Summary:
This PR implements support for a three tier cache - primary block cache, compressed secondary cache, and a nvm (local flash) secondary cache. This allows more effective utilization of the nvm cache, and minimizes the number of reads from local flash by caching compressed blocks in the compressed secondary cache.
The basic design is as follows -
1. A new secondary cache implementation, ```TieredSecondaryCache```, is introduced. It keeps the compressed and nvm secondary caches and manages the movement of blocks between them and the primary block cache. To setup a three tier cache, we allocate a ```CacheWithSecondaryAdapter```, with a ```TieredSecondaryCache``` instance as the secondary cache.
2. The table reader passes both the uncompressed and compressed block to ```FullTypedCacheInterface::InsertFull```, allowing the block cache to optionally store the compressed block.
3. When there's a miss, the block object is constructed and inserted in the primary cache, and the compressed block is inserted into the nvm cache by calling ```InsertSaved```. This avoids the overhead of recompressing the block, as well as avoiding putting more memory pressure on the compressed secondary cache.
4. When there's a hit in the nvm cache, we attempt to insert the block in the compressed secondary cache and the primary cache, subject to the admission policy of those caches (i.e admit on second access). Blocks/items evicted from any tier are simply discarded.
We can easily implement additional admission policies if desired.
Todo (In a subsequent PR):
1. Add to db_bench and run benchmarks
2. Add to db_stress
Pull Request resolved: https://github.com/facebook/rocksdb/pull/11812
Reviewed By: pdillinger
Differential Revision: D49461842
Pulled By: anand1976
fbshipit-source-id: b40ac1330ef7cd8c12efa0a3ca75128e602e3a0b
Summary:
**Context/Summary:**
- Similar to https://github.com/facebook/rocksdb/pull/11288 but for user read such as `Get(), MultiGet(), DBIterator::XXX(), Verify(File)Checksum()`.
- For this, I refactored some user-facing `MultiGet` calls in `TransactionBase` and various types of `DB` so that it does not call a user-facing `Get()` but `GetImpl()` for passing the `ReadOptions::io_activity` check (see PR conversation)
- New user read stats breakdown are guarded by `kExceptDetailedTimers` since measurement shows they have 4-5% regression to the upstream/main.
- Misc
- More refactoring: with https://github.com/facebook/rocksdb/pull/11288, we complete passing `ReadOptions/IOOptions` to FS level. So we can now replace the previously [added](https://github.com/facebook/rocksdb/pull/9424) `rate_limiter_priority` parameter in `RandomAccessFileReader`'s `Read/MultiRead/Prefetch()` with `IOOptions::rate_limiter_priority`
- Also, `ReadAsync()` call time is measured in `SST_READ_MICRO` now
Pull Request resolved: https://github.com/facebook/rocksdb/pull/11444
Test Plan:
- CI fake db crash/stress test
- Microbenchmarking
**Build** `make clean && ROCKSDB_NO_FBCODE=1 DEBUG_LEVEL=0 make -jN db_basic_bench`
- google benchmark version: 604f6fd3f4
- db_basic_bench_base: upstream
- db_basic_bench_pr: db_basic_bench_base + this PR
- asyncread_db_basic_bench_base: upstream + [db basic bench patch for IteratorNext](https://github.com/facebook/rocksdb/compare/main...hx235:rocksdb:micro_bench_async_read)
- asyncread_db_basic_bench_pr: asyncread_db_basic_bench_base + this PR
**Test**
Get
```
TEST_TMPDIR=/dev/shm ./db_basic_bench_{null_stat|base|pr} --benchmark_filter=DBGet/comp_style:0/max_data:134217728/per_key_size:256/enable_statistics:1/negative_query:0/enable_filter:0/mmap:1/threads:1 --benchmark_repetitions=1000
```
Result
```
Coming soon
```
AsyncRead
```
TEST_TMPDIR=/dev/shm ./asyncread_db_basic_bench_{base|pr} --benchmark_filter=IteratorNext/comp_style:0/max_data:134217728/per_key_size:256/enable_statistics:1/async_io:1/include_detailed_timers:0 --benchmark_repetitions=1000 > syncread_db_basic_bench_{base|pr}.out
```
Result
```
Base:
1956,1956,1968,1977,1979,1986,1988,1988,1988,1990,1991,1991,1993,1993,1993,1993,1994,1996,1997,1997,1997,1998,1999,2001,2001,2002,2004,2007,2007,2008,
PR (2.3% regression, due to measuring `SST_READ_MICRO` that wasn't measured before):
1993,2014,2016,2022,2024,2027,2027,2028,2028,2030,2031,2031,2032,2032,2038,2039,2042,2044,2044,2047,2047,2047,2048,2049,2050,2052,2052,2052,2053,2053,
```
Reviewed By: ajkr
Differential Revision: D45918925
Pulled By: hx235
fbshipit-source-id: 58a54560d9ebeb3a59b6d807639692614dad058a
Summary:
## Context checksum
All RocksDB checksums currently use 32 bits of checking
power, which should be 1 in 4 billion false negative (FN) probability (failing to
detect corruption). This is true for random corruptions, and in some cases
small corruptions are guaranteed to be detected. But some possible
corruptions, such as in storage metadata rather than storage payload data,
would have a much higher FN rate. For example:
* Data larger than one SST block is replaced by data from elsewhere in
the same or another SST file. Especially with block_align=true, the
probability of exact block size match is probably around 1 in 100, making
the FN probability around that same. Without `block_align=true` the
probability of same block start location is probably around 1 in 10,000,
for FN probability around 1 in a million.
To solve this problem in new format_version=6, we add "context awareness"
to block checksum checks. The stored and expected checksum value is
modified based on the block's position in the file and which file it is in. The
modifications are cleverly chosen so that, for example
* blocks within about 4GB of each other are guaranteed to use different context
* blocks that are offset by exactly some multiple of 4GiB are guaranteed to use
different context
* files generated by the same process are guaranteed to use different context
for the same offsets, until wrap-around after 2^32 - 1 files
Thus, with format_version=6, if a valid SST block and checksum is misplaced,
its checksum FN probability should be essentially ideal, 1 in 4B.
## Footer checksum
This change also adds checksum protection to the SST footer (with
format_version=6), for the first time without relying on whole file checksum.
To prevent a corruption of the format_version in the footer (e.g. 6 -> 5) to
defeat the footer checksum, we change much of the footer data format
including an "extended magic number" in format_version 6 that would be
interpreted as empty index and metaindex block handles in older footer
versions. We also change the encoding of handles to free up space for
other new data in footer.
