Commit Graph

482 Commits

Author SHA1 Message Date
Siying Dong
d2dce5611a Move some files under util/ to separate dirs
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
2017-04-05 19:09:16 -07:00
Aaron Gao
af256eb2b7 build db every monday
Summary:
Rebuilding regression db at the first run every monday.
Closes https://github.com/facebook/rocksdb/pull/2093

Differential Revision: D4836961

Pulled By: lightmark

fbshipit-source-id: 22d6c25
2017-04-05 12:24:21 -07:00
Siying Dong
6ef8c620d3 Move auto_roll_logger and filename out of db/
Summary:
It is confusing to have auto_roll_logger to stay under db/, which has nothing to do with database. Move filename together as it is a dependency.
Closes https://github.com/facebook/rocksdb/pull/2080

Differential Revision: D4821141

Pulled By: siying

fbshipit-source-id: ca7d768
2017-04-03 18:39:14 -07:00
Aaron Gao
0537f515c2 fix run_remote with strong quoting
Summary:
add \' pair to avoid bash expanding before run remotely
Closes https://github.com/facebook/rocksdb/pull/2079

Differential Revision: D4821342

Pulled By: lightmark

fbshipit-source-id: 418ba41
2017-04-03 13:09:12 -07:00
Aaron Gao
bd7d13835e test remote instead run remote in regression test
Summary:
avoid exit when $? != 0
Closes https://github.com/facebook/rocksdb/pull/2076

Differential Revision: D4815655

Pulled By: lightmark

fbshipit-source-id: 829299e
2017-03-31 18:54:11 -07:00
Aaron Gao
c81a805fe6 test db existence on the remote host
Summary:
Fix the bug that previous test existence locally
Closes https://github.com/facebook/rocksdb/pull/2074

Differential Revision: D4813631

Pulled By: lightmark

fbshipit-source-id: eceb0d9
2017-03-31 14:54:17 -07:00
Aaron Gao
5fc1e6765a add -rf when remove db in regression test
Summary:
force remove db dir when rebuilding
Closes https://github.com/facebook/rocksdb/pull/2067

Differential Revision: D4811926

Pulled By: lightmark

fbshipit-source-id: ab068a2
2017-03-31 12:10:23 -07:00
Aaron Gao
da175f7ecc exit with code 2 when there is already a db_bench running in regression test
Summary: Closes https://github.com/facebook/rocksdb/pull/2063

Differential Revision: D4805507

Pulled By: lightmark

fbshipit-source-id: 59ccb18
2017-03-30 14:09:11 -07:00
Aaron Gao
f3607640a6 add ldb build to regression test
Summary:
add ldb to regression test in order to enable reuse db by creating checkpoint
Closes https://github.com/facebook/rocksdb/pull/2030

Differential Revision: D4800549

Pulled By: lightmark

fbshipit-source-id: d3a7325
2017-03-29 18:24:11 -07:00
Yi Wu
41fe9ad75b Hide usage of compaction_options_fifo from lite build
Summary:
...to fix lite build error.
Closes https://github.com/facebook/rocksdb/pull/2046

Differential Revision: D4785910

Pulled By: yiwu-arbug

fbshipit-source-id: b591f27
2017-03-28 13:39:13 -07:00
Shu Zhang
8dee8cad9e Enable fifo compaction benchmark to db_bench
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
2017-03-24 17:09:15 -07:00
Siying Dong
e474df9470 db_bench: not need to check mmap for PlainTable
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
2017-03-22 11:09:13 -07:00
Siying Dong
17866ecc3a Allow Users to change customized ldb tools' header in help printing
Summary: Closes https://github.com/facebook/rocksdb/pull/2018

Differential Revision: D4748448

Pulled By: siying

fbshipit-source-id: a54c2f9
2017-03-21 17:39:12 -07:00
Leonidas Galanis
a2a883318b remove deleted option from benchmark.sh
Summary:
Removed max_grandparent_overlap_factor from benchmark.sh since it is not a valid option anymore.
Closes https://github.com/facebook/rocksdb/pull/2015

Differential Revision: D4748229

Pulled By: lgalanis

fbshipit-source-id: c3869ea
2017-03-21 12:54:13 -07:00
Aaron Gao
78cb195595 add checkpoint to ldb
Summary: Closes https://github.com/facebook/rocksdb/pull/2017

