Package org.drasyl.util

Class ExpiringMap<K,V>

java.lang.Object

org.drasyl.util.ExpiringMap<K,V>

Type Parameters:

K - the type of keys maintained by this map

V - the type of mapped values

All Implemented Interfaces:

Map<K,V>

public class ExpiringMap<K,V>
extends Object
implements Map<K,V>

A Map that expires entries based on oldest age (when maximum size has been exceeded), write time, or last access time.

The expiration policy is only enforced on map access. There will be no automatic expiration handling running in a background thread or similar. For performance reasons the policy is not enforced on every single access, but only once every "expiration window" (Math.max(expireAfterWrite, expireAfterAccess)). Therefore, it may happen that entries are kept in the map up to the double expiration window length.

This data structure is not thread-safe!

Nested Class Summary

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

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

Constructor Summary

Constructors

Constructor	Description
ExpiringMap(long maximumSize, long expireAfterWrite, long expireAfterAccess)

Method Summary

Modifier and Type	Method	Description
void	clear()
boolean	containsKey(Object key)
boolean	containsValue(Object value)
Set<Map.Entry<K,V>>	entrySet()
V	get(Object key)
boolean	isEmpty()
Set<K>	keySet()
V	put(K key, V value)
void	putAll(Map<? extends K,? extends V> m)
V	remove(Object key)
int	size()
Collection<V>	values()

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.Map

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

Constructor Detail

ExpiringMap

public ExpiringMap(long maximumSize,
                   long expireAfterWrite,
                   long expireAfterAccess)

Parameters:

maximumSize - maximum number of entries that the map should contain. On overflow, first elements based on expiration policy are removed. -1 deactivates a size limitation.

expireAfterWrite - time in milliseconds after which elements are automatically removed from the map after being added. -1 deactivates this expiration policy.

expireAfterAccess - time in milliseconds after which elements are automatically removed from the map after last access. -1 deactivates this expiration policy. Keep in mind, that only get(Object) is treated as an element access.

Throws:

IllegalArgumentException - if maximumSize is 0, or expireAfterWrite and expireAfterAccess are both -1.

Method Detail

size

public int size()

Specified by:

size in interface Map<K,V>

isEmpty

public boolean isEmpty()

Specified by:

isEmpty in interface Map<K,V>

containsKey

public boolean containsKey(Object key)

Specified by:

containsKey in interface Map<K,V>

containsValue

public boolean containsValue(Object value)

Specified by:

containsValue in interface Map<K,V>

get

public V get(Object key)

Specified by:

get in interface Map<K,V>

put

public V put(K key,
             V value)

Specified by:

put in interface Map<K,V>

remove

public V remove(Object key)

Specified by:

remove in interface Map<K,V>

putAll

public void putAll(Map<? extends K,? extends V> m)

Specified by:

putAll in interface Map<K,V>

clear

public void clear()

Specified by:

clear in interface Map<K,V>

keySet

public Set<K> keySet()

Specified by:

keySet in interface Map<K,V>

values

public Collection<V> values()

Specified by:

values in interface Map<K,V>

entrySet

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

Specified by:

entrySet in interface Map<K,V>