## More detail: making space in footer
In order to keep footer the same size in format_version=6 (avoid change to IO
patterns), we have to free up some space for new data. We do this two ways:
* Metaindex block handle is encoded down to 4 bytes (from 10) by assuming
it immediately precedes the footer, and by assuming it is < 4GB.
* Index block handle is moved into metaindex. (I don't know why it was
in footer to begin with.)
## Performance
In case of small performance penalty, I've made a "pay as you go" optimization
to compensate: replace `MutableCFOptions` in BlockBasedTableBuilder::Rep
with the only field used in that structure after construction: `prefix_extractor`.
This makes the PR an overall performance improvement (results below).
Nevertheless I'm seeing essentially no difference going from fv=5 to fv=6,
even including that improvement for both. That's based on extreme case table
write performance testing, many files with many blocks. This is relatively
checksum intensive (small blocks) and salt generation intensive (small files).
```
(for I in `seq 1 100`; do TEST_TMPDIR=/dev/shm/dbbench2 ./db_bench -benchmarks=fillseq -memtablerep=vector -disable_wal=1 -allow_concurrent_memtable_write=false -num=3000000 -compaction_style=2 -fifo_compaction_max_table_files_size_mb=10000 -fifo_compaction_allow_compaction=0 -write_buffer_size=100000 -compression_type=none -block_size=1000; done) 2>&1 | grep micros/op | tee out
awk '{ tot += $5; n += 1; } END { print int(1.0 * tot / n) }' < out
```
Each value below is ops/s averaged over 100 runs, run simultaneously with competing
configuration for load fairness
Before -> after (both fv=5): 483530 -> 483673 (negligible)
Re-run 1: 480733 -> 485427 (1.0% faster)
Re-run 2: 483821 -> 484541 (0.1% faster)
Before (fv=5) -> after (fv=6): 482006 -> 485100 (0.6% faster)
Re-run 1: 482212 -> 485075 (0.6% faster)
Re-run 2: 483590 -> 484073 (0.1% faster)
After fv=5 -> after fv=6: 483878 -> 485542 (0.3% faster)
Re-run 1: 485331 -> 483385 (0.4% slower)
Re-run 2: 485283 -> 483435 (0.4% slower)
Re-run 3: 483647 -> 486109 (0.5% faster)
Pull Request resolved: https://github.com/facebook/rocksdb/pull/9058
Test Plan:
unit tests included (table_test, db_properties_test, salt in env_test). General DB tests
and crash test updated to test new format_version.
Also temporarily updated the default format version to 6 and saw some test failures. Almost all
were due to an inadvertent additional read in VerifyChecksum to verify the index block checksum,
though it's arguably a bug that VerifyChecksum does not appear to (re-)verify the index block
checksum, just assuming it was verified in opening the index reader (probably *usually* true but
probably not always true). Some other concerns about VerifyChecksum are left in FIXME
comments. The only remaining test failure on change of default (in block_fetcher_test) now
has a comment about how to upgrade the test.
The format compatibility test does not need updating because we have not updated the default
format_version.
Reviewed By: ajkr, mrambacher
Differential Revision: D33100915
Pulled By: pdillinger
fbshipit-source-id: 8679e3e572fa580181a737fd6d113ed53c5422ee
Summary:
In IDE navigation I find it annoying that there are two statistics.h files (etc.) and often land on the wrong one. Here I migrate several headers to use the blah.h <- blah_impl.h <- blah.cc idiom. Although clang-format wants "blah.h" to be the top include for "blah.cc", I think overall this is an improvement.
No public API changes.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/11408
Test Plan: existing tests
Reviewed By: ltamasi
Differential Revision: D45456696
Pulled By: pdillinger
fbshipit-source-id: 809d931253f3272c908cf5facf7e1d32fc507373
Summary:
Added a ticker stat, `BLOCK_CHECKSUM_MISMATCH_COUNT`, to count how many block checksum verifications detected a mismatch.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/11438
Test Plan: new unit test
Reviewed By: pdillinger
Differential Revision: D45788179
Pulled By: ajkr
fbshipit-source-id: e2b44eba7c23b3e110ebe69eaa78a710dec2590f
Summary:
We have a lot of confusing code because of mixed, sometimes
completely opposite uses of of the term "raw block" or "raw contents",
sometimes within the same source file. For example, in `BlockBasedTableBuilder`,
`raw_block_contents` and `raw_size` generally referred to uncompressed block
contents and size, while `WriteRawBlock` referred to writing a block that
is already compressed if it is going to be. Meanwhile, in
`BlockBasedTable`, `raw_block_contents` either referred to a (maybe
compressed) block with trailer, or a maybe compressed block maybe
without trailer. (Note: left as follow-up work to use C++ typing to
better sort out the various kinds of BlockContents.)
This change primarily tries to apply some consistent terminology around
the kinds of block representations, avoiding the unclear "raw". (Any
meaning of "raw" assumes some bias toward the storage layer or toward
the logical data layer.) Preferred terminology:
* **Serialized block** - bytes that go into storage. For block-based table
(usually the case) this includes the block trailer. WART: block `size` may or
may not include the trailer; need to be clear about whether it does or not.
* **Maybe compressed block** - like a serialized block, but without the
trailer (or no promise of including a trailer). Must be accompanied by a
CompressionType.
* **Uncompressed block** - "payload" bytes that are either stored with no
compression, used as input to compression function, or result of
decompression function.
* **Parsed block** - an in-memory form of a block in block cache, as it is
used by the table reader. Different C++ types are used depending on the
block type (see block_like_traits.h).
Other refactorings:
* Misc corrections/improvements of internal API comments
* Remove a few misleading / unhelpful / redundant comments.
* Use move semantics in some places to simplify contracts
* Use better parameter names to indicate which parameters are used for
outputs
* Remove some extraneous `extern`
* Various clean-ups to `CacheDumperImpl` (mostly unnecessary code)
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10408
Test Plan: existing tests
Reviewed By: akankshamahajan15
Differential Revision: D38172617
Pulled By: pdillinger
fbshipit-source-id: ccb99299f324ac5ca46996d34c5089621a4f260c
Summary:
In https://github.com/facebook/rocksdb/issues/9535, release 7.0, we hid the old block-based filter from being created using
the public API, because of its inefficiency. Although we normally maintain read compatibility
on old DBs forever, filters are not required for reading a DB, only for optimizing read
performance. Thus, it should be acceptable to remove this code and the substantial
maintenance burden it carries as useful features are developed and validated (such
as user timestamp).
