Commit Graph

4994 Commits

Author SHA1 Message Date
Andrew Kryczka 0267655dad Update change log for 4.6 release
Summary: as titled

Test Plan: N/A

Reviewers: sdong, kradhakrishnan, anthony, yhchiang, IslamAbdelRahman

Reviewed By: IslamAbdelRahman

Subscribers: leveldb, andrewkr, dhruba

Differential Revision: https://reviews.facebook.net/D55323
2016-03-12 13:51:57 -08:00
Andrew Kryczka 08304c0867 Expose RepairDB as ldb command
Summary: This will make it easier for admins and devs to use RepairDB.

Test Plan:
Tried deleting the manifest and verified it recovers:

  $ ldb --create_if_missing --db=/tmp/test_db put ok ok
  $ rm -f /tmp/test_db/MANIFEST-000001
  $ ./ldb --db=/tmp/test_db repair
  $ ldb --db=/tmp/test_db get ok
  ok

Reviewers: yhchiang, sdong, IslamAbdelRahman

Reviewed By: IslamAbdelRahman

Subscribers: leveldb, andrewkr, dhruba

Differential Revision: https://reviews.facebook.net/D55359
2016-03-12 13:50:20 -08:00
SherlockNoMad fd664a27b5 Fix Build Error 2016-03-11 22:56:25 -08:00
Islam AbdelRahman 580fede347 Aggregate hot Iterator counters in LocalStatistics (DBIter::Next perf regression)
Summary:
This patch bump the counters in the frequent code path DBIter::Next() / DBIter::Prev() in a local data members and send them to Statistics when the iterator is destroyed
A better solution will be to have thread_local implementation for Statistics

New performance
```
readseq      :       0.035 micros/op 28597881 ops/sec; 3163.7 MB/s
     1,851,568,819      stalled-cycles-frontend   #   31.29% frontend cycles idle    [49.86%]
       884,929,823      stalled-cycles-backend    #   14.95% backend  cycles idle    [50.21%]
readreverse  :       0.071 micros/op 14077393 ops/sec; 1557.3 MB/s
     3,239,575,993      stalled-cycles-frontend   #   27.36% frontend cycles idle    [49.96%]
     1,558,253,983      stalled-cycles-backend    #   13.16% backend  cycles idle    [50.14%]

```

Existing performance

```
readreverse  :       0.174 micros/op 5732342 ops/sec;  634.1 MB/s
    20,570,209,389      stalled-cycles-frontend   #   70.71% frontend cycles idle    [50.01%]
    18,422,816,837      stalled-cycles-backend    #   63.33% backend  cycles idle    [50.04%]

readseq      :       0.119 micros/op 8400537 ops/sec;  929.3 MB/s
    15,634,225,844      stalled-cycles-frontend   #   79.07% frontend cycles idle    [49.96%]
    14,227,427,453      stalled-cycles-backend    #   71.95% backend  cycles idle    [50.09%]
```

Test Plan: unit tests

Reviewers: yhchiang, sdong, igor

Reviewed By: sdong

Subscribers: andrewkr, dhruba

Differential Revision: https://reviews.facebook.net/D55107
2016-03-11 19:01:12 -08:00
SherlockNoMad 54f6b9e162 Histogram Concurrency Improvement and Time-Windowing Support 2016-03-11 16:54:25 -08:00
agiardullo 790252805d Add multithreaded transaction test
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
2016-03-11 15:16:52 -08:00
Baris Yazici e8e6cf0173 fix: handle_fatal_signal (sig=6) in std::vector<std::string, std::allocator<std::string> >::_M_range_check | c++/4.8.2/bits/stl_vector.h:794 #174
Summary:
Fix for https://github.com/facebook/mysql-5.6/issues/174

When there is no old files to purge, vector.at(i) function was crashing

if (old_info_log_file_count != 0 &&
      old_info_log_file_count >= db_options_.keep_log_file_num) {
    std::sort(old_info_log_files.begin(), old_info_log_files.end());
    size_t end = old_info_log_file_count - db_options_.keep_log_file_num;
    for (unsigned int i = 0; i <= end; i++) {
      std::string& to_delete = old_info_log_files.at(i);

Added check to old_info_log_file_count be non zero.

