Summary:
There is a new option called hybrid_mode which, when switched on,
causes HBase style compactions.  Files from L0 are
compacted back into L0. This meat of this compaction algorithm
is in PickCompactionHybrid().

All files reside in L0. That means all files have overlapping
keys. Each file has a time-bound, i.e. each file contains a
range of keys that were inserted around the same time. The
start-seqno and the end-seqno refers to the timeframe when
these keys were inserted.  Files that have contiguous seqno
are compacted together into a larger file. All files are
ordered from most recent to the oldest.

The current compaction algorithm starts to look for
candidate files starting from the most recent file. It continues to
add more files to the same compaction run as long as the
sum of the files chosen till now is smaller than the next
candidate file size. This logic needs to be debated
and validated.

The above logic should reduce write amplification to a
large extent... will publish numbers shortly.

Test Plan: dbstress runs for 6 hours with no data corruption (tested so far).

Differential Revision: https://reviews.facebook.net/D11289

Summary:
There is a new option called hybrid_mode which, when switched on,
causes HBase style compactions.  Files from L0 are
compacted back into L0. This meat of this compaction algorithm
is in PickCompactionHybrid().

All files reside in L0. That means all files have overlapping
keys. Each file has a time-bound, i.e. each file contains a
range of keys that were inserted around the same time. The
start-seqno and the end-seqno refers to the timeframe when
these keys were inserted.  Files that have contiguous seqno
are compacted together into a larger file. All files are
ordered from most recent to the oldest.

The current compaction algorithm starts to look for
candidate files starting from the most recent file. It continues to
add more files to the same compaction run as long as the
sum of the files chosen till now is smaller than the next
candidate file size. This logic needs to be debated
and validated.

The above logic should reduce write amplification to a
large extent... will publish numbers shortly.

Test Plan: dbstress runs for 6 hours with no data corruption (tested so far).

Differential Revision: https://reviews.facebook.net/D11289

Summary: as title, also removed an incorrect assertion

Test Plan: make check; db_stress --mmap_read=1; db_stress --mmap_read=0

Reviewers: dhruba, emayanke

CC: leveldb

Differential Revision: https://reviews.facebook.net/D11367

Summary:
Rocksdb allos specifying the number of files in L0 that triggers
compactions. Expose this api as a command line parameter for
running db_stress.

Test Plan: Run test

Reviewers: sheki, emayanke

Reviewed By: emayanke

CC: leveldb

Differential Revision: https://reviews.facebook.net/D11343

Summary:
This diff simplifies EnvOptions by treating it as POD, similar to Options.
- virtual functions are removed and member fields are accessed directly.
- StorageOptions is removed.
- Options.allow_readahead and Options.allow_readahead_compactions are deprecated.
- Unused global variables are removed: useOsBuffer, useFsReadAhead, useMmapRead, useMmapWrite

Test Plan: make check; db_stress

Reviewers: dhruba

CC: leveldb

Differential Revision: https://reviews.facebook.net/D11175

Summary: Make Statistics usable by client

Test Plan: make check; db_bench

Reviewers: dhruba

Reviewed By: dhruba

Differential Revision: https://reviews.facebook.net/D10899

Summary:
This is initial version. A few ways in which this could
be extended in the future are:
(a) Killing from more places in source code
(b) Hashing stack and using that hash in determining whether to crash.
    This is to avoid crashing more often at source lines that are executed
    more often.
(c) Raising exceptions or returning errors instead of killing

Test Plan:
This whole thing is for testing.

Here is part of output:

python2.7 tools/db_crashtest2.py -d 600
Running db_stress

db_stress retncode -15 output LevelDB version     : 1.5
Number of threads   : 32
Ops per thread      : 10000000
Read percentage     : 50
Write-buffer-size   : 4194304
Delete percentage   : 30
Max key             : 1000
Ratio #ops/#keys    : 320000
Num times DB reopens: 0
Batches/snapshots   : 1
Purge redundant %   : 50
Num keys per lock   : 4
Compression         : snappy
------------------------------------------------
No lock creation because test_batches_snapshots set
2013/04/26-17:55:17  Starting database operations
Created bg thread 0x7fc1f07ff700
... finished 60000 ops
Running db_stress

db_stress retncode -15 output LevelDB version     : 1.5
Number of threads   : 32
Ops per thread      : 10000000
Read percentage     : 50
Write-buffer-size   : 4194304
Delete percentage   : 30
Max key             : 1000
Ratio #ops/#keys    : 320000
Num times DB reopens: 0
Batches/snapshots   : 1
Purge redundant %   : 50
Num keys per lock   : 4
Compression         : snappy
------------------------------------------------
Created bg thread 0x7ff0137ff700
No lock creation because test_batches_snapshots set
2013/04/26-17:56:15  Starting database operations
... finished 90000 ops

Revert Plan: OK

Task ID: #2252691

Reviewers: dhruba, emayanke

Reviewed By: emayanke

CC: leveldb, haobo

Differential Revision: https://reviews.facebook.net/D10581

Summary: db can't reopen safely with disable_wal set!

