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Diffstat (limited to 'src/rocksdb/db/column_family.h')
| -rw-r--r-- | src/rocksdb/db/column_family.h | 757 |
1 files changed, 757 insertions, 0 deletions
diff --git a/src/rocksdb/db/column_family.h b/src/rocksdb/db/column_family.h new file mode 100644 index 000000000..fcc8ea2cf --- /dev/null +++ b/src/rocksdb/db/column_family.h @@ -0,0 +1,757 @@ +// Copyright (c) 2011-present, Facebook, Inc. All rights reserved. +// This source code is licensed under both the GPLv2 (found in the +// COPYING file in the root directory) and Apache 2.0 License +// (found in the LICENSE.Apache file in the root directory). +// +// Copyright (c) 2011 The LevelDB Authors. All rights reserved. +// Use of this source code is governed by a BSD-style license that can be +// found in the LICENSE file. See the AUTHORS file for names of contributors. + +#pragma once + +#include <unordered_map> +#include <string> +#include <vector> +#include <atomic> + +#include "db/memtable_list.h" +#include "db/table_cache.h" +#include "db/table_properties_collector.h" +#include "db/write_batch_internal.h" +#include "db/write_controller.h" +#include "options/cf_options.h" +#include "rocksdb/compaction_job_stats.h" +#include "rocksdb/db.h" +#include "rocksdb/env.h" +#include "rocksdb/options.h" +#include "trace_replay/block_cache_tracer.h" +#include "util/thread_local.h" + +namespace ROCKSDB_NAMESPACE { + +class Version; +class VersionSet; +class VersionStorageInfo; +class MemTable; +class MemTableListVersion; +class CompactionPicker; +class Compaction; +class InternalKey; +class InternalStats; +class ColumnFamilyData; +class DBImpl; +class LogBuffer; +class InstrumentedMutex; +class InstrumentedMutexLock; +struct SuperVersionContext; + +extern const double kIncSlowdownRatio; +// This file contains a list of data structures for managing column family +// level metadata. +// +// The basic relationships among classes declared here are illustrated as +// following: +// +// +----------------------+ +----------------------+ +--------+ +// +---+ ColumnFamilyHandle 1 | +--+ ColumnFamilyHandle 2 | | DBImpl | +// | +----------------------+ | +----------------------+ +----+---+ +// | +--------------------------+ | +// | | +-----------------------------+ +// | | | +// | | +-----------------------------v-------------------------------+ +// | | | | +// | | | ColumnFamilySet | +// | | | | +// | | +-------------+--------------------------+----------------+---+ +// | | | | | +// | +-------------------------------------+ | | +// | | | | v +// | +-------------v-------------+ +-----v----v---------+ +// | | | | | +// | | ColumnFamilyData 1 | | ColumnFamilyData 2 | ...... +// | | | | | +// +---> | | | +// | +---------+ | | +// | | MemTable| | | +// | | List | | | +// +--------+---+--+-+----+----+ +--------------------++ +// | | | | +// | | | | +// | | | +-----------------------+ +// | | +-----------+ | +// v +--------+ | | +// +--------+--------+ | | | +// | | | | +----------v----------+ +// +---> |SuperVersion 1.a +-----------------> | +// | +------+ | | MemTableListVersion | +// +---+-------------+ | | | | | +// | | | | +----+------------+---+ +// | current | | | | | +// | +-------------+ | |mem | | +// | | | | | | +// +-v---v-------+ +---v--v---+ +-----v----+ +----v-----+ +// | | | | | | | | +// | Version 1.a | | memtable | | memtable | | memtable | +// | | | 1.a | | 1.b | | 1.c | +// +-------------+ | | | | | | +// +----------+ +----------+ +----------+ +// +// DBImpl keeps a ColumnFamilySet, which references to all column families by +// pointing to respective ColumnFamilyData object of each column family. +// This is how DBImpl can list and operate on all the column families. +// ColumnFamilyHandle also points to ColumnFamilyData directly, so that +// when a user executes a query, it can directly find memtables and Version +// as well as SuperVersion to the column family, without going through +// ColumnFamilySet. +// +// ColumnFamilySet points to the latest view of the LSM-tree (list of memtables +// and SST files) indirectly, while ongoing operations may hold references +// to a current or an out-of-date SuperVersion, which in turn points to a +// point-in-time view of the LSM-tree. This