org.forgerock.openam.shared.concurrency

Class LockFactory<K>

java.lang.Object

org.forgerock.openam.shared.concurrency.LockFactory<K>

Type Parameters:

K - The type of the key used to retrieve the lock.

public class LockFactory<K>
extends Object

Lock factory is responsible for delivering up locks that are shared for a given key. This allows locking to be more fine grained as opposed to blocking all threads for all circumstances. K represents the key type used to index the lock instance. Given that K is used to indirectly index the lock, it must satisfy the hash code and equals methods.

To alleviate the responsibility of the developer and avoid potential memory leaks, the factory manages the internal clean up of unreferenced locks. Locks are cached within a WeakHashMap against a key. Each lock has a strong reference to its key, so that once all consumers of a lock give up their strong references to the lock, the single strong reference to the key from within the lock is freed. This allows the behaviour of the cache to now clear out the cached entry.

Constructor Summary

Constructors

Constructor and Description
LockFactory() Constructs a new LockFactory instance.

Method Summary

Modifier and Type	Method and Description
Lock	acquireLock(K key) Given a key, lookup/create the associated lock instance.

Methods inherited from class java.lang.Object

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

Constructor Detail

LockFactory

public LockFactory()

Constructs a new LockFactory instance.

Method Detail

acquireLock

public Lock acquireLock(K key)

Given a key, lookup/create the associated lock instance.

Parameters:

key - the key used to index a give lock instance.

Returns:

a lock instance.

Throws:

NullPointerException - if key is null.