This change completely removes the code for reading and writing the old block-based
filters, net removing about 1370 lines of code no longer needed. Options removed from
testing / benchmarking tools. The prior existence is only evident in a couple of places:
* `CacheEntryRole::kDeprecatedFilterBlock` - We can update this public API enum in
a major release to minimize source code incompatibilities.
* A warning is logged when an old table file is opened that used the old block-based
filter. This is provided as a courtesy, and would be a pain to unit test, so manual testing
should suffice. Unfortunately, sst_dump does not tell you whether a file uses
block-based filter, and the structure of the code makes it very difficult to fix.
* To detect that case, `kObsoleteFilterBlockPrefix` (renamed from `kFilterBlockPrefix`)
for metaindex is maintained (for now).
Other notes:
* In some cases where numbers are associated with filter configurations, we have had to
update the assigned numbers so that they all correspond to something that exists.
* Fixed potential stat counting bug by assuming `filter_checked = false` for cases
like `filter == nullptr` rather than assuming `filter_checked = true`
* Removed obsolete `block_offset` and `prefix_extractor` parameters from several
functions.
* Removed some unnecessary checks `if (!table_prefix_extractor() && !prefix_extractor)`
because the caller guarantees the prefix extractor exists and is compatible
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10184
Test Plan:
tests updated, manually test new warning in LOG using base version to
generate a DB
Reviewed By: riversand963
Differential Revision: D37212647
Pulled By: pdillinger
fbshipit-source-id: 06ee020d8de3b81260ffc36ad0c1202cbf463a80
Summary:
We have three related concepts:
* BlockType: an internal enum conceptually indicating a type of SST file
block
* CacheEntryRole: a user-facing enum for categorizing block cache entries,
which is also involved in associated cache entries with an appropriate
deleter. Can include categories for non-block cache entries (e.g. memory
reservations).
* TBlocklike: a C++ type for the actual type behind a void* cache entry.
We had some existing code ugliness because BlockType did not imply
TBlocklike, because of various kinds of "filter" block. This refactoring
fixes that with new BlockTypes.
More clean-up can come in later work.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10098
Test Plan: existing tests
Reviewed By: akankshamahajan15
Differential Revision: D36897945
Pulled By: pdillinger
fbshipit-source-id: 3ae496b5caa81e0a0ed85e873eb5b525e2d9a295
Summary:
In case of non sequential reads with `async_io`, `FilePRefetchBuffer::TryReadFromCacheAsync` can be called for previous blocks with `offset < bufs_[curr_].offset_` which wasn't handled correctly resulting wrong data being returned from buffer.
Since `FilePRefetchBuffer::PrefetchAsync` can be called for any data block, it sets `prev_len_` to 0 indicating `FilePRefetchBuffer::TryReadFromCacheAsync` to go for the prefetching even though offset < bufs_[curr_].offset_ This is because async prefetching is always done in second buffer (to avoid mutex) even though curr_ is empty leading to offset < bufs_[curr_].offset_ in some cases.
If prev_len_ is non zero then `TryReadFromCacheAsync` returns false if `offset < bufs_[curr_].offset_ && prev_len != 0` indicating reads are not sequential and previous call wasn't PrefetchAsync.
- This PR also simplifies `FilePRefetchBuffer::TryReadFromCacheAsync` as it was getting complicated covering different scenarios based on `async_io` enabled/disabled. If `for_compaction` is set true, it now calls `FilePRefetchBufferTryReadFromCache` following synchronous flow as before. Its decided in BlockFetcher.cc
Pull Request resolved: https://github.com/facebook/rocksdb/pull/10032
Test Plan:
1. export CRASH_TEST_EXT_ARGS=" --async_io=1"
make crash_test -j completed successfully locally
2. make crash_test -j completed successfully locally
3. Reran CircleCi mini crashtest job 4 - 5 times.
4. Updated prefetch_test for more coverage.
Reviewed By: anand1976
Differential Revision: D36579858
Pulled By: akankshamahajan15
fbshipit-source-id: 0c428d62b45e12e082a83acf533a5e37a584bedf
Summary:
The RocksDB iterator is a hierarchy of iterators. MergingIterator maintains a heap of LevelIterators, one for each L0 file and for each non-zero level. The Seek() operation naturally lends itself to parallelization, as it involves positioning every LevelIterator on the correct data block in the correct SST file. It lookups a level for a target key, to find the first key that's >= the target key. This typically involves reading one data block that is likely to contain the target key, and scan forward to find the first valid key. The forward scan may read more data blocks. In order to find the right data block, the iterator may read some metadata blocks (required for opening a file and searching the index).
This flow can be parallelized.
Design: Seek will be called two times under async_io option. First seek will send asynchronous request to prefetch the data blocks at each level and second seek will follow the normal flow and in FilePrefetchBuffer::TryReadFromCacheAsync it will wait for the Poll() to get the results and add the iterator to min_heap.
- Status::TryAgain is passed down from FilePrefetchBuffer::PrefetchAsync to block_iter_.Status indicating asynchronous request has been submitted.
- If for some reason asynchronous request returns error in submitting the request, it will fallback to sequential reading of blocks in one pass.
