Commit Graph

9429 Commits

Author SHA1 Message Date
heyongqiang
f1a7c735b5 fix complie error
Summary:

as subject

Test Plan:n/a
2012-11-05 10:30:19 -08:00
heyongqiang
d55c2ba305 Add a tool to change number of levels
Summary: as subject.

Test Plan: manually test it, will add a testcase

Reviewers: dhruba, MarkCallaghan

Differential Revision: https://reviews.facebook.net/D6345
2012-11-05 10:17:39 -08:00
Dhruba Borthakur
81f735d97c Merge branch 'master' into performance
Conflicts:
	db/db_impl.cc
	util/options.cc
2012-11-05 09:41:38 -08:00
Dhruba Borthakur
a1bd5b7752 Compilation problem introduced by previous
commit 854c66b089.

Summary:
Compilation problem introduced by previous
commit 854c66b089.

Test Plan:  make check
2012-11-04 22:04:14 -08:00
amayank
854c66b089 Make compression options configurable. These include window-bits, level and strategy for ZlibCompression
Summary: Leveldb currently uses windowBits=-14 while using zlib compression.(It was earlier 15). This makes the setting configurable. Related changes here: https://reviews.facebook.net/D6105

Test Plan: make all check

Reviewers: dhruba, MarkCallaghan, sheki, heyongqiang

Differential Revision: https://reviews.facebook.net/D6393
2012-11-02 11:26:39 -07:00
heyongqiang
3096fa7534 Add two more options: disable block cache and make table cache shard number configuable
Summary:

as subject

Test Plan:

run db_bench and db_test

Reviewers: dhruba

Reviewed By: dhruba

Differential Revision: https://reviews.facebook.net/D6111
2012-11-01 13:23:21 -07:00
Mark Callaghan
3e7e269292 Use timer to measure sleep rather than assume it is 1000 usecs
Summary:
This makes the stall timers in MakeRoomForWrite more accurate by timing
the sleeps. From looking at the logs the real sleep times are usually
about 2000 usecs each when SleepForMicros(1000) is called. The modified LOG messages are:
2012/10/29-12:06:33.271984 2b3cc872f700 delaying write 13 usecs for level0_slowdown_writes_trigger
2012/10/29-12:06:34.688939 2b3cc872f700 delaying write 1728 usecs for rate limits with max score 3.83

Task ID: #

Blame Rev:

Test Plan:
run db_bench, look at DB/LOG

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/D6297
2012-10-30 07:21:37 -07:00
heyongqiang
fb8d437325 fix test failure
Summary: as subject

Test Plan: db_test

Reviewers: dhruba, MarkCallaghan

Reviewed By: MarkCallaghan

Differential Revision: https://reviews.facebook.net/D6309
2012-10-29 18:55:52 -07:00
heyongqiang
925f60d39d add a test case to make sure chaning num_levels will fail Summary:
Summary: as subject

Test Plan: db_test

Reviewers: dhruba, MarkCallaghan

Reviewed By: MarkCallaghan

Differential Revision: https://reviews.facebook.net/D6303
2012-10-29 15:27:07 -07:00
Dhruba Borthakur
53e04311b1 Merge branch 'master' into performance
Conflicts:
	db/db_bench.cc
	util/options.cc
2012-10-29 14:18:00 -07:00
Dhruba Borthakur
321dfdc3ae Allow having different compression algorithms on different levels.
Summary:
The leveldb API is enhanced to support different compression algorithms at
different levels.

This adds the option min_level_to_compress to db_bench that specifies
the minimum level for which compression should be done when
compression is enabled. This can be used to disable compression for levels
0 and 1 which are likely to suffer from stalls because of the CPU load
for memtable flushes and (L0,L1) compaction.  Level 0 is special as it
gets frequent memtable flushes. Level 1 is special as it frequently
gets all:all file compactions between it and level 0. But all other levels
could be the same. For any level N where N > 1, the rate of sequential
IO for that level should be the same. The last level is the
exception because it might not be full and because files from it are
not read to compact with the next larger level.

The same amount of time will be spent doing compaction at any
level N excluding N=0, 1 or the last level. By this standard all
of those levels should use the same compression. The difference is that
the loss (using more disk space) from a faster compression algorithm
is less significant for N=2 than for N=3. So we might be willing to
trade disk space for faster write rates with no compression
for L0 and L1, snappy for L2, zlib for L3. Using a faster compression
algorithm for the mid levels also allows us to reclaim some cpu
without trading off much loss in disk space overhead.

Also note that little is to be gained by compressing levels 0 and 1. For
a 4-level tree they account for 10% of the data. For a 5-level tree they
account for 1% of the data.

