Package org.apache.sling.graphql.helpers.lazyloading

Class LazyLoadingMap<K,T>

java.lang.Object

java.util.AbstractMap<K,V>

java.util.HashMap<K,T>

org.apache.sling.graphql.helpers.lazyloading.LazyLoadingMap<K,T>

All Implemented Interfaces:

Serializable, Cloneable, Map<K,T>

public class LazyLoadingMap<K,T>
extends HashMap<K,T>

A HashMap that optionally uses Suppliers to provide its values. Each Supplier is called at most once, if the corresponding value is requested. Some "global" operations requires all values to be computed, and should be considered costly. Like HashMap, this class is NOT thread safe. If needed, Collections.synchronizedMap(java.util.Map<K, V>) can be used to synchronize it. Note that remove(java.lang.Object) behaves slightly differently than the HashMap version.

See Also:

• Serialized Form

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
class	LazyLoadingMap.Stats	Statistics on Supplier usage

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
LazyLoadingMap()

Method Summary

Modifier and Type	Method	Description
void	clear()
LazyLoadingMap<K,T>	computeAllThrowsException(boolean b)	Optionally throw a RuntimeException if computeAll is called
LazyLoadingMap<K,T>	computeValueOnRemove(boolean b)	Optionally compute the value on remove, so that it doesn't return null
boolean	containsKey(Object key)
boolean	containsValue(Object value)	Calls computeAll - should be avoided if possible
Set<Map.Entry<K,T>>	entrySet()	Calls computeAll - should be avoided if possible
boolean	equals(Object o)	Calls computeAll - should be avoided if possible
T	get(Object key)
LazyLoadingMap<K,T>.Stats	getStats()	Return statistics on our suppliers, for metrics etc.
int	hashCode()
boolean	isEmpty()
Set<K>	keySet()
Supplier<T>	put(K key, Supplier<T> supplier)	Adds a Supplier that provides a lazy loaded value.
T	remove(Object key)	Unless computeValueOnRemove(boolean) is set to true, this returns null to avoid calling a supplier "for nothing".
int	size()
Collection<T>	values()	Calls computeAll - should be avoided if possible

Methods inherited from class java.util.HashMap

clone, compute, computeIfAbsent, computeIfPresent, forEach, getOrDefault, merge, put, putAll, putIfAbsent, remove, replace, replace, replaceAll

Methods inherited from class java.util.AbstractMap

toString

Methods inherited from class java.lang.Object

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

Constructor Details

LazyLoadingMap

public LazyLoadingMap()

Method Details

equals

public boolean equals(Object o)

Calls computeAll - should be avoided if possible

Specified by:

equals in interface Map<K,T>

Overrides:

equals in class AbstractMap<K,T>

hashCode

public int hashCode()

Specified by:

hashCode in interface Map<K,T>

Overrides:

hashCode in class AbstractMap<K,T>

put

public Supplier<T> put(K key,
 Supplier<T> supplier)

Adds a Supplier that provides a lazy loaded value. Removes existing value with the same key if it exists.

get

public T get(Object key)

Specified by:

get in interface Map<K,T>

Overrides:

get in class HashMap<K,T>

remove

public T remove(Object key)

Unless computeValueOnRemove(boolean) is set to true, this returns null to avoid calling a supplier "for nothing".

Specified by:

remove in interface Map<K,T>

Overrides:

remove in class HashMap<K,T>

clear

public void clear()

Specified by:

clear in interface Map<K,T>

Overrides:

clear in class HashMap<K,T>

containsKey

public boolean containsKey(Object key)

Specified by:

containsKey in interface Map<K,T>

Overrides:

containsKey in class HashMap<K,T>

size

public int size()

Specified by:

size in interface Map<K,T>

Overrides:

size in class HashMap<K,T>

isEmpty

public boolean isEmpty()

Specified by:

isEmpty in interface Map<K,T>

Overrides:

isEmpty in class HashMap<K,T>

keySet

public Set<K> keySet()

Specified by:

keySet in interface Map<K,T>

Overrides:

keySet in class HashMap<K,T>

values

public Collection<T> values()

Calls computeAll - should be avoided if possible

Specified by:

values in interface Map<K,T>

Overrides:

values in class HashMap<K,T>

entrySet

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

Calls computeAll - should be avoided if possible

Specified by:

entrySet in interface Map<K,T>

Overrides:

entrySet in class HashMap<K,T>

containsValue

public boolean containsValue(Object value)

Calls computeAll - should be avoided if possible

Specified by:

containsValue in interface Map<K,T>

Overrides:

containsValue in class HashMap<K,T>

getStats

public LazyLoadingMap<K,T>.Stats getStats()

Return statistics on our suppliers, for metrics etc.

computeValueOnRemove

public LazyLoadingMap<K,T> computeValueOnRemove(boolean b)

Optionally compute the value on remove, so that it doesn't return null

computeAllThrowsException

public LazyLoadingMap<K,T> computeAllThrowsException(boolean b)

Optionally throw a RuntimeException if computeAll is called