Summary:
Universal size-amp-triggered compaction was pulling the final sorted run into the compaction without checking whether any of its files are already being compacted. When all compactions are automatic, it is safe since it verifies the second-last sorted run is not already being compacted, which implies the last sorted run is also not being compacted (in automatic compaction multiple sorted runs are always compacted together). But with manual compaction, files in the last sorted run can be compacted independently, so the last sorted run also must be checked.
We were seeing the below assertion failure in `db_stress`. Also the test case included in this PR repros the failure.
```
db_universal_compaction_test: db/compaction.cc:312: void rocksdb::Compaction::MarkFilesBeingCompacted(bool): Assertion `mark_as_compacted ? !inputs_[i][j]->being_compacted : inputs_[i][j]->being_compacted' failed.
Aborted (core dumped)
```
Closes https://github.com/facebook/rocksdb/pull/4055
Differential Revision: D8630094
Pulled By: ajkr
fbshipit-source-id: ac3b30a874678b76e113d4f6c42c1260411b08f8
Summary:
Pass in `for_compaction` to `BlockBasedTableIterator` via `BlockBasedTableReader::NewIterator`.
In 7103559f49, `for_compaction` was set in `BlockBasedTable::Rep` via `BlockBasedTable::SetupForCompaction`. In hindsight it was not the right decision; it also caused TSAN to complain.
Closes https://github.com/facebook/rocksdb/pull/4048
Differential Revision: D8601056
Pulled By: sagar0
fbshipit-source-id: 30127e898c15c38c1080d57710b8c5a6d64a0ab3
Summary:
Top-level index in partitioned index/filter blocks are small and could be pinned in memory. So far we use that by cache_index_and_filter_blocks to false. This however make it difficult to keep account of the total memory usage. This patch introduces pin_top_level_index_and_filter which in combination with cache_index_and_filter_blocks=true keeps the top-level index in cache and yet pinned them to avoid cache misses and also cache lookup overhead.
Closes https://github.com/facebook/rocksdb/pull/4037
Differential Revision: D8596218
Pulled By: maysamyabandeh
fbshipit-source-id: 3a5f7f9ca6b4b525b03ff6bd82354881ae974ad2
Summary:
For example calling CompactionFilter is always timed and gives the user no way to disable.
This PR will disable the timer if `Statistics::stats_level_` (which is part of DBOptions) is `kExceptDetailedTimers`
Closes https://github.com/facebook/rocksdb/pull/4029
Differential Revision: D8583670
Pulled By: miasantreble
fbshipit-source-id: 913be9fe433ae0c06e88193b59d41920a532307f
Summary:
We potentially need this information for tracing, profiling and diagnosis.
Closes https://github.com/facebook/rocksdb/pull/4026
Differential Revision: D8555214
Pulled By: riversand963
fbshipit-source-id: 4263e06c00b6d5410b46aa46eb4e358ff2161dd2
Summary:
b555ed30a4 makes the BlockBasedTableIterator to be invalidated if the current position if over the upper bound. However, this can bring performance regression to the case of multiple Seek()s hitting the same data block but all out of upper bound.
For example, if an SST file has a data block containing following keys : {a, z}
The user sets the upper bound to be "x", and it executed following queries:
Seek("b")
Seek("c")
Seek("d")
Before the upper bound optimization, these queries always come to this same current data block of the iterator, but now inside each Seek() the data block is read from the block cache but is returned again.
To prevent this regression case, we keep the current data block iterator if it is upper bound.
Closes https://github.com/facebook/rocksdb/pull/4004
Differential Revision: D8463192
Pulled By: siying
fbshipit-source-id: 8710628b30acde7063a097c3184d6c4333a8ef81
Summary:
The Block object assumes contents are uncompressed. Block's constructor tries to read the number of restarts, but does not get an accurate number when its contents are compressed, which is causing issues like https://github.com/facebook/rocksdb/issues/3843.
