de.aristaflow.adept2.util.locking

Class OptimisticObjectLockManager<O,L>

java.lang.Object

de.aristaflow.adept2.util.locking.ObjectLockManager<O,L>

de.aristaflow.adept2.util.locking.OptimisticObjectLockManager<O,L>

Type Parameters:

O - The type of the objects to be locked (locked object type).

L - The type of the objects that lock (lock owning type).

public class OptimisticObjectLockManager<O,L>
extends ObjectLockManager<O,L>

A manager for (optimistically) locking objects with reentrant locks whereas the locks are itself object specific. No synchronisation takes place, it may happen that lock objects are created and not used at all since another lock has been created concurrently.
Optimistic locking is usually better in environments where locks live short and are not very reentrant.

Author:

Ulrich Kreher

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
protected static class	OptimisticObjectLockManager.LockRemover<O,L> When unlocking an object for the last time (count is 0), this will remove the corresponding locked object from the map containing all locked objects.

Field Summary

Fields

Modifier and Type	Field and Description
protected java.lang.reflect.Constructor<? extends ReentrantLock<L>>	lockConstr The constructor for instantiating lock implementations.
protected java.util.concurrent.ConcurrentMap<O,ReentrantLock<L>>	objectLocks A mapping from the locked object to the corresponding locking object.
protected boolean	serviceLogger Whether the constructor of the lock implementation accepts the service logger.

Fields inherited from class de.aristaflow.adept2.util.locking.ObjectLockManager

lockCountManager, lockType, logger

Constructor Summary

Constructors

Constructor and Description
OptimisticObjectLockManager(java.lang.Class<? extends LockCountManager<? super L>> lockCountManager, java.lang.Class<? extends ReentrantLock<L>> lock, java.lang.String lockType, java.util.logging.Logger logger) Creates a new ObjectLockManager with the designated lock count manager providing the "equality" for the designated reentrant locks and of the designated type using optimistic locking.

Method Summary

Modifier and Type	Method and Description
protected void	getLockForObjectReadWriteDirect(boolean writeLock, L lockingObject, O lockedObject, long timeout) Cf. documentation of ObjectLockManager.getLockForObject(boolean, Object, Object, long).
protected ReentrantLock<L>	getObjectLock(O lockedObject) Gets the lock for the designated object.

Methods inherited from class de.aristaflow.adept2.util.locking.ObjectLockManager

getLockForObject, getLockForObject, hasLock, unlockObject

Methods inherited from class java.lang.Object

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

Field Detail

objectLocks

protected final java.util.concurrent.ConcurrentMap<O,ReentrantLock<L>> objectLocks

A mapping from the locked object to the corresponding locking object.

lockConstr

protected final java.lang.reflect.Constructor<? extends ReentrantLock<L>> lockConstr

The constructor for instantiating lock implementations.

serviceLogger

protected final boolean serviceLogger

Whether the constructor of the lock implementation accepts the service logger. Otherwise the usual class logger will be used for all locks.

Constructor Detail

OptimisticObjectLockManager

public OptimisticObjectLockManager(java.lang.Class<? extends LockCountManager<? super L>> lockCountManager,
                                   java.lang.Class<? extends ReentrantLock<L>> lock,
                                   java.lang.String lockType,
                                   java.util.logging.Logger logger)
                            throws java.lang.reflect.InvocationTargetException

Creates a new ObjectLockManager with the designated lock count manager providing the "equality" for the designated reentrant locks and of the designated type using optimistic locking.
This constructor checks whether the designated lock class and the lock count manager class can be instantiated with the appropriate constructors.

Parameters:

lockCountManager - The lock count manager that encapsulates what locking objects are treated as equal when acquiring a lock. The provided class needs an accessible (public) constructor without parameters.

lock - The reentrant lock to be used for locking. The provided class needs an accessible (public) constructor with accepting the designated lockCountManager (of type Class<? extends LockCountManager<? super L>>), a boolean as well as an instance of LockNotification.

lockType - The type of locks managed by the created object. This is for user information only.

logger - The logger for log messages.

Throws:

java.lang.reflect.InvocationTargetException - If there are problems instantiating the designated lock count manager or the reentrant lock, an InvocationTargetException will be thrown. This prevents problems at runtime when actually retrieving a lock (which requires creating the corresponding objects).

Method Detail

getObjectLock

protected ReentrantLock<L> getObjectLock(O lockedObject)

Description copied from class: ObjectLockManager

Gets the lock for the designated object. This allows subclasses to use their own data structure for lock management.

Specified by:

getObjectLock in class ObjectLockManager<O,L>

Parameters:

lockedObject - The locked object for which to retrieve the corresponding reentrant lock.

Returns:

The reentrant lock for the designated locked object or null in case the designated object is not locked.

getLockForObjectReadWriteDirect

protected void getLockForObjectReadWriteDirect(boolean writeLock,
                                               L lockingObject,
                                               O lockedObject,
                                               long timeout)
                                        throws java.lang.InterruptedException,
                                               java.util.concurrent.TimeoutException

Description copied from class: ObjectLockManager

Cf. documentation of ObjectLockManager.getLockForObject(boolean, Object, Object, long). Implementors can rely on the first boolean to be set appropriately depending on present locks.

Specified by:

getLockForObjectReadWriteDirect in class ObjectLockManager<O,L>

Parameters:

writeLock - Whether to acquire a write lock. This will already be adapted to a write lock if required, that is, requesting a read lock while having the write lock already.

lockingObject - The object locking the designated object.

lockedObject - The object to lock.

timeout - The time to wait for the lock. A timeout <= 0 means to wait forever (or until the lock is granted).

Throws:

java.lang.InterruptedException - If the thread is interrupted while waiting for the lock, an InterruptedException will be thrown.

java.util.concurrent.TimeoutException - If the designated timeout elapsed before the lock can be acquired, a TimeoutException will be thrown.