net.sf.ehcache.store
Class LruMemoryStore.SpoolingLinkedHashMap

java.lang.Object
  java.util.AbstractMap<K,V>
      java.util.HashMap<K,V>
          java.util.LinkedHashMap
              net.sf.ehcache.store.LruMemoryStore.SpoolingLinkedHashMap

All Implemented Interfaces:

Serializable, Cloneable, Map

Enclosing class:

LruMemoryStore

public final class LruMemoryStore.SpoolingLinkedHashMap
extends LinkedHashMap

An extension of LinkedHashMap which overrides removeEldestEntry(java.util.Map.Entry) to persist cache entries to the auxiliary cache before they are removed.

This implementation also provides LRU by access order.

See Also:

Serialized Form

Nested Class Summary

Nested classes/interfaces inherited from class java.util.AbstractMap

AbstractMap.SimpleEntry<K,V>, AbstractMap.SimpleImmutableEntry<K,V>

Constructor Summary

LruMemoryStore.SpoolingLinkedHashMap()
Default constructor.

Method Summary

Object	put(Object key, Object value)
protected boolean	removeEldestEntry(Map.Entry eldest) Returns true if this map should remove its eldest entry.

Methods inherited from class java.util.LinkedHashMap

clear, containsValue, get

Methods inherited from class java.util.HashMap

clone, containsKey, entrySet, isEmpty, keySet, putAll, remove, size, values

Methods inherited from class java.util.AbstractMap

equals, hashCode, toString

Methods inherited from class java.lang.Object

finalize, getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface java.util.Map

containsKey, entrySet, equals, hashCode, isEmpty, keySet, putAll, remove, size, values

Constructor Detail

LruMemoryStore.SpoolingLinkedHashMap

public LruMemoryStore.SpoolingLinkedHashMap()

Default constructor. Will create an initial capacity of 100, a loading of .75 and LRU by access order.

Method Detail

removeEldestEntry

protected final boolean removeEldestEntry(Map.Entry eldest)

Returns true if this map should remove its eldest entry. This method is invoked by put and putAll after inserting a new entry into the map. It provides the implementer with the opportunity to remove the eldest entry each time a new one is added. This is useful if the map represents a cache: it allows the map to reduce memory consumption by deleting stale entries.

Will return true if:

1. the element has expired
2. the cache size is greater than the in-memory actual. In this case we spool to disk before returning.

Overrides:

removeEldestEntry in class LinkedHashMap

Parameters:

eldest - The least recently inserted entry in the map, or if this is an access-ordered map, the least recently accessed entry. This is the entry that will be removed it this method returns true. If the map was empty prior to the put or putAll invocation resulting in this invocation, this will be the entry that was just inserted; in other words, if the map contains a single entry, the eldest entry is also the newest.

Returns:

true if the eldest entry should be removed from the map; false if it should be retained.

put

public Object put(Object key,
                  Object value)

Specified by:

put in interface Map

Overrides:

put in class HashMap