This PR address this issue by skipping reconstruction of restart points when blocks are known to be compressed. Somehow the restart points can be read directly when Snappy is used and some tests (for example https://github.com/facebook/rocksdb/blob/master/db/db_block_cache_test.cc#L196) expects blocks to be fully constructed even when Snappy compression is used, so here we keep the restart point logic for Snappy.
Closes https://github.com/facebook/rocksdb/pull/3996
Differential Revision: D8416186
Pulled By: miasantreble
fbshipit-source-id: 002c0b62b9e5d89fb7736563d354ce0023c8cb28
Summary:
Don't call the OnTableFileCreated listener callback when a 0 size SST
file gets created by Flush. Doing so causes an assertion failure in db_stress. It is also not correct behavior as we call env->DeleteFile() for such files right before the notification.
Closes https://github.com/facebook/rocksdb/pull/4003
Differential Revision: D8461385
Pulled By: anand1976
fbshipit-source-id: ae92d4f921c2e2cff981ad58f4929ed8b609f35d
Summary:
Add a new DB property to DB::GetProperty(), which returns the option.statistics. Test is updated to pass.
Closes https://github.com/facebook/rocksdb/pull/3966
Differential Revision: D8311139
Pulled By: zhichao-cao
fbshipit-source-id: ea78f4727358c807b0e5a0ea62e09defb10ad9ac
Summary:
Verify table will load SST into `TableCache`
it occupy memory & `TableCache`‘s capacity ...
but no logic use them
it's unnecessary ...
so , we verify them after all sub compact finished
Closes https://github.com/facebook/rocksdb/pull/3979
Differential Revision: D8389946
Pulled By: ajkr
fbshipit-source-id: 54bd4f474f9e7b3accf39c3068b1f36a27ec4c49
Summary:
The SST file sizes changed slightly after the improvement of PR #3970
which reduces the size of the properties block. Before PR #3970 a size
ratio compaction included all of the first four flushed files but it
only includes two files after. We increase the size_ratio universal
compaction option to make that compaction include all four files again.
Closes https://github.com/facebook/rocksdb/pull/3995
Differential Revision: D8426925
Pulled By: fgwu
fbshipit-source-id: 1429c38672e9f4fb4d4881fd4b06db45c4861d62
Summary:
A recent change pushed down the upper bound checking to child iterators. However, this causes the logic of following sequence wrong:
Seek(key);
if (!Valid()) SeekToLast();
Because !Valid() may be caused by upper bounds, rather than the end of the iterator. In this case SeekToLast() points to totally wrong places. This can cause wrong results, infinite loops, or segfault in some cases.
This sequence is called when changing direction from forward to backward. And this by itself also implicitly happen during reseeking optimization in Prev().
Fix this bug by using SeekForPrev() rather than this sequuence, as what is already done in prefix extrator case.
Closes https://github.com/facebook/rocksdb/pull/3989
Differential Revision: D8385422
Pulled By: siying
fbshipit-source-id: 429e869990cfd2dc389421e0836fc496bed67bb4
Summary:
format_version 3 changes the format of index blocks by storing user keys instead of the internal keys, which saves 8-bytes per key. This patch extends the format to top-level indexes in partitioned index/filters.
Closes https://github.com/facebook/rocksdb/pull/3958
Differential Revision: D8294615
Pulled By: maysamyabandeh
fbshipit-source-id: 17666cc16b8076c363972e2308e31547e835f0fe
Summary:
CompactFiles checked whether the existing files conflicted with the chosen compaction. But it missed checking whether future files would conflict, i.e., when another compaction was simultaneously writing new files to the same range at the same output level.
Closes https://github.com/facebook/rocksdb/pull/3926
Differential Revision: D8218996
Pulled By: ajkr
fbshipit-source-id: 21cb00a6fed4c8c62d3ed2ff810962e6bdc2fdfb
Summary:
PR https://github.com/facebook/rocksdb/pull/3838 made some changes that triggers lint warnings.
Run `make format` to fix formatting as suggested by siying .