With compression enabled:
* memtable flush rate is ~18MB/second
* (L0,L1) compaction rate is ~30MB/second

With compression enabled but min_level_to_compress=2
* memtable flush rate is ~320MB/second
* (L0,L1) compaction rate is ~560MB/second

This practicaly takes the same code from https://reviews.facebook.net/D6225
but makes the leveldb api more general purpose with a few additional
lines of code.

Test Plan: make check

Differential Revision: https://reviews.facebook.net/D6261
2012-10-29 11:48:09 -07:00
Mark Callaghan
acc8567b24 Add more rates to db_bench output
Summary:
Adds the "MB/sec in" and "MB/sec out" to this line:
Amplification: 1.7 rate, 0.01 GB in, 0.02 GB out, 8.24 MB/sec in, 13.75 MB/sec out

Changes all values to be reported per interval and since test start for this line:
... thread 0: (10000,60000) ops and (19155.6,27307.5) ops/second in (0.522041,2.197198) seconds

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/D6291
2012-10-29 11:30:07 -07:00
Dhruba Borthakur
de7689b1d7 Fix unit test failure caused by delaying deleting obsolete files.
Summary:
A previous commit 4c107587ed introduced
the idea that some version updates might not delete obsolete files.
This means that if a unit test blindly counts the number of files
in the db directory it might not represent the true state of the database.

Use GetLiveFiles() insteads to count the number of live files in the database.

Test Plan:
make check
2012-10-29 11:12:24 -07:00
Mark Callaghan
70c42bf05f Adds DB::GetNextCompaction and then uses that for rate limiting db_bench
Summary:
Adds a method that returns the score for the next level that most
needs compaction. That method is then used by db_bench to rate limit threads.
Threads are put to sleep at the end of each stats interval until the score
is less than the limit. The limit is set via the --rate_limit=$double option.
The specified value must be > 1.0. Also adds the option --stats_per_interval
to enable additional metrics reported every stats interval.

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/D6243
2012-10-29 10:17:43 -07:00
Kai Liu
8965c8d0b9 Add the missing util/auto_split_logger.h
Summary:

Test Plan:

Reviewers:

CC:

Task ID: 1803577

Blame Rev:
2012-10-26 15:23:50 -07:00
Kai Liu
d50f8eb603 Enable LevelDb to create a new log file if current log file is too large.
Summary: Enable LevelDb to create a new log file if current log file is too large.

Test Plan:
Write a script and manually check the generated info LOG.

Task ID: 1803577

Blame Rev:

Reviewers: dhruba, heyongqiang

Reviewed By: heyongqiang

CC: zshao

Differential Revision: https://reviews.facebook.net/D6003
2012-10-26 14:55:02 -07:00
Mark Callaghan
3a91b78b23 Keep build_detect_platform portable
Summary:
AFAIK proper /bin/sh does not support "+=". Note that only our
changes use "+=". The Google code does A="$A + $B" rather than A+=$B.

Task ID: #

Blame Rev:

Test Plan:
build

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/D6231
2012-10-26 14:20:04 -07:00
Mark Callaghan
65855dd8d4 Normalize compaction stats by time in compaction
Summary:
I used server uptime to compute per-level IO throughput rates. I
intended to use time spent doing compaction at that level. This fixes that.

Task ID: #

Blame Rev:

Test Plan:
run db_bench, look at results

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/D6237
2012-10-26 14:19:13 -07:00
Dhruba Borthakur
ea9e087851 Merge branch 'master' into performance
Conflicts:
	db/db_bench.cc
	db/db_impl.cc
	db/db_test.cc
2012-10-26 08:57:56 -07:00
Dhruba Borthakur
8eedf13a82 Fix unit test failure caused by delaying deleting obsolete files.
Summary:
A previous commit 4c107587ed introduced
the idea that some version updates might not delete obsolete files.
This means that if a unit test blindly counts the number of files
in the db directory it might not represent the true state of the database.

Use GetLiveFiles() insteads to count the number of live files in the database.

Test Plan: make check

Reviewers: heyongqiang, MarkCallaghan

Reviewed By: MarkCallaghan

Differential Revision: https://reviews.facebook.net/D6207
2012-10-26 08:42:05 -07:00
Dhruba Borthakur
5b0fe6c73b Greedy algorithm for picking files to compact.
Summary:
It is best if we pick the largest file to compact in a level.
This reduces the write amplification factor for compactions.
Each level has an auxiliary data structure called files_by_size_
that sorts all files by their size. This data structure is
updated when a new version is created.

