Commit Graph

4018 Commits

Author SHA1 Message Date
agiardullo
af06d1a871 Transactions: Release Locks when rolling back to a savepoint
Summary: Transaction::RollbackToSavePoint() will now release any locks that were taken since the previous SavePoint.  To do this cleanly, I moved tracked_keys_ management into TransactionBase.

Test Plan: New Transaction test.

Reviewers: igor, rven, sdong

Reviewed By: sdong

Subscribers: dhruba, spetrunia, leveldb

Differential Revision: https://reviews.facebook.net/D46761
2015-09-15 10:50:01 -07:00
Andres Noetzli
5266ed3cc5 Fixed arena_test failure due to malloc_usable_size()
Summary:
ArenaTest.MemoryAllocatedBytes on Travis failed:
https://travis-ci.org/facebook/rocksdb/jobs/79887849 . This is probably due to
malloc_usable_size() returning a value greater than the requested size. From
the man page:

   The value returned by malloc_usable_size() may be greater than the requested
   size of the allocation because of alignment and minimum size constraints.
   Although the excess bytes can be overwritten by the application without ill
   effects, this is not good programming practice: the number of excess bytes
   in an allocation depends on the underlying implementation.

Test Plan: make arena_test && ./arena_test

Reviewers: rven, anthony, yhchiang, aekmekji, sdong, igor

Reviewed By: igor

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D46743
2015-09-15 10:49:53 -07:00
Andres Noetzli
7584091c7f Fixed bug in compaction iterator
Summary:
During the refactoring, the condition that makes sure that compaction
filters are only applied to records newer than the latest snapshot
got butchered. This patch fixes the condition and adds a test case.

Test Plan: make db_compaction_filter_test && ./db_compaction_filter_test

Reviewers: rven, anthony, yhchiang, sdong, aekmekji, igor

Reviewed By: igor

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D46707
2015-09-15 10:49:37 -07:00
Igor Canadi
af7cdbf647 Run full test suite in Travis
Summary: With old travis infrastructure, we couldn't run the whole test suite without crashing. Now we transfered to the new architecture and are able to run full `make check` instead of just db_test.

Test Plan:
https://travis-ci.org/facebook/rocksdb/builds/79591564

This test has failed, true, but it's actual problem with tests:
* t8316104 -- Failed ColumnFamilyTest.ReadDroppedColumnFamily and also https://github.com/facebook/rocksdb/issues/673
* Too many open files:

    db/db_universal_compaction_test.cc:514: Failure
    Put(1, Key(i % num_keys), Key(i))
    IO error: /tmp/rocksdbtest-501/db_universal_compaction_prallel_test/000331.sst: Too many open files

Reviewers: sdong, anthony, kradhakrishnan, IslamAbdelRahman

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D46545
2015-09-10 15:38:43 -07:00
Andres Noetzli
c25f6a85bf Removed __unused__ attribute
Summary:
The current build is failing on some platforms due to an __unused__ attribute.
This patch prevents the problem by using a pattern similar to MergeHelper
(assert not on the variable but inside a condition that uses the variable). We
should have better error handling in both cases in the future.

Test Plan: make clean all check

Reviewers: rven, anthony, yhchiang, sdong, igor, aekmekji

Reviewed By: aekmekji

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D46623
2015-09-10 15:16:32 -07:00
Ari Ekmekji
6db0a939d2 Fix DBCompactionTest failure with parallel L0-L1 compactions
Summary:
The test SuggestCompactRangeNoTwoLevel0Compactions in
DBCompactionTest fails when there are parallel L0-L1 compactions
taking place because the test makes sure that only one compaction
involving L0 takes place at any given time (since before having
parallel compactions this was impossible). I changed the test to only
run with DBOptions.max_subcompactions=1 so as to not hit this issue
which is not a correctness issue but just an inherent changing of
assumptions after introducing parallel compactions.

