Summary: rocksdb uses a single global lock to protect in memory metadata. We should minimize the mutex protected code section to increase the effective parallelism of the program. See https://our.intern.facebook.com/intern/tasks/?t=2218928

Test Plan:
make check
db_bench

Reviewers: dhruba, heyongqiang

CC: zshao, leveldb

Differential Revision: https://reviews.facebook.net/D9705

Summary:
The unit test fails as our solution does not work with MMap'd files.
Disable the failing unit test. Put it back with the next diff which should fix the problem.

Test Plan: db_test

Reviewers: heyongqiang

CC: dhruba

Differential Revision: https://reviews.facebook.net/D9645

Summary:
* Add a method to check if the log reader is at EOF.
* If we know a record has been flushed force the log_reader to believe it is not at EOF, using a new method UnMarkEof().

This does not work with MMpaed files.

Test Plan: added a unit test.

Reviewers: dhruba, heyongqiang

Reviewed By: heyongqiang

CC: leveldb

Differential Revision: https://reviews.facebook.net/D9567

Summary:
The events that trigger compaction:
* opening the database
* Get -> only if seek compaction is not disabled and other checks are true
* MakeRoomForWrite -> when memtable is full
* BackgroundCall ->
  If the background thread is about to do a compaction run, it schedules
  a new background task to trigger a possible compaction. This will cause
  additional background threads to find and process other compactions that
  can run concurrently.

Test Plan: ran db_bench with overwrite and readonly alternatively.

Reviewers: sheki, MarkCallaghan

Reviewed By: sheki

CC: leveldb

Differential Revision: https://reviews.facebook.net/D9579

Summary:
This patch allows an application to specify whether to use bufferedio,
reads-via-mmaps and writes-via-mmaps per database. Earlier, there
was a global static variable that was used to configure this functionality.

The default setting remains the same (and is backward compatible):
 1. use bufferedio
 2. do not use mmaps for reads
 3. use mmap for writes
 4. use readaheads for reads needed for compaction

I also added a parameter to db_bench to be able to explicitly specify
whether to do readaheads for compactions or not.

Test Plan: make check

Reviewers: sheki, heyongqiang, MarkCallaghan

Reviewed By: sheki

CC: leveldb

Differential Revision: https://reviews.facebook.net/D9429

Summary: Some comparisons left in log_test.cc and db_test.cc complained by make

Test Plan: make

Reviewers: dhruba, sheki

Reviewed By: dhruba

Differential Revision: https://reviews.facebook.net/D9537

Summary: Makefile had options to ignore sign-comparisons and unused-parameters, which should be there. Also fixed the specific errors in the code-base

Test Plan: make

Reviewers: chip, dhruba

Reviewed By: dhruba

CC: leveldb

Differential Revision: https://reviews.facebook.net/D9531

Summary:
Add --benchmarks=levelstats option to report per-level stats (#files, #bytes)
Change readwhilewriting test to report response time for writes but exclude
them from the stats merged by all threads.
Prevent "NaN" in stats output by preventing division by 0.
Remove "o" file I committed by mistake.

Task ID: #

Blame Rev:

Test Plan:
make check

Revert Plan:

Database Impact:

Memcache Impact:

Other Notes:

EImportant:

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

Reviewers: dhruba

Reviewed By: dhruba

Differential Revision: https://reviews.facebook.net/D9513

Summary:
Rocksdb can create 0 sized log files when it is opened and closed without any operations.
The GetUpdatesSince fails currently if there is a log file of size zero.

This diff fixes this. If there is a log file is 0, it is removed form the probable_file_list

Test Plan: unit test

Reviewers: dhruba, heyongqiang

Reviewed By: heyongqiang

CC: leveldb

Differential Revision: https://reviews.facebook.net/D9507

Summary:
Instead of checking for number of files in L0. Check for number of files in the requested level.

Bug introduced in D4929 (diff trying to do too many things).

