Summary:
We would like to collect file-system-level statistics including file name, offset, length, return code, latency, etc., which requires to add callbacks to intercept file IO function calls when RocksDB is running.
To collect file-system-level statistics, users can inherit the class `EventListener`, as in `TestFileOperationListener `. Note that `TestFileOperationListener::ShouldBeNotifiedOnFileIO()` returns true.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/3933
Differential Revision: D10219571
Pulled By: riversand963
fbshipit-source-id: 7acc577a2d31097766a27adb6f78eaf8b1e8ff15
Summary:
The "je_" prefix of jemalloc APIs presents only when the macro `JEMALLOC_NO_RENAME` from jemalloc.h presents.
With the patch I'm also adding -DROCKSDB_JEMALLOC flag in buck TARGETS.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4488
Differential Revision: D10355971
Pulled By: yiwu-arbug
fbshipit-source-id: 03a2d69790a44ac89219c7525763fa937a63d95a
Summary:
This commit adds code to acquire lock on the DB LOCK file
before starting the repair process. This will prevent
multiple processes from performing repair on the same DB
simultaneously. Fixes repair_test to work with this change.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4435
Differential Revision: D10361499
Pulled By: riversand963
fbshipit-source-id: 3c512c48b7193d383b2279ccecabdb660ac1cf22
Summary:
Using `./range_del_aggregator_bench --use_collapsed=false
--num_range_tombstones=5000 --num_runs=1000`, here are the results before and
after this change:
Before:
```
=========================
Results:
=========================
AddTombstones: 1822.61 us
ShouldDelete (first): 94.5286 us
```
After:
```
=========================
Results:
=========================
AddTombstones: 199.26 us
ShouldDelete (first): 38.9344 us
```
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4487
Differential Revision: D10347288
Pulled By: abhimadan
fbshipit-source-id: d44efe3a166d583acfdc3ec1199e0892f34dbfb7
Summary:
Wrong I overwrite `WriteBatch::Handler::Continue` to return _false_ at some point, I always get the `Status::Corruption` error.
I don't think this check is used correctly here: The counter in `found` cannot reflect all entries in the WriteBatch when we exit the loop early.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4478
Differential Revision: D10317416
Pulled By: yiwu-arbug
fbshipit-source-id: cccae3382805035f9b3239b66682b5fcbba6bb61
Summary:
Even during `DBIter::Prev()`, there is a case where we need to use `RangeDelPositioningMode::kForwardTraversal`. In particular, when we hit too many internal keys for a single user key, we use seek to find the newest internal key. If it's a merge operand, we then scan forwards, collecting the merge operands. This forward scan should be using `RangeDelPositioningMode::kForwardTraversal`.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4481
Differential Revision: D10319507
Pulled By: ajkr
fbshipit-source-id: b5ce7352461f3a7696b28a5136ae0076f2bde51f
Summary:
fix#4288
Add `OnCompactionBegin` support to `rocksdb::EventListener`.
Currently, we only have these three callbacks:
- OnFlushBegin
- OnFlushCompleted
- OnCompactionCompleted
As paolococchi requested in #4288 , and ajkr agreed, we should also support `OnCompactionBegin`.
This PR is a try to implement the support of `OnCompactionBegin`.
Hope it is useful to you.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4431
Differential Revision: D10055515
Pulled By: yiwu-arbug
fbshipit-source-id: 39c0f95f8e9ff1c7ca3a10787502a17f258d2334
Summary:
I wrote a couple tests using the public API to expose/prevent the bugs we talked. In particular,
- When files have overlapping endpoints and a range tombstone spans them, ensure the largest key does not reappear to readers. This was happening due to a bug that skipped writing range tombstones to an output file when their begin key exactly matched the file's largest key.
- When a tombstone spans multiple atomic compaction units, ensure newer keys do not disappear by being compacted beneath it. This happened due to a range tombstone appearing untruncated to readers when it spanned files with overlapping endpoints, even if it extended into files without overlapping endpoints (i.e., different atomic compaction units).