Also piggyback two changes:
1) fix singleton destruction order for windows and posix env
2) fix two clang warnings
Closes https://github.com/facebook/rocksdb/pull/3954
Differential Revision: D8272041
Pulled By: miasantreble
fbshipit-source-id: 7c4fd12bd17aac13534520de0c733328aa3c6c9f
Summary:
format_version=3 changes the format of SST index. This is however not being tested currently since tests only work with the default format_version which is currently 2. The patch extends the most related tests to also test for format_version=3.
Closes https://github.com/facebook/rocksdb/pull/3942
Differential Revision: D8238413
Pulled By: maysamyabandeh
fbshipit-source-id: 915725f55753dd8e9188e802bf471c23645ad035
Summary:
Previous commit https://github.com/facebook/rocksdb/pull/3935 unhide a few test options which includes kDirectIO. However it's not supported by RocksDB lite. Need to hide this option from the lite build.
Closes https://github.com/facebook/rocksdb/pull/3943
Differential Revision: D8242757
Pulled By: miasantreble
fbshipit-source-id: 1edfad3a5d01a46bfb7eedee765981ebe02c500a
Summary:
For iterator reads, a `SuperVersion` is pinned to preserve a snapshot of SST files, and `Block`s are pinned to allow `key()` and `value()` to return pointers directly into a RocksDB memory region. This works for both non-mmap reads, where the block owns the memory region, and mmap reads, where the file owns the memory region.
For point reads with `PinnableSlice`, only the `Block` object is pinned. This works for non-mmap reads because the block owns the memory region, so even if the file is deleted after compaction, the memory region survives. However, for mmap reads, file deletion causes the memory region to which the `PinnableSlice` refers to be unmapped. The result is usually a segfault upon accessing the `PinnableSlice`, although sometimes it returned wrong results (I repro'd this a bunch of times with `db_stress`).
This PR copies the value into the `PinnableSlice` when it comes from mmap'd memory. We can tell whether the `Block` owns its memory using `Block::cachable()`, which is unset when reads do not use the provided buffer as is the case with mmap file reads. When that is false we ensure the result of `Get()` is copied.
This feels like a short-term solution as ideally we'd have the `PinnableSlice` pin the mmap'd memory so we can do zero-copy reads. It seemed hard so I chose this approach to fix correctness in the meantime.
Closes https://github.com/facebook/rocksdb/pull/3881
Differential Revision: D8076288
Pulled By: ajkr
fbshipit-source-id: 31d78ec010198723522323dbc6ea325122a46b08
Summary:
DBTestBase::OptionConfig includes the scenarios that unit tests could iterate over them by calling ChangeOptions(). Some of the options have been mistakenly put after kEnd which makes them essentially invisible to ChangeOptions() caller. This patch fixes it except for kUniversalSubcompactions which is left as TODO since it would break some unit tests.
Closes https://github.com/facebook/rocksdb/pull/3935
Differential Revision: D8230748
Pulled By: maysamyabandeh
fbshipit-source-id: edddb8fffcd161af1809fef24798ce118f8593db
Summary:
DBImpl::FindObsoleteFiles() may call GetChildren() multiple times if different CFs are on the same path. Fix it.
Closes https://github.com/facebook/rocksdb/pull/3885
Differential Revision: D8084634
Pulled By: siying
fbshipit-source-id: b471fbc251f6a05e9243304dc14c0831060cc0b0
Summary:
In order to make valgrind check test to pass in a day, remove some tests that run prohibitively slow under valgrind.
Closes https://github.com/facebook/rocksdb/pull/3924
Differential Revision: D8210184
Pulled By: siying
fbshipit-source-id: 5b06fb08f3cf57571d422d05a0dbddc9f9376f7a
Summary:
This is still WIP, but I'm hoping for early feedback on the overall approach.
