org.apache.openjpa.util
Class AbstractChangeTracker

java.lang.Object
  extended by 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.



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