Differential Revision: D4747656

Pulled By: lightmark

fbshipit-source-id: c52f160
2017-03-21 11:54:11 -07:00
Aaron Gao
93c68b642e change regression bash file with debug mode
Summary:
add debug mode for better debugging
refactor some regex
change micros/op to ops/sec
Closes https://github.com/facebook/rocksdb/pull/1999

Differential Revision: D4742806

Pulled By: lightmark

fbshipit-source-id: 0fe3ae6
2017-03-20 17:39:17 -07:00
Andrew Kryczka
e66221add4 fix db_bench rate limiter callsites
Summary:
pass nullptr as stats object for db_bench-specific rate limiters since its stats are intended to capture background write activity only.
Closes https://github.com/facebook/rocksdb/pull/1997

Differential Revision: D4726806

Pulled By: ajkr

fbshipit-source-id: 8e4b225
2017-03-16 17:54:12 -07:00
Maysam Yabandeh
11526252cc Pinnableslice (2nd attempt)
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
2017-03-13 11:54:10 -07:00
Reid Horuff
ebd5639b6d Add ability to search for key prefix in sst_dump tool
Summary:
Add the flag --prefix to the sst_dump tool
This flag is similar to, and exclusive from, the --from flag.

--prefix=0x00FF will return all rows prefixed with 0x00FF.
The --to flag may also be specified and will work as expected.

These changes were used to help in debugging the power cycle corruption issue and theses changes were tested by scanning through a udb.
Closes https://github.com/facebook/rocksdb/pull/1984

Differential Revision: D4691814

Pulled By: reidHoruff

fbshipit-source-id: 027f261
2017-03-13 10:39:12 -07:00
Maysam Yabandeh
5dae019477 Revert "Report cpu usage using time command"
Summary:
This reverts commit d43adf21bb.

The patch has caused problems in regression tests. Will revert it for now until we figure how to debug the problems regression tests.
Closes https://github.com/facebook/rocksdb/pull/1975

Differential Revision: D4682880

Pulled By: maysamyabandeh

fbshipit-source-id: 84df83a
2017-03-09 11:09:13 -08:00
Maysam Yabandeh
d43adf21bb Report cpu usage using time command
Summary:
It augments the regression benchmarks with a time command, parses the output, and print them to the SUMMARY.csv file.

I tested a variation of the script locally. Any idea how to do run a test that also involves writing to scuba tables?
Closes https://github.com/facebook/rocksdb/pull/1967

Differential Revision: D4679470

Pulled By: maysamyabandeh

fbshipit-source-id: 44dac30
2017-03-08 17:54:11 -08:00
Andrew Kryczka
2a5daa06f0 Add stderr log level for ldb backup commands
Summary:
Also extracted the common logic into a base class, BackupableCommand.
Closes https://github.com/facebook/rocksdb/pull/1939

Differential Revision: D4630121

Pulled By: ajkr

fbshipit-source-id: 04bb067
2017-03-03 13:24:15 -08:00
Islam AbdelRahman
f89b3893c0 Remove skip_table_builder_flush and default it to true
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
2017-03-02 16:54:10 -08:00
Andrew Kryczka
cc253982dd Use more default options in db_bench
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
2017-03-02 10:54:11 -08:00
Islam AbdelRahman
be3e5568be Fix unaligned reads in read cache
Summary:
- Fix unaligned reads in read cache by using RandomAccessFileReader
- Allow read cache flags in db_bench
Closes https://github.com/facebook/rocksdb/pull/1916

Differential Revision: D4610885

Pulled By: IslamAbdelRahman

fbshipit-source-id: 2aa1dc8
2017-02-27 13:09:12 -08:00
Aaron Gao
e7d902e693 add direct_io and compaction_readahead_size in db_stress
Summary:
add direct_io and compaction_readahead_size in db_stress
test direct_io under db_stress with compaction_readahead_size enabled to capture bugs found in production.
`./db_stress --allow_concurrent_memtable_write=0 --use_direct_reads --use_direct_writes --compaction_readahead_size=4096`
Closes https://github.com/facebook/rocksdb/pull/1906