Test Plan: db_test.

Reviewers: dhruba, MarkCallaghan

Reviewed By: dhruba

Differential Revision: https://reviews.facebook.net/D9483

Summary:
Add --benchmarks=updaterandom for read-modify-write workloads. This is different
from --benchmarks=readrandomwriterandom in a few ways. First, an "operation" is the
combined time to do the read & write rather than treating them as two ops. Second,
the same key is used for the read & write.

Change RandomGenerator to support rows larger than 1M. That was using "assert"
to fail and assert is compiled-away when -DNDEBUG is used.

Add more options to db_bench
--duration - sets the number of seconds for tests to run. When not set the
operation count continues to be the limit. This is used by random operation
tests.

--use_snapshot - when set GetSnapshot() is called prior to each random read.
This is to measure the overhead from using snapshots.

--get_approx - when set GetApproximateSizes() is called prior to each random
read. This is to measure the overhead for a query optimizer.

Task ID: #

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: dhruba

Reviewed By: dhruba

Differential Revision: https://reviews.facebook.net/D9267

Summary: Fix for memory leaks in rocksdb tests. Also modified the variable NUM_FAILED_TESTS to print the actual number of failed tests.

Test Plan: make <test>; valgrind --leak-check=full ./<test>

Reviewers: sheki, dhruba

Reviewed By: sheki

CC: leveldb

Differential Revision: https://reviews.facebook.net/D9333

Summary:
SizeBeingCompacted was called without any lock protection. This causes
crashes, especially when running db_bench with value_size=128K.
The fix is to compute SizeUnderCompaction while holding the mutex and
passing in these values into the call to Finalize.

(gdb) where
#4  leveldb::VersionSet::SizeBeingCompacted (this=this@entry=0x7f0b490931c0, level=level@entry=4) at db/version_set.cc:1827
#5  0x000000000043a3c8 in leveldb::VersionSet::Finalize (this=this@entry=0x7f0b490931c0, v=v@entry=0x7f0b3b86b480) at db/version_set.cc:1420
#6  0x00000000004418d1 in leveldb::VersionSet::LogAndApply (this=0x7f0b490931c0, edit=0x7f0b3dc8c200, mu=0x7f0b490835b0, new_descriptor_log=<optimized out>) at db/version_set.cc:1016
#7  0x00000000004222b2 in leveldb::DBImpl::InstallCompactionResults (this=this@entry=0x7f0b49083400, compact=compact@entry=0x7f0b2b8330f0) at db/db_impl.cc:1473
#8  0x0000000000426027 in leveldb::DBImpl::DoCompactionWork (this=this@entry=0x7f0b49083400, compact=compact@entry=0x7f0b2b8330f0) at db/db_impl.cc:1757
#9  0x0000000000426690 in leveldb::DBImpl::BackgroundCompaction (this=this@entry=0x7f0b49083400, madeProgress=madeProgress@entry=0x7f0b41bf2d1e, deletion_state=...) at db/db_impl.cc:1268
#10 0x0000000000428f42 in leveldb::DBImpl::BackgroundCall (this=0x7f0b49083400) at db/db_impl.cc:1170
#11 0x000000000045348e in BGThread (this=0x7f0b49023100) at util/env_posix.cc:941
#12 leveldb::(anonymous namespace)::PosixEnv::BGThreadWrapper (arg=0x7f0b49023100) at util/env_posix.cc:874
#13 0x00007f0b4a7cf10d in start_thread (arg=0x7f0b41bf3700) at pthread_create.c:301
#14 0x00007f0b49b4b11d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:115

Test Plan:
make check

I am running db_bench with a value size of 128K to see if the segfault is fixed.