This patch implements deletion triggered compaction, which till now only
worked for leveled, for universal style. SST files are marked for
compaction by the CompactOnDeletionCollertor table property. This is
expected to be used when free disk space is low and the user wants to
reclaim space by deleting a bunch of keys. The deletions are expected to
be dense. In such a situation, we want to avoid a full compaction due to
its space overhead.
The strategy used in this case is similar to leveled. We pick one file
from the set of files marked for compaction. We then expand the inputs
to a clean cut on the same level, and then pick overlapping files from
the next non-mepty level. Picking files from the next level can cause
the key range to expand, and we opportunistically expand inputs in the
source level to include files wholly in this key range.
The main side effect of this is that it breaks the property of no time
range overlap between levels. This shouldn't break any functionality.
Closes https://github.com/facebook/rocksdb/pull/3860
Differential Revision: D8124397
Pulled By: anand1976
fbshipit-source-id: bfa2a9dd6817930e991b35d3a8e7e61304ed3dcf
Summary:
Index blocks have the same format as data blocks. The keys therefore similarly to the keys in the data blocks are internal keys, which means that in addition to the user key it also has 8 bytes that encodes sequence number and value type. This extra 8 bytes however is not necessary in index blocks since the index keys act as an separator between two data blocks. The only exception is when the last key of a block and the first key of the next block share the same user key, in which the sequence number is required to act as a separator.
The patch excludes the sequence from index keys only if the above special case does not happen for any of the index keys. It then records that in the property block. The reader looks at the property block to see if it should expect sequence numbers in the keys of the index block.s
Closes https://github.com/facebook/rocksdb/pull/3894
Differential Revision: D8118775
Pulled By: maysamyabandeh
fbshipit-source-id: 915479f028b5799ca91671d67455ecdefbd873bd
Summary:
Please refer to earlier discussion in [issue 3609](https://github.com/facebook/rocksdb/issues/3609).
There was also an alternative fix in [PR 3888](https://github.com/facebook/rocksdb/pull/3888), but the proposed solution requires complex change.
To summarize the cause of the problem. Upon creation of a column family, a `BlockBasedTableFactory` object is `new`ed and encapsulated by a `std::shared_ptr`. Since there is no other `std::shared_ptr` pointing to this `BlockBasedTableFactory`, when the column family is dropped, the `ColumnFamilyData` is `delete`d, causing the destructor of `std::shared_ptr`. Since there is no other `std::shared_ptr`, the underlying memory is also freed.
Later when the db exits, it releases all the table readers, including the table readers that have been operating on the dropped column family. This needs to access the `table_options` owned by `BlockBasedTableFactory` that has already been deleted. Therefore, a segfault is raised.
Previous workaround is to purge all obsolete files upon `ColumnFamilyData` destruction, which leads to a force release of table readers of the dropped column family. However this does not work when the user disables file deletion.
Our solution in this PR is making a copy of `table_options` in `BlockBasedTable::Rep`. This solution increases memory copy and usage, but is much simpler.
Test plan
```
$ make -j16
$ ./column_family_test --gtest_filter=ColumnFamilyTest.CreateDropAndDestroy:ColumnFamilyTest.CreateDropAndDestroyWithoutFileDeletion
```
Expected behavior:
All tests should pass.
Closes https://github.com/facebook/rocksdb/pull/3898
Differential Revision: D8149421
Pulled By: riversand963
fbshipit-source-id: eaecc2e064057ef607fbdd4cc275874f866c3438
Summary:
Add flush_before_backup to rocksdb_backup_engine_create_new_backup. make c api able to control the flush before backup behavior.
Closes https://github.com/facebook/rocksdb/pull/3897
Differential Revision: D8157676
Pulled By: ajkr
fbshipit-source-id: 88998c62f89f087bf8672398fd7ddafabbada505
Summary:
Implement midpoint insertion strategy where new blocks will be insert to the middle of LRU list, then move the head on the first hit in cache.
Closes https://github.com/facebook/rocksdb/pull/3877
Differential Revision: D8100895
Pulled By: yiwu-arbug
fbshipit-source-id: f4bd83cb8be469e5d02072cfc8bd66011391f3da
Summary:
Explicitly specify the underlying type of enums help developers understand the physical storage.