Differential Revision: D4604514

Pulled By: IslamAbdelRahman

fbshipit-source-id: ebbf0ee
2017-02-23 11:39:14 -08:00
Sagar Vemuri
eb912a927e Remove disableDataSync option
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
2017-02-13 11:09:13 -08:00
Andrew Kryczka
3b4ac8076b Clarify ldb column family argument
Summary:
move the argument description to the right section, make it clearer that the '=' sign is required, and use it in one subcommand where it seemed forgotten before.
Closes https://github.com/facebook/rocksdb/pull/1840

Differential Revision: D4515096

Pulled By: ajkr

fbshipit-source-id: 7b5b1c1
2017-02-07 11:54:10 -08:00
Andrew Kryczka
d70ce7ee0b Move db_bench flags out of unnamed namespace
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
2017-02-07 11:39:12 -08:00
Dmitri Smirnov
0a4cdde50a Windows thread
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
2017-02-06 14:54:18 -08:00
Andrew Kryczka
37d4a79e99 Deserialize custom Statistics object in db_bench
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
2017-01-26 15:24:16 -08:00
Andrew Kryczka
17c1180603 Generalize Env registration framework
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
2017-01-25 16:09:14 -08:00
Maysam Yabandeh
d0ba8ec8f9 Revert "PinnableSlice"
Summary:
This reverts commit 54d94e9c2c.

The pull request was landed by mistake.
Closes https://github.com/facebook/rocksdb/pull/1755

Differential Revision: D4391678

Pulled By: maysamyabandeh

fbshipit-source-id: 36d5149
2017-01-08 14:24:12 -08:00
Maysam Yabandeh
54d94e9c2c 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:
 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
2017-01-08 13:54:13 -08:00
Dmitri Smirnov
e04480faed Fix MS warnings. Use ROCKSDB_Prsz for size_t.
Summary: Closes https://github.com/facebook/rocksdb/pull/1737

