Conflicts:
	db/db_bench.cc
	db/version_set.cc
	include/leveldb/options.h
	util/options.cc

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. Exposed a Count function that returns the number of updates in a batch. Could be handy for replication sequence number check.

Test Plan: make check;

Reviewers: emayanke, sheki, dhruba

CC: leveldb

Differential Revision: https://reviews.facebook.net/D11523

Summary:
With the Makefile now updated to correctly update all .o files, this
should fix the issues recompiling stringappend_test. This should also fix the
"segmentation-fault" that we were getting earlier. Now, stringappend_test should
be clean, and I have added it back to the unit-tests. Also made some minor updates
to the tests themselves.

Test Plan:
1. make clean; make stringappend_test -j 32	(will test it by itself)
2. make clean; make all check -j 32		(to run all unit tests)
3. make clean; make release			(test in release mode)
4. valgrind ./stringappend_test 		(valgrind tests)

Reviewers: haobo, jpaton, dhruba

Reviewed By: haobo

CC: leveldb

Differential Revision: https://reviews.facebook.net/D11505

Summary:
The old Makefile did not remove ALL .o and .d files, but rather only
those that happened to be in the root folder and one-level deep. This was causing
issues when recompiling files in deeper folders. This fix now causes make clean
to find ALL .o and .d files via a unix "find" command, and then remove them.

Test Plan:
make clean;
make all -j 32;

Reviewers: haobo, jpaton, dhruba

Reviewed By: haobo

CC: leveldb

Differential Revision: https://reviews.facebook.net/D11493

Summary: [start_time, end_time) is waht I'm following for the buckets and the whole time-range. Also cleaned up some code in db_ttl.* Not correcting the spacing/indenting convention for util/ldb_cmd.cc in this diff.

Test Plan: python ldb_test.py, make ttl_test, Run mcrocksdb-backup tool, Run the ldb tool on 2 mcrocksdb production backups form sigmafio033.prn1

Reviewers: vamsi, haobo

Reviewed By: vamsi

Differential Revision: https://reviews.facebook.net/D11433

Introducing timeranged scan, timeranged dump in ldb. Also the ability to count in time-batches during Dump

Summary:
Scan and Dump commands in ldb use iterator. We need to also print timestamp for ttl databases for debugging. For this I create a TtlIterator class pointer in these functions and assign it the value of Iterator pointer which actually points to t TtlIterator object, and access the new function ValueWithTS which can return TS also. Buckets feature for dump command: gives a count of different key-values in the specified time-range distributed across the time-range partitioned according to bucket-size. start_time and end_time are specified in unixtimestamp and bucket in seconds on the user-commandline
Have commented out 3 ines from ldb_test.py so that the test does not break right now. It breaks because timestamp is also printed now and I have to look at wildcards in python to compare properly.

Test Plan: python tools/ldb_test.py

Reviewers: vamsi, dhruba, haobo, sheki

Reviewed By: vamsi

CC: leveldb

Differential Revision: https://reviews.facebook.net/D11403

Summary: As title, now that db_stress supports --map_read properly

Test Plan: make crash_test

Reviewers: vamsi, emayanke, dhruba

CC: leveldb

Differential Revision: https://reviews.facebook.net/D11391

Summary: as title, use initialize list so that lines fit in 80 chars.

Test Plan: make check;

Reviewers: sheki, dhruba

Differential Revision: https://reviews.facebook.net/D11385

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: $title

Test Plan: db_bench --statistics=1

Reviewers: haobo

Reviewed By: haobo

CC: leveldb

Differential Revision: https://reviews.facebook.net/D11373

Summary:
Zlib_{Compress,Uncompress} did not handle very small input buffers properly. In addition, they did not call inflate/deflate until Z_STREAM_END was returned; it was possible for them to exit when only Z_OK had returned.

This diff also fixes a bunch of lint errors.

Test Plan: Run make check

Reviewers: dhruba, sheki, haobo

Reviewed By: dhruba

CC: leveldb

Differential Revision: https://reviews.facebook.net/D11301

Summary: This diff added an option to control the incremenal sync frequency. db_bench has a new flag bytes_per_sync for easy tuning exercise.

Test Plan: make check; db_bench

Reviewers: dhruba

CC: leveldb

Differential Revision: https://reviews.facebook.net/D11295

Summary:
simplify the printing code in db_bench
         use TickersMap and HistogramsNameMap introduced in previous diffs.

Test Plan: ./db_bench --statistics=1 and see if all the statistics are printed

Reviewers: haobo, dhruba

Reviewed By: haobo

CC: leveldb

Differential Revision: https://reviews.facebook.net/D11355

Summary:
Merge multiple multiple memtables in memory before writing it
out to a file in L0.

There is a new config parameter min_write_buffer_number_to_merge
that specifies the number of write buffers that should be merged
together to a single file in storage. The system will not flush
wrte buffers to storage unless at least these many buffers have
accumulated in memory.
The default value of this new parameter is 1, which means that
a write buffer will be immediately flushed to disk as soon it is
ready.