Closes https://github.com/facebook/rocksdb/pull/3892
Differential Revision: D8107027
Pulled By: riversand963
fbshipit-source-id: a00efecbba46df4a3c8eed0994a2d4972ad1a1d3
Summary:
DBTest.GroupCommitTest would often fail when run under valgrind because its sleeps were insufficient to guarantee a group commit had multiple entries. Instead we can use sync point to force a leader to wait until a non-leader thread has enqueued its work, thus guaranteeing a leader can do group commit work for multiple threads.
Closes https://github.com/facebook/rocksdb/pull/3883
Differential Revision: D8079429
Pulled By: ajkr
fbshipit-source-id: 61dc50fad29d2c85547842f681288de60fa29049
Summary:
By using WritableFileWriter rather than WritableFile directly, we can buffer multiple Append() calls to one write() file system call, which will be expensive to underlying Env without its own write buffering.
Closes https://github.com/facebook/rocksdb/pull/3882
Differential Revision: D8080673
Pulled By: siying
fbshipit-source-id: e0db900cb3c178166aa738f3985db65e3ae2cf1b
Summary:
Currently it is not possible to change bloom filter config without restart the db, which is causing a lot of operational complexity for users.
This PR aims to make it possible to dynamically change bloom filter config.
Closes https://github.com/facebook/rocksdb/pull/3601
Differential Revision: D7253114
Pulled By: miasantreble
fbshipit-source-id: f22595437d3e0b86c95918c484502de2ceca120c
Summary:
Change `keys_` from `set<string>` to `vector<set<string>>` so that each column
family's keys are stored in one set.
ajkr When you have a chance, can you PTAL? Thanks!
Closes https://github.com/facebook/rocksdb/pull/3871
Differential Revision: D8056447
Pulled By: riversand963
fbshipit-source-id: 650d0f9cad02b1bc005fc329ad76edbf053e6386
Summary:
`RangeDelAggregator` holds the pointers returned by `BlockIter::key()` and `BlockIter::value()` so requires the data to which they point is pinned. `BlockIter::key()` points into block memory and is guaranteed to be pinned if and only if prefix encoding is disabled (or, equivalently, restart interval is set to one). I think `BlockIter::value()` is always pinned. Added an assert for these and removed the wrong TODO about increasing restart interval, which would enable key prefix encoding and break the assertion.
Closes https://github.com/facebook/rocksdb/pull/3875
Differential Revision: D8063667
Pulled By: ajkr
fbshipit-source-id: 60b5ebcc0cdd610dd6aad9e74a23378793672c41
Summary:
Right now ReverseBytewiseComparator::FindShortestSeparator() doesn't really shorten key, and ReverseBytewiseComparator::FindShortestSuccessor() seems to return wrong results. The code is confusing too as it uses BytewiseComparatorImpl::FindShortestSeparator() but the function actually won't do anything if the the first key is larger than the second.
Implement ReverseBytewiseComparator::FindShortestSeparator() and override ReverseBytewiseComparator::FindShortestSuccessor() to be empty.
Closes https://github.com/facebook/rocksdb/pull/3836
Differential Revision: D7959762
Pulled By: siying
fbshipit-source-id: 93acb621c16ce6f23e087ae4e19f7d84d1254683
Summary:
this will fix the failing clang_check test
Closes https://github.com/facebook/rocksdb/pull/3868
Differential Revision: D8050880
Pulled By: miasantreble
fbshipit-source-id: 749932e2e4025f835c961c068d601e522a126da6
Summary:
Before this PR, Iterator/InternalIterator may simultaneously have non-ok status() and Valid() = true. That state means that the last operation failed, but the iterator is nevertheless positioned on some unspecified record. Likely intended uses of that are:
* If some sst files are corrupted, a normal iterator can be used to read the data from files that are not corrupted.