Differential Revision: D4378852

Pulled By: yiwu-arbug

fbshipit-source-id: ba8b02d
2017-01-06 16:24:14 -08:00
Yi Wu
640d724808 Update db_bench and sst_dump to test with block cache mid-point inser?
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
2017-01-03 18:39:14 -08:00
Aaron Gao
972f96b3fb direct io write support
Summary:
rocksdb direct io support

```
[gzh@dev11575.prn2 ~/rocksdb] ./db_bench -benchmarks=fillseq --num=1000000
Initializing RocksDB Options from the specified file
Initializing RocksDB Options from command-line flags
RocksDB:    version 5.0
Date:       Wed Nov 23 13:17:43 2016
CPU:        40 * Intel(R) Xeon(R) CPU E5-2660 v2 @ 2.20GHz
CPUCache:   25600 KB
Keys:       16 bytes each
Values:     100 bytes each (50 bytes after compression)
Entries:    1000000
Prefix:    0 bytes
Keys per prefix:    0
RawSize:    110.6 MB (estimated)
FileSize:   62.9 MB (estimated)
Write rate: 0 bytes/second
Compression: Snappy
Memtablerep: skip_list
Perf Level: 1
WARNING: Assertions are enabled; benchmarks unnecessarily slow
------------------------------------------------
Initializing RocksDB Options from the specified file
Initializing RocksDB Options from command-line flags
DB path: [/tmp/rocksdbtest-112628/dbbench]
fillseq      :       4.393 micros/op 227639 ops/sec;   25.2 MB/s

[gzh@dev11575.prn2 ~/roc
Closes https://github.com/facebook/rocksdb/pull/1564

Differential Revision: D4241093

Pulled By: lightmark

fbshipit-source-id: 98c29e3
2016-12-22 13:09:19 -08:00
Siying Dong
7bd725e962 db_bench: introduce --benchmark_read_rate_limit
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
2016-12-19 12:39:11 -08:00
Daniel Black
816c1e30ca gcc-7 requires include <functional> for std::function
Summary:
Fixes compile error:

In file included from ./util/statistics.h:17:0,
                 from ./util/stop_watch.h:8,
                 from ./util/perf_step_timer.h:9,
                 from ./util/iostats_context_imp.h:8,
                 from ./util/posix_logger.h:27,
                 from ./port/util_logger.h:18,
                 from ./db/auto_roll_logger.h:15,
                 from db/auto_roll_logger.cc:6:
./util/thread_local.h:65:16: error: 'function' in namespace 'std' does not name a template type
   typedef std::function<void(void*, void*)> FoldFunc;
Closes https://github.com/facebook/rocksdb/pull/1656

Differential Revision: D4318702

Pulled By: yiwu-arbug

fbshipit-source-id: 8c5d17a
2016-12-16 11:24:18 -08:00
Daniel Black
0ab6fc167f Gcc-7 buffer size insufficient
Summary:
Bunch of commits related to insufficient buffer size. Errors in individual commits.
Closes https://github.com/facebook/rocksdb/pull/1673

Differential Revision: D4332127

Pulled By: IslamAbdelRahman

fbshipit-source-id: 878f73c
2016-12-14 19:24:26 -08:00
Islam AbdelRahman
d71e728c7a Print user collected properties in sst_dump
Summary:
Include a dump of user_collected_properties in sst_dump
Closes https://github.com/facebook/rocksdb/pull/1668

Differential Revision: D4325078

Pulled By: IslamAbdelRahman

fbshipit-source-id: 226b6d6
2016-12-14 11:24:11 -08:00
Daniel Black
1f6f7e3e89 cast to signed char in ldb_cmd_test for ppc64le
Summary:
char is unsigned on power by default causing this test to fail with the FF case. ppc64 return 255 while x86 returned -1. Casting works on both platforms.
Closes https://github.com/facebook/rocksdb/pull/1500

Differential Revision: D4308775

Pulled By: yiwu-arbug

fbshipit-source-id: db3e6e0
2016-12-12 14:39:18 -08:00
Andrew Kryczka
dc64f46b1c Add db_bench option for stderr logging
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
2016-12-09 16:54:14 -08:00
Andrew Kryczka
5241e0dbfc fix db_bench argument type
Summary: Closes https://github.com/facebook/rocksdb/pull/1633

Differential Revision: D4298161

Pulled By: yiwu-arbug

fbshipit-source-id: 2c7af35
2016-12-08 11:09:14 -08:00
Andrew Kryczka
2c2ba68247 db_stress support for range deletions
Summary:
made db_stress capable of adding range deletions to its db and verifying their correctness. i'll make db_crashtest.py use this option later once the collapsing optimization (https://github.com/facebook/rocksdb/pull/1614) is committed because currently it slows down the test too much.
Closes https://github.com/facebook/rocksdb/pull/1625

Differential Revision: D4293939

Pulled By: ajkr

fbshipit-source-id: d3beb3a
2016-12-07 13:09:24 -08:00
Andrew Kryczka
fa50fffaf5 Option to expand range tombstones in db_bench
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
2016-12-06 18:09:14 -08:00
Yi Wu
56281f3a97 Add memtable_insert_with_hint_prefix_size option to db_bench
Summary:
Add memtable_insert_with_hint_prefix_size option to db_bench
Closes https://github.com/facebook/rocksdb/pull/1604

Differential Revision: D4260549

Pulled By: yiwu-arbug

fbshipit-source-id: cee5ef7
2016-12-01 16:54:16 -08:00
Islam AbdelRahman
4a21b1402c Cache heap::downheap() root comparison (optimize heap cmp call)
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
2016-12-01 13:39:14 -08:00
Igor Canadi
3f407b065c Kill flashcache code in RocksDB
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
2016-12-01 10:09:22 -08:00
Andrew Kryczka
fd43ee09da Range deletion microoptimizations
Summary:
- Made RangeDelAggregator's InternalKeyComparator member a reference-to-const so we don't need to copy-construct it. Also added InternalKeyComparator to ImmutableCFOptions so we don't need to construct one for each DBIter.
- Made MemTable::NewRangeTombstoneIterator and the table readers' NewRangeTombstoneIterator() functions return nullptr instead of NewEmptyInternalIterator to avoid the allocation. Updated callers accordingly.
Closes https://github.com/facebook/rocksdb/pull/1548

Differential Revision: D4208169

Pulled By: ajkr

fbshipit-source-id: 2fd65cf
2016-11-21 12:24:13 -08:00