Summary:
Move some files under util/ to new directories env/, monitoring/ options/ and cache/
Closes https://github.com/facebook/rocksdb/pull/2090
Differential Revision: D4833681
Pulled By: siying
fbshipit-source-id: 2fd8bef
Summary:
Added fifo benchmark to db_bench.
One thing i am not sure is that i am using CompactRange() instead of CompactFiles(). (may cause performance skew because CompactionRange() is not happening in current thread?) For CompactFiles(), for some reason FIFO compaction doesn't work as expected. More insight is welcomed. I guess FIFO compaction doesn't work with file names? igorcanadi
test cmd:
./db_bench --compaction_style=2 --benchmarks=fillseqdeterministic --disable_auto_compactions --num_levels=1 --fifo_compaction_max_table_files_size_mb=10
---------------------- DB 0 LSM ---------------------
Level[0]: /000014.sst(size: 4211014 bytes)
fillseqdeterministic : 4.731 micros/op 211381 ops/sec; 23.4 MB/s
Closes https://github.com/facebook/rocksdb/pull/1734
Differential Revision: D4774964
Pulled By: siying
fbshipit-source-id: 9d08df6
Summary:
PlainTable now supports non-mmap mode. We don't need to check it anymore.
Closes https://github.com/facebook/rocksdb/pull/1882
Differential Revision: D4751643
Pulled By: siying
fbshipit-source-id: ab14540
Summary:
PinnableSlice
Summary:
Currently the point lookup values are copied to a string provided by the
user. This incures an extra memcpy cost. This patch allows doing point lookup
via a PinnableSlice which pins the source memory location (instead of
copying their content) and releases them after the content is consumed
by the user. The old API of Get(string) is translated to the new API
underneath.
Here is the summary for improvements:
value 100 byte: 1.8% regular, 1.2% merge values
value 1k byte: 11.5% regular, 7.5% merge values
value 10k byte: 26% regular, 29.9% merge values
The improvement for merge could be more if we extend this approach to
pin the merge output and delay the full merge operation until the user
actually needs it. We have put that for future work.
PS:
Sometimes we observe a small decrease in performance when switching from
t5452014 to this patch but with the old Get(string) API. The d
Closes https://github.com/facebook/rocksdb/pull/1756
Differential Revision: D4391738
Pulled By: maysamyabandeh
fbshipit-source-id: 6f3edd3
Summary:
This option is needed to be enabled for Direct IO
and I cannot think of a reason where we need to disable it
remove it and default it to true
Closes https://github.com/facebook/rocksdb/pull/1944
Differential Revision: D4641088
Pulled By: IslamAbdelRahman
fbshipit-source-id: d7085b9
Summary:
The default behavior was too weird because, previously, we got the L0 file size limit (64MB) from Options default and L1+ file size limit (2MB) from the hardcoded value. We should get both from Options default.
Closes https://github.com/facebook/rocksdb/pull/1943
Differential Revision: D4640301
Pulled By: ajkr
fbshipit-source-id: fd8c0fd
Summary:
Remove disableDataSync, and another similarly named disable_data_sync options.
This is being done to simplify options, and also because the performance gains of this feature can be achieved by other methods.
Closes https://github.com/facebook/rocksdb/pull/1859
Differential Revision: D4541292
Pulled By: sagar0
fbshipit-source-id: 5b3a6ca
Summary:
I want to be able to, e.g., DECLARE_string(statistics_string); in my application such that I can override the default value of statistics_string. For this to work, we need to remove the unnamed namespace containing all the flags, and make sure all variables/functions covered by that namespace are static.
Replaces #1828 due to internal tool issues.
Closes https://github.com/facebook/rocksdb/pull/1844
Differential Revision: D4515124
Pulled By: ajkr
fbshipit-source-id: 23b695e
Summary:
introduce new methods into a public threadpool interface,
- allow submission of std::functions as they allow greater flexibility.
- add Joining methods to the implementation to join scheduled and submitted jobs with
an option to cancel jobs that did not start executing.
- Remove ugly `#ifdefs` between pthread and std implementation, make it uniform.
- introduce pimpl for a drop in replacement of the implementation
- Introduce rocksdb::port::Thread typedef which is a replacement for std::thread. On Posix Thread defaults as before std::thread.
- Implement WindowsThread that allocates memory in a more controllable manner than windows std::thread with a replaceable implementation.
- should be no functionality changes.
