org.apache.openjpa.util
Class AbstractLRSProxyCollection

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

All Implemented Interfaces:

Iterable, Collection, Set, Predicate, ChangeTracker, CollectionChangeTracker, LRSProxy, Proxy

Direct Known Subclasses:

LRSProxyCollection

public abstract class AbstractLRSProxyCollection
extends Object
implements Set, LRSProxy, Predicate, CollectionChangeTracker

A collection proxy designed for collections backed by extremely large result sets in which each call to iterator() may perform a database query. Changes to the collection are tracked through a ChangeTracker. This collection has the following limitations:

• The size method may return Integer.MAX_VALUE.
• The collection cannot contain duplicate elements.

Author:

Abe White

Constructor Summary

AbstractLRSProxyCollection(Class elementType, boolean ordered, OpenJPAConfiguration conf)
Constructor.

Method Summary

boolean	add(Object o)
boolean	addAll(Collection all)
void	added(Object val) Record that the given element was added.
void	clear()
boolean	contains(Object o)
boolean	containsAll(Collection all)
Object	copy(Object orig) Return an unproxied copy of the given instance.
protected abstract int	count() Return the number of elements in the collection, or Integer.MAX_VALUE.
boolean	evaluate(Object o)
Collection	getAdded() Return the collection of values that need to be added to the managed container.
Collection	getChanged() Return the set of elements that have changed.
ChangeTracker	getChangeTracker() Return the change tracker for this proxy, or null if none.
int	getNextSequence() The next element sequence value for this proxy at load time.
OpenJPAStateManager	getOwner() Return the owning object.
int	getOwnerField() Return the owning field index.
Collection	getRemoved() Return the set of values that need to be removed from the managed container.
protected abstract boolean	has(Object o) Return whether the collection contains the given element.
boolean	isEmpty()
boolean	isTracking() Return true if this tracker has an up-to-date view of all the changes to the container it is managing.
Iterator	iterator()
protected abstract Iterator	itr() Implement this method to return an iterator over the contents of the collection.
boolean	remove(Object o)
boolean	removeAll(Collection all)
void	removed(Object val) Record that the given element was removed.
boolean	retainAll(Collection all)
void	setNextSequence(int seq) The maximum element sequence value for this proxy at load time.
void	setOwner(OpenJPAStateManager sm, int field) Reset the state of the proxy, and set the owning instance of the proxy and the name of the field it is assigned to.
int	size()
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.
Object[]	toArray()
Object[]	toArray(Object[] a)
protected Object	writeReplace()

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.Set

equals, hashCode

Constructor Detail

AbstractLRSProxyCollection

public AbstractLRSProxyCollection(Class elementType,
                                  boolean ordered,
                                  OpenJPAConfiguration conf)

Constructor.

Parameters:

elementType - the allowed type of elements, or null for no restrictions

ordered - true if this collection is ordered

Method Detail

setOwner

public void setOwner(OpenJPAStateManager sm,
                     int field)

Description copied from interface: Proxy

Reset the state of the proxy, and set the owning instance of the proxy and the name of the field it is assigned to. Set to null to indicate that the proxy is no longer managed.

Specified by:

setOwner in interface Proxy

getOwner

public OpenJPAStateManager getOwner()

Description copied from interface: Proxy

Return the owning object.

Specified by:

getOwner in interface Proxy

getOwnerField

public int getOwnerField()

Description copied from interface: Proxy

Return the owning field index.

Specified by:

getOwnerField in interface Proxy

getChangeTracker

public ChangeTracker getChangeTracker()

Description copied from interface: Proxy

Return the change tracker for this proxy, or null if none.

Specified by:

getChangeTracker in interface Proxy

copy

public Object copy(Object orig)

Description copied from interface: Proxy

Return an unproxied copy of the given instance. This method is used by proxy managers to create backup values for use in rollback.

Specified by:

copy in interface Proxy

add

public boolean add(Object o)

Specified by:

add in interface Collection

Specified by:

add in interface Set

addAll

public boolean addAll(Collection all)

Specified by:

addAll in interface Collection

Specified by:

addAll in interface Set

remove

public boolean remove(Object o)

Specified by:

remove in interface Collection

Specified by:

remove in interface Set

removeAll

public boolean removeAll(Collection all)

Specified by:

removeAll in interface Collection

Specified by:

removeAll in interface Set

retainAll

public boolean retainAll(Collection all)

Specified by:

retainAll in interface Collection

Specified by:

retainAll in interface Set

clear

public void clear()

Specified by:

clear in interface Collection

Specified by:

clear in interface Set

contains

public boolean contains(Object o)

Specified by:

contains in interface Collection

Specified by:

contains in interface Set

containsAll

public boolean containsAll(Collection all)

Specified by:

containsAll in interface Collection

Specified by:

containsAll in interface Set

toArray

public Object[] toArray()

Specified by:

toArray in interface Collection

Specified by:

toArray in interface Set

toArray

public Object[] toArray(Object[] a)

Specified by:

toArray in interface Collection

Specified by:

toArray in interface Set

size

public int size()

Specified by:

size in interface Collection

Specified by:

size in interface Set

isEmpty

public boolean isEmpty()

Specified by:

isEmpty in interface Collection

Specified by:

isEmpty in interface Set

iterator

public Iterator iterator()

Specified by:

iterator in interface Iterable

Specified by:

iterator in interface Collection

Specified by:

iterator in interface Set

writeReplace

protected Object writeReplace()
                       throws ObjectStreamException

Throws:

ObjectStreamException

itr

protected abstract Iterator itr()

Implement this method to return an iterator over the contents of the collection. This method may be invoked multiple times. The returned iterator does not have to support the Iterator.remove() method, and may implement Closeable.

has

protected abstract boolean has(Object o)

Return whether the collection contains the given element.

count

protected abstract int count()

Return the number of elements in the collection, or Integer.MAX_VALUE.

evaluate

public boolean evaluate(Object o)

Specified by:

evaluate in interface Predicate

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

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

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

public void added(Object val)

Description copied from interface: CollectionChangeTracker

Record that the given element was added.

Specified by:

added in interface CollectionChangeTracker

removed

public void removed(Object val)

Description copied from interface: CollectionChangeTracker

Record that the given element was removed.

Specified by:

removed in interface CollectionChangeTracker

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