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4476
Differential Revision: D10286001
Pulled By: ajkr
fbshipit-source-id: bb5ca51d0f90812fb37bfe1d01aec93f7eda55aa
Summary:
There is a bug when the write queue leader is blocked on a write
delay/stop, and the queue has writers with WriteOptions::no_slowdown set
to true. They are not woken up until the write stall is cleared.
The fix introduces a dummy writer inserted at the tail to indicate a
write stall and prevent further inserts into the queue, and a condition
variable that writers who can tolerate slowdown wait on before adding
themselves to the queue. The leader calls WriteThread::BeginWriteStall()
to add the dummy writer and then walk the queue to fail any writers with
no_slowdown set. Once the stall clears, the leader calls
WriteThread::EndWriteStall() to remove the dummy writer and signal the
condition variable.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4475
Differential Revision: D10285827
Pulled By: anand1976
fbshipit-source-id: 747465e5e7f07a829b1fb0bc1afcd7b93f4ab1a9
Summary:
this avoids a few copies of std::string and other structs
in the context of range-based for loops. instead of copying
the values for each iteration, use a const reference to avoid
copying.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4459
Differential Revision: D10282045
Pulled By: sagar0
fbshipit-source-id: 5012e910dca279abd2be847e1fb432d96274edfb
Summary:
To more accurately truncate range tombstones at SST boundaries,
we now represent them in RangeDelAggregator using InternalKeys, which
are end-key-exclusive as they were before this change.
During compaction, "atomic compaction unit boundaries" (the range of
keys contained in neighbouring and overlaping SSTs) are propagated down
to RangeDelAggregator to truncate range tombstones at those boundariies
instead. See https://github.com/facebook/rocksdb/pull/4432#discussion_r221072219 and https://github.com/facebook/rocksdb/pull/4432#discussion_r221138683
for motivating examples.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4432
Differential Revision: D10263952
Pulled By: abhimadan
fbshipit-source-id: 2fe85ff8a02b3a6a2de2edfe708012797a7bd579
Summary:
Currently statistics are supposed to be dumped to info log at intervals of `options.stats_dump_period_sec`. However the implementation choice was to bind it with compaction thread, meaning if the database has been serving very light traffic, the stats may not get dumped at all.
We decided to separate stats dumping into a new timed thread using `TimerQueue`, which is already used in blob_db. This will allow us schedule new timed tasks with more deterministic behavior.
Tested with db_bench using `--stats_dump_period_sec=20` in command line:
> LOG:2018/09/17-14:07:45.575025 7fe99fbfe700 [WARN] [db/db_impl.cc:605] ------- DUMPING STATS -------
LOG:2018/09/17-14:08:05.643286 7fe99fbfe700 [WARN] [db/db_impl.cc:605] ------- DUMPING STATS -------
LOG:2018/09/17-14:08:25.691325 7fe99fbfe700 [WARN] [db/db_impl.cc:605] ------- DUMPING STATS -------
LOG:2018/09/17-14:08:45.740989 7fe99fbfe700 [WARN] [db/db_impl.cc:605] ------- DUMPING STATS -------
LOG content:
> 2018/09/17-14:07:45.575025 7fe99fbfe700 [WARN] [db/db_impl.cc:605] ------- DUMPING STATS -------
2018/09/17-14:07:45.575080 7fe99fbfe700 [WARN] [db/db_impl.cc:606]
** DB Stats **
Uptime(secs): 20.0 total, 20.0 interval
Cumulative writes: 4447K writes, 4447K keys, 4447K commit groups, 1.0 writes per commit group, ingest: 5.57 GB, 285.01 MB/s
Cumulative WAL: 4447K writes, 0 syncs, 4447638.00 writes per sync, written: 5.57 GB, 285.01 MB/s
Cumulative stall: 00:00:0.012 H:M:S, 0.1 percent
Interval writes: 4447K writes, 4447K keys, 4447K commit groups, 1.0 writes per commit group, ingest: 5700.71 MB, 285.01 MB/s
Interval WAL: 4447K writes, 0 syncs, 4447638.00 writes per sync, written: 5.57 MB, 285.01 MB/s
Interval stall: 00:00:0.012 H:M:S, 0.1 percent
