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// 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 "util/thread_local.h"
namespace rocksdb {
class Version;
class VersionSet;
class MemTable;
class MemTableListVersion;
class CompactionPicker;
class Compaction;
class InternalKey;
class InternalStats;
class ColumnFamilyData;
class DBImpl;
class LogBuffer;
class InstrumentedMutex;
class InstrumentedMutexLock;
extern const double kIncSlowdownRatio;
// 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 {
// create while holding the mutex
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;
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 {
: ColumnFamilyHandleImpl(nullptr, nullptr, nullptr) {}
void SetCFD(ColumnFamilyData* _cfd) { internal_cfd_ = _cfd; }
virtual ColumnFamilyData* cfd() const override { return internal_cfd_; }
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).
MemTable* mem;
MemTableListVersion* imm;
Version* current;
MutableCFOptions mutable_cf_options;
// Version number of the current SuperVersion
uint64_t version_number;
InstrumentedMutex* db_mutex;
// should be called outside the mutex
SuperVersion() = default;
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(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;
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 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,
class ColumnFamilySet;
// This class keeps all the data that a column family needs.
// Most methods require DB mutex held, unless otherwise noted
class 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, std::memory_order_relaxed); }
// 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, std::memory_order_relaxed);
assert(old_refs > 0);
return old_refs == 1;
// 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_; }
// 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_; }
// thread-safe
const EnvOptions* 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_; }
// REQUIRES: DB mutex held
Status SetOptions(
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
void SetMemtable(MemTable* new_mem) { 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;
// A flag to tell a manual compaction is to compact all levels together
// instad of for 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,
uint32_t output_path_id, const InternalKey* begin,
const InternalKey* end, InternalKey** compaction_end,
bool* manual_conflict);
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(InstrumentedMutex* db_mutex);
// thread-safe
// Get SuperVersion stored in thread local storage. If it does not exist,
// get a reference from a current SuperVersion.
SuperVersion* GetThreadLocalSuperVersion(InstrumentedMutex* db_mutex);
// 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()
SuperVersion* InstallSuperVersion(SuperVersion* new_superversion,
InstrumentedMutex* db_mutex,
const MutableCFOptions& mutable_cf_options);
SuperVersion* InstallSuperVersion(SuperVersion* new_superversion,
InstrumentedMutex* db_mutex);
void ResetThreadLocalSuperVersions();
// Protected by DB mutex
void set_pending_flush(bool value) { pending_flush_ = value; }
void set_pending_compaction(bool value) { pending_compaction_ = value; }
bool pending_flush() { return pending_flush_; }
bool pending_compaction() { return pending_compaction_; }
// 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
void RecalculateWriteStallConditions(
const MutableCFOptions& mutable_cf_options);
void set_initialized() {; }
bool initialized() const { return initialized_.load(); }
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 EnvOptions& env_options,
ColumnFamilySet* column_family_set);
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_;
bool dropped_; // true if client dropped it
const InternalKeyComparator internal_comparator_;
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_;
// 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 pending_flush_;
// If true --> this ColumnFamily is currently present in
// DBImpl::compaction_queue_
bool pending_compaction_;
uint64_t prev_compaction_needed_bytes_;
// if the database was opened with 2pc enabled
bool allow_2pc_;
// 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 {
// ColumnFamilySet supports iteration
class iterator {
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_; }
ColumnFamilyData* current_;
ColumnFamilySet(const std::string& dbname,
const ImmutableDBOptions* db_options,
const EnvOptions& env_options, Cache* table_cache,
WriteBufferManager* write_buffer_manager,
WriteController* write_controller);
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_; }
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 EnvOptions env_options_;
Cache* table_cache_;
WriteBufferManager* write_buffer_manager_;
WriteController* write_controller_;
// 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 {
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_; }
ColumnFamilySet* column_family_set_;
ColumnFamilyData* current_;
ColumnFamilyHandleInternal handle_;
extern uint32_t GetColumnFamilyID(ColumnFamilyHandle* column_family);
extern const Comparator* GetColumnFamilyUserComparator(
ColumnFamilyHandle* column_family);
} // namespace rocksdb