guarantees the memtables and SST +// files being operated on will not go away, until the SuperVersion is +// unreferenced to 0 and destoryed. +// +// The following graph illustrates a possible referencing relationships: +// +// Column +--------------+ current +-----------+ +// Family +---->+ +------------------->+ | +// Data | SuperVersion +----------+ | Version A | +// | 3 | imm | | | +// Iter2 +----->+ | +-------v------+ +-----------+ +// +-----+--------+ | MemtableList +----------------> Empty +// | | Version r | +-----------+ +// | +--------------+ | | +// +------------------+ current| Version B | +// +--------------+ | +----->+ | +// | | | | +-----+-----+ +// Compaction +>+ SuperVersion +-------------+ ^ +// Job | 2 +------+ | |current +// | +----+ | | mem | +------------+ +// +--------------+ | | +---------------------> | +// | +------------------------> MemTable a | +// | mem | | | +// +--------------+ | | +------------+ +// | +--------------------------+ +// Iter1 +-----> SuperVersion | | +------------+ +// | 1 +------------------------------>+ | +// | +-+ | mem | MemTable b | +// +--------------+ | | | | +// | | +--------------+ +-----^------+ +// | |imm | MemtableList | | +// | +--->+ Version s +------------+ +// | +--------------+ +// | +--------------+ +// | | MemtableList | +// +------>+ Version t +--------> Empty +// imm +--------------+ +// +// In this example, even if the current LSM-tree consists of Version A and +// memtable a, which is also referenced by SuperVersion, two older SuperVersion +// SuperVersion2 and Superversion1 still exist, and are referenced by a +// compaction job and an old iterator Iter1, respectively. SuperVersion2 +// contains Version B, memtable a and memtable b; SuperVersion1 contains +// Version B and memtable b (mutable). As a result, Version B and memtable b +// are prevented from being destroyed or deleted. + +// ColumnFamilyHandleImpl is the class that clients use to access different +// column families. It has non-trivial destructor, which gets called when client +// is done using the column family +class ColumnFamilyHandleImpl : public ColumnFamilyHandle { + public: + // create while holding the mutex + ColumnFamilyHandleImpl( + ColumnFamilyData* cfd, DBImpl* db, InstrumentedMutex* mutex); + // destroy without mutex + virtual ~ColumnFamilyHandleImpl(); + virtual ColumnFamilyData* cfd() const { return cfd_; } + + virtual uint32_t GetID() const override; + virtual const std::string& GetName() const override; + virtual Status GetDescriptor(ColumnFamilyDescriptor* desc) override; + virtual const Comparator* GetComparator() const override; + + private: + ColumnFamilyData* cfd_; + DBImpl* db_; + InstrumentedMutex* mutex_; +}; + +// Does not ref-count ColumnFamilyData +// We use this dummy ColumnFamilyHandleImpl because sometimes MemTableInserter +// calls DBImpl methods. When this happens, MemTableInserter need access to +// ColumnFamilyHandle (same as the client would need). In that case, we feed +// MemTableInserter dummy ColumnFamilyHandle and enable it to call DBImpl +// methods +class ColumnFamilyHandleInternal : public ColumnFamilyHandleImpl { + public: + ColumnFamilyHandleInternal() + : ColumnFamilyHandleImpl(nullptr, nullptr, nullptr), internal_cfd_(nullptr) {} + + void SetCFD(ColumnFamilyData* _cfd) { internal_cfd_ = _cfd; } + virtual ColumnFamilyData* cfd() const override { return internal_cfd_; } + + private: + ColumnFamilyData* internal_cfd_; +}; + +// holds references to memtable, all immutable memtables and version +struct SuperVersion { + // Accessing members of this class is not thread-safe and requires external + // synchronization (ie db mutex held or on write thread). + ColumnFamilyData* cfd; + MemTable* mem; + MemTableListVersion* imm; + Version* current; + MutableCFOptions mutable_cf_options; + // Version number of the current SuperVersion + uint64_t version_number; + WriteStallCondition write_stall_condition; + + InstrumentedMutex* db_mutex; + + // should be called outside the mutex + SuperVersion() = default; + ~SuperVersion(); + SuperVersion* Ref(); + // If Unref() returns true, Cleanup() should be called with mutex held + // before deleting this SuperVersion. + bool Unref(); + + // call these two methods with