** Compaction Stats [default] **
Level Files Size Score Read(GB) Rn(GB) Rnp1(GB) Write(GB) Wnew(GB) Moved(GB) W-Amp Rd(MB/s) Wr(MB/s) Comp(sec) Comp(cnt) Avg(sec) KeyIn KeyDrop
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4382
Differential Revision: D9933051
Pulled By: miasantreble
fbshipit-source-id: 6d12bb1e4977674eea4bf2d2ac6d486b814bb2fa
Summary:
- Fix DBImpl API race condition
The timeline of execution flow is as follow:
```
timeline user_thread1 user_thread2
t1 | cfh = GetColumnFamilyHandleUnlocked(0)
t2 | id1 = cfh->GetID()
t3 | GetColumnFamilyHandleUnlocked(1)
t4 | id2 = cfh->GetID()
V
```
The original implementation return a pointer to a stateful variable, so that the return `ColumnFamilyHandle` will be changed when another thread calls `GetColumnFamilyHandleUnlocked` with different `column family id`
- Expose ColumnFamily ID to compaction event listener
- Fix the return status of `DBImpl::GetLatestSequenceForKey`
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4391
Differential Revision: D10221243
Pulled By: yiwu-arbug
fbshipit-source-id: dec60ee9ff0c8261a2f2413a8506ec1063991993
Summary:
The controller you requested could not be found. PTAL
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4466
Differential Revision: D10241358
Pulled By: yiwu-arbug
fbshipit-source-id: 99664eb286860a6c8844d50efeb0ef6f0e10dd1e
Summary:
It also renames InstallMemtableFlushResults to MaybeInstallMemtableFlushResults to clarify its contract.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4464
Differential Revision: D10224918
Pulled By: maysamyabandeh
fbshipit-source-id: 04e3f2d8542002cb9f8010cb436f5152751b3cbe
Summary:
The contract of snprintf says that it returns "The number of characters that would have been written if n had been sufficiently large" http://www.cplusplus.com/reference/cstdio/snprintf/
The existing code however was assuming that the return value is the actual number of written bytes and uses that to reposition the starting point on the next call to snprintf. This leads to buffer overflow when the last call to snprintf has filled up the buffer.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4465
Differential Revision: D10224080
Pulled By: maysamyabandeh
fbshipit-source-id: 40f44e122d15b0db439812a0a361167cf012de3e
Summary:
This fix is for `level == 0` in `GetOverlappingInputs()`:
- In `GetOverlappingInputs()`, if `level == 0`, it has potential
risk of overflow if `i == 0`.
- Optmize process when `expand = true`, the expected complexity
can be reduced to O(n).
Signed-off-by: JiYou <jiyou09@gmail.com>
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4385
Differential Revision: D10181001
Pulled By: riversand963
fbshipit-source-id: 46eef8a1d1605c9329c164e6471cd5c5b6de16b5
Summary:
Before running CompactFilesTest.SentinelCompressionType, we should check
whether zlib and snappy are supported.
CompactFilesTest.SentinelCompressionType is a newly added test. Compilation and
linking with different options, e.g. COMPILE_WITH_TSAN, COMPILE_WITH_ASAN, etc.
lead to generation of different binaries. On the one hand, it's not clear why
zlib or snappy is present under ASAN, but not under TSAN. On the other hand,
changing the compilation flags for TSAN or ASAN seems a bigger change worth much
more attention. To unblock the cont-runs, I suggest that we simply add these
two checks at the beginning of the test, as we did for
GeneralTableTest.ApproximateOffsetOfCompressed in table/table_test.cc.
Future actions include invesigating the absence of zlib and snappy when
compiling with TSAN, i.e. COMPILE_WITH_TSAN=1, if necessary.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4443
Differential Revision: D10140935
Pulled By: riversand963
fbshipit-source-id: 62f96d1e685386accd2ef0b98f6f754d3fd67b3e
Summary:
In DBCompactionTestWithParam::ManualLevelCompactionOutputPathId, there is
a race condition between `DBTestBase::GetSstFileCount` and
`DBImpl::PurgeObsoleteFiles`. The following graph explains why.
