net.sf.ehcache.store.chm
Class SelectableConcurrentHashMap

java.lang.Object
  java.util.AbstractMap<K,V>
      net.sf.ehcache.store.chm.ConcurrentHashMap<Object,Element>
          net.sf.ehcache.store.chm.SelectableConcurrentHashMap

All Implemented Interfaces:

Serializable, ConcurrentMap<Object,Element>, Map<Object,Element>

public class SelectableConcurrentHashMap
extends ConcurrentHashMap<Object,Element>

SelectableConcurrentHashMap subclasses a repackaged version of ConcurrentHashMap ito allow efficient random sampling of the map values.

The random sampling technique involves randomly selecting a map Segment, and then selecting a number of random entry chains from that segment.

Author:

Chris Dennis

See Also:

Serialized Form

Nested Class Summary

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

AbstractMap.SimpleImmutableEntry<K,V>

Nested classes/interfaces inherited from interface java.util.Map

Map.Entry<K,V>

Constructor Summary

SelectableConcurrentHashMap(int initialCapacity, float loadFactor, int concurrency)

Method Summary

Element[]	getRandomValues(int size, Object keyHint)
int	quickSize() Returns the number of key-value mappings in this map without locking anything.

Methods inherited from class net.sf.ehcache.store.chm.ConcurrentHashMap

clear, contains, containsKey, containsValue, elements, entrySet, get, hash, isEmpty, keys, keySet, put, putAll, putIfAbsent, remove, remove, replace, replace, size, values

Methods inherited from class java.util.AbstractMap

clone, equals, hashCode, toString

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.Map

equals, hashCode

Constructor Detail

SelectableConcurrentHashMap

public SelectableConcurrentHashMap(int initialCapacity,
                                   float loadFactor,
                                   int concurrency)

Method Detail

getRandomValues

public Element[] getRandomValues(int size,
                                 Object keyHint)

quickSize

public int quickSize()

Returns the number of key-value mappings in this map without locking anything. This may not give the exact element count as locking is avoided. If the map contains more than Integer.MAX_VALUE elements, returns Integer.MAX_VALUE.

Returns:

the number of key-value mappings in this map