Closes https://github.com/facebook/rocksdb/pull/1823
Differential Revision: D4492902
Pulled By: siying
fbshipit-source-id: c74cb11
Summary:
Added -statistics_string to deserialize a Statistics object using the factory functions registered by applications.
Closes https://github.com/facebook/rocksdb/pull/1812
Differential Revision: D4469811
Pulled By: ajkr
fbshipit-source-id: 2d80862
Summary:
The Env registration framework supports registering client Envs and selecting which one to instantiate according to a text field. This enabled things like adding the -env_uri argument to db_bench, so the same binary could be reused with different Envs just by changing CLI config.
Now this problem has come up again in a non-Env context, as I want to instantiate a client Statistics implementation from db_bench, which is configured entirely via text parameters. Also, in the future we may wish to use it for deserializing client objects when loading OPTIONS file.
This diff generalizes the Env registration logic to work with arbitrary types.
- Generalized registration and instantiation code by templating them
- The entire implementation is in a header file as that's Google style guide's recommendation for template definitions
- Pattern match with std::regex_match rather than checking prefix, which was the previous behavior
- Rename functions/files to be non-Env-specific
Closes https://github.com/facebook/rocksdb/pull/1776
Differential Revision: D4421933
Pulled By: ajkr
fbshipit-source-id: 34647d1
Summary:
Currently the point lookup values are copied to a string provided by the user.
This incures an extra memcpy cost. This patch allows doing point lookup
via a PinnableSlice which pins the source memory location (instead of
copying their content) and releases them after the content is consumed
by the user. The old API of Get(string) is translated to the new API
underneath.
Here is the summary for improvements:
1. value 100 byte: 1.8% regular, 1.2% merge values
2. value 1k byte: 11.5% regular, 7.5% merge values
3. value 10k byte: 26% regular, 29.9% merge values
The improvement for merge could be more if we extend this approach to
pin the merge output and delay the full merge operation until the user
actually needs it. We have put that for future work.
PS:
Sometimes we observe a small decrease in performance when switching from
t5452014 to this patch but with the old Get(string) API. The difference
is a little and could be noise. More importantly it is safely
cancelled
Closes https://github.com/facebook/rocksdb/pull/1732
Differential Revision: D4374613
Pulled By: maysamyabandeh
fbshipit-source-id: a077f1a
Summary:
?tion
Add flags in db_bench to test with block cache mid-point insertion.
Also update sst_dump to dump total block sizes of each type. I find it
useful to look at these test db stats and I don't know if we have them
elsewhere.
Closes https://github.com/facebook/rocksdb/pull/1706
Differential Revision: D4355812
Pulled By: yiwu-arbug
fbshipit-source-id: 3e4a348
Summary:
Add the parameter in db_bench to help users to measure latency histogram with constant read rate.
Closes https://github.com/facebook/rocksdb/pull/1683
Differential Revision: D4341387
Pulled By: siying
fbshipit-source-id: 1b4b276
Summary:
The info log file ("LOG") is stored in the db directory by default. When the db is on a distributed env, this is unnecessarily slow. So, I added an option to db_bench to just print the info log messages to stderr.
Closes https://github.com/facebook/rocksdb/pull/1641
Differential Revision: D4309348
Pulled By: ajkr
fbshipit-source-id: 1e6f851
Summary:
When enabled, this option replaces range tombstones with a sequence of
point tombstones covering the same range. This can be used to A/B test perf of
range tombstones vs sequential point tombstones, and help us find the cross-over
point, i.e., the size of the range above which range tombstones outperform point
tombstones.
Closes https://github.com/facebook/rocksdb/pull/1594
Differential Revision: D4246312
Pulled By: ajkr
fbshipit-source-id: 3b00b23
Summary:
Reduce number of comparisons in heap by caching which child node in the first level is smallest (left_child or right_child)
So next time we can compare directly against the smallest child
I see that the total number of calls to comparator drops significantly when using this optimization
Before caching (~2mil key comparison for iterating the DB)
```
$ DEBUG_LEVEL=0 make db_bench -j64 && ./db_bench --benchmarks="readseq" --db="/dev/shm/heap_opt" --use_existing_db --disable_auto_compactions --cache_size=1000000000 --perf_level=2
readseq : 0.338 micros/op 2959201 ops/sec; 327.4 MB/s user_key_comparison_count = 2000008
```
After caching (~1mil key comparison for iterating the DB)
```
$ DEBUG_LEVEL=0 make db_bench -j64 && ./db_bench --benchmarks="readseq" --db="/dev/shm/heap_opt" --use_existing_db --disable_auto_compactions --cache_size=1000000000 --perf_level=2
readseq : 0.309 micros/op 3236801 ops/sec; 358.1 MB/s user_key_comparison_count = 1000011
```
It also improves
Closes https://github.com/facebook/rocksdb/pull/1600
Differential Revision: D4256027
Pulled By: IslamAbdelRahman
fbshipit-source-id: 76fcc66
Summary:
Now that we have userspace persisted cache, we don't need flashcache anymore.
