tkrzw::LRUCache< VALUETYPE > Class Template Reference

LRU cache. More...

#include <tkrzw_containers.h>

Classes
class	Iterator
	Iterator to access each record. More...

Public Member Functions
	LRUCache (size_t capacity)
	Constructor. More...
std::shared_ptr< VALUETYPE >	Add (int64_t id, VALUETYPE *value)
	Adds a record. More...
void	GiveBack (int64_t id, std::shared_ptr< VALUETYPE > &&value)
	Gives back a record which has been removed. More...
std::shared_ptr< VALUETYPE >	Get (int64_t id)
	Gets the value of a record. More...
void	Remove (int64_t id)
	Removes a record. More...
std::shared_ptr< VALUETYPE >	RemoveLRU (int64_t *id=nullptr)
	Removes the least recent used record. More...
size_t	Size () const
	Gets the number of records. More...
bool	IsEmpty () const
	Checks whether no records exist. More...
bool	IsSaturated () const
	Checks whether stored records exceeds the capacity. More...
void	Clear ()
	Removes all records. More...
Iterator	MakeIterator ()
	Makes an iterator for each record. More...

Detailed Description

template<class VALUETYPE>
class tkrzw::LRUCache< VALUETYPE >

LRU cache.

Parameters

VALUETYPE

the value type.

Constructor & Destructor Documentation

LRUCache()

template<typename VALUETYPE >

tkrzw::LRUCache< VALUETYPE >::LRUCache

(

size_t

capacity

)

Constructor.

Parameters

capacity

The maximum number of records in the cache.

Member Function Documentation

Add()

template<typename VALUETYPE >

std::shared_ptr< VALUETYPE > tkrzw::LRUCache< VALUETYPE >::Add	(	int64_t	id,
		VALUETYPE *	value
	)

Adds a record.

Parameters

id	The ID of the record.
value	The pointer to the value object. Ownership is taken.

Returns

A shared pointer to the value object.

If there is an existing record of the same ID, the new value object is just deleted and the return value refers to the existing record.

GiveBack()

template<typename VALUETYPE >

void tkrzw::LRUCache< VALUETYPE >::GiveBack	(	int64_t	id,
		std::shared_ptr< VALUETYPE > &&	value
	)

Gives back a record which has been removed.

Parameters

id	The ID of the record.
value	The moved pointer to the value object. Ownership is taken.

Get()

template<typename VALUETYPE >

std::shared_ptr< VALUETYPE > tkrzw::LRUCache< VALUETYPE >::Get

(

int64_t

id

)

Gets the value of a record.

Parameters

id	The ID of the record.

Returns

A shared pointer to the value object. It points to nullptr on failure.

Remove()

template<typename VALUETYPE >

void tkrzw::LRUCache< VALUETYPE >::Remove

(

int64_t

id

)

Removes a record.

Parameters

id	The ID of the record.

RemoveLRU()

template<typename VALUETYPE >

std::shared_ptr< VALUETYPE > tkrzw::LRUCache< VALUETYPE >::RemoveLRU

(

int64_t *

id = nullptr

)

Removes the least recent used record.

Parameters

id	The pointer to store the ID of the record. If it is nullptr, it is ignored.

Returns

A shared pointer to the value object. It points to nullptr on failure.

Size()

template<typename VALUETYPE >

size_t tkrzw::LRUCache< VALUETYPE >::Size

Gets the number of records.

Returns

The number of records.

IsEmpty()

template<typename VALUETYPE >

bool tkrzw::LRUCache< VALUETYPE >::IsEmpty

Checks whether no records exist.

Returns

True if there's no record or false if there are one or more records.

IsSaturated()

template<typename VALUETYPE >

bool tkrzw::LRUCache< VALUETYPE >::IsSaturated

Checks whether stored records exceeds the capacity.

Returns

True if stored records exceeds the capacity or false if not.

Clear()

template<typename VALUETYPE >

void tkrzw::LRUCache< VALUETYPE >::Clear

Removes all records.

MakeIterator()

template<typename VALUETYPE >

LRUCache< VALUETYPE >::Iterator tkrzw::LRUCache< VALUETYPE >::MakeIterator

Makes an iterator for each record.

Returns

The iterator for each record.