Test Plan: make db_stress; run db_stress with disable_wal and reopens set and see error

Reviewers: dhruba, vamsi

Reviewed By: dhruba

CC: leveldb

Differential Revision: https://reviews.facebook.net/D10857

Summary: Will help while debugging if the generated value is truncated at proper length.

Test Plan: make db_stress;/db_stress --max_key=10000 --db=/tmp/mcr --threads=1 --ops_per_thread=10000

Reviewers: dhruba, vamsi

Reviewed By: vamsi

Differential Revision: https://reviews.facebook.net/D10845

Summary:
When opened with DBTimestamp::Open call, timestamps are prepended to and stripped from the value during subsequent Put and Get calls respectively. The Timestamp is used to discard values in Get and custom compaction filter which have exceeded their TTL which is specified during Open.
Have made a temporary change to Makefile to let us test with the temporary file TestTime.cc. Have also changed the private members of db_impl.h to protected to let them be inherited by the new class DBTimestamp

Test Plan: make db_timestamp; TestTime.cc(will not check it in) shows how to use the apis currently, but I will write unit-tests shortly

Reviewers: dhruba, vamsi, haobo, sheki, heyongqiang, vkrest

Reviewed By: vamsi

CC: zshao, xjin, vkrest, MarkCallaghan

Differential Revision: https://reviews.facebook.net/D10311

Summary: The crash_test depends on db_stress to work with pre-existing dir

Test Plan: make db_stress; Run db_stress with 'destroy_db_initially=0'

Reviewers: vamsi, dhruba

Reviewed By: dhruba

CC: leveldb

Differential Revision: https://reviews.facebook.net/D10041

Summary: For sanity w.r.t. the way we split up the reopens equally among the ops/thread

Test Plan: make db_stress; db_stress --ops_per_thread=10 --reopens=10 => error

Reviewers: vamsi, dhruba

Reviewed By: dhruba

CC: leveldb

Differential Revision: https://reviews.facebook.net/D10023

Summary: The script runs and kills the stress test periodically. Default values have been used in the script now. Should I make this a part of the Makefile or automated rocksdb build? The values can be easily changed in the script right now, but should I add some support for variable values or input to the script? I believe the script achieves its objective of unsafe crashes and reopening to expect sanity in the database.

Test Plan: python tools/db_crashtest.py

Reviewers: dhruba, vamsi, MarkCallaghan

Reviewed By: vamsi

CC: leveldb

Differential Revision: https://reviews.facebook.net/D9369

Summary:
Earlier Statistics object was a raw pointer. This meant the user had to clear up
the Statistics object after creating the database. In most use cases the database is created in a function and the statistics pointer is out of scope. Hence the statistics object would never be deleted.
Now Using a shared_ptr to manage this.

Want this in before the next release.

Test Plan: make all check.

Reviewers: dhruba, emayanke

Reviewed By: emayanke

CC: leveldb

Differential Revision: https://reviews.facebook.net/D9735

Summary:
Also added some comments and fixed some bugs in
stats reporting. Now the stats seem to match what is expected.

Test Plan:
[nponnekanti@dev902 /data/users/nponnekanti/rocksdb] ./db_stress --test_batches_snapshots=1 --ops_per_thread=1000 --threads=1 --max_key=320
LevelDB version     : 1.5
Number of threads   : 1
Ops per thread      : 1000
Read percentage     : 10
Delete percentage   : 30
Max key             : 320
Ratio #ops/#keys    : 3
Num times DB reopens: 10
Batches/snapshots   : 1
Num keys per lock   : 4
Compression         : snappy
------------------------------------------------
No lock creation because test_batches_snapshots set
2013/03/04-15:58:56  Starting database operations
2013/03/04-15:58:56  Reopening database for the 1th time
2013/03/04-15:58:56  Reopening database for the 2th time
2013/03/04-15:58:56  Reopening database for the 3th time
2013/03/04-15:58:56  Reopening database for the 4th time
Created bg thread 0x7f4542bff700
2013/03/04-15:58:56  Reopening database for the 5th time
2013/03/04-15:58:56  Reopening database for the 6th time
2013/03/04-15:58:56  Reopening database for the 7th time
2013/03/04-15:58:57  Reopening database for the 8th time
2013/03/04-15:58:57  Reopening database for the 9th time
2013/03/04-15:58:57  Reopening database for the 10th time
2013/03/04-15:58:57  Reopening database for the 11th time
2013/03/04-15:58:57  Limited verification already done during gets
Stress Test : 1811.551 micros/op 552 ops/sec
            : Wrote 0.10 MB (0.05 MB/sec) (598% of 1011 ops)
            : Wrote 6050 times
            : Deleted 3050 times
            : 500/900 gets found the key
            : Got errors 0 times