Test Plan: run existing tests

Reviewers: gunnarku, vasilep, sdong, yhchiang

Reviewed By: yhchiang

Subscribers: andrewkr, webscalesql-eng, dhruba

Differential Revision: https://reviews.facebook.net/D55245
2016-03-11 11:11:45 -08:00
Andrew Kryczka d9620239d2 Cleanup stale manifests outside of full purge
Summary:
- Keep track of obsolete manifests in VersionSet
- Updated FindObsoleteFiles() to put obsolete manifests in the JobContext for later use by PurgeObsoleteFiles()
- Added test case that verifies a stale manifest is deleted by a non-full purge

Test Plan:
  $ ./backupable_db_test --gtest_filter=BackupableDBTest.ChangeManifestDuringBackupCreation

Reviewers: IslamAbdelRahman, yoshinorim, sdong

Reviewed By: sdong

Subscribers: andrewkr, leveldb, dhruba

Differential Revision: https://reviews.facebook.net/D55269
2016-03-10 18:16:21 -08:00
Yi Wu f71fc77b7c Cache to have an option to fail Cache::Insert() when full
Summary:
Cache to have an option to fail Cache::Insert() when full. Update call sites to check status and handle error.

I totally have no idea what's correct behavior of all the call sites when they encounter error. Please let me know if you see something wrong or more unit test is needed.

Test Plan: make check -j32, see tests pass.

Reviewers: anthony, yhchiang, andrewkr, IslamAbdelRahman, kradhakrishnan, sdong

Reviewed By: sdong

Subscribers: andrewkr, dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D54705
2016-03-10 17:35:19 -08:00
Igor Canadi ee8cc35201 Merge pull request #938 from alexander-fenster/master
added --no_value option to ldb scan to dump key only
2016-03-10 16:44:52 -08:00
Yueh-Hsuan Chiang 765597fa78 Update compaction score right after CompactFiles forms a compaction
Summary:
This is a follow-up patch of https://reviews.facebook.net/D54891.
As the information about files being compacted will also be used
when making compaction decision, it is necessary to update the compaction
score when a compaction plan has been made but not yet execute.

This patch adds a missing call to update the compaction score in
CompactFiles().

Test Plan: compact_files_test

Reviewers: sdong, IslamAbdelRahman, kradhakrishnan, yiwu, andrewkr

Reviewed By: andrewkr

Subscribers: andrewkr, dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D55227
2016-03-10 14:34:28 -08:00
Alexander Fenster f0161c37b0 formatting fix 2016-03-10 13:34:42 -08:00
Yueh-Hsuan Chiang aa3f02d50c Improve comment in compaction.h and compaction_picker.h
Summary:
ReleaseCompactionFiles must be called when DB mutex is held,
but the documentation is mission.

Test Plan: no code change

Reviewers: anthony, IslamAbdelRahman, kradhakrishnan, sdong

Reviewed By: sdong

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D54987
2016-03-08 16:46:41 -08:00
agiardullo 2200295ee1 optimistic transactions support for reinitialization
Summary: Extend optimization in D53835 to optimistic transactions for completeness.

Test Plan: added test

Reviewers: sdong, IslamAbdelRahman, horuff, jkedgar

Reviewed By: horuff

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D55059
2016-03-07 19:03:09 -08:00
Islam AbdelRahman badd6b7846 Ignore db_test2
Summary: Add db_test2 to .gitignore

Test Plan: make sure db_test2 dont show in "git status"

Reviewers: sdong, yhchiang, andrewkr, anthony

Reviewed By: anthony

Subscribers: dhruba

Differential Revision: https://reviews.facebook.net/D55191
2016-03-07 15:56:16 -08:00
agiardullo 200080ed72 Improve snapshot handling for Transaction reinitialization
Summary: Previously, reusing a transaction (by passing it as an argument to BeginTransaction) would not clear the transaction's snapshot.  This is not a clear, well-definited behavior.