Test Plan: make check

Differential Revision: https://reviews.facebook.net/D11241

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:
https://code.google.com/p/leveldb/issues/detail?can=1&q=178&colspec=ID%20Type%20Status%20Priority%20Milestone%20Owner%20Summary&id=178

Ported the solution as is to RocksDB.

Test Plan: moved the unit test as manual_compaction_test

Reviewers: dhruba

Reviewed By: dhruba

CC: leveldb

Differential Revision: https://reviews.facebook.net/D11331

Summary: Add a histogram to track WriteBlock times

Test Plan: db_bench and print

Reviewers: haobo, dhruba

Reviewed By: haobo

CC: leveldb

Differential Revision: https://reviews.facebook.net/D11319

Summary:
I'm concerned about a random seg-fault that sometimes occurs when
running stringappend_test. I will investigate further. First, I am removing
stringappend_test from the regular release tests, and making some clean-ups
to the code.

Test Plan:
1. make stringappend_test
2. ./stringappend_test

Reviewers: haobo, dhruba

Reviewed By: haobo

CC: leveldb

Differential Revision: https://reviews.facebook.net/D11313

Summary:
Use a bit set to keep track of which random number is generated.
        Currently only supports single-threaded. All our perf tests are run with threads=1
        Copied over bitset implementation from common/datastructures

Test Plan: printed the generated keys, and verified all keys were present.

Reviewers: MarkCallaghan, haobo, dhruba

Reviewed By: MarkCallaghan

CC: leveldb

Differential Revision: https://reviews.facebook.net/D11247

Test Plan: make release

Reviewers: haobo, dhruba, jpaton

Reviewed By: haobo

CC: leveldb

Differential Revision: https://reviews.facebook.net/D11307

Summary: This hopefully gives the right semantics to compaction filter. Will write a small wiki to explain the ideas.

Test Plan: make check; db_stress

Reviewers: dhruba

CC: leveldb

Differential Revision: https://reviews.facebook.net/D11121

Summary: Table is setup for compaction using Table::SetupForCompaction. So read block calls can be differentiated b/w Gets/Compaction. Use this and measure times.

Test Plan: db_bench --statistics=1

Reviewers: dhruba, haobo

Reviewed By: haobo

CC: leveldb, MarkCallaghan

Differential Revision: https://reviews.facebook.net/D11217

Summary: As title

Test Plan: db_crashtest

Reviewers: vamsi, emayanke

CC: leveldb

Differential Revision: https://reviews.facebook.net/D11271

Summary:
During compaction, we sync the output files after they are fully written out. This causes unnecessary blocking of the compaction thread and burstiness of the write traffic.
This diff simply asks the OS to sync data incrementally as they are written, on the background. The hope is that, at the final sync, most of the data are already on disk and we would block less on the sync call. Thus, each compaction runs faster and we could use fewer number of compaction threads to saturate IO.
In addition, the write traffic will be smoothed out, hopefully reducing the IO P99 latency too.

Some quick tests show 10~20% improvement in per thread compaction throughput. Combined with posix advice on compaction read, just 5 threads are enough to almost saturate the udb flash bandwidth for 800 bytes write only benchmark.
What's more promising is that, with saturated IO, iostat shows average wait time is actually smoother and much smaller.
For the write only test 800bytes test:
Before the change:  await  occillate between 10ms and 3ms
After the change: await ranges 1-3ms

Will test against read-modify-write workload too, see if high read latency P99 could be resolved.

Will introduce a parameter to control the sync interval in a follow up diff after cleaning up EnvOptions.

Test Plan: make check; db_bench; db_stress

Reviewers: dhruba

CC: leveldb

Differential Revision: https://reviews.facebook.net/D11115

Summary:
Preliminary! Introduced the --use_multiget=1 and --keys_per_multiget=n
flags for db_bench. Also updated and tested the ReadRandom() method
to include an option to use multiget. By default,
keys_per_multiget=100.

Preliminary tests imply that multiget is at least 1.25x faster per
key than regular get.

Will continue adding Multiget for ReadMissing, ReadHot,
RandomWithVerify, ReadRandomWriteRandom; soon. Will also think
about ways to better verify benchmarks.

Test Plan:
1. make db_bench
2. ./db_bench --benchmarks=fillrandom
3. ./db_bench --benchmarks=readrandom --use_existing_db=1
	      --use_multiget=1 --threads=4 --keys_per_multiget=100
4. ./db_bench --benchmarks=readrandom --use_existing_db=1
	      --threads=4
5. Verify ops/sec (and 1000000 of 1000000 keys found)

Reviewers: haobo, MarkCallaghan, dhruba

Reviewed By: MarkCallaghan

CC: leveldb

Differential Revision: https://reviews.facebook.net/D11127

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:
Completed the implementation for the Redis API for Lists.
The Redis API uses rocksdb as a backend to persistently
store maps from key->list. It supports basic operations
for appending, inserting, pushing, popping, and accessing
a list, given its key.

