org.apache.openjpa.kernel
Class VersionLockManager

java.lang.Object
  org.apache.openjpa.kernel.AbstractLockManager
      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.