org.archive.util
Interface ObjectIdentityCache<K,V>

Type Parameters:

V -

All Superinterfaces:

java.io.Closeable

All Known Implementing Classes:

CachedBdbMap, ObjectIdentityBdbCache, ObjectIdentityMemCache

public interface ObjectIdentityCache<K,V>
extends java.io.Closeable

An object cache for create-once-by-name-and-then-reuse objects. Objects are added, but never removed. Subsequent get()s using the same key will return the exact same object, UNLESS all such objects have been forgotten, in which case a new object MAY be returned. This allows implementors (such as ObjectIdentityBdbCache or CachedBdbMap) to page out (aka 'expunge') instances to persistent storage while they're not being used. However, as long as they are used (referenced), all requests for the same-named object will share a reference to the same object, and the object may be mutated in place without concern for explicitly persisting its state to disk.

Method Summary

void	close() close/release any associated resources
V	get(K key) get the object under the given key/name
V	getOrUse(K key, Supplier<V> supplierOrNull) get the object under the given key/name, using (and remembering) the object supplied by the supplier if no prior mapping exists
java.util.Set<K>	keySet() set of all keys
int	size() count of name-to-object contained
void	sync() force the persistent backend, if any, to be updated with all live object state

Method Detail

get

V get(K key)

get the object under the given key/name

getOrUse

V getOrUse(K key,
           Supplier<V> supplierOrNull)

get the object under the given key/name, using (and remembering) the object supplied by the supplier if no prior mapping exists

sync

void sync()

force the persistent backend, if any, to be updated with all live object state

close

void close()

close/release any associated resources

Specified by:

close in interface java.io.Closeable

size

int size()

count of name-to-object contained

keySet

java.util.Set<K> keySet()

set of all keys