Reviewers: MarkCallaghan, sheki, emayanke

Reviewed By: sheki

CC: leveldb

Differential Revision: https://reviews.facebook.net/D9279

Summary:
If there is an error while writing an edit to the manifest file, the manifest
file is closed and reopened to check if the edit made it in. However, if the
re-opening of the manifest is unsuccessful and options.paranoid_checks is set
t true, then the db refuses to accept new puts, effectively putting the db
in readonly mode.

In a future diff, I would like to make the default value of paranoid_check
to true.

Test Plan: make check

Reviewers: sheki

Reviewed By: sheki

CC: leveldb

Differential Revision: https://reviews.facebook.net/D9201

Summary:
Store the last flushed, seq no. in db_impl. Check against it in
transaction Log iterator. Do not attempt to read ahead if we do not know
if the data is flushed completely.
Does not work if flush is disabled. Any ideas on fixing that?
* Minor change, iter->Next is called the first time automatically for
* the first time.

Test Plan:
existing test pass.
More ideas on testing this?
Planning to run some stress test.

Reviewers: dhruba, heyongqiang

CC: leveldb

Differential Revision: https://reviews.facebook.net/D9087

Summary:
The compaction process zeros out sequence numbers if the output is
part of the bottommost level.
The Slice is supposed to refer to an immutable data buffer. The
merger that implements the priority queue while reading kvs as
the input of a compaction run reies on this fact. The bug was that
were updating the sequence number of a record in-place and that was
causing suceeding invocations of the merger to return kvs in
arbitrary order of sequence numbers.
The fix is to copy the key to a local memory buffer before setting
its seqno to 0.

Test Plan:
Set Options.purge_redundant_kvs_while_flush = false and then run
db_stress --ops_per_thread=1000 --max_key=320

Reviewers: emayanke, sheki

Reviewed By: emayanke

CC: leveldb

Differential Revision: https://reviews.facebook.net/D9147

Summary:
TableCache->file is not used. remove it.
I kept the TableAndFile structure and will clean it up in a future patch.

Test Plan: make clean check

Reviewers: sheki, chip

Reviewed By: chip

CC: leveldb

Differential Revision: https://reviews.facebook.net/D9075

Summary:
This adds the rate_delay_limit_milliseconds option to make the delay
configurable in MakeRoomForWrite when the max compaction score is too high.
This delay is called the Ln slowdown. This change also counts the Ln slowdown
per level to make it possible to see where the stalls occur.

From IO-bound performance testing, the Level N stalls occur:
* with compression -> at the largest uncompressed level. This makes sense
                      because compaction for compressed levels is much
                      slower. When Lx is uncompressed and Lx+1 is compressed
                      then files pile up at Lx because the (Lx,Lx+1)->Lx+1
                      compaction process is the first to be slowed by
                      compression.
* without compression -> at level 1

Task ID: #1832108

Blame Rev:

Test Plan:
run with real data, added test

Revert Plan:

Database Impact:

Memcache Impact:

Other Notes:

EImportant:

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

Reviewers: dhruba

Reviewed By: dhruba

Differential Revision: https://reviews.facebook.net/D9045

Summary:
Rocks accumulates recent writes and deletes in the in-memory memtable.
When the memtable is full, it writes the contents on the memtable to
a file in L0.

This patch removes redundant records at the time of the flush. If there
are multiple versions of the same key in the memtable, then only the
most recent one is dumped into the output file. The purging of
redundant records occur only if the most recent snapshot is earlier
than the earliest record in the memtable.

Should we switch on this feature by default or should we keep this feature
turned off in the default settings?

Test Plan: Added test case to db_test.cc

Reviewers: sheki, vamsi, emayanke, heyongqiang

Reviewed By: sheki

CC: leveldb

Differential Revision: https://reviews.facebook.net/D8991

Summary:
1. the default value for key size is still 16
2. enable the ability to set the key size via command line --key_size=

Test Plan:
build & run db_banch and pass some value via command line.
verify it works correctly.

