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| Author | SHA1 | Message | Date | |
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Josh Kang
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4b983da055 |
Spell out special member functions (rule of five) (#15387)
Summary: Pull Request resolved: https://github.com/facebook/rocksdb/pull/15387 ## Summary RocksDB's `.clang-tidy` enables `cppcoreguidelines-special-member-functions`, `cppcoreguidelines-virtual-class-destructor` and the noexcept-move checks, and clang warns `-Wdeprecated-copy-with-user-provided-dtor`. A full scan reports 476 findings. In most of them, a class declares a destructor (or copy operations) but leaves the rest of copy/move implicit. That has two costs. Readers can't tell whether a class may be copied or moved. And resource-owning classes keep an implicit copy that would double-free if anyone ever used it. This diff resolves 453 of the 476. Approach, picked per class from least to most invasive: 1. An empty user-provided destructor becomes `= default`. This covers most interface classes, such as `virtual ~X() {}` -> `= default`. If the class is still copied, that would only rename the deprecated-copy warning, so the destructor is removed instead when nothing needs it (`Customizable`, `TableFactory` and `InternalKeyComparator` inherit a virtual one; `IteratorWrapperBase` isn't polymorphic), and `MemTableRep::KeyComparator` gets defaulted copy and move. 2. Classes whose copy is already deleted get explicitly deleted move operations too. Move was already unavailable, so this only documents it. 3. Resource-owning classes that are never copied get deleted copy and move operations. Examples: the C API wrapper structs, which run a `destructor_` callback (edited in `tools/c_api_gen/c_base.cc` and regenerated into `db/c.cc`); `ShardedCache`, which frees its shards; iterator wrappers; and RAII handles. 4. Value types that are copied or moved get the missing operations as `= default`, which keeps their current behavior. 5. Exception specifications of existing functions are unchanged, except for `WriteBatch`'s move assignment (below): no other `noexcept` is added or removed. Only the move operations this diff newly declares (`Comparator`, `FileSampledStats` and the thread-local `Entry`) are `noexcept`; they copy only scalars or atomics. `WriteBatch`'s copy and move assignment destroyed `*this` and placement-new'ed a new `WriteBatch` over it. That is undefined behavior when `*this` is a subclass, and if the copy constructor threw, `*this` was left destroyed and was later destroyed again. Move assignment now assigns member-wise and ends in the same state as the move constructor, which leaves `has_key_with_ts_`, the timestamp-size tracking and the other fields it doesn't copy at their defaults. `rep_` is swapped through a temporary, because a plain string move-assignment can keep the old buffer (e.g. a large batch reset with `batch = WriteBatch()` would keep its memory). Nothing in it can throw, so it is now `noexcept`. Copy assignment copies into a temporary and moves it in, so a throwing copy leaves `*this` unchanged. Bugs this exposed and fixed: - `RestoreAfterCopyOrCreateWorkItem` (backup engine): the hand-written move constructor and assignment moved only some fields, so `from_file` and `to_file` were empty after `push_back(std::move(...))`. A restore that hit a checksum mismatch then reported "While restoring -> : ..." without file names. It now uses the compiler-generated moves, which are still `noexcept`. - `ExternalSstFileIngestionJob` lived in a `std::vector`, and its destructor frees raw-owned pointers, so the implicit copy used on vector reallocation would double-free. Its file batches also point into its own inline file storage, so neither a copy nor a move is safe after `Prepare()`. Copy and move are now deleted, and `DBImpl` holds jobs through `std::unique_ptr`. Compatibility: no public class loses an operation users can call. Public interfaces mostly only get `virtual ~X() = default;`. `WriteBatch`'s move assignment becomes `noexcept`, which is not part of the mangled name, so the ABI doesn't change. `SubcompactionJobInfo` and `CompactionJobInfo` intentionally stay C++20 aggregates, so users' aggregate and designated initializers keep compiling. `Configurable`, `CompareInterface`, `WriteBatchBase`, `ObjectLibrary::Entry` and `MemTableRep::KeyComparator` declare defaulted copy and move, and `Customizable` no longer declares a destructor. As a result, `Configurable` and `Customizable` subclasses that declare no destructor or copy operations of their own now move their registered-options list instead of copying it. In-tree, these are the mutable-options adapters, the table factories, the memory allocators and test classes; all are held through smart pointers or used in place, and `Clone()` copies, so none is moved by value. Not changed (23): `IODebugContext` (custom deep copy plus a `std::shared_mutex`), `DBWithColumnFamilies` in db_bench (stored in a `std::vector` with non-movable members), `Snapshot`'s protected virtual destructor (intended), `ManagedSnapshot`, the `SubcompactionJobInfo` and `CompactionJobInfo` aggregates, and the 16 noexcept-move-constructor and noexcept-swap findings on existing functions, including `autovector`'s move assignment (adding `noexcept` would change their exception specifications). Copying `ManagedSnapshot` already double-releases the snapshot. Fixing that needs a real move implementation and is a behavior change, so it is left for a separate diff. Reviewed By: rban1 Differential Revision: D123186309 fbshipit-source-id: 6f8e57e233e12199a007407130bb9a1f6d52e8d1 |
