tkrzw::DoubleLRUCache< VALUETYPE > Class Template Reference

Double-layered LRU cache. More...

#include <tkrzw_containers.h>

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

Public Member Functions
	DoubleLRUCache (size_t hot_capacity, size_t warm_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, bool promotion)
	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::DoubleLRUCache< VALUETYPE >

Double-layered LRU cache.

Parameters

VALUETYPE

the value type.

Constructor & Destructor Documentation

DoubleLRUCache()

template<typename VALUETYPE >

tkrzw::DoubleLRUCache< VALUETYPE >::DoubleLRUCache	(	size_t	hot_capacity,
		size_t	warm_capacity
	)

Constructor.

Parameters

hot_capacity	The maximum number of records in the hot cache.
warm_capacity	The maximum number of records in the worm cache.

Member Function Documentation

Add()

template<typename VALUETYPE >

std::shared_ptr< VALUETYPE > tkrzw::DoubleLRUCache< 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::DoubleLRUCache< 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::DoubleLRUCache< VALUETYPE >::Get	(	int64_t	id,
		bool	promotion
	)

Gets the value of a record.

Parameters

id	The ID of the record.
promotion	True if the record can be promoted to the hot list.

Returns

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

Remove()

template<typename VALUETYPE >

void tkrzw::DoubleLRUCache< VALUETYPE >::Remove

(

int64_t

id

)

Removes a record.

Parameters

id	The ID of the record.

RemoveLRU()

template<typename VALUETYPE >

std::shared_ptr< VALUETYPE > tkrzw::DoubleLRUCache< 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::DoubleLRUCache< VALUETYPE >::Size

Gets the number of records.

Returns

The number of records.

IsEmpty()

template<typename VALUETYPE >

bool tkrzw::DoubleLRUCache< 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::DoubleLRUCache< 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::DoubleLRUCache< VALUETYPE >::Clear

Removes all records.

MakeIterator()

template<typename VALUETYPE >

DoubleLRUCache< VALUETYPE >::Iterator tkrzw::DoubleLRUCache< VALUETYPE >::MakeIterator

Makes an iterator for each record.

Returns

The iterator for each record.