Reviewers: sheki

Reviewed By: sheki

CC: leveldb

Differential Revision: https://reviews.facebook.net/D8943

Summary:
scripted NULL to nullptr in
* include/leveldb/
* db/
* table/
* util/

Test Plan: make all check

Reviewers: dhruba, emayanke

Reviewed By: emayanke

CC: leveldb

Differential Revision: https://reviews.facebook.net/D9003

Summary:
There was an artifical limit of 50K files per database. This is
insifficient if the database is 1 TB in size and each file is 2 MB.

Test Plan: make check

Reviewers: sheki, emayanke

Reviewed By: emayanke

CC: leveldb

Differential Revision: https://reviews.facebook.net/D8919

Summary:
Use only the counter mechanism. Do away with
incNumFileOpens, incNumFileClose, incNumFileErrors
s/NULL/nullptr/g in db/table_cache.cc

Test Plan: make clean check

Reviewers: dhruba, heyongqiang, emayanke

Reviewed By: dhruba

CC: leveldb

Differential Revision: https://reviews.facebook.net/D8841

Summary: just record time consumed in compaction

Test Plan: compile

Reviewers: dhruba

Reviewed By: dhruba

CC: leveldb

Differential Revision: https://reviews.facebook.net/D8781

Summary:
* Counters for bytes read and write.
as a part of this diff, I want to=>
* Measure compaction times. @dhruba can you point which function, should
* I time to get Compaction-times. Was looking at CompactRange.

Test Plan: db_test

Reviewers: dhruba, emayanke

CC: leveldb

Differential Revision: https://reviews.facebook.net/D8763

Summary:
I had added FLAGS_numdistinct and FLAGS_deletepercent for randomwithverify
but forgot to add cmdline parsing for those flags.

Test Plan:
[nponnekanti@dev902 /data/users/nponnekanti/rocksdb] ./db_bench --benchmarks=randomwithverify --numdistinct=500
LevelDB:    version 1.5
Date:       Thu Feb 21 10:34:40 2013
CPU:        24 * Intel(R) Xeon(R) CPU           X5650  @ 2.67GHz
CPUCache:   12288 KB
Keys:       16 bytes each
Values:     100 bytes each (50 bytes after compression)
Entries:    1000000
RawSize:    110.6 MB (estimated)
FileSize:   62.9 MB (estimated)
Compression: snappy
WARNING: Assertions are enabled; benchmarks unnecessarily slow
------------------------------------------------
Created bg thread 0x7fbf90bff700
randomwithverify :       4.693 micros/op 213098 ops/sec; ( get:900000 put:80000 del:20000 total:1000000 found:714556)

[nponnekanti@dev902 /data/users/nponnekanti/rocksdb] ./db_bench --benchmarks=randomwithverify --deletepercent=5
LevelDB:    version 1.5
Date:       Thu Feb 21 10:35:03 2013
CPU:        24 * Intel(R) Xeon(R) CPU           X5650  @ 2.67GHz
CPUCache:   12288 KB
Keys:       16 bytes each
Values:     100 bytes each (50 bytes after compression)
Entries:    1000000
RawSize:    110.6 MB (estimated)
FileSize:   62.9 MB (estimated)
Compression: snappy
WARNING: Assertions are enabled; benchmarks unnecessarily slow
------------------------------------------------
Created bg thread 0x7fe14dfff700
randomwithverify :       4.883 micros/op 204798 ops/sec; ( get:900000 put:50000 del:50000 total:1000000 found:443847)
[nponnekanti@dev902 /data/users/nponnekanti/rocksdb]
[nponnekanti@dev902 /data/users/nponnekanti/rocksdb] ./db_bench --benchmarks=randomwithverify --deletepercent=5 --numdistinct=500
LevelDB:    version 1.5
Date:       Thu Feb 21 10:36:18 2013
CPU:        24 * Intel(R) Xeon(R) CPU           X5650  @ 2.67GHz
CPUCache:   12288 KB
Keys:       16 bytes each
Values:     100 bytes each (50 bytes after compression)
Entries:    1000000
RawSize:    110.6 MB (estimated)
FileSize:   62.9 MB (estimated)
Compression: snappy
WARNING: Assertions are enabled; benchmarks unnecessarily slow
------------------------------------------------
Created bg thread 0x7fc31c7ff700
randomwithverify :       4.920 micros/op 203233 ops/sec; ( get:900000 put:50000 del:50000 total:1000000 found:445522)

