Package org.hibernate.event.spi

Class MergeContext

java.lang.Object

org.hibernate.event.spi.MergeContext

All Implemented Interfaces:

Map<Object,Object>

public class MergeContext
extends Object
implements Map<Object,Object>

MergeContext is a specialized Map implementation used by a merge event listener to keep track of each entity being merged and its corresponding managed result. An entity to be merged may to be added to the MergeContext before the merge operation cascades to the entity.

• A merge entity (the mergeEntity method parameter) is an entity being merged via Session.merge(Object mergeEntity).
• A managed entity (the managedEntity method parameter) is the managed entity that is the result of merging an entity.

A merge entity can be transient, detached, or managed. If it is managed, then it is identical to its resulting managed entity.

If put(Object mergeEntity, Object managedEntity) is called, and this MergeContext already contains an entry with a different entity as the key, but with the same (managed entity) value, this means that multiple entity representations for the same persistent entity are being merged. In this situation, EntityCopyObserver.entityCopyDetected( Object managedEntity, Object mergeEntity1, Object mergeEntity2, EventSource) is called to determine an appropriate resolution.

There are several restrictions.

• Methods that return collections (e.g., keySet(), values(), entrySet()) return an unmodifiable view of the collection.
• If managedEntity or put(Object mergeEntity, Object managedEntity, boolean isOperatedOn) is executed and this MergeContext already contains a cross reference for mergeEntity, then managedEntity must be identical to the entity already associated with mergeEntity.
• If putAll(Map map) is executed, the previous restriction applies to each entry in the Map.
• The remove(Object) operation is not supported; the only way to remove data from a MergeContext is by calling clear().
• The map returned by invertMap() will only contain the "newest" (most recently added) managed-to-merge cross-reference to its merge entity.

The following method is intended to be used by an implementation of MergeEventListener to add a merge entity and its corresponding managed entity to a MergeContext and indicate if the merge operation is being performed on the merge entity yet.

put(Object mergeEntity, Object managedEntity, boolean isOperatedOn)

The following method is intended to be used by a MergeEventListener to indicate whether the merge operation is being performed on a merge entity already in the MergeContext:

setOperatedOn(Object mergeEntity, boolean isOperatedOn)

Nested Class Summary

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

Map.Entry<K extends Object,V extends Object>

Constructor Summary

Constructors

Constructor	Description
MergeContext(EventSource session, EntityCopyObserver entityCopyObserver)

Method Summary

Modifier and Type	Method	Description
void	clear()	Clears the MergeContext.
boolean	containsKey(Object mergeEntity)	Returns true if this MergeContext contains a cross-reference for the specified merge entity to a managed entity result.
boolean	containsValue(Object managedEntity)	Returns true if this MergeContext contains a cross-reference from the specified managed entity to a merge entity.
Set<Map.Entry<Object,Object>>	entrySet()	Returns an unmodifiable set view of the merge-to-managed entity cross-references contained in this MergeContext.
Object	get(Object mergeEntity)	Returns the managed entity associated with the specified merge Entity.
Map<Object,Object>	invertMap()	Returns an unmodifiable map view of the managed-to-merge entity cross-references.
boolean	isEmpty()	Returns true if this MergeContext contains no merge-to-managed entity cross-references.
boolean	isOperatedOn(Object mergeEntity)	Returns true if the listener is performing the merge operation on the specified merge entity.
Set<Object>	keySet()	Returns an unmodifiable set view of the merge entities contained in this MergeContext
Object	put(Object mergeEntity, Object managedEntity)	Associates the specified merge entity with the specified managed entity result in this MergeContext.
Object	put(Object mergeEntity, Object managedEntity, boolean isOperatedOn)	Associates the specified merge entity with the specified managed entity in this MergeContext.
void	putAll(Map<?,?> map)	Copies all of the mappings from the specified Map to this MergeContext.
Object	remove(Object mergeEntity)	The remove operation is not supported.
void	setOperatedOn(Object mergeEntity, boolean isOperatedOn)	Set flag to indicate if the listener is performing the merge operation on the specified merge entity.
int	size()	Returns the number of merge-to-managed entity cross-references in this MergeContext
Collection<Object>	values()	Returns an unmodifiable Set view of managed entities contained in this MergeContext.