db mutex held + // Cleanup unrefs mem, imm and current. Also, it stores all memtables + // that needs to be deleted in to_delete vector. Unrefing those + // objects needs to be done in the mutex + void Cleanup(); + void Init(ColumnFamilyData* new_cfd, MemTable* new_mem, + MemTableListVersion* new_imm, Version* new_current); + + // The value of dummy is not actually used. kSVInUse takes its address as a + // mark in the thread local storage to indicate the SuperVersion is in use + // by thread. This way, the value of kSVInUse is guaranteed to have no + // conflict with SuperVersion object address and portable on different + // platform. + static int dummy; + static void* const kSVInUse; + static void* const kSVObsolete; + + private: + std::atomic<uint32_t> refs; + // We need to_delete because during Cleanup(), imm->Unref() returns + // all memtables that we need to free through this vector. We then + // delete all those memtables outside of mutex, during destruction + autovector<MemTable*> to_delete; +}; + +extern Status CheckCompressionSupported(const ColumnFamilyOptions& cf_options); + +extern Status CheckConcurrentWritesSupported( + const ColumnFamilyOptions& cf_options); + +extern Status CheckCFPathsSupported(const DBOptions& db_options, + const ColumnFamilyOptions& cf_options); + +extern ColumnFamilyOptions SanitizeOptions(const ImmutableDBOptions& db_options, + const ColumnFamilyOptions& src); +// Wrap user defined table proproties collector factories `from cf_options` +// into internal ones in int_tbl_prop_collector_factories. Add a system internal +// one too. +extern void GetIntTblPropCollectorFactory( + const ImmutableCFOptions& ioptions, + std::vector<std::unique_ptr<IntTblPropCollectorFactory>>* + int_tbl_prop_collector_factories); + +class ColumnFamilySet; + +// This class keeps all the data that a column family needs. +// Most methods require DB mutex held, unless otherwise noted +class ColumnFamilyData { + public: + ~ColumnFamilyData(); + + // thread-safe + uint32_t GetID() const { return id_; } + // thread-safe + const std::string& GetName() const { return name_; } + + // Ref() can only be called from a context where the caller can guarantee + // that ColumnFamilyData is alive (while holding a non-zero ref already, + // holding a DB mutex, or as the leader in a write batch group). + void Ref() { refs_.fetch_add(1); } + + // Unref decreases the reference count, but does not handle deletion + // when the count goes to 0. If this method returns true then the + // caller should delete the instance immediately, or later, by calling + // FreeDeadColumnFamilies(). Unref() can only be called while holding + // a DB mutex, or during single-threaded recovery. + bool Unref() { + int old_refs = refs_.fetch_sub(1); + assert(old_refs > 0); + return old_refs == 1; + } + + // UnrefAndTryDelete() decreases the reference count and do free if needed, + // return true if this is freed else false, UnrefAndTryDelete() can only + // be called while holding a DB mutex, or during single-threaded recovery. + bool UnrefAndTryDelete(); + + // SetDropped() can only be called under following conditions: + // 1) Holding a DB mutex, + // 2) from single-threaded write thread, AND + // 3) from single-threaded VersionSet::LogAndApply() + // After dropping column family no other operation on that column family + // will be executed. All the files and memory will be, however, kept around + // until client drops the column family handle. That way, client can still + // access data from dropped column family. + // Column family can be dropped and still alive. In that state: + // *) Compaction and flush is not executed on the dropped column family. + // *) Client can continue reading from column family. Writes will fail unless + // WriteOptions::ignore_missing_column_families is true + // When the dropped column family is unreferenced, then we: + // *) Remove column family from the linked list maintained by ColumnFamilySet + // *) delete all memory associated with that column family + // *) delete all the files associated with that column family + void SetDropped(); + bool IsDropped() const { return dropped_.load(std::memory_order_relaxed); } + + // thread-safe + int NumberLevels() const { return