- If the data already exists in prefetch_buffer, it will return the data without prefetching further and it will be treated as single pass of seek.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/9994
Test Plan:
- **Run Regressions.**
```
./db_bench -db=/tmp/prefix_scan_prefetch_main -benchmarks="fillseq" -key_size=32 -value_size=512 -num=5000000 -use_direct_io_for_flush_and_compaction=true -target_file_size_base=16777216
```
i) Previous release 7.0 run for normal prefetching with async_io disabled:
```
./db_bench -use_existing_db=true -db=/tmp/prefix_scan_prefetch_main -benchmarks="seekrandom" -key_size=32 -value_size=512 -num=5000000 -use_direct_reads=true -seek_nexts=327680 -duration=120 -ops_between_duration_checks=1
Initializing RocksDB Options from the specified file
Initializing RocksDB Options from command-line flags
RocksDB: version 7.0
Date: Thu Mar 17 13:11:34 2022
CPU: 24 * Intel Core Processor (Broadwell)
CPUCache: 16384 KB
Keys: 32 bytes each (+ 0 bytes user-defined timestamp)
Values: 512 bytes each (256 bytes after compression)
Entries: 5000000
Prefix: 0 bytes
Keys per prefix: 0
RawSize: 2594.0 MB (estimated)
FileSize: 1373.3 MB (estimated)
Write rate: 0 bytes/second
Read rate: 0 ops/second
Compression: Snappy
Compression sampling rate: 0
Memtablerep: SkipListFactory
Perf Level: 1
------------------------------------------------
DB path: [/tmp/prefix_scan_prefetch_main]
seekrandom : 483618.390 micros/op 2 ops/sec; 338.9 MB/s (249 of 249 found)
```
ii) normal prefetching after changes with async_io disable:
```
./db_bench -use_existing_db=true -db=/tmp/prefix_scan_prefetch_main -benchmarks="seekrandom" -key_size=32 -value_size=512 -num=5000000 -use_direct_reads=true -seek_nexts=327680 -duration=120 -ops_between_duration_checks=1
Set seed to 1652922591315307 because --seed was 0
Initializing RocksDB Options from the specified file
Initializing RocksDB Options from command-line flags
RocksDB: version 7.3
Date: Wed May 18 18:09:51 2022
CPU: 32 * Intel Xeon Processor (Skylake)
CPUCache: 16384 KB
Keys: 32 bytes each (+ 0 bytes user-defined timestamp)
Values: 512 bytes each (256 bytes after compression)
Entries: 5000000
Prefix: 0 bytes
Keys per prefix: 0
RawSize: 2594.0 MB (estimated)
FileSize: 1373.3 MB (estimated)
Write rate: 0 bytes/second
Read rate: 0 ops/second
Compression: Snappy
Compression sampling rate: 0
Memtablerep: SkipListFactory
Perf Level: 1
------------------------------------------------
DB path: [/tmp/prefix_scan_prefetch_main]
seekrandom : 483080.466 micros/op 2 ops/sec 120.287 seconds 249 operations; 340.8 MB/s (249 of 249 found)
```
iii) db_bench with async_io enabled completed succesfully
```
./db_bench -use_existing_db=true -db=/tmp/prefix_scan_prefetch_main -benchmarks="seekrandom" -key_size=32 -value_size=512 -num=5000000 -use_direct_reads=true -seek_nexts=327680 -duration=120 -ops_between_duration_checks=1 -async_io=1 -adaptive_readahead=1
Set seed to 1652924062021732 because --seed was 0
Initializing RocksDB Options from the specified file
Initializing RocksDB Options from command-line flags
RocksDB: version 7.3
Date: Wed May 18 18:34:22 2022
CPU: 32 * Intel Xeon Processor (Skylake)
CPUCache: 16384 KB
Keys: 32 bytes each (+ 0 bytes user-defined timestamp)
Values: 512 bytes each (256 bytes after compression)
Entries: 5000000
Prefix: 0 bytes
Keys per prefix: 0
RawSize: 2594.0 MB (estimated)
FileSize: 1373.3 MB (estimated)
Write rate: 0 bytes/second
Read rate: 0 ops/second
Compression: Snappy
Compression sampling rate: 0
Memtablerep: SkipListFactory
Perf Level: 1
------------------------------------------------
DB path: [/tmp/prefix_scan_prefetch_main]
seekrandom : 553913.576 micros/op 1 ops/sec 120.199 seconds 217 operations; 293.6 MB/s (217 of 217 found)
```
- db_stress with async_io disabled completed succesfully
```
export CRASH_TEST_EXT_ARGS=" --async_io=0"
make crash_test -j
```
I**n Progress**: db_stress with async_io is failing and working on debugging/fixing it.
Reviewed By: anand1976
Differential Revision: D36459323
Pulled By: akankshamahajan15
fbshipit-source-id: abb1cd944abe712bae3986ae5b16704b3338917c
Summary:
ToString() is created as some platform doesn't support std::to_string(). However, we've already used std::to_string() by mistake for 16 months (in db/db_info_dumper.cc). This commit just remove ToString().
Pull Request resolved: https://github.com/facebook/rocksdb/pull/9955
Test Plan: Watch CI tests
Reviewed By: riversand963
Differential Revision: D36176799
fbshipit-source-id: bdb6dcd0e3a3ab96a1ac810f5d0188f684064471
Summary:
If FilePrefetchBuffer object is destroyed and then later Poll() calls callback on object which has been destroyed, it gives segfault on accessing destroyed object. It was caught after adding unit tests that tests Posix implementation of ReadAsync and Poll APIs.
This PR also updates and fixes existing IOURing tests which were not running locally because RocksDbIOUringEnable function wasn't defined and IOUring was disabled for those tests
Pull Request resolved: https://github.com/facebook/rocksdb/pull/9777
Test Plan: Added new unit test
Reviewed By: anand1976
Differential Revision: D35254002
Pulled By: akankshamahajan15
fbshipit-source-id: 68e80054ffb14ae25c255920ebc6548ca5f130a1
Summary:
Fixes https://github.com/facebook/rocksdb/issues/9718
The verify_checksums flag of read_options should be passed to the read options used by the BlockFetcher in a couple of cases where it is not at present. It will now happen (but did not, previously) on iteration and on [multi]get, where a fetcher is created as part of the iterate/get call.
This may result in much better performance in a few workloads where the client chooses to remove verification.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/9767
Reviewed By: mrambacher
Differential Revision: D35218986
Pulled By: jay-zhuang
fbshipit-source-id: 329d29764bb70fbc7f2673440bc46c107a813bc8
Summary:
In FilePrefetchBuffer if reads are sequential, after prefetching call ReadAsync API to prefetch data asynchronously so that in next prefetching data will be available. Data prefetched asynchronously will be readahead_size/2. It uses two buffers, one for synchronous prefetching and one for asynchronous. In case, the data is overlapping, the data is copied from both buffers to third buffer to make it continuous.