This failed after landing https://reviews.facebook.net/D43269#inline-321303
so now this should fix it

Test Plan: make all && make check

Reviewers: yhchiang, igor, anthony, noetzli, sdong

Reviewed By: sdong

Subscribers: dhruba

Differential Revision: https://reviews.facebook.net/D46617
2015-09-10 14:37:00 -07:00
Andres Noetzli
8aa1f15197 Refactored common code of Builder/CompactionJob out into a CompactionIterator
Summary:
Builder and CompactionJob share a lot of fairly complex code. This patch
refactors this code into a separate class, the CompactionIterator. Because the
shared code is fairly complex, this patch hopefully improves maintainability.
While there are is a lot of potential for further improvements, the patch is
intentionally pretty close to the original structure because the change is
already complex enough.

Test Plan: make clean all check && ./db_stress

Reviewers: rven, anthony, yhchiang, sdong, igor

Reviewed By: igor

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D46197
2015-09-10 14:35:25 -07:00
krad
41bce05869 CI job improvements
Summary: Added more jobs and refactored code express the jobs more cleanly

Test Plan: Manual test

Reviewers: igor sdong

CC: leveldb@

Task ID: #6968635

Blame Rev:
2015-09-10 14:29:41 -07:00
Igor Canadi
95ffc5d2bc Correct ASSERT_OK() in ReadDroppedColumnFamily
Summary: ReadDroppedColumnFamily is consistently failing in Travis CI environment (can't repro locally). I suspect it might be failing with non-OK status. This diff will give us more info about the failure.

Test Plan: none

Reviewers: sdong, kradhakrishnan

Reviewed By: kradhakrishnan

Subscribers: kradhakrishnan, dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D46611
2015-09-10 14:17:12 -07:00
Ari Ekmekji
3c37b3cccd Determine boundaries of subcompactions
Summary:
Up to this point, the subcompactions that make up a compaction
job have been divided based on the key range of the L1 files, and each
subcompaction has handled the key range of only one file. However
DBOption.max_subcompactions allows the user to designate how many
subcompactions at most to perform. This patch updates the
CompactionJob::GetSubcompactionBoundaries() to determine these
divisions accordingly based on that option and other input/system factors.

The current approach orders the starting and/or ending keys of certain
compaction input files and then generates a histogram to approximate the
size covered by the key range between each consecutive pair of keys. Then
it groups these ranges into groups so that the sizes are approximately equal
to one another. The approach has also been adapted to work for universal
compaction as well instead of just for level-based compaction as it was before.

These subcompactions are then executed in parallel by locally spawning
threads, one for each. The results are then aggregated and the compaction
completed.

Test Plan: make all && make check

Reviewers: yhchiang, anthony, igor, noetzli, sdong

Reviewed By: sdong

Subscribers: MarkCallaghan, dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D43269
2015-09-10 13:50:00 -07:00
krad
1126644082 Relaxing consistency detection to include errors while inserting to memtable as WAL recovery error.
Summary: The current code, considers data to be consistent if the record
checksum passes. We do have customer issues where the record checksum passed but
the data was incomprehensible. There is no way to get out of this error case
since all WAL recovery model will consider this error as unrelated to WAL.

Relaxing the definition and including errors while inserting to memtable as WAL
errors and handing them as per the recovery level.

Test Plan: Used customer dump to verify the fix for different level. The db
opens for kSkipAnyCorruptedRecords and kPointInTimeRecovery, but fails for
kAbsoluteConsistency and kTolerateCorruptedTailRecords.

Reviewers: sdon igor

CC: leveldb@

Task ID: #7918721

Blame Rev:
2015-09-10 12:56:17 -07:00
sdong
abc7f5fdb2 Make DBTest.ReadLatencyHistogramByLevel more robust
Summary: DBTest.ReadLatencyHistogramByLevel was not written as expected. After writes, reads aren't guaranteed to hit data written. It was not expected. Fix it.

Test Plan: Run the test multiple times

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

Reviewed By: igor

Subscribers: leveldb, dhruba

Differential Revision: https://reviews.facebook.net/D46587
2015-09-10 11:32:19 -07:00
Igor Canadi
ac9bcb55ce Set max_open_files based on ulimit
Summary: We should never set max_open_files to be bigger than the system's ulimit. Otherwise we will get "Too many open files" errors. See an example in this Travis run: https://travis-ci.org/facebook/rocksdb/jobs/79591566

Test Plan:
make check

I will also verify that max_max_open_files is reasonable.

