org.waarp.common.lru

Class AbstractLruCache<K,V>

java.lang.Object

org.waarp.common.lru.AbstractLruCache<K,V>

All Implemented Interfaces:

InterfaceLruCache<K,V>

Direct Known Subclasses:

SynchronizedLruCache

public abstract class AbstractLruCache<K,V>
extends Object
implements InterfaceLruCache<K,V>

Base class for concrete implementations

Author:

Damian Momot

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	AbstractLruCache(long ttl) Constructs BaseLruCache

Method Summary

Modifier and Type	Method and Description
boolean	contains(K key) Checks whether cache contains valid entry for key
protected InterfaceLruCacheEntry<V>	createEntry(V value, long ttl) Creates new LruCacheEntry.
V	get(K key) Returns value cached with key.
V	get(K key, Callable<V> callback) Tries to get element from cache.
V	get(K key, Callable<V> callback, long ttl) Tries to get element from cache.
protected abstract InterfaceLruCacheEntry<V>	getEntry(K key) Returns LruCacheEntry mapped by key or null if it does not exist
long	getTtl() Returns cache TTL
protected V	getValue(K key) Tries to retrieve value by it's key.
boolean	isEmpty() Checks whether cache is empty.
void	put(K key, V value) Puts value under key into cache.
void	put(K key, V value, long ttl) Puts value under key into cache with desired TTL
protected abstract void	putEntry(K key, InterfaceLruCacheEntry<V> entry) Puts entry into cache
void	setNewTtl(long ttl) Set a new TTL (for newly set objects only, not changing old values).
void	updateTtl(K key) Update the TTL of the associated object if it still exists

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.waarp.common.lru.InterfaceLruCache

clear, forceClearOldest, getCapacity, remove, size, values

Constructor Detail

AbstractLruCache

protected AbstractLruCache(long ttl)

Constructs BaseLruCache

Parameters:

ttl -

Throws:

IllegalArgumentException - if ttl is not positive

Method Detail

contains

public final boolean contains(K key)

Description copied from interface: InterfaceLruCache

Checks whether cache contains valid entry for key

Specified by:

contains in interface InterfaceLruCache<K,V>

Returns:

true if cache contains key and entry is valid

createEntry

protected InterfaceLruCacheEntry<V> createEntry(V value,
                                                long ttl)

Creates new LruCacheEntry.

It can be used to change implementation of LruCacheEntry

Parameters:

value -

ttl -

Returns:

LruCacheEntry

get

public V get(K key)

Description copied from interface: InterfaceLruCache

Returns value cached with key.

Specified by:

get in interface InterfaceLruCache<K,V>

Returns:

value or null if key doesn't exist or entry is not valid

get

public final V get(K key,
                   Callable<V> callback)
            throws Exception

Description copied from interface: InterfaceLruCache

Tries to get element from cache. If get fails callback is used to create element and returned value is stored in cache.

Default TTL is used

Specified by:

get in interface InterfaceLruCache<K,V>

Returns:

Value

Throws:

Exception - if callback throws exception

get

public final V get(K key,
                   Callable<V> callback,
                   long ttl)
            throws Exception

Description copied from interface: InterfaceLruCache

Tries to get element from cache. If get fails callback is used to create element and returned value is stored in cache

Specified by:

get in interface InterfaceLruCache<K,V>

ttl - time to live in milliseconds

Returns:

Value

Throws:

Exception - if callback throws exception

getTtl

public final long getTtl()

Description copied from interface: InterfaceLruCache

Returns cache TTL

Specified by:

getTtl in interface InterfaceLruCache<K,V>

Returns:

ttl in milliseconds

setNewTtl

public final void setNewTtl(long ttl)

Description copied from interface: InterfaceLruCache

Set a new TTL (for newly set objects only, not changing old values).

Specified by:

setNewTtl in interface InterfaceLruCache<K,V>

getEntry

protected abstract InterfaceLruCacheEntry<V> getEntry(K key)

Returns LruCacheEntry mapped by key or null if it does not exist

Parameters:

key -

Returns:

LruCacheEntry

updateTtl

public final void updateTtl(K key)

Description copied from interface: InterfaceLruCache

Update the TTL of the associated object if it still exists

Specified by:

updateTtl in interface InterfaceLruCache<K,V>

getValue

protected final V getValue(K key)

Tries to retrieve value by it's key. Automatically removes entry if it's not valid (LruCacheEntry.getValue() returns null)

Parameters:

key -

Returns:

Value

isEmpty

public final boolean isEmpty()

Description copied from interface: InterfaceLruCache

Checks whether cache is empty.

If any entry exists (including invalid one) this method will return true

Specified by:

isEmpty in interface InterfaceLruCache<K,V>

Returns:

true if no entries are stored in cache

put

public final void put(K key,
                      V value)

Description copied from interface: InterfaceLruCache

Puts value under key into cache. Default TTL is used

Specified by:

put in interface InterfaceLruCache<K,V>

put

public void put(K key,
                V value,
                long ttl)

Description copied from interface: InterfaceLruCache

Puts value under key into cache with desired TTL

Specified by:

put in interface InterfaceLruCache<K,V>

ttl - time to live in milliseconds

putEntry

protected abstract void putEntry(K key,
                                 InterfaceLruCacheEntry<V> entry)

Puts entry into cache

Parameters:

key -

entry -