cachemere::policy::ConstraintMemory< Key, KeyHash, Value > Class Template Reference

Memory constraint. More...

#include <constraint_memory.h>

Public Member Functions
	ConstraintMemory (size_t max_memory)
	Constructor. More...
void	clear ()
	Clears the policy.
bool	can_add (const Key &key, const CacheItem &item)
	Determines whether an insertion candidate can be added into the cache. More...
bool	can_replace (const Key &key, const CacheItem &old_item, const CacheItem &new_item)
	Determines whether an item already in cache can be updated. More...
bool	is_satisfied ()
	Returns whether the constraint is satisfied. More...
void	update (size_t max_memory)
	Update the cache constraint. More...
size_t	memory () const
	Get the amount of memory currently used by the cache. More...
size_t	maximum_memory () const
	Get the maximum amount of memory that can be used by the cache. More...
void	on_insert (const Key &key, const CacheItem &item)
	Insertion event handler. More...
void	on_update (const Key &key, const CacheItem &old_item, const CacheItem &new_item)
	Update event handler. More...
void	on_evict (const Key &key, const CacheItem &item)
	Eviction event handler. More...

Detailed Description

template<typename Key, typename KeyHash, typename Value>
class cachemere::policy::ConstraintMemory< Key, KeyHash, Value >

Memory constraint.

Use this when the constraint of the cache should be how many bytes of memory it uses.

Template Parameters

Key	The type of the keys used to identify items in the cache.
KeyHash	The type of the hasher used to hash item keys.
Value	The type of the values stored in the cache.

Constructor & Destructor Documentation

ConstraintMemory()

template<class K , class KH , class V >

cachemere::policy::ConstraintMemory< K, KH, V >::ConstraintMemory ( size_t  max_memory )

explicit

Constructor.

Parameters

max_memory

The maximum amount of memory to be used by the cache, in bytes.

Member Function Documentation

can_add()

template<typename Key , typename KeyHash , typename Value >

bool cachemere::policy::ConstraintMemory< K, KH, V >::can_add	(	const Key &	key,
		const CacheItem &	item
	)

Determines whether an insertion candidate can be added into the cache.

That is, whether the constraint would still be satisfied after inserting the candidate.

Parameters

key	The key of the insertion candidate.
item	The candidate item.

Returns

Whether the item can be added in cache.

can_replace()

template<typename Key , typename KeyHash , typename Value >

bool cachemere::policy::ConstraintMemory< K, KH, V >::can_replace	(	const Key &	key,
		const CacheItem &	old_item,
		const CacheItem &	new_item
	)

Determines whether an item already in cache can be updated.

That is, whether the key can be updated to the new value while still satisfying the constraint.

Parameters

key	The key to be updated.
old_item	The current value of the key in cache.
new_item	The value that would replace the current value.

Returns

Whether the item can be replaced.

is_satisfied()

template<class K , class KH , class V >

bool cachemere::policy::ConstraintMemory< K, KH, V >::is_satisfied

Returns whether the constraint is satisfied.

Used by the cache after a constraint update to compute how many items should be evicted, if any.

Returns

Whether the cache constraint is satisfied.

maximum_memory()

template<class K , class KH , class V >

size_t cachemere::policy::ConstraintMemory< K, KH, V >::maximum_memory

Get the maximum amount of memory that can be used by the cache.

Returns

The maximum amount of memory, in bytes.

memory()

template<class K , class KH , class V >

size_t cachemere::policy::ConstraintMemory< K, KH, V >::memory

Get the amount of memory currently used by the cache.

Returns

The current amount of memory used, in bytes.

on_evict()

template<typename Key , typename KeyHash , typename Value >

void cachemere::policy::ConstraintMemory< K, KH, V >::on_evict	(	const Key &	key,
		const CacheItem &	item
	)

Eviction event handler.

Removes the item at the back of the list - ensuring it has the provided key.

Parameters

key	The key that was evicted.
item	The item that was evicted.

on_insert()

template<typename Key , typename KeyHash , typename Value >

void cachemere::policy::ConstraintMemory< K, KH, V >::on_insert	(	const Key &	key,
		const CacheItem &	item
	)

Insertion event handler.

Adds the size of this item to the amount of memory used.

Parameters

key	The key of the inserted item.
item	The item that has been inserted in cache.

on_update()

template<typename Key , typename KeyHash , typename Value >

void cachemere::policy::ConstraintMemory< K, KH, V >::on_update	(	const Key &	key,
		const CacheItem &	old_item,
		const CacheItem &	new_item
	)

Update event handler.

Updates the amount of memory used to reflect the size difference between the old and the new value.

Parameters

key	The key that has been updated in the cache.
old_item	The old value for this key.
new_item	The new value for this key

update()

template<class K , class KH , class V >

void cachemere::policy::ConstraintMemory< K, KH, V >::update

(

size_t

max_memory

)

Update the cache constraint.

Sets a new maximum amount of memory.

Parameters

max_memory

The new maximum amount of memory to be used by the cache.

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The documentation for this class was generated from the following files:

• include/cachemere/policy/constraint_memory.h
• include/cachemere/policy/constraint_memory.hpp