On-memory database manager implemented with std::unordered_map. More...

#include <tkrzw_dbm_std.h>

Classes
class	Iterator
	Iterator for each record. More...

Public Member Functions
	StdHashDBM (int64_t num_buckets=-1)
	Default constructor. More...

	StdHashDBM (std::unique_ptr< File > file, int64_t num_buckets=-1)
	Constructor with a file object. More...

	~StdHashDBM ()
	Destructor. More...

	StdHashDBM (const StdHashDBM &rhs)=delete
	Copy and assignment are disabled. More...

StdHashDBM &	operator= (const StdHashDBM &rhs)=delete

Status	Open (const std::string &path, bool writable, int32_t options=File::OPEN_DEFAULT) override
	Opens a database file. More...

Status	Close () override
	Closes the database file. More...

Status	Process (std::string_view key, RecordProcessor *proc, bool writable) override
	Processes a record with a processor. More...

Status	ProcessMulti (const std::vector< std::pair< std::string_view, DBM::RecordProcessor * >> &key_proc_pairs, bool writable) override
	Processes multiple records with processors. More...

Status	ProcessFirst (RecordProcessor *proc, bool writable) override
	Processes the first record with a processor. More...

Status	ProcessEach (RecordProcessor *proc, bool writable) override
	Processes each and every record in the database with a processor. More...

Status	Count (int64_t *count) override
	Gets the number of records. More...

Status	GetFileSize (int64_t *size) override
	Gets the current file size of the database. More...

Status	GetFilePath (std::string *path) override
	Gets the path of the database file. More...

Status	GetTimestamp (double *timestamp) override
	Gets the timestamp in seconds of the last modified time. More...

Status	Clear () override
	Removes all records. More...

Status	Rebuild () override
	Rebuilds the entire database. More...

Status	ShouldBeRebuilt (bool *tobe) override
	Checks whether the database should be rebuilt. More...

Status	Synchronize (bool hard, FileProcessor *proc=nullptr) override
	Synchronizes the content of the database to the file system. More...

std::vector< std::pair< std::string, std::string > >	Inspect () override
	Inspects the database. More...

bool	IsOpen () const override
	Checks whether the database is open. More...

bool	IsWritable () const override
	Checks whether the database is writable. More...

bool	IsHealthy () const override
	Checks whether the database condition is healthy. More...

bool	IsOrdered () const override
	Checks whether ordered operations are supported. More...

std::unique_ptr< DBM::Iterator >	MakeIterator () override
	Makes an iterator for each record. More...

std::unique_ptr< DBM >	MakeDBM () const override
	Makes a new DBM object of the same concrete class. More...

UpdateLogger *	GetUpdateLogger () const override
	Gets the logger to write all update operations. More...

void	SetUpdateLogger (UpdateLogger *update_logger) override
	Sets the logger to write all update operations. More...

File *	GetInternalFile () const
	Gets the pointer to the internal file object. More...

Public Member Functions inherited from tkrzw::DBM
virtual	~DBM ()=default
	Destructor. More...

virtual Status	Process (std::string_view key, RecordLambdaType rec_lambda, bool writable)
	Processes a record with a lambda function. More...

virtual Status	Get (std::string_view key, std::string *value=nullptr)
	Gets the value of a record of a key. More...

virtual std::string	GetSimple (std::string_view key, std::string_view default_value="")
	Gets the value of a record of a key, in a simple way. More...

virtual Status	GetMulti (const std::vector< std::string_view > &keys, std::map< std::string, std::string > *records)
	Gets the values of multiple records of keys, with a string view vector. More...

virtual Status	GetMulti (const std::initializer_list< std::string_view > &keys, std::map< std::string, std::string > *records)
	Gets the values of multiple records of keys, with an initializer list. More...

virtual Status	GetMulti (const std::vector< std::string > &keys, std::map< std::string, std::string > *records)
	Gets the values of multiple records of keys, with a string vector. More...

virtual Status	Set (std::string_view key, std::string_view value, bool overwrite=true, std::string *old_value=nullptr)
	Sets a record of a key and a value. More...

virtual Status	SetMulti (const std::map< std::string_view, std::string_view > &records, bool overwrite=true)
	Sets multiple records, with a map of string views. More...

virtual Status	SetMulti (const std::initializer_list< std::pair< std::string_view, std::string_view >> &records, bool overwrite=true)
	Sets multiple records, with an initializer list. More...

virtual Status	SetMulti (const std::map< std::string, std::string > &records, bool overwrite=true)
	Sets multiple records, with a map of strings. More...

virtual Status	Remove (std::string_view key, std::string *old_value=nullptr)
	Removes a record of a key. More...

virtual Status	RemoveMulti (const std::vector< std::string_view > &keys)
	Removes records of keys, with a string view vector. More...

