de.caff.generics

Class RecreatingLeastRecentlyUsedCache<K,V>

java.lang.Object

de.caff.generics.LeastRecentlyUsedCache<K,V>

de.caff.generics.RecreatingLeastRecentlyUsedCache<K,V>

public class RecreatingLeastRecentlyUsedCache<K,V>
extends LeastRecentlyUsedCache<K,V>

A least recently used cache which also allows to predefine a way to recreate lost entries.

A good way to use it is construction with a function which is able to recreate the value for a given key and calling only the get(Object) method.

Since:

May 10, 2021

Author:

Rammi

Field Summary

Fields inherited from class de.caff.generics.LeastRecentlyUsedCache

map

Constructor Summary

Constructors

Constructor and Description
RecreatingLeastRecentlyUsedCache(int mostRecentLimit, FragileFunction1<V,? extends java.lang.Exception,K> recreator, Procedure2<K,java.lang.Exception> errorHandler) Constructor.
RecreatingLeastRecentlyUsedCache(int mostRecentLimit, java.util.function.Function<K,V> recreator) Constructor.

Method Summary

Modifier and Type	Method and Description
void	cleanup() Remove all key-value pairs which are no longer available.
V	get(K key) Get the value for the given key.
int	getNumRecreations() Get the number of times the recreation function was called.
V	remove(K key) Remove a key-value pair from this cache.

Methods inherited from class de.caff.generics.LeastRecentlyUsedCache

clear, computeIfAbsent, getLeastRecentCacheDepth, getLeastRecentlyUsed, getNumGarbageCollected, getNumHits, getNumMisses, isEmpty, keys, put, size

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

RecreatingLeastRecentlyUsedCache

public RecreatingLeastRecentlyUsedCache(int mostRecentLimit,
                                        @NotNull
                                        java.util.function.Function<K,V> recreator)

Constructor.

Parameters:

mostRecentLimit - maximal number of cached values, non-negative

recreator - creator for values which are currently not present

RecreatingLeastRecentlyUsedCache

public RecreatingLeastRecentlyUsedCache(int mostRecentLimit,
                                        @NotNull
                                        FragileFunction1<V,? extends java.lang.Exception,K> recreator,
                                        @NotNull
                                        Procedure2<K,java.lang.Exception> errorHandler)

Constructor.

This allows to use an recreator which might throw an exception. In case of exceptions obviously nothing is created, but the errorHandler will be called with the key an exception.

Parameters:

mostRecentLimit - maximal number of cached values, non-negative

recreator - creator for values which are currently not present

errorHandler - error handler for exceptions during the recreation

Method Detail

get

@Nullable
public V get(@NotNull
                       K key)

Description copied from class: LeastRecentlyUsedCache

Get the value for the given key.

Overrides:

get in class LeastRecentlyUsedCache<K,V>

Parameters:

key - key associated with the requested value

Returns:

null when the required value was never added to this cache or when it was garbage collected in the meantime, otherwise the cached object associated with the given key

cleanup

public void cleanup()

Description copied from class: LeastRecentlyUsedCache

Remove all key-value pairs which are no longer available.

Overrides:

cleanup in class LeastRecentlyUsedCache<K,V>

remove

@Nullable
public V remove(K key)

Description copied from class: LeastRecentlyUsedCache

Remove a key-value pair from this cache.

Overrides:

remove in class LeastRecentlyUsedCache<K,V>

Parameters:

key - key of the key-value pair

Returns:

removed object if it was still cached, or null if the object was either never cached at all or has been garbage collected

getNumRecreations

public int getNumRecreations()

Get the number of times the recreation function was called.

Returns:

number of recreations