Closes https://github.com/facebook/rocksdb/pull/1588
Differential Revision: D4245114
Pulled By: igorcanadi
fbshipit-source-id: e2c1c72
Summary:
Added a few options to configure when to add range tombstones during
any benchmark involving writes.
Closes https://github.com/facebook/rocksdb/pull/1522
Differential Revision: D4187388
Pulled By: ajkr
fbshipit-source-id: 2c8a473
Summary:
Fix the bug that --dump_malloc_stats is set before opening the DB.
Closes https://github.com/facebook/rocksdb/pull/1447
Differential Revision: D4106001
Pulled By: siying
fbshipit-source-id: 4e746da
Summary:
ZSTD 1.0.0 is coming. We can finally add a support of ZSTD without worrying about compatibility.
Still keep ZSTDNotFinal for compatibility reason.
Test Plan: Run all tests. Run db_bench with ZSTD version with RocksDB built with ZSTD 1.0 and older.
Reviewers: andrewkr, IslamAbdelRahman
Reviewed By: IslamAbdelRahman
Subscribers: cyan, igor, IslamAbdelRahman, leveldb, andrewkr, dhruba
Differential Revision: https://reviews.facebook.net/D63141
Summary: Fix using `arg[i].thread` after deleting it
Test Plan: run clang_analyze
Subscribers: andrewkr, dhruba
Differential Revision: https://reviews.facebook.net/D63171
Summary: To reduce number of options, merge source_compaction_factor, max_grandparent_overlap_bytes and expanded_compaction_factor into max_compaction_bytes.
Test Plan: Add two new unit tests. Run all existing tests, including jtest.
Reviewers: yhchiang, igor, IslamAbdelRahman
Reviewed By: IslamAbdelRahman
Subscribers: leveldb, andrewkr, dhruba
Differential Revision: https://reviews.facebook.net/D59829
Summary:
Add ReadOptions::read_amp_bytes_per_bit option which allow us to create a bitmap for every data block we read
the bitmap will contain (block_size / read_amp_bytes_per_bit) bits.
We will use this bitmap to mark which bytes have been used of the block so we can calculate the read amplification
Test Plan: added new tests
Reviewers: andrewkr, yhchiang, sdong
Reviewed By: sdong
Subscribers: yiwu, leveldb, march, andrewkr, dhruba
Differential Revision: https://reviews.facebook.net/D58707
Summary:
Clock-based cache implemenetation aim to have better concurreny than
default LRU cache. See inline comments for implementation details.
Test Plan:
Update cache_test to run on both LRUCache and ClockCache. Adding some
new tests to catch some of the bugs that I fixed while implementing the
cache.
Reviewers: kradhakrishnan, sdong
Reviewed By: sdong
Subscribers: andrewkr, dhruba, leveldb
Differential Revision: https://reviews.facebook.net/D61647
Summary:
This is a proof of concept of a RocksDB blob log file. The actual value of the Put() is appended to a blob log using normal data block format, and the handle of the block is written as the value of the key in RocksDB.
The prototype only supports Put() and Get(). It doesn't support DB restart, garbage collection, Write() call, iterator, snapshots, etc.
Test Plan: Add unit tests.
Reviewers: arahut
Reviewed By: arahut
Subscribers: kradhakrishnan, leveldb, andrewkr, dhruba
Differential Revision: https://reviews.facebook.net/D61485
Summary: As title.
Test Plan: Run the benchmark with and without the parameter.
Reviewers: yiwu, andrewkr, lightmark, IslamAbdelRahman
Reviewed By: IslamAbdelRahman
Subscribers: leveldb, andrewkr, dhruba
Differential Revision: https://reviews.facebook.net/D61491
Summary: Add a benchmark to `db_bench`. In this benchmark, a write thread will populate time series data in the format of 'id | timestamp', and multiple read threads will randomly retrieve all data from one id at a time.
