org.jasig.portal.services
Class EntityLockService

java.lang.Object
  org.jasig.portal.services.EntityLockService

public class EntityLockService
extends java.lang.Object

This is a bootstrap class and facade for the IEntityLockService implementation. It presents a simple api for acquiring lock objects, IEntityLocks, that can be used to control concurrent access to portal entities in a multi-server environment. (See org.jasig.portal.concurrency.IEntityLockService for a fuller description.)

Currently supported lock types are IEntityLockService.READ_LOCK and IEntityLockService.WRITE_LOCK.

If I want to lock an entity for update, I ask the service for a write lock:

Class type = anEntity.getClass(); // maybe hard-coded(?)
String key = anEntity.getKey();
EntityIdentifier ei = new EntityIdentifier(key, type);
String owner = getThePortalUserId();
IEntityLock lock = EntityLockService.instance().newWriteLock(ei, owner);


Or maybe:

IEntityLock lock = EntityLockService.instance().newWriteLock(ei, owner, duration);


If there are no conflicting locks on the entity, the service returns the requested lock. If I acquire the lock, I know that no other client will be able to get a conflicting lock, and from then on, I communicate with the service via the lock:

lock.convert(int newType); // See IEntityLockService for types.
lock.isValid();
lock.release();
lock.renew();


A READ lock guarantees shared access; other clients can get READ locks but not WRITE locks. A WRITE lock guarantees exclusive access; no other clients can get either READ or WRITE locks on the entity.

Version:

$Revision: 1.11 $

Author:

Dan Ellentuck

Field Summary

private static EntityLockService	instance
private IEntityLockService	lockService
private static org.apache.commons.logging.Log	log

Constructor Summary

private

EntityLockService() Creates new EntityLockService

Method Summary

private void	initialize()
static EntityLockService	instance()
IEntityLock	newReadLock(java.lang.Class entityType, java.lang.String entityKey, java.lang.String owner) Returns a read lock for the entity type, entity key and owner.
IEntityLock	newReadLock(java.lang.Class entityType, java.lang.String entityKey, java.lang.String owner, int duration) Returns a read lock for the entity type, entity key and owner.
IEntityLock	newReadLock(EntityIdentifier entityID, java.lang.String owner) Returns a read lock for the IBasicEntity and owner.
IEntityLock	newReadLock(EntityIdentifier entityID, java.lang.String owner, int durationSecs) Returns a read lock for the IBasicEntity, owner and duration.
IEntityLock	newWriteLock(java.lang.Class entityType, java.lang.String entityKey, java.lang.String owner) Returns a write lock for the entity type, entity key and owner.
IEntityLock	newWriteLock(java.lang.Class entityType, java.lang.String entityKey, java.lang.String owner, int durationSecs) Returns a write lock for the entity type, entity key and owner.
IEntityLock	newWriteLock(EntityIdentifier entityID, java.lang.String owner) Returns a write lock for the IBasicEntity and owner.
IEntityLock	newWriteLock(EntityIdentifier entityID, java.lang.String owner, int durationSecs) Returns a write lock for the IBasicEntity, owner and duration.

Methods inherited from class java.lang.Object

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

Field Detail

log

private static final org.apache.commons.logging.Log log

instance

private static EntityLockService instance

lockService

private IEntityLockService lockService

Constructor Detail

EntityLockService

private EntityLockService()
                   throws LockingException

Creates new EntityLockService

Throws:

LockingException

Method Detail

initialize

private void initialize()
                 throws LockingException

Throws:

LockingException

instance

public static EntityLockService instance()
                                  throws LockingException

Throws:

LockingException

newReadLock

public IEntityLock newReadLock(java.lang.Class entityType,
                               java.lang.String entityKey,
                               java.lang.String owner)
                        throws LockingException

Returns a read lock for the entity type, entity key and owner.

Parameters:

entityType - Class

entityKey - String

owner - String

Returns:

org.jasig.portal.concurrency.locking.IEntityLock

Throws:

LockingException

newReadLock

public IEntityLock newReadLock(java.lang.Class entityType,
                               java.lang.String entityKey,
                               java.lang.String owner,
                               int duration)
                        throws LockingException

Returns a read lock for the entity type, entity key and owner.

Parameters:

entityType - Class

entityKey - String

owner - String

duration - int (in seconds)

Returns:

org.jasig.portal.concurrency.locking.IEntityLock

Throws:

LockingException

newReadLock

public IEntityLock newReadLock(EntityIdentifier entityID,
                               java.lang.String owner)
                        throws LockingException

Returns a read lock for the IBasicEntity and owner.

Parameters:

entityID - EntityIdentifier

owner - String

Returns:

org.jasig.portal.concurrency.locking.IEntityLock

Throws:

LockingException

newReadLock

public IEntityLock newReadLock(EntityIdentifier entityID,
                               java.lang.String owner,
                               int durationSecs)
                        throws LockingException

Returns a read lock for the IBasicEntity, owner and duration.

Parameters:

entityID - EntityIdentifier

owner - String

durationSecs - int

Returns:

org.jasig.portal.concurrency.locking.IEntityLock

Throws:

LockingException

newWriteLock

public IEntityLock newWriteLock(java.lang.Class entityType,
                                java.lang.String entityKey,
                                java.lang.String owner)
                         throws LockingException

Returns a write lock for the entity type, entity key and owner.

Parameters:

entityType - Class

entityKey - String

owner - String

Returns:

org.jasig.portal.concurrency.locking.IEntityLock

Throws:

LockingException

newWriteLock

public IEntityLock newWriteLock(java.lang.Class entityType,
                                java.lang.String entityKey,
                                java.lang.String owner,
                                int durationSecs)
                         throws LockingException

Returns a write lock for the entity type, entity key and owner.

Parameters:

entityType - Class

entityKey - String

owner - String

durationSecs - int

Returns:

org.jasig.portal.concurrency.locking.IEntityLock

Throws:

LockingException

newWriteLock

public IEntityLock newWriteLock(EntityIdentifier entityID,
                                java.lang.String owner)
                         throws LockingException

Returns a write lock for the IBasicEntity and owner.

Parameters:

entityID - EntityIdentifier

owner - String

Returns:

org.jasig.portal.concurrency.locking.IEntityLock

Throws:

LockingException

newWriteLock

public IEntityLock newWriteLock(EntityIdentifier entityID,
                                java.lang.String owner,
                                int durationSecs)
                         throws LockingException

Returns a write lock for the IBasicEntity, owner and duration.

Parameters:

entityID - EntityIdentifier

owner - String

durationSecs - int

Returns:

org.jasig.portal.concurrency.locking.IEntityLock

Throws:

LockingException