Reviewers: anthony, kradhakrishnan, IslamAbdelRahman, sdong

Reviewed By: sdong

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D46551
2015-09-10 10:49:28 -07:00
Igor Canadi
4cbd2f9aa3 Merge pull request #714 from facebook/travisformac
Run travis tests on OS X
2015-09-09 20:22:49 -07:00
Igor Canadi
d0df54d1f9 Run travis tests on OS X 2015-09-09 19:56:08 -07:00
Igor Canadi
a55e5a52ae Merge pull request #711 from facebook/testtravis
Upgrade travis to new architecture
2015-09-09 18:44:44 -07:00
Igor Canadi
2b676d5bbe Upgrade travis to new architecture 2015-09-09 18:40:35 -07:00
Andres Noetzli
c66d53feed Fixed minor issue in CompressionTypeSupported()
Summary:
CompressionTypeSupported was returning LZ4_Supported() for
kZSTDNotFinalCompression. This patch changes it to ZSTD_Supported().

Test Plan: make clean all check

Reviewers: rven, anthony, yhchiang, sdong, igor

Reviewed By: igor

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D46521
2015-09-09 16:36:19 -07:00
Islam AbdelRahman
f3f2032c46 Release RocksDB 4.0.0
Summary: Release RocksDB 4.0.0

Test Plan: no test

Reviewers: sdong, yhchiang, anthony, rven, kradhakrishnan, igor

Reviewed By: igor

Subscribers: dhruba

Differential Revision: https://reviews.facebook.net/D46515
2015-09-09 16:01:03 -07:00
agiardullo
44b6e99e1b update max_write_buffer_number_to_maintain docblock
Summary: fix comment

Test Plan: n/a

Reviewers: sdong, IslamAbdelRahman

Reviewed By: IslamAbdelRahman

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D46455
2015-09-09 13:36:38 -07:00
agiardullo
aa6eed0c1e Transaction stats
Summary: Added funtions to fetch the number of locked keys in a transaction, the number of pending puts/merge/deletes, and the elapsed time

Test Plan: unit tests

Reviewers: yoshinorim, jkedgar, rven, sdong, yhchiang, igor

Reviewed By: igor

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D45417
2015-09-09 13:35:53 -07:00
agiardullo
25dbc579f5 Update HISTORY file for transactions
Summary: Move line about pessimistic transactions to the correct place in the history file and no longer refer to it as 'experimental'

Test Plan: n/a

Reviewers: igor, sdong, IslamAbdelRahman

Reviewed By: IslamAbdelRahman

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D46449
2015-09-09 13:27:19 -07:00
krad
52386a1e73 Minor fix to sandcastle jobs commands
Summary: Dropping parallel compilation since that seen to introduce compilation
errors spuriously

Test Plan: Run the command manually

Reviewers: sdon igor

CC: leveldb@

Task ID: #6968635

Blame Rev:
2015-09-09 10:54:50 -07:00
agiardullo
b5b2b75e52 better tuning of arena block size
Summary: Currently, if users didn't set options.arena_block_size, we set "result.arena_block_size = result.write_buffer_size / 10". It makes result.arena_block_size not a multiplier of 4KB, even if options.write_buffer_size is a multiplier of MBs. When calling malloc to arena_block_size, we may waste a small amount of memory for it. We now make the default to be /8 or /16 and align it to 4KB.

Test Plan: unit tests

Reviewers: sdong

Reviewed By: sdong

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D46467
2015-09-08 20:53:32 -07:00
sdong
342ba80895 Make DBTest.OptimizeFiltersForHits more deterministic
Summary:
This commit makes DBTest.OptimizeFiltersForHits more deterministic by:
(1) make key inserts more random
(2) make sure L0 has one file
(3) make file size smaller compared to level target so L1 will cover more range.

Test Plan: Run the test many times.