Test Plan: Run the benchmark: `num=134217728;bpl=536870912;mb=67108864;overlap=10;mcz=2;del=300000000;levels=6;ctrig=4;delay=8;stop=12;wbn=3;mbc=20;wbs=134217728;dds=0;sync=0;t=32;vs=800;bs=4096;cs=17179869184;of=500000;wps=0;si=10000000; kir=100000; dir=/data/users/jhli/test/; ./db_bench --benchmarks=timeseries --disable_seek_compaction=1 --mmap_read=0 --statistics=1 --histogram=1 --num=$num --threads=$t --value_size=$vs --block_size=$bs --cache_size=$cs --bloom_bits=10 --cache_numshardbits=6 --open_files=$of --verify_checksum=1 --db=$dir --sync=$sync --disable_wal=0 --compression_type=none --stats_interval=$si --compression_ratio=1 --disable_data_sync=$dds --write_buffer_size=$wbs --target_file_size_base=$mb --max_write_buffer_number=$wbn --max_background_compactions=$mbc --level0_file_num_compaction_trigger=$ctrig --level0_slowdown_writes_trigger=$delay --level0_stop_writes_trigger=$stop --num_levels=$levels --delete_obsolete_files_period_micros=$del --min_level_to_compress=$mcz --max_grandparent_overlap_factor=$overlap --stats_per_interval=1 --max_bytes_for_level_base=$bpl --use_existing_db=0 --key_id_range=$kir`
Reviewers: andrewkr, sdong
Reviewed By: sdong
Subscribers: lgalanis, andrewkr, dhruba, leveldb
Differential Revision: https://reviews.facebook.net/D60651
Summary: Extend the option memtable_prefix_bloom_huge_page_tlb_size from just putting memtable bloom filter to huge page to memtable itself too.
Test Plan: Run all existing tests.
Reviewers: IslamAbdelRahman, yhchiang, andrewkr
Reviewed By: andrewkr
Subscribers: leveldb, andrewkr, dhruba
Differential Revision: https://reviews.facebook.net/D60513
* Fixed Windows build error in CMakeLists.txt and perf_level error in db_bench_tool.cc
* Changed hard-coded perf levels in db_bench_tool.cc to enum values from perf_level.h
* Replaced remaining FLAGS_perf_level > 0
Summary:
This diff makes the following improvement in regression_test.sh:
1. Add NUM_OPS and DELETE_TEST_PATH to regression_test.sh:
* NUM_OPS: The number of operations that will be issued
in EACH thread.
Default: $NUM_KEYS / $NUM_THREADS
* DELETE_TEST_PATH: If true, then the test directory
will be deleted after the script ends.
Default: 0
2. Add more information in SUMMARY.csv
3. Fix a bug in regression_test.sh where each thread in fillseq will all issue $NUM_KEYS writes.
4. Add --deletes in db_bench, which allows us to control the number of deletes instead of must using FLAGS_num.
Test Plan: run regression test with and without DELETE_TEST_PATH and NUM_OPS
Reviewers: yiwu, sdong, IslamAbdelRahman, gunnarku
Reviewed By: gunnarku
Subscribers: andrewkr, dhruba, leveldb
Differential Revision: https://reviews.facebook.net/D60039
Summary: filter_deltes is not a frequently used feature. Remove it.
Test Plan: Run all test suites.
Reviewers: igor, yhchiang, IslamAbdelRahman
Reviewed By: IslamAbdelRahman
Subscribers: leveldb, andrewkr, dhruba
Differential Revision: https://reviews.facebook.net/D59427
Summary:
memtable_prefix_bloom_probes is not a critical option. Remove it to reduce number of options.
It's easier for users to make mistakes with memtable_prefix_bloom_bits, turn it to memtable_prefix_bloom_bits_ratio
Test Plan: Run all existing tests
Reviewers: yhchiang, igor, IslamAbdelRahman
Reviewed By: IslamAbdelRahman
Subscribers: gunnarku, yoshinorim, MarkCallaghan, leveldb, andrewkr, dhruba
Differential Revision: https://reviews.facebook.net/D59199
Summary:
Added an option, --env_uri. When provided, it is used as an argument to
NewEnvFromUri(), which instantiates an Env based on it.