Test Plan: make check

Differential Revision: https://reviews.facebook.net/D6195
2012-10-25 18:27:53 -07:00
Dhruba Borthakur
8fb5f40468 firstIndex fix for multi-threaded compaction code.
Summary:
Prior to multi-threaded compaction, wrap-around would be done by using
current_->files_[level[0]. With this change we should be
using the first file for which f->being_compacted is not true.

1ca0584345 (commitcomment-2041516)

Test Plan: make check

Differential Revision: https://reviews.facebook.net/D6165
2012-10-25 08:44:47 -07:00
Mark Callaghan
e7206f43ee Improve statistics
Summary:
This adds more statistics to be reported by GetProperty("leveldb.stats").
The new stats include time spent waiting on stalls in MakeRoomForWrite.
This also includes the total amplification rate where that is:
    (#bytes of sequential IO during compaction) / (#bytes from Put)
This also includes a lot more data for the per-level compaction report.
* Rn(MB) - MB read from level N during compaction between levels N and N+1
* Rnp1(MB) - MB read from level N+1 during compaction between levels N and N+1
* Wnew(MB) - new data written to the level during compaction
* Amplify - ( Write(MB) + Rnp1(MB) ) / Rn(MB)
* Rn - files read from level N during compaction between levels N and N+1
* Rnp1 - files read from level N+1 during compaction between levels N and N+1
* Wnp1 - files written to level N+1 during compaction between levels N and N+1
* NewW - new files written to level N+1 during compaction
* Count - number of compactions done for this level

This is the new output from DB::GetProperty("leveldb.stats"). The old output stopped at Write(MB)

                               Compactions
Level  Files Size(MB) Time(sec) Read(MB) Write(MB)  Rn(MB) Rnp1(MB) Wnew(MB) Amplify Read(MB/s) Write(MB/s)   Rn Rnp1 Wnp1 NewW Count
-------------------------------------------------------------------------------------------------------------------------------------
  0        3        6        33        0       576       0        0      576    -1.0       0.0         1.3     0    0    0    0   290
  1      127      242       351     5316      5314     570     4747      567    17.0      12.1        12.1   287 2399 2685  286    32
  2      161      328        54      822       824     326      496      328     4.0       1.9         1.9   160  251  411  160   161
Amplification: 22.3 rate, 0.56 GB in, 12.55 GB out
Uptime(secs): 439.8
Stalls(secs): 206.938 level0_slowdown, 0.000 level0_numfiles, 24.129 memtable_compaction

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 -
(cherry picked from commit ecdeead38f86cc02e754d0032600742c4f02fec8)

Reviewers: dhruba

Differential Revision: https://reviews.facebook.net/D6153
2012-10-24 14:21:38 -07:00
Dhruba Borthakur
47bce26aca Merge branch 'master' into performance 2012-10-23 22:32:54 -07:00
Dhruba Borthakur
3b06f94fa2 Merge branch 'master' into performance
Conflicts:
	db/db_impl.cc
	db/db_impl.h
	db/version_set.cc
2012-10-23 22:30:07 -07:00
Mark Callaghan
51d2adfbeb Fix broken build. Add stdint.h to get uint64_t
Summary:
I still get failures from this. Not sure whether there was a fix in progress.

Task ID: #

Blame Rev:

Test Plan:
compile

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/D6147
2012-10-23 14:58:53 -07:00
Dhruba Borthakur
4c107587ed Delete files outside the mutex.
Summary:
The compaction process deletes a large number of files. This takes
quite a bit of time and is best done outside the mutex lock.

Test Plan: make check

Differential Revision: https://reviews.facebook.net/D6123
2012-10-22 11:53:23 -07:00
heyongqiang
5010daa7a8 add "seek_compaction" to log for better debug Summary:
Summary: as subject

Test Plan: compile

Reviewers: dhruba

Reviewed By: dhruba

CC: MarkCallaghan

Differential Revision: https://reviews.facebook.net/D6117
2012-10-22 10:00:25 -07:00
Dhruba Borthakur
3489cd615c Merge branch 'master' into performance
Conflicts:
	db/db_impl.cc
	db/db_impl.h
2012-10-21 02:15:19 -07:00
Dhruba Borthakur
f95219fb32 Delete files outside the mutex.
Summary:
The compaction process deletes a large number of files. This takes
quite a bit of time and is best done outside the mutex lock.

