org.apache.openjpa.util
Class AbstractChangeTracker

java.lang.Object
  org.apache.openjpa.util.AbstractChangeTracker

All Implemented Interfaces:

ChangeTracker

Direct Known Subclasses:

CollectionChangeTrackerImpl, MapChangeTrackerImpl

public abstract class AbstractChangeTracker
extends Object
implements ChangeTracker

Base class that provides utilities to change trackers.

Author:

Abe White

Field Summary

protected Collection	add Collection of added items.
protected Collection	change Collection of changed items.
protected Collection	rem Collection of removed items.

Constructor Summary

AbstractChangeTracker()
Constructor; supply configuration.

Method Summary

protected abstract void	add(Object val) Mark the given value as added.
protected void	added(Object val) Notify the tracker that the given object was added.
protected abstract void	change(Object val) Mark the given value as changed.
protected void	changed(Object val) Notify the tracker that the given object was changed.
Collection	getAdded() Return the collection of values that need to be added to the managed container.
boolean	getAutoOff() Whether to automatically stop tracking when the number of changes exceeds the container size.
Collection	getChanged() Return the set of elements that have changed.
int	getNextSequence() The next element sequence value for this proxy at load time.
Collection	getRemoved() Return the set of values that need to be removed from the managed container.
protected int	initialSequence() Return the initial sequence value for this proxy.
boolean	isTracking() Return true if this tracker has an up-to-date view of all the changes to the container it is managing.
protected Set	newSet() Create a new set for storing adds/removes/changes.
protected abstract void	remove(Object val) Mark the given value as removed.
protected void	removed(Object val) Notify the tracker that the given object was removed.
protected void	reset() Reset the state of the tracker.
void	setAutoOff(boolean autoOff) Whether to automatically stop tracking when the number of changes exceeds the container size.
void	setNextSequence(int seq) The maximum element sequence value for this proxy at load time.
void	startTracking() Reset the state of the change tracker, and turn change tracking back on if it has been disabled.
void	stopTracking() Tell the tracker to stop tracking changes for its container.

Methods inherited from class java.lang.Object

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

Field Detail

add

protected Collection add

Collection of added items. May be null.

rem

protected Collection rem

Collection of removed items. May be null.

change

protected Collection change

Collection of changed items. May be null.

Constructor Detail

AbstractChangeTracker

public AbstractChangeTracker()

Constructor; supply configuration.

Method Detail

getAutoOff

public boolean getAutoOff()

Whether to automatically stop tracking when the number of changes exceeds the container size. Defaults to true.

setAutoOff

public void setAutoOff(boolean autoOff)

Whether to automatically stop tracking when the number of changes exceeds the container size. Defaults to true.

isTracking

public boolean isTracking()

Description copied from interface: ChangeTracker

Return true if this tracker has an up-to-date view of all the changes to the container it is managing.

Specified by:

isTracking in interface ChangeTracker

startTracking

public void startTracking()

Description copied from interface: ChangeTracker

Reset the state of the change tracker, and turn change tracking back on if it has been disabled.

Specified by:

startTracking in interface ChangeTracker

initialSequence

protected int initialSequence()

Return the initial sequence value for this proxy. Typically this is the container size. Assumes an unordered collection by default, returning 0.

stopTracking

public void stopTracking()

Description copied from interface: ChangeTracker

Tell the tracker to stop tracking changes for its container.

Specified by:

stopTracking in interface ChangeTracker

reset

protected void reset()

Reset the state of the tracker.

getAdded

public Collection getAdded()

Description copied from interface: ChangeTracker

Return the collection of values that need to be added to the managed container.

Specified by:

getAdded in interface ChangeTracker

getRemoved

public Collection getRemoved()

Description copied from interface: ChangeTracker

Return the set of values that need to be removed from the managed container.

Specified by:

getRemoved in interface ChangeTracker

getChanged

public Collection getChanged()

Description copied from interface: ChangeTracker

Return the set of elements that have changed. In maps, this marks a possible change in value for a key. In collections, this marks an element that has been removed and re-added.

Specified by:

getChanged in interface ChangeTracker

added

protected void added(Object val)

Notify the tracker that the given object was added.

add

protected abstract void add(Object val)

Mark the given value as added.

removed

protected void removed(Object val)

Notify the tracker that the given object was removed.

remove

protected abstract void remove(Object val)

Mark the given value as removed.

changed

protected void changed(Object val)

Notify the tracker that the given object was changed.

change

protected abstract void change(Object val)

Mark the given value as changed.

getNextSequence

public int getNextSequence()

Description copied from interface: ChangeTracker

The next element sequence value for this proxy at load time. If the data store keeps this proxy's data in sequence order but allows holes for removed objects, the implementation can set the next sequence at load time, then retrieve it and start from there for added objects at flush time. This value is set back to 0 if the proxy stops tracking changes. For ordered proxies, it is set to the proxy's size when the proxy starts tracking changes again.

Specified by:

getNextSequence in interface ChangeTracker

setNextSequence

public void setNextSequence(int seq)

Description copied from interface: ChangeTracker

The maximum element sequence value for this proxy at load time. If the data store keeps this proxy's data in sequence order but allows holes for removed objects, the implementation can set the next sequence at load time, then retrieve it and start from there for added objects at flush time. This value is set back to 0 if the proxy stops tracking changes. For ordered proxies, it is set to the proxy's size when the proxy starts tracking changes again.

Specified by:

setNextSequence in interface ChangeTracker

newSet

protected Set newSet()

Create a new set for storing adds/removes/changes. Takes into account whether we need to use an identity set or standard set.