Package com.yahoo.collections

Class CopyOnWriteHashMap<K,V>

java.lang.Object

java.util.AbstractMap<K,V>

com.yahoo.collections.CopyOnWriteHashMap<K,V>

All Implemented Interfaces:

Cloneable, Map<K,V>

public class CopyOnWriteHashMap<K,V>
extends AbstractMap<K,V>
implements Cloneable

A hashmap wrapper which defers cloning of the enclosed map until it is written to. Use this to make clones cheap in maps which are often not further modified.

As with regular maps, this can only be used safely if the content of the map is immutable. If not, the copyMap(java.util.Map<K, V>) method can be overridden to perform a deep clone.

Author:

bratseth

Nested Class Summary

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

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

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

Map.Entry<K extends Object,V extends Object>

Constructor Summary

Constructors

Constructor	Description
CopyOnWriteHashMap()
CopyOnWriteHashMap(int capacity)
CopyOnWriteHashMap(Map<K,V> map)

Method Summary

Modifier and Type	Method	Description
CopyOnWriteHashMap<K,V>	clone()
protected Map<K,V>	copyMap(Map<K,V> original)	Make a copy of the given map with the requisite deepness.
Set<Map.Entry<K,V>>	entrySet()
boolean	equals(Object other)
int	hashCode()
V	put(K key, V value)
V	remove(Object key)	Override to avoid using iterator.remove

Methods inherited from class java.util.AbstractMap

clear, containsKey, containsValue, get, isEmpty, keySet, putAll, size, toString, values

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.Map

compute, computeIfAbsent, computeIfPresent, forEach, getOrDefault, merge, putIfAbsent, remove, replace, replace, replaceAll

Constructor Detail

CopyOnWriteHashMap

public CopyOnWriteHashMap()

CopyOnWriteHashMap

public CopyOnWriteHashMap(int capacity)

CopyOnWriteHashMap

public CopyOnWriteHashMap(Map<K,V> map)

Method Detail

copyMap

protected Map<K,V> copyMap(Map<K,V> original)

Make a copy of the given map with the requisite deepness. This default implementation does return new HashMap<>(original);

clone

public CopyOnWriteHashMap<K,V> clone()

Overrides:

clone in class AbstractMap<K,V>

entrySet

public Set<Map.Entry<K,V>> entrySet()

Specified by:

entrySet in interface Map<K,V>

Specified by:

entrySet in class AbstractMap<K,V>

put

public V put(K key,
             V value)

Specified by:

put in interface Map<K,V>

Overrides:

put in class AbstractMap<K,V>

remove

public V remove(Object key)

Override to avoid using iterator.remove

Specified by:

remove in interface Map<K,V>

Overrides:

remove in class AbstractMap<K,V>

equals

public boolean equals(Object other)

Specified by:

equals in interface Map<K,V>

Overrides:

equals in class AbstractMap<K,V>

hashCode

public int hashCode()

Specified by:

hashCode in interface Map<K,V>

Overrides:

hashCode in class AbstractMap<K,V>