org.apache.openjpa.util
Class AbstractLRSProxyMap

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

All Implemented Interfaces:

Map, Predicate, ChangeTracker, LRSProxy, MapChangeTracker, Proxy

public abstract class AbstractLRSProxyMap
extends Object
implements Map, LRSProxy, MapChangeTracker, Predicate

A map proxy designed for maps backed by extremely large result sets in which each call to get(java.lang.Object) or containsKey(java.lang.Object) may perform a database query. Changes to the map are tracked through a ChangeTracker. This map has the following limitations:

• The size method may return Integer.MAX_VALUE.
• Null keys and values are not supported.

Author:

Abe White

Nested Class Summary

Nested classes/interfaces inherited from interface java.util.Map

Map.Entry<K,V>

Constructor Summary

AbstractLRSProxyMap(Class keyType, Class valueType)

Method Summary

void	added(Object key, Object val) Record that the given entry was added to the map.
void	changed(Object key, Object orig, Object val) Record that the given entry was altered.
void	clear()
boolean	containsKey(Object key)
boolean	containsValue(Object val)
Object	copy(Object orig) Return an unproxied copy of the given instance.
protected abstract int	count() Return the number of entries in the map, or Integer.MAX_VALUE.
Set	entrySet()
boolean	evaluate(Object obj)
Object	get(Object key)
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.
boolean	getTrackKeys() Whether to track keys or values.
protected abstract boolean	hasKey(Object key) Return whether the given key exists in the map.
protected abstract boolean	hasValue(Object value) Return whether the given value exists in the map.
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.
protected abstract Iterator	itr() Implement this method to return an iterator over the entries in the map.
protected abstract Collection	keys(Object value) Return all keys for the given value.
Set	keySet()
Object	put(Object key, Object value)
void	putAll(Map m)
Object	remove(Object key)
void	removed(Object key, Object val) Record that the given entry was removed from the map.
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.
void	setTrackKeys(boolean keys) Whether to track keys or values.
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.
protected abstract Object	value(Object key) Return the value of the given key.
Collection	values()
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.Map

equals, hashCode

Constructor Detail

AbstractLRSProxyMap

public AbstractLRSProxyMap(Class keyType,
                           Class valueType)

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

size

public int size()

Specified by:

size in interface Map

isEmpty

public boolean isEmpty()

Specified by:

isEmpty in interface Map

containsKey

public boolean containsKey(Object key)

Specified by:

containsKey in interface Map

containsValue

public boolean containsValue(Object val)

Specified by:

containsValue in interface Map

get

public Object get(Object key)

Specified by:

get in interface Map

put

public Object put(Object key,
                  Object value)

Specified by:

put in interface Map

putAll

public void putAll(Map m)

Specified by:

putAll in interface Map

remove

public Object remove(Object key)

Specified by:

remove in interface Map

clear

public void clear()

Specified by:

clear in interface Map

keySet

public Set keySet()

Specified by:

keySet in interface Map

values

public Collection values()

Specified by:

values in interface Map

entrySet

public Set entrySet()

Specified by:

entrySet in interface Map

writeReplace

protected Object writeReplace()
                       throws ObjectStreamException

Throws:

ObjectStreamException

hasKey

protected abstract boolean hasKey(Object key)

Return whether the given key exists in the map.

hasValue

protected abstract boolean hasValue(Object value)

Return whether the given value exists in the map.

keys

protected abstract Collection keys(Object value)

Return all keys for the given value.

value

protected abstract Object value(Object key)

Return the value of the given key.

itr

protected abstract Iterator itr()

Implement this method to return an iterator over the entries in the map. Each returned object must implement the Map.Entry interface. This method may be invoked multiple times. The iterator does not have to support the Iterator.remove() method, and may implement Closeable.

count

protected abstract int count()

Return the number of entries in the map, or Integer.MAX_VALUE.

evaluate

public boolean evaluate(Object obj)

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

getTrackKeys

public boolean getTrackKeys()

Description copied from interface: MapChangeTracker

Whether to track keys or values. Defaults to keys. If you set to values, it is assumed there is a 1-1 correlation between keys and values in this map.

Specified by:

getTrackKeys in interface MapChangeTracker

setTrackKeys

public void setTrackKeys(boolean keys)

Description copied from interface: MapChangeTracker

Whether to track keys or values. Defaults to keys. If you set to values, it is assumed there is a 1-1 correlation between keys and values in this map.

Specified by:

setTrackKeys in interface MapChangeTracker

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 key,
                  Object val)

Description copied from interface: MapChangeTracker

Record that the given entry was added to the map.

Specified by:

added in interface MapChangeTracker

removed

public void removed(Object key,
                    Object val)

Description copied from interface: MapChangeTracker

Record that the given entry was removed from the map.

Specified by:

removed in interface MapChangeTracker

changed

public void changed(Object key,
                    Object orig,
                    Object val)

Description copied from interface: MapChangeTracker

Record that the given entry was altered.

Specified by:

changed in interface MapChangeTracker

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