org.postgresql.util

Class ExpiringCache<K,V>

java.lang.Object

org.postgresql.util.ExpiringCache<K,V>

Type Parameters:

K - The type of the key to store

V - The type of the value to store

All Implemented Interfaces:

Map<K,V>

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

Expiring Cache class. This cache uses a LinkedHashMap to store values with a specific time they were stored. Items that exceed the expired time will be removed when attempting to retrieve them.

Nested Class Summary

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

Map.Entry<K,V>

Constructor Summary

Constructors

Constructor and Description
ExpiringCache(int expireTimeMs) Expiring cache constructor

Method Summary

Modifier and Type	Method and Description
void	clear() Clears all mapping from the cache
boolean	containsKey(Object key) Checks if the cache contains a specific key
boolean	containsValue(Object value) Checks if the cache contains a specific value
Set<Map.Entry<K,V>>	entrySet() Returns a Set view of the keys
V	get(Object key) Retrieves the value from a key
int	getExpireTime() Accessor method for expireTimeMs
boolean	isEmpty() Checks whether or not it is empty
Set<K>	keySet() Returns a Set view of the keys
V	put(K key, V value) Associates a specificed value with a specified key in this map
void	putAll(Map<? extends K,? extends V> m) Copies the content from one map to the current map
V	remove(Object key) Removes the mapping for a key if it's present.
void	setExpireTime(int expireTimeMs) Mutator method for expireTimeMs.
int	size() Retrieves the number of items stored
Collection<V>	values() Returns a Collection view of the keys

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

ExpiringCache

public ExpiringCache(int expireTimeMs)

Expiring cache constructor

Parameters:

expireTimeMs - The expired time in Ms

Method Detail

setExpireTime

public void setExpireTime(int expireTimeMs)

Mutator method for expireTimeMs. Sets the expired time for the cache

Parameters:

expireTimeMs - The expired time in Ms

getExpireTime

public int getExpireTime()

Accessor method for expireTimeMs

Returns:

Returns the time it takes for the cache to be "expired"

size

public int size()

Retrieves the number of items stored

Specified by:

size in interface Map<K,V>

Returns:

The size of items stored

isEmpty

public boolean isEmpty()

Checks whether or not it is empty

Specified by:

isEmpty in interface Map<K,V>

Returns:

True if it's empty

containsKey

public boolean containsKey(Object key)

Checks if the cache contains a specific key

Specified by:

containsKey in interface Map<K,V>

Parameters:

key - The key to search for

Returns:

True if the cache contains the key

containsValue

public boolean containsValue(Object value)

Checks if the cache contains a specific value

Specified by:

containsValue in interface Map<K,V>

Parameters:

value - The value to search for

Returns:

True if the cache contains that value

get

public V get(Object key)

Retrieves the value from a key

Specified by:

get in interface Map<K,V>

Parameters:

key - The key in the key-value pair

Returns:

The value from the key

put

public V put(K key,
             V value)

Associates a specificed value with a specified key in this map

Specified by:

put in interface Map<K,V>

Parameters:

key - The key in the key-value pair

value - The value in the key-value pair

Returns:

The previously associated value of the key. If there isn't any then it would return null

remove

public V remove(Object key)

Removes the mapping for a key if it's present.

Specified by:

remove in interface Map<K,V>

Parameters:

key - The key in the map

Returns:

The value associated with the key, or null if there were no mappings for the key.

putAll

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

Copies the content from one map to the current map

Specified by:

putAll in interface Map<K,V>

Parameters:

m - The map to copy from

clear

public void clear()

Clears all mapping from the cache

Specified by:

clear in interface Map<K,V>

keySet

public Set<K> keySet()

Returns a Set view of the keys

Specified by:

keySet in interface Map<K,V>

Returns:

A set view of the keys in the cache

values

public Collection<V> values()

Returns a Collection view of the keys

Specified by:

values in interface Map<K,V>

Returns:

A collection view of the keys in the cache

entrySet

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

Returns a Set view of the keys

Specified by:

entrySet in interface Map<K,V>

Returns:

A set view of the mappings in the cache