virtual Status	RemoveMulti (const std::initializer_list< std::string_view > &keys)
	Removes records of keys, with an initializer list. More...

virtual Status	RemoveMulti (const std::vector< std::string > &keys)
	Removes records of keys, with a string vector. More...

virtual Status	Append (std::string_view key, std::string_view value, std::string_view delim="")
	Appends data at the end of a record of a key. More...

virtual Status	AppendMulti (const std::map< std::string_view, std::string_view > &records, std::string_view delim="")
	Appends data to multiple records, with a map of string views. More...

virtual Status	AppendMulti (const std::initializer_list< std::pair< std::string_view, std::string_view >> &records, std::string_view delim="")
	Appends data to multiple records, with an initializer list. More...

virtual Status	AppendMulti (const std::map< std::string, std::string > &records, std::string_view delim="")
	Appends data to multiple records, with a map of strings. More...

virtual Status	CompareExchange (std::string_view key, std::string_view expected, std::string_view desired, std::string actual=nullptr, bool found=nullptr)
	Compares the value of a record and exchanges if the condition meets. More...

virtual Status	Increment (std::string_view key, int64_t increment=1, int64_t *current=nullptr, int64_t initial=0)
	Increments the numeric value of a record. More...

virtual int64_t	IncrementSimple (std::string_view key, int64_t increment=1, int64_t initial=0)
	Increments the numeric value of a record, in a simple way. More...

virtual Status	ProcessMulti (const std::vector< std::pair< std::string_view, RecordProcessor * >> &key_proc_pairs, bool writable)=0
	Processes multiple records with processors. More...

virtual Status	ProcessMulti (const std::vector< std::pair< std::string_view, RecordLambdaType >> &key_lambda_pairs, bool writable)
	Processes multiple records with lambda functions. More...

virtual Status	CompareExchangeMulti (const std::vector< std::pair< std::string_view, std::string_view >> &expected, const std::vector< std::pair< std::string_view, std::string_view >> &desired)
	Compares the values of records and exchanges if the condition meets. More...

virtual Status	Rekey (std::string_view old_key, std::string_view new_key, bool overwrite=true, bool copying=false, std::string *value=nullptr)
	Changes the key of a record. More...

virtual Status	ProcessFirst (RecordLambdaType rec_lambda, bool writable)
	Processes the first record with a lambda function. More...

virtual Status	PopFirst (std::string key=nullptr, std::string value=nullptr)
	Gets the first record and removes it. More...

virtual Status	PushLast (std::string_view value, double wtime=-1, std::string *key=nullptr)
	Adds a record with a key of the current timestamp. More...

virtual Status	ProcessEach (RecordLambdaType rec_lambda, bool writable)
	Processes each and every record in the database with a lambda function. More...

virtual int64_t	CountSimple ()
	Gets the number of records, in a simple way. More...

virtual int64_t	GetFileSizeSimple ()
	Gets the current file size of the database, in a simple way. More...

virtual std::string	GetFilePathSimple ()
	Gets the path of the database file, in a simple way. More...

virtual double	GetTimestampSimple ()
	Gets the timestamp of the last modified time, in a simple way. More...

virtual bool	ShouldBeRebuiltSimple ()
	Checks whether the database should be rebuilt, in a simple way. More...

virtual Status	CopyFileData (const std::string &dest_path, bool sync_hard=false)
	Copies the content of the database file to another file. More...

virtual Status	Export (DBM *dest_dbm)
	Exports all records to another database. More...

const std::type_info &	GetType () const
	Gets the type information of the actual class. More...

Static Public Attributes
static constexpr int64_t	DEFAULT_NUM_BUCKETS = 1048583
	The default value of the number of buckets. More...

Static Public Attributes inherited from tkrzw::DBM
static const std::string_view	ANY_DATA
	The special string_view value to represent any data. More...

Additional Inherited Members
Public Types inherited from tkrzw::DBM
typedef std::function< std::string_view(std::string_view, std::string_view)>	RecordLambdaType
	Lambda function type to process a record. More...

Detailed Description

On-memory database manager implemented with std::unordered_map.

All operations are thread-safe; Multiple threads can access the same database concurrently.

Constructor & Destructor Documentation

◆ StdHashDBM() [1/3]

tkrzw::StdHashDBM::StdHashDBM ( int64_t num_buckets = -1 )

explicit

Default constructor.

Parameters

num_buckets The number of buckets of the rebuild hash table. -1 means that the default value 1048583 is set.

◆ StdHashDBM() [2/3]

tkrzw::StdHashDBM::StdHashDBM	(	std::unique_ptr< File >	file,
		int64_t	num_buckets = `-1`
	)

explicit

Constructor with a file object.