* When using read_tier = kBlockCacheTier, read the data that's in block cache, skipping over the data that is not.
However, this behavior wasn't documented well (and until recently the wiki on github had misleading incorrect information). In the code there's a lot of confusion about the relationship between status() and Valid(), and about whether Seek()/SeekToLast()/etc reset the status or not. There were a number of bugs caused by this confusion, both inside rocksdb and in the code that uses rocksdb (including ours).
This PR changes the convention to:
* If status() is not ok, Valid() always returns false.
* Any seek operation resets status. (Before the PR, it depended on iterator type and on particular error.)
This does sacrifice the two use cases listed above, but siying said it's ok.
Overview of the changes:
* A commit that adds missing status checks in MergingIterator. This fixes a bug that actually affects us, and we need it fixed. `DBIteratorTest.NonBlockingIterationBugRepro` explains the scenario.
* Changes to lots of iterator types to make all of them conform to the new convention. Some bug fixes along the way. By far the biggest changes are in DBIter, which is a big messy piece of code; I tried to make it less big and messy but mostly failed.
* A stress-test for DBIter, to gain some confidence that I didn't break it. It does a few million random operations on the iterator, while occasionally modifying the underlying data (like ForwardIterator does) and occasionally returning non-ok status from internal iterator.
To find the iterator types that needed changes I searched for "public .*Iterator" in the code. Here's an overview of all 27 iterator types:
Iterators that didn't need changes:
* status() is always ok(), or Valid() is always false: MemTableIterator, ModelIter, TestIterator, KVIter (2 classes with this name anonymous namespaces), LoggingForwardVectorIterator, VectorIterator, MockTableIterator, EmptyIterator, EmptyInternalIterator.
* Thin wrappers that always pass through Valid() and status(): ArenaWrappedDBIter, TtlIterator, InternalIteratorFromIterator.
Iterators with changes (see inline comments for details):
* DBIter - an overhaul:
- It used to silently skip corrupted keys (`FindParseableKey()`), which seems dangerous. This PR makes it just stop immediately after encountering a corrupted key, just like it would for other kinds of corruption. Let me know if there was actually some deeper meaning in this behavior and I should put it back.
- It had a few code paths silently discarding subiterator's status. The stress test caught a few.
- The backwards iteration code path was expecting the internal iterator's set of keys to be immutable. It's probably always true in practice at the moment, since ForwardIterator doesn't support backwards iteration, but this PR fixes it anyway. See added DBIteratorTest.ReverseToForwardBug for an example.
- Some parts of backwards iteration code path even did things like `assert(iter_->Valid())` after a seek, which is never a safe assumption.
- It used to not reset status on seek for some types of errors.
- Some simplifications and better comments.
- Some things got more complicated from the added error handling. I'm open to ideas for how to make it nicer.
* MergingIterator - check status after every operation on every subiterator, and in some places assert that valid subiterators have ok status.
* ForwardIterator - changed to the new convention, also slightly simplified.
* ForwardLevelIterator - fixed some bugs and simplified.
* LevelIterator - simplified.
* TwoLevelIterator - changed to the new convention. Also fixed a bug that would make SeekForPrev() sometimes silently ignore errors from first_level_iter_.
* BlockBasedTableIterator - minor changes.
* BlockIter - replaced `SetStatus()` with `Invalidate()` to make sure non-ok BlockIter is always invalid.
* PlainTableIterator - some seeks used to not reset status.
* CuckooTableIterator - tiny code cleanup.
* ManagedIterator - fixed some bugs.
* BaseDeltaIterator - changed to the new convention and fixed a bug.
* BlobDBIterator - seeks used to not reset status.
* KeyConvertingIterator - some small change.