This feature is under ReadOptions::async_io and is under experimental.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/9674
Test Plan:
1. Add new unit tests
2. Run **db_stress** to make sure nothing crashes.
- Normal prefetch without `async_io` ran successfully:
```
export CRASH_TEST_EXT_ARGS=" --async_io=0"
make crash_test -j
```
3. **Run Regressions**.
i) Main branch without any change for normal prefetching with async_io disabled:
```
./db_bench -db=/tmp/prefix_scan_prefetch_main -benchmarks="fillseq" -key_size=32 -value_size=512 -num=5000000 -
use_direct_io_for_flush_and_compaction=true -target_file_size_base=16777216
```
```
./db_bench -use_existing_db=true -db=/tmp/prefix_scan_prefetch_main -benchmarks="seekrandom" -key_size=32 -value_size=512 -num=5000000 -use_direct_reads=true -seek_nexts=327680 -duration=120 -ops_between_duration_checks=1
Initializing RocksDB Options from the specified file
Initializing RocksDB Options from command-line flags
RocksDB: version 7.0
Date: Thu Mar 17 13:11:34 2022
CPU: 24 * Intel Core Processor (Broadwell)
CPUCache: 16384 KB
Keys: 32 bytes each (+ 0 bytes user-defined timestamp)
Values: 512 bytes each (256 bytes after compression)
Entries: 5000000
Prefix: 0 bytes
Keys per prefix: 0
RawSize: 2594.0 MB (estimated)
FileSize: 1373.3 MB (estimated)
Write rate: 0 bytes/second
Read rate: 0 ops/second
Compression: Snappy
Compression sampling rate: 0
Memtablerep: SkipListFactory
Perf Level: 1
------------------------------------------------
DB path: [/tmp/prefix_scan_prefetch_main]
seekrandom : 483618.390 micros/op 2 ops/sec; 338.9 MB/s (249 of 249 found)
```
ii) normal prefetching after changes with async_io disable:
```
./db_bench -use_existing_db=true -db=/tmp/prefix_scan_prefetch_withchange -benchmarks="seekrandom" -key_size=32 -value_size=512 -num=5000000 -use_direct_reads=true -seek_nexts=327680 -duration=120 -ops_between_duration_checks=1
Initializing RocksDB Options from the specified file
Initializing RocksDB Options from command-line flags
RocksDB: version 7.0
Date: Thu Mar 17 14:11:31 2022
CPU: 24 * Intel Core Processor (Broadwell)
CPUCache: 16384 KB
Keys: 32 bytes each (+ 0 bytes user-defined timestamp)
Values: 512 bytes each (256 bytes after compression)
Entries: 5000000
Prefix: 0 bytes
Keys per prefix: 0
RawSize: 2594.0 MB (estimated)
FileSize: 1373.3 MB (estimated)
Write rate: 0 bytes/second
Read rate: 0 ops/second
Compression: Snappy
Compression sampling rate: 0
Memtablerep: SkipListFactory
Perf Level: 1
------------------------------------------------
DB path: [/tmp/prefix_scan_prefetch_withchange]
seekrandom : 471347.227 micros/op 2 ops/sec; 348.1 MB/s (255 of 255 found)
```
Reviewed By: anand1976
Differential Revision: D34731543
Pulled By: akankshamahajan15
fbshipit-source-id: 8e23aa93453d5fe3c672b9231ad582f60207937f
Summary:
Users can set the priority for file reads associated with their operation by setting `ReadOptions::rate_limiter_priority` to something other than `Env::IO_TOTAL`. Rate limiting `VerifyChecksum()` and `VerifyFileChecksums()` is the motivation for this PR, so it also includes benchmarks and minor bug fixes to get that working.
`RandomAccessFileReader::Read()` already had support for rate limiting compaction reads. I changed that rate limiting to be non-specific to compaction, but rather performed according to the passed in `Env::IOPriority`. Now the compaction read rate limiting is supported by setting `rate_limiter_priority = Env::IO_LOW` on its `ReadOptions`.
There is no default value for the new `Env::IOPriority` parameter to `RandomAccessFileReader::Read()`. That means this PR goes through all callers (in some cases multiple layers up the call stack) to find a `ReadOptions` to provide the priority. There are TODOs for cases I believe it would be good to let user control the priority some day (e.g., file footer reads), and no TODO in cases I believe it doesn't matter (e.g., trace file reads).
The API doc only lists the missing cases where a file read associated with a provided `ReadOptions` cannot be rate limited. For cases like file ingestion checksum calculation, there is no API to provide `ReadOptions` or `Env::IOPriority`, so I didn't count that as missing.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/9424
Test Plan:
- new unit tests
- new benchmarks on ~50MB database with 1MB/s read rate limit and 100ms refill interval; verified with strace reads are chunked (at 0.1MB per chunk) and spaced roughly 100ms apart.
- setup command: `./db_bench -benchmarks=fillrandom,compact -db=/tmp/testdb -target_file_size_base=1048576 -disable_auto_compactions=true -file_checksum=true`
- benchmarks command: `strace -ttfe pread64 ./db_bench -benchmarks=verifychecksum,verifyfilechecksums -use_existing_db=true -db=/tmp/testdb -rate_limiter_bytes_per_sec=1048576 -rate_limit_bg_reads=1 -rate_limit_user_ops=true -file_checksum=true`
- crash test using IO_USER priority on non-validation reads with https://github.com/facebook/rocksdb/issues/9567 reverted: `python3 tools/db_crashtest.py blackbox --max_key=1000000 --write_buffer_size=524288 --target_file_size_base=524288 --level_compaction_dynamic_level_bytes=true --duration=3600 --rate_limit_bg_reads=true --rate_limit_user_ops=true --rate_limiter_bytes_per_sec=10485760 --interval=10`
Reviewed By: hx235
Differential Revision: D33747386
Pulled By: ajkr
fbshipit-source-id: a2d985e97912fba8c54763798e04f006ccc56e0c
Summary:
I'm working on a new format_version=6 to support context
checksum (https://github.com/facebook/rocksdb/issues/9058) and this includes much of the refactoring and test
updates to support that change.
Test coverage data and manual inspection agree on dead code in
block_based_table_reader.cc (removed).
Pull Request resolved: https://github.com/facebook/rocksdb/pull/9240
Test Plan:
tests enhanced to cover more cases etc.
Extreme case performance testing indicates small % regression in fillseq (w/ compaction), though CPU profile etc. doesn't suggest any explanation. There is enhanced correctness checking in Footer::DecodeFrom, but this should be negligible.
TEST_TMPDIR=/dev/shm/ ./db_bench -benchmarks=fillseq -memtablerep=vector -allow_concurrent_memtable_write=false -num=30000000 -checksum_type=1 --disable_wal={false,true}
(Each is ops/s averaged over 50 runs, run simultaneously with competing configuration for load fairness)
Before w/ wal: 454512
After w/ wal: 444820 (-2.1%)
Before w/o wal: 1004560
After w/o wal: 998897 (-0.6%)
Since this doesn't modify WAL code, one would expect real effects to be larger in w/o wal case.
This regression will be corrected in a follow-up PR.
Reviewed By: ajkr
Differential Revision: D32813769
Pulled By: pdillinger
fbshipit-source-id: 444a244eabf3825cd329b7d1b150cddce320862f
Summary:
The patch adds a new BlobDB configuration option `blob_compaction_readahead_size`
that can be used to enable prefetching data from blob files during compaction.