Parameters

file	The file object to handle the data. The ownership is taken.
num_buckets	The number of buckets of the rebuild hash table. -1 means that the default value 1048583 is set.

◆ ~StdHashDBM()

tkrzw::StdHashDBM::~StdHashDBM ( )

Destructor.

◆ StdHashDBM() [3/3]

tkrzw::StdHashDBM::StdHashDBM ( const StdHashDBM & rhs )

explicitdelete

Copy and assignment are disabled.

Member Function Documentation

◆ Open()

Status tkrzw::StdHashDBM::Open	(	const std::string &	path,
		bool	writable,
		int32_t	options = `File::OPEN_DEFAULT`
	)

overridevirtual

Opens a database file.

Parameters

path	A path of the file.
writable	If true, the file is writable. If false, it is read-only.
options	Bit-sum options of File::OpenOption enums for opening the file.

Returns: The result status.

As this database is an on-memory database, you can set records and retrieve them without opening a file. If you open a file, records are loaded from the file.

Implements tkrzw::DBM.

◆ Close()

Status tkrzw::StdHashDBM::Close ( )

overridevirtual

Closes the database file.

Returns: The result status.

If a file is opened as writable, records are saved in the file.

Implements tkrzw::DBM.

◆ Process()

Status tkrzw::StdHashDBM::Process	(	std::string_view	key,
		RecordProcessor *	proc,
		bool	writable
	)

overridevirtual

Processes a record with a processor.

Parameters

key	The key of the record.
proc	The pointer to the processor object.
writable	True if the processor can edit the record.

Returns: The result status.

If the specified record exists, the ProcessFull of the processor is called. Otherwise, the ProcessEmpty of the processor is called.

Implements tkrzw::DBM.

◆ ProcessMulti()

Status tkrzw::StdHashDBM::ProcessMulti	(	const std::vector< std::pair< std::string_view, DBM::RecordProcessor * >> &	key_proc_pairs,
		bool	writable
	)

override

Processes multiple records with processors.

Parameters

key_proc_pairs	Pairs of the keys and their processor objects.
writable	True if the processors can edit the records.

Returns: The result status.

Precondition: The database is opened. The writable parameter should be consistent to the open mode.

If the specified record exists, the ProcessFull of the processor is called. Otherwise, the ProcessEmpty of the processor is called.

◆ ProcessFirst()

Status tkrzw::StdHashDBM::ProcessFirst	(	RecordProcessor *	proc,
		bool	writable
	)

overridevirtual

Processes the first record with a processor.

Parameters

proc	The pointer to the processor object.
writable	True if the processor can edit the record.

Returns: The result status.

If the first record exists, the ProcessFull of the processor is called. Otherwise, this method fails and no method of the processor is called. This method can be slow because it can scan all buckets.

Implements tkrzw::DBM.

◆ ProcessEach()

Status tkrzw::StdHashDBM::ProcessEach	(	RecordProcessor *	proc,
		bool	writable
	)

overridevirtual

Processes each and every record in the database with a processor.

Parameters

proc	The pointer to the processor object.
writable	True if the processor can edit the record.

Returns: The result status.

The ProcessFull of the processor is called repeatedly for each record. The ProcessEmpty of the processor is called once before the iteration and once after the iteration.

Implements tkrzw::DBM.

◆ Count()

Status tkrzw::StdHashDBM::Count ( int64_t * count )

overridevirtual

Gets the number of records.

Parameters

count The pointer to an integer object to contain the result count.

Returns: The result status.

Implements tkrzw::DBM.

◆ GetFileSize()

Status tkrzw::StdHashDBM::GetFileSize ( int64_t * size )

overridevirtual

Gets the current file size of the database.

Parameters

size	The pointer to an integer object to contain the result size.

Returns: The result status.

Implements tkrzw::DBM.

◆ GetFilePath()

Status tkrzw::StdHashDBM::GetFilePath ( std::string * path )

overridevirtual

Gets the path of the database file.

Parameters

path	The pointer to a string object to contain the result path.

Returns: The result status.

Implements tkrzw::DBM.

◆ GetTimestamp()

Status tkrzw::StdHashDBM::GetTimestamp ( double * timestamp )

overridevirtual

Gets the timestamp in seconds of the last modified time.

Parameters

timestamp The pointer to a double object to contain the timestamp.

Returns: The result status.

The timestamp is updated when the database opened in the writable mode is closed or synchronized, even if no updating opertion is done.

Implements tkrzw::DBM.

◆ Clear()

Status tkrzw::StdHashDBM::Clear ( )

overridevirtual

Removes all records.

Returns: The result status.

Implements tkrzw::DBM.

◆ Rebuild()

Status tkrzw::StdHashDBM::Rebuild ( )

overridevirtual

Rebuilds the entire database.

