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path: root/util/cast_util.h
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2024-03-15Create an UnownedPtr type (#12447)Peter Dillinger
Summary: ... that is more hygienic as an "optional reference" than a raw pointer, and likely more efficient than std::optional<std::reference_wrapper<T>>. Pull Request resolved: https://github.com/facebook/rocksdb/pull/12447 Test Plan: unit test included (with manual verification that "must not compile" sections currently do not) Reviewed By: jowlyzhang Differential Revision: D54957917 Pulled By: pdillinger fbshipit-source-id: bbd89218df803617b1a170ebddc9e56c9b52bf93
2023-10-06Bootstrap, pre-populate seqno_to_time_mapping (#11922)Peter Dillinger
Summary: This change has two primary goals (follow-up to https://github.com/facebook/rocksdb/issues/11917, https://github.com/facebook/rocksdb/issues/11920): * Ensure the DB seqno_to_time_mapping has entries that allow us to put a good time lower bound on any writes that happen after setting up preserve/preclude options (either in a new DB, new CF, SetOptions, etc.) and haven't yet aged out of that time window. This allows us to remove a bunch of work-arounds in tests. * For new DBs using preserve/preclude options, automatically reserve some sequence numbers and pre-map them to cover the time span back to the preserve/preclude cut-off time. In the future, this will allow us to import data from another DB by key, value, and write time by assigning an appropriate seqno in this DB for that write time. Note that the pre-population (historical mappings) does not happen if the original options at DB Open time do not have preserve/preclude, so it is recommended to create initial column families at that time with create_missing_column_families, to take advantage of this (future) feature. (Adding these historical mappings after DB Open would risk non-monotonic seqno_to_time_mapping, which is dubious if not dangerous.) Recommended follow-up: * Solve existing race conditions (not memory safety) where parallel operations like CreateColumnFamily or SetDBOptions could leave the wrong setting in effect. * Make SeqnoToTimeMapping more gracefully handle a possible case in which too many mappings are added for the time range of concern. It seems like there could be cases where data is massively excluded from the cold tier because of entries falling off the front of the mapping list (causing GetProximalSeqnoBeforeTime() to return 0). (More investigation needed.) No release note for the minor bug fix because this is still an experimental feature with limited usage. Pull Request resolved: https://github.com/facebook/rocksdb/pull/11922 Test Plan: tests added / updated Reviewed By: jowlyzhang Differential Revision: D49956563 Pulled By: pdillinger fbshipit-source-id: 92beb918c3a298fae9ca8e509717b1067caa1519
2023-05-24Improve memory efficiency of many OptimisticTransactionDBs (#11439)Peter Dillinger
Summary: Currently it's easy to use a ton of memory with many small OptimisticTransactionDB instances, because each one by default allocates a million mutexes (40 bytes each on my compiler) for validating transactions. It even puts a lot of pressure on the allocator by allocating each one individually! In this change: * Create a new object and option that enables sharing these buckets of mutexes between instances. This is generally good for load balancing potential contention as various DBs become hotter or colder with txn writes. About the only cases where this sharing wouldn't make sense (e.g. each DB usually written by one thread) are cases that would be better off with OccValidationPolicy::kValidateSerial which doesn't use the buckets anyway. * Allocate the mutexes in a contiguous array, for efficiency * Add an option to ensure the mutexes are cache-aligned. In several other places we use cache-aligned mutexes but OptimisticTransactionDB historically does not. It should be a space-time trade-off the user can choose. * Provide some visibility into the memory used by the mutex buckets with an ApproximateMemoryUsage() function (also used in unit testing) * Share code with other users of "striped" mutexes, appropriate refactoring for customization & efficiency (e.g. using FastRange instead of modulus) Pull Request resolved: https://github.com/facebook/rocksdb/pull/11439 Test Plan: unit tests added. Ran sized-up versions of stress test in unit test, including a before-and-after performance test showing no consistent difference. (NOTE: OptimisticTransactionDB not currently covered by db_stress!) Reviewed By: ltamasi Differential Revision: D45796393 Pulled By: pdillinger fbshipit-source-id: ae2b3a26ad91ceeec15debcdc63ff48df6736a54
2021-12-10More refactoring ahead of footer & meta changes (#9240)Peter Dillinger
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
2021-09-10Fix and detect headers with missing dependencies (#8893)Peter Dillinger
Summary: It's always annoying to find a header does not include its own dependencies and only works when included after other includes. This change adds `make check-headers` which validates that each header can be included at the top of a file. Some headers are excluded e.g. because of platform or external dependencies. rocksdb_namespace.h had to be re-worked slightly to enable checking for failure to include it. (ROCKSDB_NAMESPACE is a valid namespace name.) Fixes mostly involve adding and cleaning up #includes, but for FileTraceWriter, a constructor was out-of-lined to make a forward declaration sufficient. This check is not currently run with `make check` but is added to CircleCI build-linux-unity since that one is already relatively fast. Pull Request resolved: https://github.com/facebook/rocksdb/pull/8893 Test Plan: existing tests and resolving issues detected by new check Reviewed By: mrambacher Differential Revision: D30823300 Pulled By: pdillinger fbshipit-source-id: 9fff223944994c83c105e2e6496d24845dc8e572
2020-07-02Replace reinterpret_cast with static_cast_with_check (#7067)Jay Zhuang
Summary: Replace `reinterpret_cast` with `static_cast_with_check` for `DBImpl` and `ColumnFamilyHandleImpl`. Pull Request resolved: https://github.com/facebook/rocksdb/pull/7067 Reviewed By: siying Differential Revision: D22361587 Pulled By: jay-zhuang fbshipit-source-id: dfe9e8f3af39c3d27cc372c55ab9ad905eb0a5a1
2020-02-20Replace namespace name "rocksdb" with ROCKSDB_NAMESPACE (#6433)sdong
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
2017-07-31Add a missing "once" in .hSiying Dong
Summary: Closes https://github.com/facebook/rocksdb/pull/2670 Differential Revision: D5529018 Pulled By: siying fbshipit-source-id: 10a378933d509035d2dbe502247dd85fcea09789
2017-07-28Replace dynamic_cast<>Siying Dong
Summary: Replace dynamic_cast<> so that users can choose to build with RTTI off, so that they can save several bytes per object, and get tiny more memory available. Some nontrivial changes: 1. Add Comparator::GetRootComparator() to get around the internal comparator hack 2. Add the two experiemental functions to DB 3. Add TableFactory::GetOptionString() to avoid unnecessary casting to get the option string 4. Since 3 is done, move the parsing option functions for table factory to table factory files too, to be symmetric. Closes https://github.com/facebook/rocksdb/pull/2645 Differential Revision: D5502723 Pulled By: siying fbshipit-source-id: fd13cec5601cf68a554d87bfcf056f2ffa5fbf7c