This is important when using storage with higher latencies like HDDs or remote filesystems.
If enabled, prefetching is used for all cases when blobs are read during compaction,
namely garbage collection, compaction filters (when the existing value has to be read from
a blob file), and `Merge` (when the value of the base `Put` is stored in a blob file).
Pull Request resolved: https://github.com/facebook/rocksdb/pull/9187
Test Plan: Ran `make check` and the stress/crash test.
Reviewed By: riversand963
Differential Revision: D32565512
Pulled By: ltamasi
fbshipit-source-id: 87be9cebc3aa01cc227bec6b5f64d827b8164f5d
Summary:
* Checksums are now checked on meta blocks unless specifically
suppressed or not applicable (e.g. plain table). (Was other way around.)
This means a number of cases that were not checking checksums now are,
including direct read TableProperties in Version::GetTableProperties
(fixed in meta_blocks ReadTableProperties), reading any block from
PersistentCache (fixed in BlockFetcher), read TableProperties in
SstFileDumper (ldb/sst_dump/BackupEngine) before table reader open,
maybe more.
* For that to work, I moved the global_seqno+TableProperties checksum
logic to the shared table/ code, because that is used by many utilies
such as SstFileDumper.
* Also for that to work, we have to know when we're dealing with a block
that has a checksum (trailer), so added that capability to Footer based
on magic number, and from there BlockFetcher.
* Knowledge of trailer presence has also fixed a problem where other
table formats were reading blocks including bytes for a non-existant
trailer--and awkwardly kind-of not using them, e.g. no shared code
checking checksums. (BlockFetcher compression type was populated
incorrectly.) Now we only read what is needed.
* Minimized code duplication and differing/incompatible/awkward
abstractions in meta_blocks.{cc,h} (e.g. SeekTo in metaindex block
without parsing block handle)
* Moved some meta block handling code from table_properties*.*
* Moved some code specific to block-based table from shared table/ code
to BlockBasedTable class. The checksum stuff means we can't completely
separate it, but things that don't need to be in shared table/ code
should not be.
* Use unique_ptr rather than raw ptr in more places. (Note: you can
std::move from unique_ptr to shared_ptr.)
Without enhancements to GetPropertiesOfAllTablesTest (see below),
net reduction of roughly 100 lines of code.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/9163
Test Plan:
existing tests and
* Enhanced DBTablePropertiesTest.GetPropertiesOfAllTablesTest to verify that
checksums are now checked on direct read of table properties by TableCache
(new test would fail before this change)
* Also enhanced DBTablePropertiesTest.GetPropertiesOfAllTablesTest to test
putting table properties under old meta name
* Also generally enhanced that same test to actually test what it was
supposed to be testing already, by kicking things out of table cache when
we don't want them there.
Reviewed By: ajkr, mrambacher
Differential Revision: D32514757
Pulled By: pdillinger
fbshipit-source-id: 507964b9311d186ae8d1131182290cbd97a99fa9
Summary:
Renaming ImmutableCFOptions::info_log and statistics to logger and stats. This is stage 2 in creating an ImmutableOptions class. It is necessary because the names match those in ImmutableOptions and have different types.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/8227
Reviewed By: jay-zhuang
Differential Revision: D28000967
Pulled By: mrambacher
fbshipit-source-id: 3bf2aa04e8f1e8724d825b7deacf41080c14420b
Summary:
To propagate the IOStatus from file reads to RocksDB read logic, some of the existing status needs to be replaced by IOStatus.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/8130
Test Plan: make check
Reviewed By: anand1976
Differential Revision: D27440188
Pulled By: zhichao-cao
fbshipit-source-id: bbe7622c2106fe4e46871d60f7c26944e5030d78
Summary:
Introduces and uses a SystemClock class to RocksDB. This class contains the time-related functions of an Env and these functions can be redirected from the Env to the SystemClock.
Many of the places that used an Env (Timer, PerfStepTimer, RepeatableThread, RateLimiter, WriteController) for time-related functions have been changed to use SystemClock instead. There are likely more places that can be changed, but this is a start to show what can/should be done. Over time it would be nice to migrate most (if not all) of the uses of the time functions from the Env to the SystemClock.
There are several Env classes that implement these functions. Most of these have not been converted yet to SystemClock implementations; that will come in a subsequent PR. It would be good to unify many of the Mock Timer implementations, so that they behave similarly and be tested similarly (some override Sleep, some use a MockSleep, etc).
Additionally, this change will allow new methods to be introduced to the SystemClock (like https://github.com/facebook/rocksdb/issues/7101 WaitFor) in a consistent manner across a smaller number of classes.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/7858
Reviewed By: pdillinger
Differential Revision: D26006406
Pulled By: mrambacher
fbshipit-source-id: ed10a8abbdab7ff2e23d69d85bd25b3e7e899e90
Summary:
Return the Status from TryReadFromCache() in an argument to make it easier to report prefetch errors to the user.
Tests:
make crash_test
make check
Pull Request resolved: https://github.com/facebook/rocksdb/pull/7816
Reviewed By: akankshamahajan15
Differential Revision: D25717222
Pulled By: anand1976
fbshipit-source-id: c320d3c12d4146bda16df78ff6927eee584c1810
Summary:
With mmap enabled on an uncompressed file, we were previously always doing a heap allocation to obtain the scratch buffer for `RandomAccessFileReader::Read()`. However, that allocation was unnecessary as the underlying file reader returned a pointer into its mapped memory, not the provided scratch buffer. This PR makes passes the `BlockFetcher`'s inline buffer as the scratch buffer if the data block is small enough (less than `kDefaultStackBufferSize` bytes, currently 5000). Ideally we would not pass a scratch buffer at all for an mmap read; however, the `RandomAccessFile::Read()` API guarantees such a buffer is provided, and non-standard implementations may be relying on it even when `Options::allow_mmap_reads == true`. In that case, this PR still works but introduces an extra copy from the inline buffer to a heap buffer.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/7043
Reviewed By: cheng-chang
Differential Revision: D22320606
Pulled By: ajkr
fbshipit-source-id: ad964dd23df34e07d979c6032c2dfe5454c98b52
Summary:
Current implementation of the ```read_options.deadline``` option only checks the deadline for random file reads during point lookups. This PR extends the checks to file opens, prefetches and preloads as part of table open.