```
Timeline db_compact_test_t bg_flush_t bg_compact_t
| [initiate bg flush and
| start waiting]
| flush
| DeleteObsoleteFiles
| [waken up by bg_flush_t which
| signaled in DeleteObsoleteFiles]
|
| [initiate compaction and
| start waiting]
|
| [compact,
| set manual.done to true]
| [signal at the end of
| BackgroundCallFlush]
|
| [waken up by bg_flush_t
| which signaled before
| returning from
| BackgroundCallFlush]
|
| Check manual.done is true
|
| GetSstFileCount <-- race condition --> PurgeObsoleteFiles
V
```
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4440
Differential Revision: D10122628
Pulled By: riversand963
fbshipit-source-id: 3ede73c39fee6ad804dc6ac1ed84759c7e63977f
Summary:
Previously `CompactFiles` with `CompressionType::kDisableCompressionOption` caused program to crash on assertion failure. This PR fixes the crash by adding support for that setting. Now, that setting will cause RocksDB to choose compression according to the column family's options.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4438
Differential Revision: D10115761
Pulled By: ajkr
fbshipit-source-id: a553c6fa76fa5b6f73b0d165d95640da6f454122
Summary:
`FindFile()` and `FindFileInRange()` actually works as the same
of `std::lower_bound()`. Use `std::lower_bound()` to reduce the
repeated code.
- change `FindFile()` and `FindFileInRange()` to use `std::lower_bound()`
Signed-off-by: JiYou <jiyou09@gmail.com>
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4372
Differential Revision: D9919677
Pulled By: ajkr
fbshipit-source-id: f74aaa30e2f80e410e299c5a5bca4eaf2a7a26de
Summary:
Improve log handling when avoid_flush_during_recovery=true.
1. restore total_log_size_ after recovery, by summing up existing log sizes. Fixes#4253.
2. truncate the last existing log, since this log can contain preallocated space and it will be a waste to keep the space. It avoids a crash loop of user application cause a lot of log with non-trivial size being created and ultimately take up all disk space.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4405
Differential Revision: D9953933
Pulled By: yiwu-arbug
fbshipit-source-id: 967780fee8acec7f358b6eb65190fb4684f82e56
Summary:
The CollapsedRangeDelMap was entirely mishandling tombstones at the same
sequence number when the tombstones did not have identical start and end
keys. Such tombstones are common since 90fc40690, which causes
tombstones to be split during compactions.
For example, if the tombstone [a, c) @ 1 lies across a compaction
boundary at b, it will be split into [a, b) @ 1 and [b, c) @ 1. Without
this patch, the collapsed range deletion map would look like this:
a -> 1
b -> 1
c -> 0
Notice how the b -> 1 entry is redundant. When the tombstones overlap,
the problem is even worse. Consider tombstones [a, c) @ 1 and [b, d) @
1, which produces this map without this patch:
a -> 1
b -> 1
c -> 0
d -> 0
This map is corrupt, as a map can never contain adjacent sentinel (zero)
entries. When the iterator advances from b to c, it will notice that c
is a sentinel enty and skip to d--but d is also a sentinel entry! Asking
what tombstone this iterator points to will trigger an assertion, as it
is not pointing to a valid tombstone.
/cc ajkr
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4424
Differential Revision: D10039248
Pulled By: abhimadan
fbshipit-source-id: 6d737c1e88d60e80cf27286726627ba44463e7f4
Summary:
Improve time measurements for AddTombstones to only include the
call and not the VectorIterator setup. Also add a new
add_tombstones_per_run flag to call AddTombstones multiple times per
aggregator, which will help simulate more realistic workloads.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4395
Differential Revision: D9996811
Pulled By: abhimadan
fbshipit-source-id: 5865a95c323fbd9b3606493013664b4890fe5a02
Summary:
Make the CompactOnDeletionCollectorFactory class public, and provide
methods to update the window size and deletion trigger params. These
will take effect on subsequent created SST files.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4403
Differential Revision: D9976857
Pulled By: anand1976
fbshipit-source-id: 31dbf0511c12fa2bb9b2a7ba620079e0ee09cf48
Summary:
Add a unit test for range collapsing when non-default comparator is used. This exposes the bug fixed in #4386.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4388
Differential Revision: D9918252
Pulled By: ajkr
fbshipit-source-id: 99501b96b251eab41791a7e33b27055ee36c5c39
Summary:
The Comparator passed to CollapsedRangeDelMap was not used for
operator less of the std::map `rep_` object contained in
CollapsedRangeDelMap. So the map was always sorted using the
default ByteWiseComparator, which seems wrong.