Closes https://github.com/facebook/rocksdb/pull/3810
Differential Revision: D7888019
Pulled By: al13n321
fbshipit-source-id: 4aaf6d3421c545d16722a815b2fa2e7912bc851d
Summary:
log_ contract specifies that it should not be modified unless both mutex_ and log_write_mutex_ are held. log_.erase however does that with only holding mutex_. This causes a race condition with two_write_queues since logs_.back is read with holding only log_write_mutex_ (which is correct according to logs_ contract) but logs_.erase is called concurrently. This is probably the cause of logs_.back returning nullptr in https://github.com/facebook/rocksdb/issues/3852 although I could not reproduce it.
Fixes https://github.com/facebook/rocksdb/issues/3852
Closes https://github.com/facebook/rocksdb/pull/3859
Differential Revision: D8026103
Pulled By: maysamyabandeh
fbshipit-source-id: ee394e00fe4aa520d884c5ef87981e9d6b5ccb28
Summary:
TSAN reports a false alarm for lock-order-inversion in DBWriteTest.IOErrorOnWALWritePropagateToWriteThreadFollower but Open and FlushWAL are not run concurrently. Suppressing the error by skipping FlushWAL in the test until TSAN is fixed.
The alternative would be to use
```
TSAN_OPTIONS="suppressions=tsan-suppressions.txt" ./db_write_test
```
but it does not seem straightforward to integrate it to our test infra.
Closes https://github.com/facebook/rocksdb/pull/3854
Differential Revision: D8000202
Pulled By: maysamyabandeh
fbshipit-source-id: fde33483d963a7ad84d3145123821f64960a4802
Summary:
This feature was introduced for universal compaction in cc01985d. At that point we thought it'd be used only to prevent long-running universal full compactions from blocking short-lived upper-level compactions. Now we have a level compaction user who could benefit from it since they use more expensive compression algorithm in the bottom level. So enable it for level.
Closes https://github.com/facebook/rocksdb/pull/3835
Differential Revision: D7957179
Pulled By: ajkr
fbshipit-source-id: 177285d2cef3b650b6a4d81dc5db84bc441c9fe4
Summary:
Currently manual_wal_flush if set in the options will be used only for the wal files created during wal switch. The configuration thus does not affect the first wal file. The patch fixes that and also update the related unit tests.
This PR is built on top of https://github.com/facebook/rocksdb/pull/3756
Closes https://github.com/facebook/rocksdb/pull/3824
Differential Revision: D7909153
Pulled By: maysamyabandeh
fbshipit-source-id: 024ed99d2555db06bf096c902b998e432bb7b9ce
Summary:
Previously `DBOptions::use_direct_io_for_flush_and_compaction=true` combined with `DBOptions::use_direct_reads=false` could cause RocksDB to simultaneously read from two file descriptors for the same file, where background reads used direct I/O and foreground reads used buffered I/O. Our measurements found this mixed-mode I/O negatively impacted foreground read perf, compared to when only buffered I/O was used.
This PR makes the mixed-mode I/O situation impossible by repurposing `DBOptions::use_direct_io_for_flush_and_compaction` to only apply to background writes, and `DBOptions::use_direct_reads` to apply to all reads. There is no risk of direct background direct writes happening simultaneously with buffered reads since we never read from and write to the same file simultaneously.
Closes https://github.com/facebook/rocksdb/pull/3829
Differential Revision: D7915443
Pulled By: ajkr
fbshipit-source-id: 78bcbf276449b7e7766ab6b0db246f789fb1b279
Summary:
`ReadaheadRandomAccessFile` had an unwritten assumption, which was that its wrapped file's `Read()` function always copies into the provided scratch buffer. Actually this was not true when the wrapped file was `PosixMmapReadableFile`, whose `Read()` implementation does no copying and instead returns a `Slice` pointing directly into the `mmap`'d memory region. This PR:
- prevents `ReadaheadRandomAccessFile` from ever wrapping mmap readable files
- adds an assert for the assumption `ReadaheadRandomAccessFile` makes about the wrapped file's use of scratch buffer
Closes https://github.com/facebook/rocksdb/pull/3813
Differential Revision: D7891513
Pulled By: ajkr
fbshipit-source-id: dc64a55222d6af280c39a1852ee39e9e9d7cde7d