Test Plan: improved test

Reviewers: sdong, IslamAbdelRahman, horuff, jkedgar

Reviewed By: jkedgar

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D55053
2016-03-07 13:28:11 -08:00
Islam AbdelRahman 171c8e80b1 Update dependencies / Fix Clang
Summary:
Update dependencies and fix broken clang symlink

version changes
```
zstd 0.4.7 => 0.5.1
jemalloc 4.0.3 => master
```

Test Plan:
make check -j64
USE_CLANG=1 make check -j64
ROCKSDB_FBCODE_BUILD_WITH_481=1 make check -j64

Reviewers: sdong, yhchiang, anthony, andrewkr

Subscribers: dhruba

Differential Revision: https://reviews.facebook.net/D55179
2016-03-07 12:57:19 -08:00
sdong 294bdf9ee2 Change Property name from "rocksdb.current_version_number" to "rocksdb.current-super-version-number"
Summary: I realized I again is wrong about the naming convention. Let me change it to the correct one.

Test Plan: Run unit tests.

Reviewers: IslamAbdelRahman, kradhakrishnan, yhchiang, andrewkr

Reviewed By: andrewkr

Subscribers: leveldb, dhruba

Differential Revision: https://reviews.facebook.net/D55041
2016-03-04 18:15:29 -08:00
Yueh-Hsuan Chiang bf1c4089db Use pure if-then check instead of assert in EraseColumnFamilyInfo
Summary:
Use pure if-then check instead of assert in EraseColumnFamilyInfo
when the specified column family does not found in the cf_info_map_.
So the second deletion will be no op instead of crash.

Test Plan: existing test.

Reviewers: sdong, anthony, kradhakrishnan, IslamAbdelRahman

Reviewed By: IslamAbdelRahman

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D55023
2016-03-04 16:03:31 -08:00
Yueh-Hsuan Chiang a7d4eb2f34 Fix a bug where flush does not happen when a manual compaction is running
Summary:
Currently, when rocksdb tries to run manual compaction to refit data into a level,
there's a ReFitLevel() process that requires no bg work is currently running.
When RocksDB plans to ReFitLevel(), it will do the following:

 1. pause scheduling new bg work.
 2. wait until all bg work finished
 3. do the ReFitLevel()
 4. unpause scheduling new bg work.

However, as it pause scheduling new bg work at step one and waiting for all bg work
finished in step 2, RocksDB will stop flushing until all bg work is done (which
could take a long time.)

This patch fix this issue by changing the way ReFitLevel() pause the background work:

1. pause scheduling compaction.
2. wait until all bg work finished.
3. pause scheduling flush
4. do ReFitLevel()
5. unpause both flush and compaction.

The major difference is that.  We only pause scheduling compaction in step 1 and wait
for all bg work finished in step 2.  This prevent flush being blocked for a long time.
Although there's a very rare case that ReFitLevel() might be in starvation in step 2,
but it's less likely the case as flush typically finish very fast.

Test Plan: existing test.

Reviewers: anthony, IslamAbdelRahman, kradhakrishnan, sdong

Reviewed By: sdong

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D55029
2016-03-04 14:24:52 -08:00
Gunnar Kudrjavets 68189f7e1b Update benchmarks used to measure subcompaction performance
Summary: After closely working with Mark, Siying, and Yueh-Hsuan this set of changes reflects the updates needed to measure RocksDB subcompaction performance in a correct manner. The essence of the benchmark is executing `fillrandom` followed by `compact` with the correct set of options for various number of subcompactions specified.

Test Plan: Tested internally to verify correctness and reliability.

Reviewers: sdong, yhchiang, MarkCallaghan

Reviewed By: MarkCallaghan

Subscribers: dhruba

Differential Revision: https://reviews.facebook.net/D55089
2016-03-04 12:32:11 -08:00
Islam AbdelRahman dfe96c72c3 Fix WriteLevel0TableForRecovery file delete protection
Summary:
The call to

```
CaptureCurrentFileNumberInPendingOutputs()
```

should be before

```
versions_->NewFileNumber()
```
Right now we are not actually protecting the file from being deleted

Test Plan: make check

Reviewers: sdong, anthony, yhchiang

Reviewed By: yhchiang

Subscribers: dhruba

Differential Revision: https://reviews.facebook.net/D54645
2016-03-03 18:25:07 -08:00
Igor Canadi 451678c8c9 Merge pull request #1025 from SherlockNoMad/BuildFix
Fix Windows build
2016-03-03 15:24:25 -08:00
SherlockNoMad 58ecd91326 Fix Windows build 2016-03-03 15:08:24 -08:00
Andrew Kryczka 501927ffc4 [backupable db] Remove file size embedded in name workaround
Summary:
Now that we get sizes efficiently, we no longer need the workaround to
embed file size in filename.