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Yu Zhang
|
9a72cf1a61 |
Add timestamp support in dump_wal/dump/idump (#12690)
Summary: As titled. For dumping wal files, since a mapping from column family id to the user comparator object is needed to print the timestamp in human readable format, option `[--db=<db_path>]` is added to `dump_wal` command to allow the user to choose to optionally open the DB as read only instance and dump the wal file with better timestamp formatting. Pull Request resolved: https://github.com/facebook/rocksdb/pull/12690 Test Plan: Manually tested dump_wal: [dump a wal file specified with --walfile] ``` >> ./ldb --walfile=$TEST_DB/000004.log dump_wal --print_value >>1,1,28,13,PUT(0) : 0x666F6F0100000000000000 : 0x7631 (Column family id: [0] contained in WAL are not opened in DB. Applied default hex formatting for user key. Specify --db=<db_path> to open DB for better user key formatting if it contains timestamp.) ``` [dump with --db specified for better timestamp formatting] ``` >> ./ldb --walfile=$TEST_DB/000004.log dump_wal --db=$TEST_DB --print_value >> 1,1,28,13,PUT(0) : 0x666F6F|timestamp:1 : 0x7631 ``` dump: [dump a file specified with --path] ``` >>./ldb --path=/tmp/rocksdbtest-501/column_family_test_75359_17910784957761284041/000004.log dump Sequence,Count,ByteSize,Physical Offset,Key(s) : value 1,1,28,13,PUT(0) : 0x666F6F0100000000000000 : 0x7631 (Column family id: [0] contained in WAL are not opened in DB. Applied default hex formatting for user key. Specify --db=<db_path> to open DB for better user key formatting if it contains timestamp.) ``` [dump db specified with --db] ``` >> ./ldb --db=/tmp/rocksdbtest-501/column_family_test_75359_17910784957761284041 dump >> foo|timestamp:1 ==> v1 Keys in range: 1 ``` idump ``` ./ldb --db=$TEST_DB idump 'foo|timestamp:1' seq:1, type:1 => v1 Internal keys in range: 1 ``` Reviewed By: ltamasi Differential Revision: D57755382 Pulled By: jowlyzhang fbshipit-source-id: a0a2ef80c92801cbf7bfccc64769c1191824362e |
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Yu Zhang
|
1104eaa35e |
Add initial support for TimedPut API (#12419)
Summary:
This PR adds support for `TimedPut` API. We introduced a new type `kTypeValuePreferredSeqno` for entries added to the DB via the `TimedPut` API.
The life cycle of such an entry on the write/flush/compaction paths are:
1) It is initially added to memtable as:
`<user_key, seq, kTypeValuePreferredSeqno>: {value, write_unix_time}`
2) When it's flushed to L0 sst files, it's converted to:
`<user_key, seq, kTypeValuePreferredSeqno>: {value, preferred_seqno}`
when we have easy access to the seqno to time mapping.
3) During compaction, if certain conditions are met, we swap in the `preferred_seqno` and the entry will become:
`<user_key, preferred_seqno, kTypeValue>: value`. This step helps fast track these entries to the cold tier if they are eligible after the sequence number swap.
On the read path:
A `kTypeValuePreferredSeqno` entry acts the same as a `kTypeValue` entry, the unix_write_time/preferred seqno part packed in value is completely ignored.
Needed follow ups:
1) The seqno to time mapping accessible in flush needs to be extended to cover the `write_unix_time` for possible `kTypeValuePreferredSeqno` entries. This also means we need to track these `write_unix_time` in memtable.
2) Compaction filter support for the new `kTypeValuePreferredSeqno` type for feature parity with other `kTypeValue` and equivalent types.
3) Stress test coverage for the feature
Pull Request resolved: https://github.com/facebook/rocksdb/pull/12419
Test Plan: Added unit tests
Reviewed By: pdillinger
Differential Revision: D54920296
Pulled By: jowlyzhang
fbshipit-source-id: c8b43f7a7c465e569141770e93c748371ff1da9e
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Yu Zhang
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11ebddb1d4 |
Add utils to use for handling user defined timestamp size record in WAL (#11451)
Summary: Add a util method `HandleWriteBatchTimestampSizeDifference` to handle a `WriteBatch` read from WAL log when user-defined timestamp size record is written and read. Two check modes are added: `kVerifyConsistency` that just verifies the recorded timestamp size are consistent with the running ones. This mode is to be used by `db_impl_secondary` for opening a DB as secondary instance. It will also be used by `db_impl_open` before the user comparator switch support is added to make a column switch between enabling/disable UDT feature. The other mode `kReconcileInconsistency` will be used by `db_impl_open` later when user comparator can be changed. Another change is to extract a method `CollectColumnFamilyIdsFromWriteBatch` in db_secondary_impl.h into its standalone util file so it can be shared. Pull Request resolved: https://github.com/facebook/rocksdb/pull/11451 Test Plan: ``` make check ./udt_util_test ``` Reviewed By: ltamasi Differential Revision: D45894386 Pulled By: jowlyzhang fbshipit-source-id: b96790777f154cddab6d45d9ba2e5d20ebc6fe9d |