Revert Plan: OK

Task ID: #

Reviewers: dhruba, emayanke

Reviewed By: dhruba

CC: leveldb

Differential Revision: https://reviews.facebook.net/D8769

Summary: Added RandomWithVerify benchmark option.

Test Plan:
This whole diff is to test.
[nponnekanti@dev902 /data/users/nponnekanti/rocksdb] ./db_bench --benchmarks=randomwithverify
LevelDB:    version 1.5
Date:       Tue Feb 19 17:50:28 2013
CPU:        24 * Intel(R) Xeon(R) CPU           X5650  @ 2.67GHz
CPUCache:   12288 KB
Keys:       16 bytes each
Values:     100 bytes each (50 bytes after compression)
Entries:    1000000
RawSize:    110.6 MB (estimated)
FileSize:   62.9 MB (estimated)
Compression: snappy
WARNING: Assertions are enabled; benchmarks unnecessarily slow
------------------------------------------------
Created bg thread 0x7fa9c3fff700
randomwithverify :       5.004 micros/op 199836 ops/sec; ( get:900000 put:80000 del:20000 total:1000000 found:711992)

Revert Plan: OK

Task ID: #

Reviewers: dhruba, emayanke

Reviewed By: dhruba

CC: leveldb

Differential Revision: https://reviews.facebook.net/D8685

Summary:
Changed the Get and Scan options with openForReadOnly mode to have access to the memtable.
Changed the visibility of NewInternalIterator in db_impl from private to protected so that
the derived class db_impl_read_only can call that in its NewIterator function for the
scan case. The previous approach which changed the default for flush_on_destroy_ from false to true
caused many problems in the unit tests due to empty sst files that it created. All
unit tests pass now.

Test Plan: make clean; make all check; ldb put and get and scans

Reviewers: dhruba, heyongqiang, sheki

Reviewed By: dhruba

CC: kosievdmerwe, zshao, dilipj, kailiu

Differential Revision: https://reviews.facebook.net/D8697

Summary:
* Introduce is histogram in statistics.h
* stop watch to measure time.
* introduce two timers as a poc.
Replaced NULL with nullptr to fight some lint errors
Should be useful for google.

Test Plan:
ran db_bench and check stats.
make all check

Reviewers: dhruba, heyongqiang

Reviewed By: dhruba

CC: leveldb

Differential Revision: https://reviews.facebook.net/D8637

Revert "Fix for the weird behaviour encountered by ldb Get where it could read only the second-latest value"

This reverts commit 4c696ed0.

Summary:
    c_test: db/filename.cc:74: std::string leveldb::DescriptorFileName(const string&,....

Test Plan:
  this is a failure in a unit test

Differential Revision: https://reviews.facebook.net/D8667

Summary:
The sequence numbers in each record eat up plenty of space on storage.
The optimization zeroes out sequence numbers on kvs in the Lmax
layer that are earlier than the earliest snapshot.

Test Plan: Unit test attached.