Test Plan:
  $ ./backupable_db_test

Reviewers: sdong

Reviewed By: sdong

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D55035
2016-03-03 13:32:20 -08:00
sdong ef204df7ef Compaction always needs to be removed from level0_compactions_in_progress_ for universal compaction
Summary: We always put compaction to level0_compactions_in_progress_ for universal compaction, so we should also remove it. The bug causes assert failure when running manual compaction.

Test Plan:
TEST_TMPDIR=/dev/shm/ ./db_bench --benchmarks=fillrandom,compact --subcompactions=16 --compaction_style=1
always fails on my host. After the fix, it doesn't fail any more.

Reviewers: IslamAbdelRahman, andrewkr, kradhakrishnan, yhchiang

Reviewed By: yhchiang

Subscribers: leveldb, dhruba

Differential Revision: https://reviews.facebook.net/D55017
2016-03-02 21:23:28 -08:00
sdong e79ad9e184 Add Iterator Property rocksdb.iterator.version_number
Summary: We want to provide a way to detect whether an iterator is stale and needs to be recreated. Add a iterator property to return version number.

Test Plan: Add two unit tests for it.

Reviewers: IslamAbdelRahman, yhchiang, anthony, kradhakrishnan, andrewkr

Reviewed By: andrewkr

Subscribers: leveldb, dhruba

Differential Revision: https://reviews.facebook.net/D54921
2016-03-02 16:23:59 -08:00
sdong 19ea40f8b6 Subcompaction boundary keys should not terminate after an empty level
Summary: Now we skip to add boundary keys to subcompaction candidates since we see an empty level. This makes subcompaction almost disabled for universal compaction. We should consider all files instead.

Test Plan: Run existing tests.

Reviewers: IslamAbdelRahman, andrewkr, yhchiang

Reviewed By: yhchiang

Subscribers: leveldb, dhruba

Differential Revision: https://reviews.facebook.net/D55005
2016-03-02 15:45:07 -08:00
Omar Sandoval deb08b8226 Add parsing of missing DB options
Summary: There are a few options in struct DBOptions that aren't handled by options_helper.cc. Add those missing options so they can be used by GetDBOptionsFromString() and friends.

Test Plan: Updated options_test.cc, reran all tests.

Reviewers: sdong, yhchiang

Reviewed By: yhchiang

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D54603
2016-03-02 10:34:14 -08:00
Andrew Kryczka f8e90e8753 Get file attributes in bulk for VerifyBackup and CreateNewBackup
Summary:
For VerifyBackup(), backup files can be spread across "shared/",
"shared_checksum/", and "private/" subdirectories, so we have to
bulk get all three.

For CreateNewBackup(), we make two separate bulk calls: one for the
data files and one for WAL files.

There is also a new helper function, ExtendPathnameToSizeBytes(),
that translates the file attributes vector to a map. I decided to leave
GetChildrenFileAttributes()'s (from D53781) return type as vector to
keep it consistent with GetChildren().

Depends on D53781.

Test Plan:
verified relevant unit tests

  $ ./backupable_db_test

Reviewers: IslamAbdelRahman, sdong

Reviewed By: sdong

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D53919
2016-03-01 19:33:33 -08:00
sdong 12fd9b1868 Change BlockBasedTableOptions.format_version default to 2
Summary: BlockBasedTableOptions.format_version = 2 uses better encoding format. Now it's the time to make it default.

Test Plan: Run all existing tests.

Reviewers: igor, yhchiang, anthony, kradhakrishnan, andrewkr, IslamAbdelRahman

Reviewed By: IslamAbdelRahman

Subscribers: MarkCallaghan, leveldb, dhruba

Differential Revision: https://reviews.facebook.net/D54879
2016-03-01 14:28:52 -08:00
sdong 4572a2d8c0 Update current version to 4.6
Summary: 4.5 is already cut, we can now increase the version in 4.6.