ioptions_.num_levels; } + + void SetLogNumber(uint64_t log_number) { log_number_ = log_number; } + uint64_t GetLogNumber() const { return log_number_; } + + void SetFlushReason(FlushReason flush_reason) { + flush_reason_ = flush_reason; + } + FlushReason GetFlushReason() const { return flush_reason_; } + // thread-safe + const FileOptions* soptions() const; + const ImmutableCFOptions* ioptions() const { return &ioptions_; } + // REQUIRES: DB mutex held + // This returns the MutableCFOptions used by current SuperVersion + // You should use this API to reference MutableCFOptions most of the time. + const MutableCFOptions* GetCurrentMutableCFOptions() const { + return &(super_version_->mutable_cf_options); + } + // REQUIRES: DB mutex held + // This returns the latest MutableCFOptions, which may be not in effect yet. + const MutableCFOptions* GetLatestMutableCFOptions() const { + return &mutable_cf_options_; + } + + // REQUIRES: DB mutex held + // Build ColumnFamiliesOptions with immutable options and latest mutable + // options. + ColumnFamilyOptions GetLatestCFOptions() const; + + bool is_delete_range_supported() { return is_delete_range_supported_; } + + // Validate CF options against DB options + static Status ValidateOptions(const DBOptions& db_options, + const ColumnFamilyOptions& cf_options); +#ifndef ROCKSDB_LITE + // REQUIRES: DB mutex held + Status SetOptions( + const DBOptions& db_options, + const std::unordered_map<std::string, std::string>& options_map); +#endif // ROCKSDB_LITE + + InternalStats* internal_stats() { return internal_stats_.get(); } + + MemTableList* imm() { return &imm_; } + MemTable* mem() { return mem_; } + Version* current() { return current_; } + Version* dummy_versions() { return dummy_versions_; } + void SetCurrent(Version* _current); + uint64_t GetNumLiveVersions() const; // REQUIRE: DB mutex held + uint64_t GetTotalSstFilesSize() const; // REQUIRE: DB mutex held + uint64_t GetLiveSstFilesSize() const; // REQUIRE: DB mutex held + void SetMemtable(MemTable* new_mem) { + uint64_t memtable_id = last_memtable_id_.fetch_add(1) + 1; + new_mem->SetID(memtable_id); + mem_ = new_mem; + } + + // calculate the oldest log needed for the durability of this column family + uint64_t OldestLogToKeep(); + + // See Memtable constructor for explanation of earliest_seq param. + MemTable* ConstructNewMemtable(const MutableCFOptions& mutable_cf_options, + SequenceNumber earliest_seq); + void CreateNewMemtable(const MutableCFOptions& mutable_cf_options, + SequenceNumber earliest_seq); + + TableCache* table_cache() const { return table_cache_.get(); } + + // See documentation in compaction_picker.h + // REQUIRES: DB mutex held + bool NeedsCompaction() const; + // REQUIRES: DB mutex held + Compaction* PickCompaction(const MutableCFOptions& mutable_options, + LogBuffer* log_buffer); + + // Check if the passed range overlap with any running compactions. + // REQUIRES: DB mutex held + bool RangeOverlapWithCompaction(const Slice& smallest_user_key, + const Slice& largest_user_key, + int level) const; + + // Check if the passed ranges overlap with any unflushed memtables + // (immutable or mutable). + // + // @param super_version A referenced SuperVersion that will be held for the + // duration of this function. + // + // Thread-safe + Status RangesOverlapWithMemtables(const autovector<Range>& ranges, + SuperVersion* super_version, bool* overlap); + + // A flag to tell a manual compaction is to compact all levels together + // instead of a specific level. + static const int kCompactAllLevels; + // A flag to tell a manual compaction's output is base level. + static const int kCompactToBaseLevel; + // REQUIRES: DB mutex held + Compaction* CompactRange(const MutableCFOptions& mutable_cf_options, + int input_level, int output_level, + const CompactRangeOptions& compact_range_options, + const InternalKey* begin, const InternalKey* end, + InternalKey** compaction_end, bool* manual_conflict, + uint64_t max_file_num_to_ignore); + + CompactionPicker* compaction_picker() { return compaction_picker_.get(); } + // thread-safe + const Comparator* user_comparator() const { + return internal_comparator_.user_comparator(); + } + // thread-safe + const InternalKeyComparator& internal_comparator() const { + return internal_comparator_; + } + + const std::vector<std::unique_ptr<IntTblPropCollectorFactory>>* + int_tbl_prop_collector_factories() const { + return &int_tbl_prop_collector_factories_; + } + + SuperVersion* GetSuperVersion() { return super_version_; } + // thread-safe + // Return a already referenced SuperVersion to be used safely. + SuperVersion* GetReferencedSuperVersion(DBImpl* db); + // thread-safe + // Get SuperVersion stored in thread local storage. If it does not exist, + // get a reference from a current SuperVersion. + SuperVersion* GetThreadLocalSuperVersion(DBImpl* db); + // Try to return SuperVersion back to thread local storage. Retrun true on + // success and false on failure. It fails when the thread local storage + // contains anything other than SuperVersion::kSVInUse flag. + bool ReturnThreadLocalSuperVersion(SuperVersion* sv); + // thread-safe + uint64_t GetSuperVersionNumber() const { + return super_version_number_.load(); + } + // will return a pointer to SuperVersion* if previous SuperVersion + // if its reference count is zero and needs deletion or nullptr if not + // As argument takes a pointer to allocated SuperVersion to enable + // the clients to allocate SuperVersion outside of mutex. + // IMPORTANT: Only call this from DBImpl::InstallSuperVersion() + void InstallSuperVersion(SuperVersionContext* sv_context, + InstrumentedMutex* db_mutex, + const MutableCFOptions& mutable_cf_options); + void InstallSuperVersion(SuperVersionContext* sv_context, + InstrumentedMutex* db_mutex); + + void ResetThreadLocalSuperVersions(); + + // Protected by DB mutex + void set_queued_for_flush(bool value) { queued_for_flush_ = value; } + void set_queued_for_compaction(bool value) { queued_for_compaction_ = value; } + bool queued_for_flush() { return queued_for_flush_; } + bool queued_for_compaction() { return queued_for_compaction_; } + + enum class WriteStallCause { + kNone, + kMemtableLimit, + kL0FileCountLimit, + kPendingCompactionBytes, + }; + static std::pair<WriteStallCondition, WriteStallCause> + GetWriteStallConditionAndCause(int num_unflushed_memtables, int num_l0_files, + uint64_t num_compaction_needed_bytes, + const MutableCFOptions& mutable_cf_options); + + // Recalculate some small conditions, which are changed only during + // compaction, adding new memtable and/or + // recalculation of compaction score. These values are used in + // DBImpl::MakeRoomForWrite function to decide, if it need to make + // a write stall + WriteStallCondition RecalculateWriteStallConditions( + const MutableCFOptions& mutable_cf_options); + + void set_initialized() { initialized_.store(true); } + + bool initialized() const { return initialized_.load(); } + + const ColumnFamilyOptions& initial_cf_options() { + return initial_cf_options_; + } + + Env::WriteLifeTimeHint CalculateSSTWriteHint(int level); + + // created_dirs remembers directory created, so that we don't need to call + // the same data creation operation again. + Status AddDirectories( + std::map<std::string, std::shared_ptr<Directory>>* created_dirs); + + Directory* GetDataDir(size_t path_id) const; + + ThreadLocalPtr* TEST_GetLocalSV() { return local_sv_.get(); } + + private: + friend class ColumnFamilySet; + ColumnFamilyData(uint32_t id, const std::string& name, + Version* dummy_versions, Cache* table_cache, + WriteBufferManager* write_buffer_manager, + const ColumnFamilyOptions& options, + const ImmutableDBOptions& db_options, + const FileOptions& file_options, + ColumnFamilySet* column_family_set, + BlockCacheTracer* const block_cache_tracer); + + uint32_t id_; + const std::string name_; + Version* dummy_versions_; // Head of circular doubly-linked list of versions. + Version* current_; // == dummy_versions->prev_ + + std::atomic<int> refs_; // outstanding references to ColumnFamilyData + std::atomic<bool> initialized_; + std::atomic<bool> dropped_; // true if client dropped it + + const InternalKeyComparator internal_comparator_; + std::vector<std::unique_ptr<IntTblPropCollectorFactory>> + int_tbl_prop_collector_factories_; + + const ColumnFamilyOptions initial_cf_options_; + const ImmutableCFOptions ioptions_; + MutableCFOptions mutable_cf_options_; + + const bool