Passing the specified Comparator through for usage in that map
object fixes actual problems we were seeing with RangeDelete operations
that do not delete keys as expected when using a custom Comparator.
I found that the tests in current master crash when I run them locally,
both with and without my patch, at the very same location. I therefore
don't know if the patch breaks something else, but it seems to fix
RangeDeletion issues in our product that uses RocksDB.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4386
Differential Revision: D9916506
Pulled By: ajkr
fbshipit-source-id: 27bff8c775831f089dde8c5289df7343d88b2d66
Summary:
Value delta encoding in format_version 4 requires the differences between the size of two consecutive handles to be sent to BlockBuilder::Add. This applies not only to indexes on blocks but also the indexes on indexes and filters in partitioned indexes and filters respectively. The patch fixes a bug where the partitioned filters would encode the entire size of the handle rather than the difference of the size with the last size.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4381
Differential Revision: D9879505
Pulled By: maysamyabandeh
fbshipit-source-id: 27a22e49b482b927fbd5629dc310c46d63d4b6d1
Summary:
To measure the results of upcoming DeleteRange v2 work, this commit adds
simple benchmarks for RangeDelAggregator. It measures the average time
for AddTombstones and ShouldDelete calls.
Using this to compare the results before #4014 and on the latest master (using the default arguments) produces the following results:
Before #4014:
```
=======================
Results:
=======================
AddTombstones: 1356.28 us
ShouldDelete: 0.401732 us
```
Latest master:
```
=======================
Results:
=======================
AddTombstones: 740.82 us
ShouldDelete: 0.383271 us
```
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4363
Differential Revision: D9881676
Pulled By: abhimadan
fbshipit-source-id: 793e7d61aa4b9d47eb917bbcc03f08695b5e5442
Summary:
1. Add override keyword to overridden virtual functions in EventListener
2. Fix a memory corruption that can happen during DB shutdown when in
read-only mode due to a background write error
3. Fix uninitialized buffers in error_handler_test.cc that cause
valgrind to complain
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4375
Differential Revision: D9875779
Pulled By: anand1976
fbshipit-source-id: 022ede1edc01a9f7e21ecf4c61ef7d46545d0640
Summary:
This commit implements automatic recovery from a Status::NoSpace() error
during background operations such as write callback, flush and
compaction. The broad design is as follows -
1. Compaction errors are treated as soft errors and don't put the
database in read-only mode. A compaction is delayed until enough free
disk space is available to accomodate the compaction outputs, which is
estimated based on the input size. This means that users can continue to
write, and we rely on the WriteController to delay or stop writes if the
compaction debt becomes too high due to persistent low disk space
condition
2. Errors during write callback and flush are treated as hard errors,
i.e the database is put in read-only mode and goes back to read-write
only fater certain recovery actions are taken.
3. Both types of recovery rely on the SstFileManagerImpl to poll for
sufficient disk space. We assume that there is a 1-1 mapping between an
SFM and the underlying OS storage container. For cases where multiple
DBs are hosted on a single storage container, the user is expected to
allocate a single SFM instance and use the same one for all the DBs. If
no SFM is specified by the user, DBImpl::Open() will allocate one, but
this will be one per DB and each DB will recover independently. The
recovery implemented by SFM is as follows -
a) On the first occurance of an out of space error during compaction,
subsequent
compactions will be delayed until the disk free space check indicates
enough available space. The required space is computed as the sum of
input sizes.