Test Plan: Not needed.

Reviewers: anthony, kradhakrishnan, andrewkr, yhchiang, IslamAbdelRahman

Reviewed By: IslamAbdelRahman

Subscribers: leveldb, dhruba

Differential Revision: https://reviews.facebook.net/D54963
2016-03-01 14:26:44 -08:00
sdong 74b660702e Rename iterator property "rocksdb.iterator.is.key.pinned" => "rocksdb.iterator.is-key-pinned"
Summary: Rename iterator property to folow property naming convention.

Test Plan: Run all existing tests.

Reviewers: andrewkr, anthony, yhchiang, kradhakrishnan, IslamAbdelRahman

Reviewed By: IslamAbdelRahman

Subscribers: leveldb, dhruba

Differential Revision: https://reviews.facebook.net/D54957
2016-03-01 13:47:12 -08:00
Islam AbdelRahman 6743135ea1 Fix DB::AddFile() issue when PurgeObsoleteFiles() is called
Summary:
In some situations the DB will scan all existing files in the DB path and delete the ones that are Obsolete.
If this happen during adding an external sst file. this could cause the file to be deleted while we are adding it.
This diff fix this issue

Test Plan:
unit test to reproduce the bug
existing unit tests

Reviewers: sdong, yhchiang, andrewkr

Reviewed By: andrewkr

Subscribers: dhruba

Differential Revision: https://reviews.facebook.net/D54627
2016-03-01 12:05:29 -08:00
sdong 432f3adf2c Add DB Property "rocksdb.current_version_number"
Summary: Add a DB Property "rocksdb.current_version_number" for users to monitor version changes and stale iterators.

Test Plan: Add a unit test.

Reviewers: andrewkr, yhchiang, kradhakrishnan, IslamAbdelRahman

Reviewed By: IslamAbdelRahman

Subscribers: leveldb, dhruba

Differential Revision: https://reviews.facebook.net/D54927
2016-03-01 10:55:40 -08:00
Adam Retter 188bb2e7ad Fix formatting identified by `arc lint` 2016-03-01 16:00:45 +00:00
Adam Retter 0f2d2fcff6 Refactored tests to use try-with-resources 2016-03-01 16:00:45 +00:00
Adam Retter f8e02c7825 Deprecate org.rocksdb.AbstractNativeReference#dispose() and implement java.lang.AutoCloseable 2016-03-01 16:00:45 +00:00
Adam Retter 0f2fdfe23a Fix the javadoc and the formatting of the base-classes for objects with native references 2016-03-01 16:00:44 +00:00
sdong b5b1db167a Recompute compaction score after scheduling manual compaction
Summary: After we made manual compaction runnable concurrently with automaticallly compaction, we need to run ComputeCompactionScore() to prepare a coming compaction picking call before the compaction finishes.

Test Plan: Run existing tests.

Reviewers: yhchiang, IslamAbdelRahman, andrewkr, kradhakrishnan, anthony, igor

Reviewed By: igor

Subscribers: leveldb, dhruba

Differential Revision: https://reviews.facebook.net/D54891
2016-02-29 17:17:51 -08:00
agiardullo 5ea9aa3c14 TransactionDB:ReinitializeTransaction
Summary: Add function to reinitialize a transaction object so that it can be reused.  This is an optimization so users can potentially avoid reallocating transaction objects.

Test Plan: added tests

Reviewers: yhchiang, kradhakrishnan, IslamAbdelRahman, sdong

Reviewed By: sdong

Subscribers: jkedgar, dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D53835
2016-02-29 16:27:32 -08:00
sdong 1f5954147b Introduce Iterator::GetProperty() and replace Iterator::IsKeyPinned()
Summary:
Add Iterator::GetProperty(), a way for users to communicate with iterator, and turn Iterator::IsKeyPinned() with it.
As a follow-up, I'll ask a property as the version number attached to the iterator

Test Plan: Rerun existing tests and add a negative test case.