Reviewers: rven, IslamAbdelRahman, kradhakrishnan, igor, anthony

Reviewed By: anthony

Subscribers: leveldb, dhruba

Differential Revision: https://reviews.facebook.net/D46461
2015-09-08 19:31:34 -07:00
Andres Notzli
e17e92ea19 Relaxed assert in forward iterator
Summary:
It looks like in some cases an assert in SeekInternal failed when computing the
hints for the next level because user_key was the same as the largest key and
not strictly smaller. Relaxing the assert to expect smaller or equal keys.

Test Plan: make clean all check

Reviewers: sdong

Reviewed By: sdong

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D46443
2015-09-08 17:15:11 -07:00
agiardullo
5e94f68f35 TransactionDB Custom Locking API
Summary:
Prototype of API to allow MyRocks to override default Mutex/CondVar used by transactions with their own implementations.  They would simply need to pass their own implementations of Mutex/CondVar to the templated TransactionDB::Open().

Default implementation of TransactionDBMutex/TransactionDBCondVar provided (but the code is not currently changed to use this).

Let me know if this API makes sense or if it should be changed

Test Plan: n/a

Reviewers: yhchiang, rven, igor, sdong, spetrunia

Reviewed By: spetrunia

Subscribers: maykov, dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D43761
2015-09-08 17:03:57 -07:00
Andres Notzli
0ccf2db385 Fixed broken build due to format specifier
Summary:
Clang expects %llu for uint64_t, while gcc expects %lu. Replaced the format
specifier with a format macro. This should fix the build on gcc and Clang.

Test Plan: Build on gcc and clang.

Reviewers: rven, anthony, yhchiang, sdong, igor

Reviewed By: igor

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D46431
2015-09-08 15:46:16 -07:00
Andres Noetzli
6bdc484fd8 Added Equal method to Comparator interface
Summary:
In some cases, equality comparisons can be done more efficiently than three-way
comparisons. There are quite a few places in the code where we only care about
equality. This patch adds an Equal() method that defaults to using the
Compare() method.

Test Plan: make clean all check

Reviewers: rven, anthony, yhchiang, igor, sdong

Reviewed By: igor

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D46233
2015-09-08 15:30:49 -07:00
Amit Arya
7a31960ee9 Tests for ManifestDumpCommand and ListColumnFamiliesCommand
Summary:
Added tests for two LDBCommands namely i) ManifestDumpCommand and ii) ListColumnFamiliesCommand.
+ Minor fix in the sscanf formatter (along relace C cast with C++ cast) + replacing localtime with localtime_r which is thread safe.

Test Plan: make all && ./tools/ldb_test.py

Reviewers: anthony, igor, IslamAbdelRahman, kradhakrishnan, lgalanis, rven, sdong

Reviewed By: sdong

Subscribers: leveldb, dhruba

Differential Revision: https://reviews.facebook.net/D45819
2015-09-08 14:23:42 -07:00
krad
778cf4449b Adding email notification.
Summary: The email notifications needs to be at command level and the job level.
Adding command level notification.

Test Plan: Run command manually

Reviewers: igor sdong

CC: leveldb@

Task ID: #6968635

Blame Rev:
2015-09-08 14:19:03 -07:00
Andres Noetzli
3a0df7f161 Fixed comparison in ForwardIterator when computing hint for GetNextLevelIndex()
Summary: When computing the hint for GetNextLevelIndex(), ForwardIterator was doing a redundant comparison. This patch fixes the comparison (using https://github.com/facebook/rocksdb/blob/master/db/version_set.cc#L158 as a reference) and moves it inside an assert because we expect `level_files[f_idx]` to contain the next key after Seek(), so user_key should always be smaller than the largest key.

Test Plan: make clean all check

Reviewers: rven, anthony, yhchiang, igor, sdong

Reviewed By: sdong

Subscribers: tnovak, sdong, dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D46227
2015-09-08 09:47:54 -07:00
Venkatesh Radhakrishnan
91f3c90792 Fix case when forward iterator misses a new update
Summary:
This diff fixes a case when the forward iterator misses a new
insert when the mutable iterator is not current. The test is also
improved and the check for deleted iterators is made more informative.