Test Plan:
built a simple binary that registers ChrootEnv for prefix "/", then
ran:
$ ./tmp --env_uri /tmp/ --db /abcde
/tmp/ is the chroot directory and /abcde is the db_name. Then I verified
db_bench uses /tmp/abcde
Reviewers: sdong, kradhakrishnan, lightmark
Reviewed By: lightmark
Subscribers: andrewkr, dhruba, leveldb
Differential Revision: https://reviews.facebook.net/D59325
Summary:
This patch allows db_bench to initialize it's RocksDB Options via a
options file, specified by the --options_file flag. Note that if
--options_file flag is set, then it has higher priority than the
command-line argument.
Test Plan: db_bench_tool_test
Reviewers: sdong, IslamAbdelRahman, kradhakrishnan, yiwu, andrewkr
Reviewed By: andrewkr
Subscribers: andrewkr, dhruba, leveldb
Differential Revision: https://reviews.facebook.net/D58533
Summary:
Added a new abstraction to cache page to RocksDB designed for the read
cache use.
RocksDB current block cache is more of an object cache. For the persistent read cache
project, what we need is a page cache equivalent. This changes adds a cache
abstraction to RocksDB to cache pages called PersistentCache. PersistentCache can cache
uncompressed pages or raw pages (content as in filesystem). The user can
choose to operate PersistentCache either in COMPRESSED or UNCOMPRESSED mode.
Blame Rev:
Test Plan: Run unit tests
Reviewers: sdong
Subscribers: andrewkr, dhruba, leveldb
Differential Revision: https://reviews.facebook.net/D55707
Summary:
This diff includes an initial script running a set of benchmarks for
regression test. The script does the following things:
checkout the specified rocksdb commit (or origin/master as default)
make clean && DEBUG_LEVEL=0 make db_bench
setup test directories
run set of benchmarks and store results
Currently, the script will run couple benchmarks, store all the benchmark
output, extract micros per op and percentile information for each benchmark
and store them in a single SUMMARY.csv file. The SUMMARY.csv will make the
follow-up regression detection easier.
In addition, the current script only takes env arguments to set important
attributes of db_bench. Will follow-up with a patch that allows db_bench
to construct options from an options file.
Test Plan:
NUM_KEYS=100 ./tools/regression_test.sh
Sample SUMMARY.csv file:
commit id, benchmark, ms-per-op, p50, p75, p99, p99.9, p99.99
7e23ddf575890510e7d2fc7a79b31a1bbf317917, fillseq, 15.28, 54.66, 77.14, 5000.00, 17900.00, 18483.00
7e23ddf575890510e7d2fc7a79b31a1bbf317917, overwrite, 13.54, 57.69, 86.39, 3000.00, 15600.00, 17013.00
7e23ddf575890510e7d2fc7a79b31a1bbf317917, readrandom, 1.04, 0.80, 1.67, 293.33, 395.00, 504.00
7e23ddf575890510e7d2fc7a79b31a1bbf317917, readwhilewriting, 2.75, 1.01, 1.87, 200.00, 460.00, 485.00
7e23ddf575890510e7d2fc7a79b31a1bbf317917, deleterandom, 3.64, 48.12, 70.09, 200.00, 336.67, 347.00
7e23ddf575890510e7d2fc7a79b31a1bbf317917, seekrandom, 24.31, 391.87, 513.69, 872.73, 990.00, 1048.00
7e23ddf575890510e7d2fc7a79b31a1bbf317917, seekrandomwhilewriting, 14.02, 185.14, 294.15, 700.00, 1440.00, 1527.00
Reviewers: sdong, IslamAbdelRahman, kradhakrishnan, yiwu, andrewkr, gunnarku
Reviewed By: gunnarku
Subscribers: gunnarku, MarkCallaghan, andrewkr, dhruba, leveldb
Differential Revision: https://reviews.facebook.net/D57597
Summary:
Introduced option to dump malloc statistics using new option flag.
Added new command line option to db_bench tool to enable this
funtionality.
Also extended build to support environments with/without jemalloc.
Test Plan:
1) Build rocksdb using `make` command. Launch the following command
`./db_bench --benchmarks=fillrandom --dump_malloc_stats=true
--num=10000000` end verified that jemalloc dump is present in LOG file.
2) Build rocksdb using `DISABLE_JEMALLOC=1 make db_bench -j32` and ran
the same db_bench tool and found the following message in LOG file:
"Please compile with jemalloc to enable malloc dump".
3) Also built rocksdb using `make` command on MacOS to verify behavior
in non-FB environment.