[nponnekanti@dev902 /data/users/nponnekanti/rocksdb] ./db_stress --ops_per_thread=1000 --threads=1 --max_key=320
LevelDB version     : 1.5
Number of threads   : 1
Ops per thread      : 1000
Read percentage     : 10
Delete percentage   : 30
Max key             : 320
Ratio #ops/#keys    : 3
Num times DB reopens: 10
Batches/snapshots   : 0
Num keys per lock   : 4
Compression         : snappy
------------------------------------------------
Creating 80 locks
2013/03/04-15:58:17  Starting database operations
2013/03/04-15:58:17  Reopening database for the 1th time
2013/03/04-15:58:17  Reopening database for the 2th time
2013/03/04-15:58:17  Reopening database for the 3th time
2013/03/04-15:58:17  Reopening database for the 4th time
Created bg thread 0x7fc0f5bff700
2013/03/04-15:58:17  Reopening database for the 5th time
2013/03/04-15:58:17  Reopening database for the 6th time
2013/03/04-15:58:18  Reopening database for the 7th time
2013/03/04-15:58:18  Reopening database for the 8th time
2013/03/04-15:58:18  Reopening database for the 9th time
2013/03/04-15:58:18  Reopening database for the 10th time
2013/03/04-15:58:18  Reopening database for the 11th time
2013/03/04-15:58:18  Starting verification
Stress Test : 1836.258 micros/op 544 ops/sec
            : Wrote 0.01 MB (0.01 MB/sec) (59% of 1011 ops)
            : Wrote 605 times
            : Deleted 305 times
            : 50/90 gets found the key
            : Got errors 0 times
2013/03/04-15:58:18  Verification successful

Revert Plan: OK

Task ID: #

Reviewers: emayanke, dhruba

Reviewed By: emayanke

CC: leveldb

Differential Revision: https://reviews.facebook.net/D9081

Summary: In light of the new option introduced by commit 806e2643 where the database has an option to compact before flushing to disk, we want the stress test to test both sides of the option. Have made it to 'deterministically' and configurably change that option for reopens.

Test Plan: make db_stress; ./db_stress with some differnet options

Reviewers: dhruba, vamsi

Reviewed By: dhruba

CC: leveldb, sheki

Differential Revision: https://reviews.facebook.net/D9165

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:
Currently the test tracks all writes in memory and
uses it for verification at the end. This has 4 problems:
(a) It needs mutex for each write to ensure in-memory update
and leveldb update are done atomically. This slows down the
benchmark.
(b) Verification phase at the end is time consuming as well
(c) Does not test batch writes or snapshots
(d) We cannot kill the test and restart multiple times in a
loop because in-memory state will be lost.

I am adding a FLAGS_multi that does MultiGet/MultiPut/MultiDelete
instead of get/put/delete to get/put/delete a group of related
keys with same values atomically. Every get retrieves the group
of keys and checks that their values are same. This does not have
the above problems but the downside is that it does less amount
of validation than the other approach.

Test Plan:
This whole this is a test! Here is a small run. I am doing larger run now.

[nponnekanti@dev902 /data/users/nponnekanti/rocksdb] ./db_stress --ops_per_thread=10000 --multi=1 --ops_per_key=25
LevelDB version     : 1.5
Number of threads   : 32
Ops per thread      : 10000
Read percentage     : 10
Delete percentage   : 30
Max key             : 2147483648
Num times DB reopens: 10
Num keys per lock   : 4
Compression         : snappy
------------------------------------------------
Creating 536870912 locks
2013/02/20-16:59:32  Starting database operations
Created bg thread 0x7f9ebcfff700
2013/02/20-16:59:37  Reopening database for the 1th time
2013/02/20-16:59:46  Reopening database for the 2th time
2013/02/20-16:59:57  Reopening database for the 3th time
2013/02/20-17:00:11  Reopening database for the 4th time
2013/02/20-17:00:25  Reopening database for the 5th time
2013/02/20-17:00:36  Reopening database for the 6th time
2013/02/20-17:00:47  Reopening database for the 7th time
2013/02/20-17:00:59  Reopening database for the 8th time
2013/02/20-17:01:10  Reopening database for the 9th time
2013/02/20-17:01:20  Reopening database for the 10th time
2013/02/20-17:01:31  Reopening database for the 11th time
2013/02/20-17:01:31  Starting verification
Stress Test : 109.125 micros/op 22191 ops/sec
            : Wrote 0.00 MB (0.23 MB/sec) (59% of 32 ops)
            : Deleted 10 times
2013/02/20-17:01:31  Verification successful