Test Plan:
  - Compile with: make redis_test
  - Test with: ./redis_test
  - Run all unit tests (for all rocksdb) with: make all check
  - To use an interactive REDIS client use: ./redis_test -m
  - To clean the database before use:       ./redis_test -m -d

Reviewers: haobo, dhruba, zshao

Reviewed By: haobo

CC: leveldb

Differential Revision: https://reviews.facebook.net/D10833

Summary:
The code was such that if multi-threaded-compactions as well
as seek compaction are enabled then it submits multiple
compaction request for the same range of keys. This causes
extraneous sst-files to accumulate at various levels.

Test Plan:
I am not able to write a very good unit test for this one
but can easily reproduce this bug with 'dbstress' with the
following options.

batch=1;maxk=100000000;ops=100000000;ro=0;fm=2;bpl=10485760;of=500000; wbn=3; mbc=20; mb=2097152; wbs=4194304; dds=1; sync=0;  t=32; bs=16384; cs=1048576; of=500000; ./db_stress --disable_seek_compaction=0 --mmap_read=0 --threads=$t --block_size=$bs --cache_size=$cs --open_files=$of --verify_checksum=1 --db=/data/mysql/leveldb/dbstress.dir --sync=$sync --disable_wal=1 --disable_data_sync=$dds --write_buffer_size=$wbs --target_file_size_base=$mb --target_file_size_multiplier=$fm --max_write_buffer_number=$wbn --max_background_compactions=$mbc --max_bytes_for_level_base=$bpl --reopen=$ro --ops_per_thread=$ops --max_key=$maxk --test_batches_snapshots=$batch

Reviewers: leveldb, emayanke

Reviewed By: emayanke

Differential Revision: https://reviews.facebook.net/D11055

Summary: Added logic to make another WriteBatch with Timestamps during the Write function execution in TTL class. Also expanded the ttl_test to test for it. Have done nothing for Merge for now.

Test Plan: make ttl_test;./ttl_test

Reviewers: haobo, vamsi, dhruba

Reviewed By: haobo

CC: leveldb

Differential Revision: https://reviews.facebook.net/D10827

Summary: Fix refering freed memory in earlier commit by https://reviews.facebook.net/D11181

Test Plan: make check

Reviewers: haobo, sheki

Reviewed By: haobo

CC: leveldb

Differential Revision: https://reviews.facebook.net/D11193

Summary: the assert was wrong in D11145. Broke build

Test Plan: make db_bench run it

Reviewers: dhruba, haobo, emayanke

Reviewed By: dhruba

CC: leveldb

Differential Revision: https://reviews.facebook.net/D11187

Summary:
The current code prints the name of the InternalKeyComparator
in the log file. We would also like to print the name of the
user-specified comparator for easier debugging.

Test Plan: make check

Reviewers: sheki

Reviewed By: sheki

CC: leveldb

Differential Revision: https://reviews.facebook.net/D11181

Summary: Provide a  map of histograms and ticker vs strings. Fb303 libraries can use this to provide the mapping. We will not have to duplicate the code during release.

Test Plan: db_bench with statistics=1

Reviewers: dhruba, haobo

Reviewed By: dhruba

CC: leveldb

Differential Revision: https://reviews.facebook.net/D11145

Summary:
Without this files could be written out to a level greater than the maximum level possible and is the source of the segfaults that wormhole awas getting. The sequence of steps that was followed:
1. WriteLevel0Table was called when memtable was to be flushed for a file.
2. PickLevelForMemTableOutput was called to determine the level to which this file should be pushed.
3. PickLevelForMemTableOutput returned a wrong result because max_mem_compaction_level was equal to 2 even when num_levels was equal to 0.
The fix to re-initialize max_mem_compaction_level based on num_levels passed seems correct.

Test Plan: make all check; Also made a dummy file to mimic the wormhole-file behaviour which was causing the segfaults and found that the same segfault occurs without this change and not with this.

Reviewers: dhruba, haobo

Reviewed By: dhruba

CC: leveldb

Differential Revision: https://reviews.facebook.net/D11157

Summary: These extra options caught some bugs. Will be run via Jenkins now with the crash_test

Test Plan: ./make crashtest

Reviewers: dhruba, vamsi

Reviewed By: dhruba

CC: leveldb

Differential Revision: https://reviews.facebook.net/D11151

Summary:
I think the check for "error" that I added had caused
false alarm. Fixed that.

Test Plan:
Revert Plan: OK

Task ID: #

Reviewers: emayanke, dhruba

Reviewed By: emayanke

Differential Revision: https://reviews.facebook.net/D11139

Summary: as title

Test Plan: db_bench --statistics=1 check for statistic.

Reviewers: dhruba, haobo

Reviewed By: dhruba

CC: leveldb

Differential Revision: https://reviews.facebook.net/D11109