is_delete_range_supported_; + + std::unique_ptr<TableCache> table_cache_; + + std::unique_ptr<InternalStats> internal_stats_; + + WriteBufferManager* write_buffer_manager_; + + MemTable* mem_; + MemTableList imm_; + SuperVersion* super_version_; + + // An ordinal representing the current SuperVersion. Updated by + // InstallSuperVersion(), i.e. incremented every time super_version_ + // changes. + std::atomic<uint64_t> super_version_number_; + + // Thread's local copy of SuperVersion pointer + // This needs to be destructed before mutex_ + std::unique_ptr<ThreadLocalPtr> local_sv_; + + // pointers for a circular linked list. we use it to support iterations over + // all column families that are alive (note: dropped column families can also + // be alive as long as client holds a reference) + ColumnFamilyData* next_; + ColumnFamilyData* prev_; + + // This is the earliest log file number that contains data from this + // Column Family. All earlier log files must be ignored and not + // recovered from + uint64_t log_number_; + + std::atomic<FlushReason> flush_reason_; + + // An object that keeps all the compaction stats + // and picks the next compaction + std::unique_ptr<CompactionPicker> compaction_picker_; + + ColumnFamilySet* column_family_set_; + + std::unique_ptr<WriteControllerToken> write_controller_token_; + + // If true --> this ColumnFamily is currently present in DBImpl::flush_queue_ + bool queued_for_flush_; + + // If true --> this ColumnFamily is currently present in + // DBImpl::compaction_queue_ + bool queued_for_compaction_; + + uint64_t prev_compaction_needed_bytes_; + + // if the database was opened with 2pc enabled + bool allow_2pc_; + + // Memtable id to track flush. + std::atomic<uint64_t> last_memtable_id_; + + // Directories corresponding to cf_paths. + std::vector<std::shared_ptr<Directory>> data_dirs_; +}; + +// ColumnFamilySet has interesting thread-safety requirements +// * CreateColumnFamily() or RemoveColumnFamily() -- need to be protected by DB +// mutex AND executed in the write thread. +// CreateColumnFamily() should ONLY be called from VersionSet::LogAndApply() AND +// single-threaded write thread. It is also called during Recovery and in +// DumpManifest(). +// RemoveColumnFamily() is only called from SetDropped(). DB mutex needs to be +// held and it needs to be executed from the write thread. SetDropped() also +// guarantees that it will be called only from single-threaded LogAndApply(), +// but this condition is not that important. +// * Iteration -- hold DB mutex, but you can release it in the body of +// iteration. If you release DB mutex in body, reference the column +// family before the mutex and unreference after you unlock, since the column +// family might get dropped when the DB mutex is released +// * GetDefault() -- thread safe +// * GetColumnFamily() -- either inside of DB mutex or from a write thread +// * GetNextColumnFamilyID(), GetMaxColumnFamily(), UpdateMaxColumnFamily(), +// NumberOfColumnFamilies -- inside of DB mutex +class ColumnFamilySet { + public: + // ColumnFamilySet supports iteration + class iterator { + public: + explicit iterator(ColumnFamilyData* cfd) + : current_(cfd) {} + iterator& operator++() { + // dropped column families might still be included in this iteration + // (we're only removing them when client drops the last reference to the + // column family). + // dummy is never dead, so this will never be infinite + do { + current_ = current_->next_; + } while (current_->refs_.load(std::memory_order_relaxed) == 0); + return *this; + } + bool operator!=(const iterator& other) { + return this->current_ != other.current_; + } + ColumnFamilyData* operator*() { return current_; } + + private: + ColumnFamilyData* current_; + }; + + ColumnFamilySet(const std::string& dbname, + const ImmutableDBOptions* db_options, + const FileOptions& file_options, Cache* table_cache, + WriteBufferManager* write_buffer_manager, + WriteController* write_controller, + BlockCacheTracer* const block_cache_tracer); + ~ColumnFamilySet(); + + ColumnFamilyData* GetDefault() const; + // GetColumnFamily() calls return nullptr if column family is not found + ColumnFamilyData* GetColumnFamily(uint32_t id) const; + ColumnFamilyData* GetColumnFamily(const std::string& name) const; + // this