org.apache.openjpa.kernel
Class VersionLockManager

java.lang.Object
  extended by org.apache.openjpa.kernel.AbstractLockManager
      extended by org.apache.openjpa.kernel.VersionLockManager
All Implemented Interfaces:
LockLevels, LockManager, Closeable
Direct Known Subclasses:
PessimisticLockManager

public class VersionLockManager
extends AbstractLockManager

LockManager implementation that provides support for version checking and version updating when locks are acquired. This lock manager may be used standalone or extended for additional locking.

Author:
Marc Prud'hommeaux

Field Summary
 
Fields inherited from class org.apache.openjpa.kernel.AbstractLockManager
ctx, log
 
Fields inherited from interface org.apache.openjpa.kernel.LockLevels
LOCK_NONE, LOCK_READ, LOCK_WRITE
 
Constructor Summary
VersionLockManager()
           
 
Method Summary
 int getLockLevel(OpenJPAStateManager sm)
          Returns the given instance's lock level, assuming that the state's lock object is a number.
 boolean getVersionCheckOnReadLock()
          Whether or not we should force a version check at commit time when a read lock is requested in order to verify read consistency.
 boolean getVersionUpdateOnWriteLock()
          Whether or not we should force an update to the version at commit time when a write lock is requested.
 void lock(OpenJPAStateManager sm, int level, int timeout, Object sdata)
          Delegates to lockInternal(org.apache.openjpa.kernel.OpenJPAStateManager, int, long, java.lang.Object) after traversing to owning instance (if embedded) and assuring that the instance is persistent, is not new, and is not already locked at a higher level.
protected  void lockInternal(OpenJPAStateManager sm, int level, long timeout, Object sdata)
          Marks the instance's transactional status in accordance with the settings of getVersionCheckOnReadLock() and getVersionUpdateOnWriteLock().
 void release(OpenJPAStateManager sm)
          Nulls given instance's lock object.
protected  void setLockLevel(OpenJPAStateManager sm, int level)
          Sets the given instance's lock level to the given number.
 void setVersionCheckOnReadLock(boolean versionCheckOnReadLock)
          Whether or not we should force a version check at commit time when a read lock is requested in order to verify read consistency.
 void setVersionUpdateOnWriteLock(boolean versionUpdateOnWriteLock)
          Whether or not we should force an update to the version at commit time when a write lock is requested.
 
Methods inherited from class org.apache.openjpa.kernel.AbstractLockManager
beginTransaction, close, endTransaction, getContext, lockAll, setContext
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

VersionLockManager

public VersionLockManager()
Method Detail

getLockLevel

public int getLockLevel(OpenJPAStateManager sm)
Returns the given instance's lock level, assuming that the state's lock object is a number. If the given instance is embedded, traverses to its owner. Override if lock is not stored as a number.


setLockLevel

protected void setLockLevel(OpenJPAStateManager sm,
                            int level)
Sets the given instance's lock level to the given number. Override to store something else as the lock.


release

public void release(OpenJPAStateManager sm)
Nulls given instance's lock object.

See Also:
OpenJPAStateManager.setLock(java.lang.Object)

lock

public void lock(OpenJPAStateManager sm,
                 int level,
                 int timeout,
                 Object sdata)
Delegates to lockInternal(org.apache.openjpa.kernel.OpenJPAStateManager, int, long, java.lang.Object) after traversing to owning instance (if embedded) and assuring that the instance is persistent, is not new, and is not already locked at a higher level. After locking, calls setLockLevel(org.apache.openjpa.kernel.OpenJPAStateManager, int) with the given level.

Parameters:
sm - the object to lock
level - one of the lock constants defined in LockLevels, or a custom level
timeout - the timeout in milliseconds, or a negative number for no timeout
sdata - the context information passed from the store manager to the persistence context, if any; lock managers specific to a certain back end may be able to take advantage of this; others should ignore it
See Also:
OpenJPAStateManager.setLock(java.lang.Object)

lockInternal

protected void lockInternal(OpenJPAStateManager sm,
                            int level,
                            long timeout,
                            Object sdata)
Marks the instance's transactional status in accordance with the settings of getVersionCheckOnReadLock() and getVersionUpdateOnWriteLock(). Override to perform additional locking.

See Also:
StoreContext.transactional(java.lang.Object, boolean, org.apache.openjpa.kernel.OpCallbacks)

setVersionCheckOnReadLock

public void setVersionCheckOnReadLock(boolean versionCheckOnReadLock)
Whether or not we should force a version check at commit time when a read lock is requested in order to verify read consistency. Defaults to true.


getVersionCheckOnReadLock

public boolean getVersionCheckOnReadLock()
Whether or not we should force a version check at commit time when a read lock is requested in order to verify read consistency. Defaults to true.


setVersionUpdateOnWriteLock

public void setVersionUpdateOnWriteLock(boolean versionUpdateOnWriteLock)
Whether or not we should force an update to the version at commit time when a write lock is requested. Defaults to true.


getVersionUpdateOnWriteLock

public boolean getVersionUpdateOnWriteLock()
Whether or not we should force an update to the version at commit time when a write lock is requested. Defaults to true.



Copyright © 2006 Apache Software Foundation. All Rights Reserved.