Revert Plan: OK

Task ID: #

Reviewers: dhruba, emayanke

Reviewed By: emayanke

CC: leveldb

Differential Revision: https://reviews.facebook.net/D8733

Summary:
Fixed a bug in the stress-test where the correct size was not being
passed to GenerateValue. This bug was there since the beginning but assertions
were switched on in our code-base only recently.
Added comments on the top detailing how the stress test works and how to
quicken/slow it down after investigation.

Test Plan: make all check. ./db_stress

Reviewers: dhruba, asad

Reviewed By: dhruba

CC: vamsi, sheki, heyongqiang, zshao

Differential Revision: https://reviews.facebook.net/D8727

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

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:
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

Summary:
Check in LogAndApply if the file size is more than the limit set in
Options.
Things to consider : will this be expensive?

Test Plan: make all check. Inputs on a new unit test?

Reviewers: dhruba

Reviewed By: dhruba

CC: leveldb

Differential Revision: https://reviews.facebook.net/D7701

Summary:
dbstress has an option to reopen the database. Make it such that the
previous handle is not closed before we reopen, this simulates a
situation similar to a process crash.

Added new api to DMImpl to remove the lock file.

Test Plan: run db_stress

Reviewers: emayanke

Reviewed By: emayanke

CC: leveldb

Differential Revision: https://reviews.facebook.net/D6777

Summary:
Create more than one background compaction thread if specified.
This code peice is similar to what exists in db_bench.

Test Plan: make check

Differential Revision: https://reviews.facebook.net/D6753

Introducing "database reopens" into the stress test. Database will reopen after a specified number of iterations (configurable) of each thread when they will wait for the databse to reopen.

Summary: FLAGS_reopen (configurable) specifies the number of times the databse is to be reopened. FLAGS_ops_per_thread is divided into points based on that reopen field. At these points all threads come together to wait for the databse to reopen. Each thread "votes" for the database to reopen and when all have voted, the database reopens.

Test Plan: make all;./db_stress

Reviewers: dhruba, MarkCallaghan, sheki, asad, heyongqiang

Reviewed By: dhruba

Differential Revision: https://reviews.facebook.net/D6627

Summary:
disable size compaction in ldb reduce_levels, this will avoid compactions rather than the manual comapction,

added --compression=none|snappy|zlib|bzip2 and --file_size= per-file size to ldb reduce_levels command

Test Plan: run ldb

Reviewers: dhruba, MarkCallaghan

Reviewed By: dhruba

CC: sheki, emayanke

Differential Revision: https://reviews.facebook.net/D6597

Summary: Stress test modified to do deletes and later verify them

Test Plan: running the test: db_stress

Reviewers: dhruba, heyongqiang, asad, sheki, MarkCallaghan

Reviewed By: dhruba

Differential Revision: https://reviews.facebook.net/D6567

Summary:
The default compilation process now uses "-Wall" to compile.
Fix all compilation error generated by gcc.

Test Plan: make all check

Reviewers: heyongqiang, emayanke, sheki

Reviewed By: heyongqiang

CC: MarkCallaghan

Differential Revision: https://reviews.facebook.net/D6525

published in https://reviews.facebook.net/D5997.

Summary:
This patch allows compaction to occur in multiple background threads
concurrently.

If a manual compaction is issued, the system falls back to a
single-compaction-thread model. This is done to ensure correctess
and simplicity of code. When the manual compaction is finished,
the system resumes its concurrent-compaction mode automatically.

The updates to the manifest are done via group-commit approach.

Test Plan: run db_bench

Summary:

Test Plan:

Reviewers:

CC:

Task ID: #

Blame Rev:

Summary:
Created a tool that runs multiple threads that concurrently read and write to levelDB.
All writes to the DB are stored in an in-memory hashtable and verified at the end of the
test. All writes for a given key are serialzied.

Test Plan:
 - Verified by writing only a few keys and logging all writes and verifying that values read and written are correct.
 - Verified correctness of value generator.
 - Ran with various parameters of number of keys, locks, and threads.

Reviewers: dhruba, MarkCallaghan, heyongqiang

Reviewed By: dhruba

Differential Revision: https://reviews.facebook.net/D5829