Test Plan: make check

Differential Revision: https://reviews.facebook.net/D6123
2012-10-21 02:03:00 -07:00
Dhruba Borthakur
98f23cf04a Merge branch 'master' into performance
Conflicts:
	db/db_impl.cc
	db/db_impl.h
2012-10-21 01:55:19 -07:00
Dhruba Borthakur
64c4b9f0e2 Delete files outside the mutex.
Summary:
The compaction process deletes a large number of files. This takes
quite a bit of time and is best done outside the mutex lock.

Test Plan:

Reviewers:

CC:

Task ID: #

Blame Rev:
2012-10-21 01:49:48 -07:00
Dhruba Borthakur
50166999ef Merge branch 'master' into performance 2012-10-19 16:08:04 -07:00
Dhruba Borthakur
507f5aac73 Do not enable checksums for zlib compression.
Summary:
Leveldb code already calculates checksums for each block. There
is no need to generate checksums inside zlib. This patch switches-off checksum generation/checking in zlib library.

(The Inno support for zlib uses windowsBits=14 as well.)

pfabricator marks this file as binary. But here is the diff

diff --git a/port/port_posix.h b/port/port_posix.h
index 86a0927..db4e0b8 100644
--- a/port/port_posix.h
+++ b/port/port_posix.h
@@ -163,7 +163,7 @@ inline bool Snappy_Uncompress(const char* input, size_t length,
 }

 inline bool Zlib_Compress(const char* input, size_t length,
-    ::std::string* output, int windowBits = 15, int level = -1,
+    ::std::string* output, int windowBits = -14, int level = -1,
      int strategy = 0) {
 #ifdef ZLIB
   // The memLevel parameter specifies how much memory should be allocated for
@@ -223,7 +223,7 @@ inline bool Zlib_Compress(const char* input, size_t length,
 }

 inline char* Zlib_Uncompress(const char* input_data, size_t input_length,
-    int* decompress_size, int windowBits = 15) {
+    int* decompress_size, int windowBits = -14) {
 #ifdef ZLIB
   z_stream _stream;
   memset(&_stream, 0, sizeof(z_stream));

Test Plan: run db_bench with zlib compression.

Reviewers: heyongqiang, MarkCallaghan

Reviewed By: heyongqiang

Differential Revision: https://reviews.facebook.net/D6105
2012-10-19 16:06:33 -07:00
Dhruba Borthakur
e982f5a1d2 Merge branch 'master' into performance
Conflicts:
	util/options.cc
2012-10-19 15:16:42 -07:00
Dhruba Borthakur
cf5adc8016 db_bench was not correctly initializing the value for delete_obsolete_files_period_micros option.
Summary:
The parameter delete_obsolete_files_period_micros controls the
periodicity of deleting obsolete files. db_bench was reading in
this parameter intoa local variable called 'l' but was incorrectly
using another local variable called 'n' while setting it in the
db.options data structure.
This patch also logs the value of delete_obsolete_files_period_micros
in the LOG file at db startup time.

I am hoping that this will improve the overall write throughput drastically.

Test Plan: run db_bench

Reviewers: MarkCallaghan, heyongqiang

Reviewed By: MarkCallaghan

Differential Revision: https://reviews.facebook.net/D6099
2012-10-19 15:10:12 -07:00
Dhruba Borthakur
1ca0584345 This is the mega-patch multi-threaded compaction
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
2012-10-19 14:00:53 -07:00
Dhruba Borthakur
cd93e82845 Enable SSE when building with fbcode support.
Summary:
fbcode build now support SSE instructions.
Delete older version of the compile-helper fbcode.sh. This is
subsumed by fbcode.gcc471.sh.

Test Plan: run make check

Reviewers: heyongqiang, MarkCallaghan

Reviewed By: heyongqiang

Differential Revision: https://reviews.facebook.net/D6057
2012-10-18 08:43:25 -07:00
Dhruba Borthakur
aa73538f2a The deletion of obsolete files should not occur very frequently.
Summary:
The method DeleteObsolete files is a very costly methind, especially
when the number of files in a system is large. It makes a list of
all live-files and then scans the directory to compute the diff.
By default, this method is executed after every compaction run.

This patch makes it such that DeleteObsolete files is never
invoked twice within a configured period.

Test Plan: run all unit tests

Reviewers: heyongqiang, MarkCallaghan

Reviewed By: MarkCallaghan

Differential Revision: https://reviews.facebook.net/D6045
2012-10-16 10:26:10 -07:00
Dhruba Borthakur
0230866791 Enhance db_bench to allow setting the number of levels in a database.
Summary: Enhance db_bench to allow setting the number of levels in a database.