The main changes are in the ```BlockBasedTable```, partitioned index and filter readers, and ```TableCache``` to take ReadOptions as an additional parameter. In ```BlockBasedTable::Open```, in order to retain existing behavior w.r.t checksum verification and block cache usage, we filter out most of the options in ```ReadOptions``` except ```deadline```. However, having the ```ReadOptions``` gives us more flexibility to honor other options like verify_checksums, fill_cache etc. in the future.
Additional changes in callsites due to function signature changes in ```NewTableReader()``` and ```FilePrefetchBuffer```.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6982
Test Plan: Add new unit tests in db_basic_test
Reviewed By: riversand963
Differential Revision: D22219515
Pulled By: anand1976
fbshipit-source-id: 8a3b92f4a889808013838603aa3ca35229cd501b
Summary:
Although RocksDB falls over in various other ways with KVs
around 4GB or more, this change fixes how XXH32 and XXH64 were being
called by the block checksum code to support >= 4GB in case that should
ever happen, or the code copied for other uses.
This change is not a schema compatibility issue because the checksum
verification code would checksum the first (block_size + 1) mod 2^32
bytes while the checksum construction code would checksum the first
block_size mod 2^32 plus the compression type byte, meaning the
XXH32/64 checksums for >=4GB block would not match about 255/256 times.
While touching this code, I refactored to consolidate redundant
implementations, improving diagnostics and performance tracking in some
cases. Also used less confusing language in those diagnostics.
Makes https://github.com/facebook/rocksdb/issues/6875 obsolete.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6978
Test Plan:
I was able to write a test for this using an SST file writer
and VerifyChecksum in a reader. The test fails before the fix, though
I'm leaving the test disabled because I don't think it's worth the
expense of running regularly.
Reviewed By: gg814
Differential Revision: D22143260
Pulled By: pdillinger
fbshipit-source-id: 982993d16134e8c50bea2269047f901c1783726e
Summary:
Calculate ```IOOptions::timeout``` using ```ReadOptions::deadline``` and pass it to ```FileSystem::Read/FileSystem::MultiRead```. This allows us to impose a tighter bound on the time taken by Get/MultiGet on FileSystem/Envs that support IO timeouts. Even on those that don't support, check in ```RandomAccessFileReader::Read``` and ```MultiRead``` and return ```Status::TimedOut()``` if the deadline is exceeded.
For now, TableReader creation, which might do file opens and reads, are not covered. It will be implemented in another PR.
Tests:
Update existing unit tests to verify the correct timeout value is being passed
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6751
Reviewed By: riversand963
Differential Revision: D21285631
Pulled By: anand1976
fbshipit-source-id: d89af843e5a91ece866e87aa29438b52a65a8567
Summary:
In https://github.com/facebook/rocksdb/pull/6455, we modified the interface of `RandomAccessFileReader::Read` to be able to get rid of memcpy in direct IO mode.
This PR applies the new interface to `BlockFetcher` when reading blocks from SST files in direct IO mode.
Without this PR, in direct IO mode, when fetching and uncompressing compressed blocks, `BlockFetcher` will first copy the raw compressed block into `BlockFetcher::compressed_buf_` or `BlockFetcher::stack_buf_` inside `RandomAccessFileReader::Read` depending on the block size. then during uncompressing, it will copy the uncompressed block into `BlockFetcher::heap_buf_`.
In this PR, we get rid of the first memcpy and directly uncompress the block from `direct_io_buf_` to `heap_buf_`.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6689
Test Plan: A new unit test `block_fetcher_test` is added.
Reviewed By: anand1976
Differential Revision: D21006729
Pulled By: cheng-chang
fbshipit-source-id: 2370b92c24075692423b81277415feb2aed5d980
Summary:
It was incorrectly counting time even for blocks that didn't need decompression.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6658
Test Plan: make check
Reviewed By: ajkr
Differential Revision: D20883522
Pulled By: anand1976
fbshipit-source-id: 33c9c4683f54cad150ab260a69e3ef8aa9aff76a
Summary:
In direct IO mode, RandomAccessFileReader::Read allocates an internal aligned buffer, and then copies the result into the scratch buffer. If the result is only temporarily used inside a function, there is no need to do the memcpy and just let the result Slice refer to the internally allocated buffer.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6455
Test Plan: make check
Differential Revision: D20106753
Pulled By: cheng-chang
fbshipit-source-id: 44f505843837bba47a56e3fa2c4dd3bd76486b58
Summary:
When dynamically linking two binaries together, different builds of RocksDB from two sources might cause errors. To provide a tool for user to solve the problem, the RocksDB namespace is changed to a flag which can be overridden in build time.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6433
Test Plan: Build release, all and jtest. Try to build with ROCKSDB_NAMESPACE with another flag.
Differential Revision: D19977691
fbshipit-source-id: aa7f2d0972e1c31d75339ac48478f34f6cfcfb3e
Summary:
file_reader_writer.h and .cc contain several files and helper function, and it's hard to navigate. Separate it to multiple files and put them under file/
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5803
Test Plan: Build whole project using make and cmake.
Differential Revision: D17374550
fbshipit-source-id: 10efca907721e7a78ed25bbf74dc5410dea05987
Summary:
The first key is used to defer reading the data block until this file gets to the top of merging iterator's heap. For short range scans, most files never make it to the top of the heap, so this change can reduce read amplification by a lot sometimes.
Consider the following workload. There are a few data streams (we'll be calling them "logs"), each stream consisting of a sequence of blobs (we'll be calling them "records"). Each record is identified by log ID and a sequence number within the log. RocksDB key is concatenation of log ID and sequence number (big endian). Reads are mostly relatively short range scans, each within a single log. Writes are mostly sequential for each log, but writes to different logs are randomly interleaved. Compactions are disabled; instead, when we accumulate a few tens of sst files, we create a new column family and start writing to it.
So, a typical sst file consists of a few ranges of blocks, each range corresponding to one log ID (we use FlushBlockPolicy to cut blocks at log boundaries). A typical read would go like this. First, iterator Seek() reads one block from each sst file. Then a series of Next()s move through one sst file (since writes to each log are mostly sequential) until the subiterator reaches the end of this log in this sst file; then Next() switches to the next sst file and reads sequentially from that, and so on. Often a range scan will only return records from a small number of blocks in small number of sst files; in this case, the cost of initial Seek() reading one block from each file may be bigger than the cost of reading the actually useful blocks.
Neither iterate_upper_bound nor bloom filters can prevent reading one block from each file in Seek(). But this PR can: if the index contains first key from each block, we don't have to read the block until this block actually makes it to the top of merging iterator's heap, so for short range scans we won't read any blocks from most of the sst files.
