This diff fixes that.

Test Plan: Check out the LOG

Reviewers: sdong, rven, yhchiang

Reviewed By: yhchiang

Subscribers: IslamAbdelRahman, yoshinorim, dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D39729

Summary:
Universal compaction can involves in multiple levels.  However,
the current implementation of bytes_readn and bytes_readnp1
(and some other stats with postfix `n` and `np1`) assumes compaction
can only have two levels.

This patch fixes this bug and redefines bytes_readn and bytes_readnp1:
* bytes_readnp1: the number of bytes read in the compaction output level.
* bytes_readn: the total number of bytes read minus bytes_readnp1

Test Plan: Add a test in compaction_job_stats_test

Reviewers: igor, sdong, rven, anthony, kradhakrishnan, IslamAbdelRahman

Reviewed By: IslamAbdelRahman

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D40239

Test Plan: successfully compiled the code

Reviewers: sdong

Reviewed By: sdong

Subscribers: dhruba

Differential Revision: https://reviews.facebook.net/D40233

Summary:
So far, we benchmarked RocksDB by writing as fast as possible. With this change, we're able to limit our write throughput, which should help us better understand how RocksDB performes under varying write workloads.

Specifically, I'm currently interested in the shape of the graph that has write throughput on one axis and write rate on another. This should help us with designing our stall system, as we have started to do with D36351.

Test Plan:
    $ ./db_bench --benchmarks=fillrandom --benchmark_write_rate_limit=1000000
    fillrandom   :     118.523 micros/op 8437 ops/sec;    0.9 MB/s
    $ ./db_bench --benchmarks=fillrandom --benchmark_write_rate_limit=2000000
    fillrandom   :      59.136 micros/op 16910 ops/sec;    1.9 MB/s

Reviewers: MarkCallaghan, sdong

Reviewed By: sdong

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D39759

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: Block c_test in ROCKSDB_LITE as it's not supported in ROCKSDB_LITE.

Test Plan: c_test

Reviewers: sdong, rven, anthony, kradhakrishnan, IslamAbdelRahman, igor

Reviewed By: igor

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D40257

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:
This is part of an effort to better understand and optimize RocksDB stalls under high load. I added a feature to db_bench to periodically write QPS to CSV files. That way we can nicely see how our QPS changes in time (especially when DB is stalled) and can do a better job of evaluating our stall system (i.e. we want the QPS to be as constant as possible, as opposed to having bunch of stalls)

Cool part of CSV files is that we can easily graph them -- there are a bunch of tools available.

Test Plan:
Ran ./db_bench --report_interval_seconds=10 --benchmarks=fillrandom --num=10000000
and observed this in report.csv:

secs_elapsed,interval_qps
10,2725860
20,1980480
30,1863456
40,1454359
50,1460389

Reviewers: sdong, MarkCallaghan, rven, yhchiang

Reviewed By: yhchiang

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D40047

Summary: Fixed false alarm of size comparison in compaction_job_stats_test

Test Plan: compaction_job_stats_test

Reviewers: igor

Reviewed By: igor

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D39921

Summary:
Reverting this diff https://reviews.facebook.net/D39999
Will add an option to force bottom most level compaction and then re submit it

Test Plan: make check

Reviewers: igor, sdong

Reviewed By: sdong

Subscribers: dhruba

Differential Revision: https://reviews.facebook.net/D40041

Summary: If we don't have a compaction filter then we can skip compacting the bottom most level

Test Plan:
make check
added unit tests

Reviewers: yhchiang, sdong, igor

Reviewed By: sdong

Subscribers: dhruba

Differential Revision: https://reviews.facebook.net/D39999

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: With experimental feature SuggestCompactRange() we don't restrict running two L0->L1 compactions in parallel. This diff fixes this.

Test Plan: added a unit test to reproduce the failure. fixed the unit test

Reviewers: yhchiang, rven, sdong

Reviewed By: sdong

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D39981

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:
Add Env::GetThreadID(), which returns the ID of the current thread.

In addition, make GetThreadList() and InfoLog use same unique ID for the same thread.

Test Plan:
db_test
listener_test

Reviewers: igor, rven, IslamAbdelRahman, kradhakrishnan, sdong

Reviewed By: sdong

Subscribers: dhruba

Differential Revision: https://reviews.facebook.net/D39735

Summary:
Right now the level we pass to ReFitLevel is the maximum level with files (before compaction), there are multiple cases where this maximum level have changed after compaction
- all files where in L0 (now maximum level is L1)
- using kCompactionStyleUniversal (now maximum level in the last level)
- level_compaction_dynamic_level_bytes ??

We can handle each of these cases individually, but I felt it's safer to calculate max_level_with_files again if we want to do a ReFitLevel

Test Plan:
adding some tests
make -j64 check

Reviewers: igor, sdong

Reviewed By: sdong

Subscribers: ott, dhruba

Differential Revision: https://reviews.facebook.net/D39663

Summary: Some test and benchmark codes don't build for CYGWIN. Fix it.

Test Plan: Build "make all" with TARGET_OS=Cygwin on cygwin and make sure it passes.

Reviewers: rven, yhchiang, anthony, igor, kradhakrishnan

Reviewed By: igor, kradhakrishnan

Subscribers: leveldb, dhruba

Differential Revision: https://reviews.facebook.net/D39711

Summary:
When there are files marked for compaction after compactions, print extra messages to help debugging. Example:

2015/06/08-23:12:55.212855 7ff5013ff700 [default] [JOB 121] Generated table #75: 54 keys, 4807 bytes (need compaction)

2015/06/08-23:12:55.556194 7ff5013ff700 (Original Log Time 2015/06/08-23:12:55.556160) [default] compacted to: base level 1 max bytes base
10240 files[0 1 9 32 12 0 0 0] max score 0.96 (2 files need compaction), MB/sec: 0.0 rd, 0.1 wr, level 2, files in(1, 3) out(5) MB in(0.0,
0.0) out(0.0), read-write-amplify(11.3) write-amplify(5.7) OK, records in: 40, records dropped: 0

Test Plan:
Run test and see LOG files.

valgrind test DBTest.TablePropertiesNeedCompactTest

Reviewers: rven, yhchiang, kradhakrishnan, IslamAbdelRahman, igor

Reviewed By: igor

Subscribers: yoshinorim, maykov, leveldb, dhruba

Differential Revision: https://reviews.facebook.net/D39771