Returns: The result status.

Implements tkrzw::DBM.

◆ ShouldBeRebuilt()

Status tkrzw::StdHashDBM::ShouldBeRebuilt ( bool * tobe )

overridevirtual

Checks whether the database should be rebuilt.

Parameters

tobe	The pointer to a boolean object to contain the result decision.

Returns: The result status.

Implements tkrzw::DBM.

◆ Synchronize()

Status tkrzw::StdHashDBM::Synchronize	(	bool	hard,
		FileProcessor *	proc = `nullptr`
	)

overridevirtual

Synchronizes the content of the database to the file system.

Parameters

hard	True to do physical synchronization with the hardware or false to do only logical synchronization with the file system.
proc	The pointer to the file processor object, whose Process method is called while the content of the file is synchronized. If it is nullptr, it is ignored.

Returns: The result status.

If a file is opened as writable, records are saved in the file.

Implements tkrzw::DBM.

◆ Inspect()

std::vector<std::pair<std::string, std::string> > tkrzw::StdHashDBM::Inspect ( )

overridevirtual

Inspects the database.

Returns: A vector of pairs of a property name and its value.

Implements tkrzw::DBM.

◆ IsOpen()

bool tkrzw::StdHashDBM::IsOpen ( ) const

overridevirtual

Checks whether the database is open.

Returns: True if the database is open, or false if not.

Implements tkrzw::DBM.

◆ IsWritable()

bool tkrzw::StdHashDBM::IsWritable ( ) const

overridevirtual

Checks whether the database is writable.

Returns: True if the database is writable, or false if not.

Implements tkrzw::DBM.

◆ IsHealthy()

bool tkrzw::StdHashDBM::IsHealthy ( ) const

overridevirtual

Checks whether the database condition is healthy.

Returns: Always true. On-memory databases never cause system errors.

Implements tkrzw::DBM.

◆ IsOrdered()

bool tkrzw::StdHashDBM::IsOrdered ( ) const

overridevirtual

Checks whether ordered operations are supported.

Returns: Always false. Ordered operations are not supported.

Implements tkrzw::DBM.

◆ MakeIterator()

std::unique_ptr<DBM::Iterator> tkrzw::StdHashDBM::MakeIterator ( )

overridevirtual

Makes an iterator for each record.

Returns: The iterator for each record.

Implements tkrzw::DBM.

◆ MakeDBM()

std::unique_ptr<DBM> tkrzw::StdHashDBM::MakeDBM ( ) const

overridevirtual

Makes a new DBM object of the same concrete class.

Returns: The new DBM object.

Implements tkrzw::DBM.

◆ GetUpdateLogger()

UpdateLogger* tkrzw::StdHashDBM::GetUpdateLogger ( ) const

overridevirtual

Gets the logger to write all update operations.

Returns: The update logger if it has been set or nullptr if it hasn't.

Implements tkrzw::DBM.

◆ SetUpdateLogger()

void tkrzw::StdHashDBM::SetUpdateLogger ( UpdateLogger * update_logger )

overridevirtual

Sets the logger to write all update operations.

Parameters

update_logger The pointer to the update logger object. Ownership is not taken. If it is nullptr, no logger is used.

Implements tkrzw::DBM.

◆ GetInternalFile()

File* tkrzw::StdHashDBM::GetInternalFile ( ) const

Gets the pointer to the internal file object.

Returns: The pointer to the internal file object.

Accessing the internal file viorates encapsulation policy. This should be used only for testing and debugging.

Member Data Documentation

◆ DEFAULT_NUM_BUCKETS

constexpr int64_t tkrzw::StdHashDBM::DEFAULT_NUM_BUCKETS = 1048583

staticconstexpr

The default value of the number of buckets.

Classes

Public Member Functions

Static Public Attributes

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

◆ StdHashDBM() [1/3]

◆ StdHashDBM() [2/3]

◆ ~StdHashDBM()

◆ StdHashDBM() [3/3]

Member Function Documentation

◆ Open()

◆ Close()

◆ Process()

◆ ProcessMulti()

◆ ProcessFirst()

◆ ProcessEach()

◆ Count()

◆ GetFileSize()

◆ GetFilePath()

◆ GetTimestamp()

◆ Clear()

◆ Rebuild()

◆ ShouldBeRebuilt()

◆ Synchronize()

◆ Inspect()

◆ IsOpen()

◆ IsWritable()

◆ IsHealthy()

◆ IsOrdered()

◆ MakeIterator()

◆ MakeDBM()

◆ GetUpdateLogger()

◆ SetUpdateLogger()

◆ GetInternalFile()

Member Data Documentation

◆ DEFAULT_NUM_BUCKETS