This PR does the deferred block loading inside value() call. This is not ideal: there's no good way to report an IO error from inside value(). As discussed with siying offline, it would probably be better to change InternalIterator's interface to explicitly fetch deferred value and get status. I'll do it in a separate PR.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5289
Differential Revision: D15256423
Pulled By: al13n321
fbshipit-source-id: 750e4c39ce88e8d41662f701cf6275d9388ba46a
Summary:
Currently the read-ahead logic for user reads and compaction reads go through different code paths where compaction reads create new table readers and use `ReadaheadRandomAccessFile`. This change is to unify read-ahead logic to use read-ahead in BlockBasedTableReader::InitDataBlock(). As a result of the change `ReadAheadRandomAccessFile` class and `new_table_reader_for_compaction_inputs` option will no longer be used.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5431
Test Plan:
make check
Here is the benchmarking - https://gist.github.com/vjnadimpalli/083cf423f7b6aa12dcdb14c858bc18a5
Differential Revision: D15772533
Pulled By: vjnadimpalli
fbshipit-source-id: b71dca710590471ede6fb37553388654e2e479b9
Summary:
The patch brings the semantics of per-block-type read performance
context counters in sync with the generic block_read_count by only
incrementing the counter if the block was actually read from the file.
It also fixes index_block_read_count, which fell victim to the
refactoring in PR https://github.com/facebook/rocksdb/issues/5298.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5484
Test Plan: Extended the unit tests.
Differential Revision: D15887431
Pulled By: ltamasi
fbshipit-source-id: a3889759d0ac5759d56625d692cd828d1b9207a6
Summary:
When using `PRIu64` type of printf specifier, current code base does the following:
```
#ifndef __STDC_FORMAT_MACROS
#define __STDC_FORMAT_MACROS
#endif
#include <inttypes.h>
```
However, this can be simplified to
```
#include <cinttypes>
```
as long as flag `-std=c++11` is used.
This should solve issues like https://github.com/facebook/rocksdb/issues/5159
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5402
Differential Revision: D15701195
Pulled By: miasantreble
fbshipit-source-id: 6dac0a05f52aadb55e9728038599d3d2e4b59d03
Summary:
Many logging related source files are under util/. It will be more structured if they are together.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5387
Differential Revision: D15579036
Pulled By: siying
fbshipit-source-id: 3850134ed50b8c0bb40a0c8ae1f184fa4081303f
Summary:
Following files were run through automatic formatter:
db/db_impl.cc
db/db_impl.h
db/db_impl_compaction_flush.cc
db/db_impl_debug.cc
db/db_impl_files.cc
db/db_impl_readonly.h
db/db_impl_write.cc
db/dbformat.cc
db/dbformat.h
table/block.cc
table/block.h
table/block_based_filter_block.cc
table/block_based_filter_block.h
table/block_based_filter_block_test.cc
table/block_based_table_builder.cc
table/block_based_table_reader.cc
table/block_based_table_reader.h
table/block_builder.cc
table/block_builder.h
table/block_fetcher.cc
table/block_prefix_index.cc
table/block_prefix_index.h
table/block_test.cc
table/format.cc
table/format.h
I could easily run all the files, but I don't want people to feel that
I'm doing it for lines of code changes :)
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5114
Differential Revision: D14633040
Pulled By: siying
fbshipit-source-id: 3f346cb53bf21e8c10704400da548dfce1e89a52
Summary:
- If block cache disabled or not used for meta-blocks, `BlockBasedTableReader::Rep::uncompression_dict` owns the `UncompressionDict`. It is preloaded during `PrefetchIndexAndFilterBlocks`.
- If block cache is enabled and used for meta-blocks, block cache owns the `UncompressionDict`, which holds dictionary and digested dictionary when needed. It is never prefetched though there is a TODO for this in the code. The cache key is simply the compression dictionary block handle.
- New stats for compression dictionary accesses in block cache: "BLOCK_CACHE_COMPRESSION_DICT_*" and "compression_dict_block_read_count"
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4881
Differential Revision: D13663801
Pulled By: ajkr
fbshipit-source-id: bdcc54044e180855cdcc57639b493b0e016c9a3f
Summary:
This is essentially a re-submission of #4251 with a few improvements:
- Split `CompressionDict` into two separate classes: `CompressionDict` and `UncompressionDict`
- Eliminated `Init` functions. Instead do all initialization work in constructors.
- Added test case for parallel DB open, which is the scenario where #4251 failed under TSAN.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4849
Differential Revision: D13606039
Pulled By: ajkr
fbshipit-source-id: 08c236059798c710db9cbf545fce0f371232d447
Summary:
Fix block based table reader not using memory_allocator when allocating index blocks and compression dictionary blocks.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4678
Differential Revision: D13054594
Pulled By: yiwu-arbug
fbshipit-source-id: 379f25bcc665395662511c4f873f4b7b55104ce2
Summary:
We carry compression type and "cachable" variables for every block in the block cache, while they take well-known values. 8-byte is wasted for each block (2-byte for useful information but it takes 8 bytes because of padding). With this change, these two variables are removed.
The cachable information is only useful in the process of reading the block. We use other information to infer from it. For compressed blocks, the compression type is a part of the block content itself so we can get it from there.
Some code is slightly refactored so that the cachable information can flow better.
Another change is to only use class BlockContents for compressed block, and narrow the class Block to only be used for uncompressed blocks, including blocks in compressed block cache. This can make the Block class less confusing. It also saves tens of bytes for each block in compressed block cache.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4650
Differential Revision: D12969070
Pulled By: siying
fbshipit-source-id: 548b62724e9eb66993026429fd9c7c3acd1f95ed
Summary:
Rename the interface, as it is mean to be a generic interface for memory allocation.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4590
Differential Revision: D10866340
Pulled By: yiwu-arbug
fbshipit-source-id: 85cb753351a40cb856c046aeaa3f3b369eef3d16
Summary:
This is a conceptually simple change, but it touches many files to
pass the allocator through function calls.
We introduce CacheAllocator, which can be used by clients to configure
custom allocator for cache blocks. Our motivation is to hook this up
with folly's `JemallocNodumpAllocator`
(f43ce6d686/folly/experimental/JemallocNodumpAllocator.h),
but there are many other possible use cases.
Additionally, this commit cleans up memory allocation in
`util/compression.h`, making sure that all allocations are wrapped in a
unique_ptr as soon as possible.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4437
Differential Revision: D10132814
Pulled By: yiwu-arbug
fbshipit-source-id: be1343a4b69f6048df127939fea9bbc96969f564
anand76