Test Plan: DBTailingIteratorTest.*Trim

Reviewers: tnovak, sdong

Reviewed By: sdong

Subscribers: dhruba

Differential Revision: https://reviews.facebook.net/D46167
2015-09-04 14:28:45 -07:00
Igor Canadi
ff1953c890 Merge pull request #707 from dkorolev/master
Fixed a typo in INSTALL.md
2015-09-03 19:52:27 -07:00
Dima
7b463e657b Fixed a typo in INSTALL.md 2015-09-03 19:46:09 -07:00
Mayank Pundir
d9f42aa60d Adding a verifyBackup method to BackupEngine
Summary: This diff adds a verifyBackup method to BackupEngine. The method verifies the name and size of each file in the backup.

Test Plan: Unit test cases created and passing.

Reviewers: igor, benj

Subscribers: zelaine.fong, yhchiang, sdong, lgalanis, dhruba, AaronFeldman

Differential Revision: https://reviews.facebook.net/D46029
2015-09-03 17:27:21 -07:00
Paul Marinescu
50dc5f0c5a Replace BackupRateLimiter with GenericRateLimiter
Summary: BackupRateLimiter removed and uses replaced with the existing GenericRateLimiter

Test Plan:
make all check

make clean
USE_CLANG=1 make all

make clean
OPT=-DROCKSDB_LITE make release

Reviewers: leveldb, igor

Reviewed By: igor

Subscribers: igor, dhruba

Differential Revision: https://reviews.facebook.net/D46095
2015-09-03 17:00:09 -07:00
krad
20ef64cae0 Moving jobs to use gcc-4.9
Summary: Fixed the glitch in Sandcastle and added gcc-4.9 support. Moving the
jobs to 4.9

Test Plan: Manually run the script

Reviewers: sdon igor

CC: leveldb@

Task ID: #6968635

Blame Rev:
2015-09-03 15:20:36 -07:00
agiardullo
0f1aab6c12 Add SetLockTimeout for Transactions
Summary: MyRocks wants to be able to change the lock timeout of a transaction that has already started.  Expose existing SetLockTimeout function to users.

Test Plan: unit test

Reviewers: spetrunia, rven, sdong, yhchiang, igor

Reviewed By: igor

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D45987
2015-09-02 20:07:19 -07:00
Igor Canadi
14456aea52 Fix compile
Summary: There was a merge conflict with https://reviews.facebook.net/D45993

Test Plan: make check

Reviewers: sdong

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D46065
2015-09-02 16:05:53 -07:00
Igor Canadi
76f286cc82 Optimize bloom filter cache misses
Summary:
This optimizes the case when (cache_index_and_filter_blocks=1) and bloom filter is not present in the cache.

Previously we did:
1. Read meta block from file
2. Read the filter position from the meta block
3. Read the filter

Now, we pre-load the filter position on Table::Open(), so we can skip steps (1) and (2) on bloom filter cache miss. Instead of 2 IOs, we do only 1.

Test Plan: make check

Reviewers: sdong

Reviewed By: sdong

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D46047
2015-09-02 15:36:47 -07:00
Yueh-Hsuan Chiang
0e6e5472e1 Fixed a compile warning in rocksjni/loggerjnicallback.cc
Summary:
This patch fixes the following compile warning.
    java/rocksjni/loggerjnicallback.cc: In constructor ‘rocksdb::LoggerJniCallback::LoggerJniCallback(JNIEnv*, jobject)’:
    java/rocksjni/loggerjnicallback.cc:19:14: warning: unused variable ‘rs’ [-Wunused-variable]
       const jint rs = env->GetJavaVM(&m_jvm);
                  ^

Test Plan: make rocksdbjavastaticrelease

Reviewers: sdong, anthony, IslamAbdelRahman, igor

Reviewed By: igor

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D45981
2015-09-02 15:07:44 -07:00
krad
b8a962d4f5 Adding commands for few more CI jobs.
Summary: Added commands to spawn crash, stress, asan, asan_crash, clang CI jobs

Test Plan: Manual test

Reviewers: sdong

CC: leveldb@

Task ID: #6968635

Blame Rev:
2015-09-02 14:06:03 -07:00
Igor Canadi
8a2d59a356 Add Cloudera's blog post to USERS.md
Summary: As title

Test Plan: none

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

Reviewed By: sdong

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D46053
2015-09-02 14:04:51 -07:00
Andres Noetzli
3c9cef1eed Unified maps with Comparator for sorting, other cleanup
Summary:
This diff is a collection of cleanups that were initially part of D43179.
Additionally it adds a unified way of defining key-value maps that use a
Comparator for sorting (this was previously implemented in four different
places).