Also to debug build configuration change temporary changed
AM_DEFAULT_VERBOSITY = 1 in Makefile to see compiler and build
tools output. For case 1) -DROCKSDB_JEMALLOC was present in compiler
command line. For both 2) and 3) this flag was not present.
Reviewers: sdong
Reviewed By: sdong
Subscribers: andrewkr, dhruba
Differential Revision: https://reviews.facebook.net/D57321
Comparable with Snappy on comp ratio.
Implemented using Windows API, does not require external package.
Avaiable since Windows 8 and server 2012.
Use -DXPRESS=1 with CMake to enable.
Summary: It is useful to print out IO stats in flush jobs too. Extend options.compaction_measure_io_stats to flush jobs and raname it.
Test Plan: Try db_bench and see the stats are printed out.
Reviewers: yhchiang
Reviewed By: yhchiang
Subscribers: kradhakrishnan, yiwu, IslamAbdelRahman, leveldb, andrewkr, dhruba
Differential Revision: https://reviews.facebook.net/D56769
* Update db_bench_tool.cc
I fixed the wrong letters, LevelDB -> rocksDB, because I thought of LevelDB as the wrong presentation.
the following show my fix :
fprintf(stderr, "LevelDB: version %d.%d\n",
kMajorVersion, kMinorVersion);
----------------->
fprintf(stderr, "rocksDB: version %d.%d\n",
kMajorVersion, kMinorVersion);
* Update db_bench_tool.cc
* Update db_bench_tool.cc
Summary:
When a block based table file is opened, if prefetch_index_and_filter is true, it will prefetch the index and filter blocks, putting them into the block cache.
What this feature adds: when a L0 block based table file is opened, if pin_l0_filter_and_index_blocks_in_cache is true in the options (and prefetch_index_and_filter is true), then the filter and index blocks aren't released back to the block cache at the end of BlockBasedTableReader::Open(). Instead the table reader takes ownership of them, hence pinning them, ie. the LRU cache will never push them out. Meanwhile in the table reader, further accesses will not hit the block cache, thus avoiding lock contention.
Test Plan:
'export TEST_TMPDIR=/dev/shm/ && DISABLE_JEMALLOC=1 OPT=-g make all valgrind_check -j32' is OK.
I didn't run the Java tests, I don't have Java set up on my devserver.
Reviewers: sdong
Reviewed By: sdong
Subscribers: andrewkr, dhruba
Differential Revision: https://reviews.facebook.net/D56133
Summary:
When a block based table file is opened, if prefetch_index_and_filter is true, it will prefetch the index and filter blocks, putting them into the block cache.
What this feature adds: when a L0 block based table file is opened, if pin_l0_filter_and_index_blocks_in_cache is true in the options (and prefetch_index_and_filter is true), then the filter and index blocks aren't released back to the block cache at the end of BlockBasedTableReader::Open(). Instead the table reader takes ownership of them, hence pinning them, ie. the LRU cache will never push them out. Meanwhile in the table reader, further accesses will not hit the block cache, thus avoiding lock contention.
When the table reader is destroyed, it releases the pinned blocks (if there were any). This has to happen before the cache is destroyed, so I had to introduce a TableReader::Close(), to guarantee the order of destruction.
Test Plan:
Added two unit tests for this. Existing unit tests run fine (default is pin_l0_filter_and_index_blocks_in_cache=false).
DISABLE_JEMALLOC=1 OPT=-g make all valgrind_check -j32
Mac: OK.
Linux: with D55287 patched in it's OK.
Reviewers: sdong
Reviewed By: sdong
Subscribers: andrewkr, leveldb, dhruba
Differential Revision: https://reviews.facebook.net/D54801
Summary: Refactored db_bench transaction stress tests so that they can be called from unit tests as well.
Test Plan: run new unit test as well as db_bench
Reviewers: yhchiang, IslamAbdelRahman, sdong
Reviewed By: IslamAbdelRahman
Subscribers: andrewkr, dhruba, leveldb
Differential Revision: https://reviews.facebook.net/D55203
Test Plan:
Built and ran with gflags:
% ./db_bench
LevelDB: version 4.5
Date: Tue Feb 16 12:04:23 2016
CPU: 40 * Intel(R) Xeon(R) CPU E5-2660 v2 @ 2.20GHz
...
And without gflags:
% ./db_bench
Please install gflags to run rocksdb tools
%
Reviewers: sdong, igor
Reviewed By: igor
Subscribers: igor, dhruba
Differential Revision: https://reviews.facebook.net/D54243