Test Plan: run db_bench and look at LOG

Reviewers: heyongqiang, MarkCallaghan

Reviewed By: MarkCallaghan

CC: MarkCallaghan

Differential Revision: https://reviews.facebook.net/D6027
2012-10-15 10:18:49 -07:00
Dhruba Borthakur
5dc784c233 Fix compilation problem with db_stress when using C11 compiler.
Summary:

Test Plan:

Reviewers:

CC:

Task ID: #

Blame Rev:
2012-10-12 17:00:25 -07:00
Asad K Awan
24f7983b1f [tools] Add a tool to stress test concurrent writing to levelDB
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
2012-10-10 12:12:55 -07:00
Thawan Kooburat
696b290821 Add LevelDb's JNI wrapper
Summary: This implement the Java interface by using JNI

Test Plan: compile test

Reviewers: dhruba

Reviewed By: dhruba

Differential Revision: https://reviews.facebook.net/D5925
2012-10-05 13:13:49 -07:00
Thawan Kooburat
fc23714f27 Add LevelDb's Java interface
Summary:
See the wiki below
https://our.intern.facebook.com/intern/wiki/index.php/Database/leveldb/Java

Test Plan: compile test

Reviewers: dhruba

Reviewed By: dhruba

Differential Revision: https://reviews.facebook.net/D5919
2012-10-05 13:11:31 -07:00
Dhruba Borthakur
f7975ac733 Implement RowLocks for assoc schema
Summary:
Each assoc is identified by (id1, assocType). This is the rowkey.
Each row has a read/write rowlock. There is statically allocated array
of 2000 read/write locks. A rowkey is murmur-hashed to one of the
read/write locks.

assocPut and assocDelete acquires the rowlock in Write mode.
The key-updates are done within the rowlock with a atomic nosync
batch write to leveldb. Then the rowlock is released and
a write-with-sync is done to sync leveldb transaction log.

Test Plan: added unit test

Reviewers: heyongqiang

Reviewed By: heyongqiang

Differential Revision: https://reviews.facebook.net/D5859
2012-10-03 23:19:01 -07:00
Dhruba Borthakur
c1006d4276 An configurable option to write data using write instead of mmap.
Summary:
We have seen that reading data via the pread call (instead of
mmap) is much faster on Linux 2.6.x kernels. This patch makes
an equivalent option to switch off mmaps for the write path
as well.

db_bench --mmap_write=0 will use write() instead of mmap() to
write data to a file.

This change is backward compatible, the default
option is to continue using mmap for writing to a file.

Test Plan: "make check all"

Differential Revision: https://reviews.facebook.net/D5781
2012-10-03 17:08:13 -07:00
Mark Callaghan
e678a5947a Add --stats_interval option to db_bench
Summary:
The option is zero by default and in that case reporting is unchanged.
By unchanged, the interval at which stats are reported is scaled after each
report and newline is not issued after each report so one line is rewritten.
When non-zero it specifies the constant interval (in operations) at which
statistics are reported and the stats include the rate per interval. This
makes it easier to determine whether QPS changes over the duration of the test.

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

CC: heyongqiang

Differential Revision: https://reviews.facebook.net/D5817
2012-10-03 09:54:33 -07:00
Mark Callaghan
d8763abecd Fix the bounds check for the --readwritepercent option
Summary:
see above

Task ID: #

Blame Rev:

Test Plan:
run db_bench with invalid value for option

Revert Plan:

Database Impact:

Memcache Impact:

Other Notes:

EImportant:

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

Reviewers: dhruba

Reviewed By: dhruba

CC: heyongqiang

Differential Revision: https://reviews.facebook.net/D5823
2012-10-03 09:52:26 -07:00
Mark Callaghan
98804f914f Fix compiler warnings and errors in ldb.c
Summary:
stdlib.h is needed for exit()
--readhead --> --readahead

Task ID: #

Blame Rev:

Test Plan:
compile

Revert Plan:

Database Impact:

Memcache Impact:

Other Notes:

EImportant:

- begin *PUBLIC* platform impact section -
Bugzilla: #
- end platform impact -
fix compiler warnings & errors

Reviewers: dhruba

Reviewed By: dhruba

CC: heyongqiang

Differential Revision: https://reviews.facebook.net/D5805
2012-10-03 06:46:59 -07:00
Dhruba Borthakur
a58d48de79 Implement ReadWrite locks for leveldb
Summary:
Implement ReadWrite locks for leveldb. These will be helpful
to implement a read-modify-write operation (e.g. atomic increments).

Test Plan: does not modify any existing code

Reviewers: heyongqiang

Reviewed By: heyongqiang

CC: MarkCallaghan

Differential Revision: https://reviews.facebook.net/D5787
2012-10-01 22:37:39 -07:00