Test Plan: make clean check all

Reviewers: rven, anthony, yhchiang, sdong, igor

Reviewed By: igor

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D45993
2015-09-02 13:58:22 -07:00
sdong
3e0a672c50 Bug fix: table readers created by TableCache::Get() doesn't have latency histogram reported
Summary: TableCache::Get() puts parameters in the wrong places so that table readers created by Get() will not have the histogram updated.

Test Plan: Will write a unit test for that.

Subscribers: leveldb, dhruba

Differential Revision: https://reviews.facebook.net/D46035
2015-09-02 12:57:07 -07:00
Igor Canadi
b42cd6bed5 Remove the need for LATEST_BACKUP in BackupEngine
Summary:
In the first implementation of BackupEngine, LATEST_BACKUP was the commit point. The backup became committed after the write to LATEST_BACKUP completed.

However, we can avoid the need for LATEST_BACKUP. Instead of write to LATEST_BACKUP, the commit point can be the rename from `meta/<backup_id>.tmp` to `meta/<backup_id>`. Once we see that there exists a file `meta/<backup_id>` (without tmp), we can assume that backup is valid.

In this diff, we still write out the file LATEST_BACKUP. We need to do this so that we can maintain backward compatibility. However, the new version doesn't depend on this file anymore. We get the latest backup by `ls`-ing `meta` directory.

This diff depends on D41925

Test Plan: Adjusted backupable_db_test to this new behavior

Reviewers: benj, yhchiang, sdong, AaronFeldman

Reviewed By: sdong

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D42069
2015-09-02 11:49:49 -07:00
Siying Dong
0f763db20a Merge pull request #705 from yuslepukhin/rate_limiter_fix
Make WinEnv::NowMicros return system time
2015-09-02 11:35:17 -07:00
Amit Arya
20c44fefb7 t6913679: Use fallocate on LOG FILESS
Summary: Use fallocate on LOG FILES to

Test Plan:
make check
+
===check with strace===

[arya@devvm1441 ~/rocksdb] strace -e trace=fallocate ./ldb --db=/tmp/test_new scan
fallocate(3, 01, 0, 4194304)            = 0

Reviewers: sdong, anthony, IslamAbdelRahman, kradhakrishnan, lgalanis, rven, igor

Reviewed By: igor

Subscribers: leveldb, dhruba

Differential Revision: https://reviews.facebook.net/D45969
2015-09-02 11:17:02 -07:00
Dmitri Smirnov
f14c3363e1 Make WinEnv::NowMicros return system time
Previous change for the function
  555ca3e7b7 (diff-bdc04e0404c2db4fd3ac5118a63eaa4a)
  made use of the QueryPerformanceCounter to return microseconds values that do not repeat
  as std::chrono::system_clock returned values that made auto_roll_logger_test fail.

 The interface documentation does not state that we need to return
 system time describing the return value as a number of microsecs since some
 moment in time. However, because on Linux it is implemented using gettimeofday
 various pieces of code (such as GenericRateLimiter) took advantage of that
 and make use of NowMicros() as a system timestamp. Thus the previous change
 broke rate_limiter_test on Windows.

 In addition, the interface name NowMicros() suggests that it is actually
 a timestamp so people use it as such.

 This change makes use of the new system call on Windows that returns
 system time with required precision. This change preserves the fix
 for  auto_roll_logger_test and fixes rate_limiter_test.

 Note that DBTest.RateLimitingTest still fails due to a separately reported issue.
2015-09-02 11:12:07 -07:00