Differential Revision: https://reviews.facebook.net/D8619

Summary:
flush_on_destroy has a default value of false and the memtable is flushed
in the dbimpl-destructor only when that is set to true. Because we want the memtable to be flushed everytime that
the destructor is called(db is closed) and the cases where we work with the memtable only are very less
it is a good idea to give this a default value of true. Thus the put from ldb
wil have its data flushed to disk in the destructor and the next Get will be able to
read it when opened with OpenForReadOnly. The reason that ldb could read the latest value when
the db was opened in the normal Open mode is that the Get from normal Open first reads
the memtable and directly finds the latest value written there and the Get from OpenForReadOnly
doesn't have access to the memtable (which is correct because all its Put/Modify) are disabled

Test Plan: make all; ldb put and get and scans

Reviewers: dhruba, heyongqiang, sheki

Reviewed By: heyongqiang

CC: kosievdmerwe, zshao, dilipj, kailiu

Differential Revision: https://reviews.facebook.net/D8631

Summary:
* Add a SplitByTTLLogger to enable this feature. In this diff I implemented generalized AutoSplitLoggerBase class to simplify the
development of such classes.
* Refactor the existing AutoSplitLogger and fix several bugs.

Test Plan:
* Added a unit tests for different types of "auto splitable" loggers individually.
* Tested the composited logger which allows the log files to be splitted by both TTL and log size.

Reviewers: heyongqiang, dhruba

Reviewed By: heyongqiang

CC: zshao, leveldb

Differential Revision: https://reviews.facebook.net/D8037

Summary:
Previously, if you opened a db with num_levels set lower than
the database, you received the unhelpful message "Corruption:
VersionEdit: new-file entry."  Now you get a more verbose message
describing the issue.

Also, fix handling of compression_levels (both the run-over-the-end
issue and the memory management of it).

Lastly, unique_ptr'ify a couple of minor calls.

Test Plan: make check

Reviewers: dhruba

Reviewed By: dhruba

CC: leveldb

Differential Revision: https://reviews.facebook.net/D8151

Summary:
We continually rebuilt build_version.c because we put the
current date into it, but that's what __DATE__ already is.  This makes
builds faster.

This also fixes an issue with 'make clean FOO' not working properly.

Also tweak the build rules to be more consistent, always have warnings,
and add a 'make release' rule to handle flags for release builds.

Test Plan: make, make clean

Reviewers: dhruba

Reviewed By: dhruba

Differential Revision: https://reviews.facebook.net/D8139

Summary:
On some filesystems, pre-allocation can be a considerable
amount of space.  xfs in our production environment pre-allocates by
1GB, for instance.  By using fallocate to inform the kernel of our
expected file sizes, we eliminate this wasteage (that isn't recovered
until the file is closed which, in the case of LOG files, can be a
considerable amount of time).

Test Plan:
created an xfs loopback filesystem, mounted with
allocsize=4M, and ran db_stress.  LOG file without this change was 4M,
and with it it was 128k then grew to normal size.

Reviewers: dhruba

Reviewed By: dhruba

CC: adsharma, leveldb

Differential Revision: https://reviews.facebook.net/D7953

Summary:
Replace manual memory management with std::unique_ptr in a
number of places; not exhaustive, but this fixes a few leaks with file
handles as well as clarifies semantics of the ownership of file handles
with log classes.

Test Plan: db_stress, make check

Reviewers: dhruba

Reviewed By: dhruba

CC: zshao, leveldb, heyongqiang

Differential Revision: https://reviews.facebook.net/D8043

Summary: Add Tickers to count Write's and Get's

Test Plan: make check

Reviewers: dhruba, chip

Reviewed By: dhruba

CC: leveldb

Differential Revision: https://reviews.facebook.net/D7977

Summary:
Found issues with `db_test` and `db_stress` when running valgrind.

`DBImpl` had an issue where if an compaction failed then it will use the uninitialised file size of an output file is used. This manifested as the final call to output to the log in `DoCompactionWork()` branching on uninitialized memory (all the way down in printf's innards).

Test Plan:
Ran `valgrind --track_origins=yes ./db_test` and `valgrind ./db_stress` to see if issues disappeared.

Ran `make check` to see if there were no regressions.

Reviewers: vamsi, dhruba

Reviewed By: dhruba

CC: leveldb

Differential Revision: https://reviews.facebook.net/D8001