Module org.apache.jena.base

Package org.apache.jena.atlas.lib.cache

Class Cache1<K,V>

java.lang.Object

org.apache.jena.atlas.lib.cache.Cache1<K,V>

All Implemented Interfaces:

Cache<K,V>

public class Cache1<K,V>
extends Object
implements Cache<K,V>

A one-slot cache.

Constructor Summary

Constructors

Constructor	Description
Cache1()
Cache1(BiConsumer<K,V> dropHandler)

Method Summary

Modifier and Type	Method	Description
void	clear()
boolean	containsKey(K key)	Does the cache contain the key?
V	get(K key, Function<K,V> function)	Get from cache; if not present, call the Function to fill the cache slot.
V	getIfPresent(K key)	Get from cache - or return null.
boolean	isEmpty()
Iterator<K>	keys()	Iterate over all keys.
void	put(K key, V thing)	Insert into the cache
void	remove(K key)	Remove from cache - return true if key referenced an entry
long	size()	Current size of cache

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.apache.jena.atlas.lib.Cache

getOrFill, stats

Constructor Details

Cache1

public Cache1()

Cache1

public Cache1(BiConsumer<K,V> dropHandler)

Method Details

containsKey

public boolean containsKey(K key)

Description copied from interface: Cache

Does the cache contain the key?

Specified by:

containsKey in interface Cache<K,V>

Parameters:

key - The key to find. The key must not be null.

Returns:

True, if the cache contains the key, otherwise false.

getIfPresent

public V getIfPresent(K key)

Description copied from interface: Cache

Get from cache - or return null.

Specified by:

getIfPresent in interface Cache<K,V>

Parameters:

key - The key for which the value is requested. The key must not be null.

Returns:

If the cache contains an entry for the given key, the value is returned, otherwise null.

get

public V get(K key,
 Function<K,V> function)

Description copied from interface: Cache

Get from cache; if not present, call the Function to fill the cache slot. This operation should be atomic.

Specified by:

get in interface Cache<K,V>

Parameters:

key - The key, for which the value should be returned or calculated. The key must not be null.

function - If the cache does not contain the key, the callable is called to calculate a value. If the callable returns null, the key is not associated with hat value, as nulls are not accepted as values. The callable must not be null.

Returns:

Returns either the existing value or the calculated value. If callable is called and returns null, then null is returned.

clear

public void clear()

Specified by:

clear in interface Cache<K,V>

isEmpty

public boolean isEmpty()

Specified by:

isEmpty in interface Cache<K,V>

keys

public Iterator<K> keys()

Description copied from interface: Cache

Iterate over all keys. Iterating over the keys requires the caller be thread-safe.

Specified by:

keys in interface Cache<K,V>

put

public void put(K key,
 V thing)

Description copied from interface: Cache

Insert into the cache

Specified by:

put in interface Cache<K,V>

Parameters:

key - The key for the 'thing' to store. The key must not be null.

thing - If 'thing' is null, it will not be used as value, instead any existing entry with the same key will be removed.

remove

public void remove(K key)

Description copied from interface: Cache

Remove from cache - return true if key referenced an entry

Specified by:

remove in interface Cache<K,V>

Parameters:

key - The key, which shall be removed along with its value. The key must not be null.

size

public long size()

Description copied from interface: Cache

Current size of cache

Specified by:

size in interface Cache<K,V>