call will return the next available column family ID. it guarantees + // that there is no column family with id greater than or equal to the + // returned value in the current running instance or anytime in RocksDB + // instance history. + uint32_t GetNextColumnFamilyID(); + uint32_t GetMaxColumnFamily(); + void UpdateMaxColumnFamily(uint32_t new_max_column_family); + size_t NumberOfColumnFamilies() const; + + ColumnFamilyData* CreateColumnFamily(const std::string& name, uint32_t id, + Version* dummy_version, + const ColumnFamilyOptions& options); + + iterator begin() { return iterator(dummy_cfd_->next_); } + iterator end() { return iterator(dummy_cfd_); } + + // REQUIRES: DB mutex held + // Don't call while iterating over ColumnFamilySet + void FreeDeadColumnFamilies(); + + Cache* get_table_cache() { return table_cache_; } + + private: + friend class ColumnFamilyData; + // helper function that gets called from cfd destructor + // REQUIRES: DB mutex held + void RemoveColumnFamily(ColumnFamilyData* cfd); + + // column_families_ and column_family_data_ need to be protected: + // * when mutating both conditions have to be satisfied: + // 1. DB mutex locked + // 2. thread currently in single-threaded write thread + // * when reading, at least one condition needs to be satisfied: + // 1. DB mutex locked + // 2. accessed from a single-threaded write thread + std::unordered_map<std::string, uint32_t> column_families_; + std::unordered_map<uint32_t, ColumnFamilyData*> column_family_data_; + + uint32_t max_column_family_; + ColumnFamilyData* dummy_cfd_; + // We don't hold the refcount here, since default column family always exists + // We are also not responsible for cleaning up default_cfd_cache_. This is + // just a cache that makes common case (accessing default column family) + // faster + ColumnFamilyData* default_cfd_cache_; + + const std::string db_name_; + const ImmutableDBOptions* const db_options_; + const FileOptions file_options_; + Cache* table_cache_; + WriteBufferManager* write_buffer_manager_; + WriteController* write_controller_; + BlockCacheTracer* const block_cache_tracer_; +}; + +// We use ColumnFamilyMemTablesImpl to provide WriteBatch a way to access +// memtables of different column families (specified by ID in the write batch) +class ColumnFamilyMemTablesImpl : public ColumnFamilyMemTables { + public: + explicit ColumnFamilyMemTablesImpl(ColumnFamilySet* column_family_set) + : column_family_set_(column_family_set), current_(nullptr) {} + + // Constructs a ColumnFamilyMemTablesImpl equivalent to one constructed + // with the arguments used to construct *orig. + explicit ColumnFamilyMemTablesImpl(ColumnFamilyMemTablesImpl* orig) + : column_family_set_(orig->column_family_set_), current_(nullptr) {} + + // sets current_ to ColumnFamilyData with column_family_id + // returns false if column family doesn't exist + // REQUIRES: use this function of DBImpl::column_family_memtables_ should be + // under a DB mutex OR from a write thread + bool Seek(uint32_t column_family_id) override; + + // Returns log number of the selected column family + // REQUIRES: under a DB mutex OR from a write thread + uint64_t GetLogNumber() const override; + + // REQUIRES: Seek() called first + // REQUIRES: use this function of DBImpl::column_family_memtables_ should be + // under a DB mutex OR from a write thread + virtual MemTable* GetMemTable() const override; + + // Returns column family handle for the selected column family + // REQUIRES: use this function of DBImpl::column_family_memtables_ should be + // under a DB mutex OR from a write thread + virtual ColumnFamilyHandle* GetColumnFamilyHandle() override; + + // Cannot be called while another thread is calling Seek(). + // REQUIRES: use this function of DBImpl::column_family_memtables_ should be + // under a DB mutex OR from a write thread + virtual ColumnFamilyData* current() override { return current_; } + + private: + ColumnFamilySet* column_family_set_; + ColumnFamilyData* current_; + ColumnFamilyHandleInternal handle_; +}; + +extern uint32_t GetColumnFamilyID(ColumnFamilyHandle* column_family); + +extern const Comparator* GetColumnFamilyUserComparator( + ColumnFamilyHandle* column_family); + +} // namespace ROCKSDB_NAMESPACE |