Reviewers: yhchiang, andrewkr, kradhakrishnan, anthony, IslamAbdelRahman

Reviewed By: IslamAbdelRahman

Subscribers: leveldb, dhruba

Differential Revision: https://reviews.facebook.net/D54783
2016-02-29 14:01:31 -08:00
Igor Canadi 67789419fa Merge pull request #1020 from gongsu832/master
Modified Makefile and build_tools/build_detect_platform to compile on…
2016-02-29 13:12:57 -08:00
Andrew Kryczka 69c471bd9b Handle concurrent manifest update and backup creation
Summary:
Fixed two related race conditions in backup creation.

(1) CreateNewBackup() uses DB::DisableFileDeletions() to prevent table files
from being deleted while it is copying; however, the MANIFEST file could still
rotate during this time. The fix is to stop deleting the old manifest in the
rotation logic. It will be deleted safely later when PurgeObsoleteFiles() runs
(can only happen when file deletions are enabled).

(2) CreateNewBackup() did not account for the CURRENT file being mutable.
This is significant because the files returned by GetLiveFiles() contain a
particular manifest filename, but the manifest to which CURRENT refers can
change at any time. This causes problems when CURRENT changes between the call
to GetLiveFiles() and when it's copied to the backup directory. To workaround this, I
manually forge a CURRENT file referring to the manifest filename returned in
GetLiveFiles().

(2) also applies to the checkpointing code, so let me know if this approach is
good and I'll make the same change there.

Test Plan:
new test for roll manifest during backup creation.

running the test before this change:

  $ ./backupable_db_test --gtest_filter=BackupableDBTest.ChangeManifestDuringBackupCreation
  ...
  IO error: /tmp/rocksdbtest-9383/backupable_db/MANIFEST-000001: No such file or directory

running the test after this change:

  $ ./backupable_db_test --gtest_filter=BackupableDBTest.ChangeManifestDuringBackupCreation
  ...
  [ RUN      ] BackupableDBTest.ChangeManifestDuringBackupCreation
  [       OK ] BackupableDBTest.ChangeManifestDuringBackupCreation (2836 ms)

Reviewers: IslamAbdelRahman, anthony, sdong

Reviewed By: sdong

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D54711
2016-02-29 12:56:55 -08:00
root 3373c81fa8 Modify build_tools/build_detect_platform to detect and set -march=z10 on Linux s390x. 2016-02-29 15:02:52 -05:00
root 990509045f Merge branch 'master' of https://github.com/gongsu832/rocksdb
Rebase for -momit-leaf-frame-pointer fix.
2016-02-29 14:45:55 -05:00
Igor Canadi 3492889ab8 Merge pull request #1019 from javacruft/wip-omit-leaf-frame-pointer-archs
build: Improve -momit-leaf-frame-pointer usage
2016-02-29 09:32:16 -08:00
James Page 7ca731b12c build: Improve -momit-leaf-frame-pointer usage
-momit-leaf-frame-pointer is only supported on certain archs.
Detect this automatically based on which flags the compiler
understands.
2016-02-29 09:22:24 +00:00
root 21f17aaa60 Modified Makefile and build_tools/build_detect_platform to compile on Linux s390x. 2016-02-26 18:03:07 -05:00
sdong 8800975fb0 Make DBTestUniversalCompaction.IncreaseUniversalCompactionNumLevels more robust
Summary:
Based on thread scheduling, DBTestUniversalCompaction.IncreaseUniversalCompactionNumLevels can fail to flush enough files to trigger expected compactions. Fix it by waiting for flush after inserting each key.
There are failrue reported:

db/db_universal_compaction_test.cc:1134: Failure
Expected: (NumTableFilesAtLevel(options.num_levels - 1, 1)) > (0), actual: 0 vs 0

but I can't repro it. Try to fix the bug and see whether it goes away.

Test Plan: Run the test multiple time.

Reviewers: IslamAbdelRahman, anthony, andrewkr, kradhakrishnan, yhchiang

Reviewed By: yhchiang

Subscribers: leveldb, dhruba

Differential Revision: https://reviews.facebook.net/D54747
2016-02-26 11:59:31 -08:00