b) The free space check requirement will be removed once the amount of
free space is greater than the size reserved by in progress
compactions when the first error occured
c) If the out of space error is a hard error, a background thread in
SFM will poll for sufficient headroom before triggering the recovery
of the database and putting it in write-only mode. The headroom is
calculated as the sum of the write_buffer_size of all the DB instances
associated with the SFM
4. EventListener callbacks will be called at the start and completion of
automatic recovery. Users can disable the auto recov ery in the start
callback, and later initiate it manually by calling DB::Resume()
Todo:
1. More extensive testing
2. Add disk full condition to db_stress (follow-on PR)
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4164
Differential Revision: D9846378
Pulled By: anand1976
fbshipit-source-id: 80ea875dbd7f00205e19c82215ff6e37da10da4a
Summary:
Because `base_files` and `added_files` both are sorted, using a merge
operation to these two sorted arrays is more effective. The complexity
is reduced to linear time.
- optmize the merge complexity.
- move the `NDEBUG` of sorted `added_files` out of merge process.
Signed-off-by: JiYou <jiyou09@gmail.com>
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4366
Differential Revision: D9833592
Pulled By: ajkr
fbshipit-source-id: dd32b67ebdca4c20e5e9546ab8082cecefe99fd0
Summary:
The code is dead in RocksDB as `log::Reader::initial_offset_` is always zero. We should delete it so we don't have to maintain it like in #4359.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4362
Differential Revision: D9817829
Pulled By: ajkr
fbshipit-source-id: 474a2c679e5bd273b40608f3a5332931d9eefe6d
Summary:
Please consider this small PR providing access to the `MemoryUsage::GetApproximateMemoryUsageByType` function in plain C API. Actually I'm working on Go application and now trying to investigate the reasons of high memory consumption (#4313). Go [wrappers](https://github.com/tecbot/gorocksdb) are built on the top of Rocksdb C API. According to the #706, `MemoryUsage::GetApproximateMemoryUsageByType` is considered as the best option to get database internal memory usage stats, but it wasn't supported in C API yet.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4340
Differential Revision: D9655135
Pulled By: ajkr
fbshipit-source-id: a3d2f3f47c143ae75862fbcca2f571ea1b49e14a
Summary:
`RangeDelAggregator::AddTombstones` contained an assertion which stated that, if a range tombstone extended past the largest key in the sstable, then `FileMetaData::largest` must have a sentinel sequence number of `kMaxSequenceNumber`, which implies that the tombstone's end key is safe to truncate. However, `largest` will not be a sentinel key when the next sstable in the level's smallest key is equal to the current sstable's largest key, which caused the assertion to fail.
The assertion must hold for the truncation to be safe, so it has been moved to an additional check on end-key truncation.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4356
Differential Revision: D9760891
Pulled By: abhimadan
fbshipit-source-id: 7c20c3885cd919dcd14f291f88fd27aa33defebc
Summary:
TransactionOptions::skip_concurrency_control allows pessimistic transactions to skip the overhead of concurrency control. This could be as an optimization if the application knows that the transaction would not have any conflict with concurrent transactions. It is currently used during recovery assuming (i) application guarantees no conflict between prepared transactions in the WAL (ii) application guarantees that recovered transactions will be rolled back/commit before new transactions start.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4346
Differential Revision: D9759149
Pulled By: maysamyabandeh
fbshipit-source-id: f896e84fa58b0b584be904c7fd3883a41ea3215b
Summary:
In C++ 11, the order of argument and move evaluation in a statement such
as below is unspecified -
foo(a.b).bar(std::move(a))
The compiler is free to evaluate std::move(a) first, and then a.b is unspecified.
In C++ 17, this will be safe if a draft proposal around function
chaining rules is accepted.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4348
Differential Revision: D9688810
Pulled By: anand1976
fbshipit-source-id: e4651d0ca03dcf007e50371a0fc72c0d1e710fb4
Summary:
As you know, almost all compilers support "pragma once" keyword instead of using include guards. To be keep consistency between header files, all header files are edited.
Besides this, try to fix some warnings about loss of data.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4339
Differential Revision: D9654990
Pulled By: ajkr
fbshipit-source-id: c2cf3d2d03a599847684bed81378c401920ca848