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

compute, computeIfAbsent, computeIfPresent, equals, forEach, getOrDefault, hashCode, merge, putIfAbsent, remove, replace, replace, replaceAll

Constructor Detail

MergeContext

public MergeContext(EventSource session,
                    EntityCopyObserver entityCopyObserver)

Method Detail

clear

public void clear()

Clears the MergeContext.

Specified by:

clear in interface Map<Object,Object>

containsKey

public boolean containsKey(Object mergeEntity)

Returns true if this MergeContext contains a cross-reference for the specified merge entity to a managed entity result.

Specified by:

containsKey in interface Map<Object,Object>

Parameters:

mergeEntity - must be non-null

Returns:

true if this MergeContext contains a cross-reference for the specified merge entity

Throws:

NullPointerException - if mergeEntity is null

containsValue

public boolean containsValue(Object managedEntity)

Returns true if this MergeContext contains a cross-reference from the specified managed entity to a merge entity.

Specified by:

containsValue in interface Map<Object,Object>

Parameters:

managedEntity - must be non-null

Returns:

true if this MergeContext contains a cross-reference from the specified managed entity to a merge entity

Throws:

NullPointerException - if managedEntity is null

entrySet

public Set<Map.Entry<Object,Object>> entrySet()

Returns an unmodifiable set view of the merge-to-managed entity cross-references contained in this MergeContext.

Specified by:

entrySet in interface Map<Object,Object>

Returns:

an unmodifiable set view of the merge-to-managed entity cross-references contained in this MergeContext

See Also:

Collections.unmodifiableSet(Set)

get

public Object get(Object mergeEntity)

Returns the managed entity associated with the specified merge Entity.

Specified by:

get in interface Map<Object,Object>

Parameters:

mergeEntity - the merge entity; must be non-null

Returns:

the managed entity associated with the specified merge Entity

Throws:

NullPointerException - if mergeEntity is null

isEmpty

public boolean isEmpty()

Returns true if this MergeContext contains no merge-to-managed entity cross-references.

Specified by:

isEmpty in interface Map<Object,Object>

Returns:

true if this MergeContext contains no merge-to-managed entity cross-references.

keySet

public Set<Object> keySet()

Returns an unmodifiable set view of the merge entities contained in this MergeContext

Specified by:

keySet in interface Map<Object,Object>

Returns:

an unmodifiable set view of the merge entities contained in this MergeContext

See Also:

Collections.unmodifiableSet(Set)

put

public Object put(Object mergeEntity,
                  Object managedEntity)

Associates the specified merge entity with the specified managed entity result in this MergeContext. If this MergeContext already contains a cross-reference for mergeEntity when this method is called, then managedEntity must be the same as what is already associated with mergeEntity.

This method assumes that the merge process is not yet operating on mergeEntity. Later when mergeEntity enters the merge process, setOperatedOn(Object, boolean) should be called.

Specified by:

put in interface Map<Object,Object>

Parameters:

mergeEntity - the merge entity; must be non-null

managedEntity - the managed entity result; must be non-null

Returns:

previous managed entity associated with specified merge entity, or null if there was no mapping for mergeEntity.

Throws:

NullPointerException - if mergeEntity or managedEntity is null

IllegalArgumentException - if managedEntity is not the same as the previous managed entity associated with merge entity

IllegalStateException - if internal cross-references are out of sync,

put

public Object put(Object mergeEntity,
                  Object managedEntity,
                  boolean isOperatedOn)

Associates the specified merge entity with the specified managed entity in this MergeContext. If this MergeContext already contains a cross-reference for mergeEntity when this method is called, then managedEntity must be the same as what is already associated with mergeEntity.

Parameters:

mergeEntity - the merge entity; must be non-null

managedEntity - the managed entity; must be non-null

isOperatedOn - indicates if the merge operation is performed on the mergeEntity.

Returns:

previous managed entity associated with specified merge entity, or null if there was no mapping for mergeEntity.

Throws:

NullPointerException - if mergeEntity or managedEntity is null

IllegalArgumentException - if managedEntity is not the same as the previous managed entity associated with mergeEntity

IllegalStateException - if internal cross-references are out of sync,

putAll

public void putAll(Map<?,?> map)

Copies all of the mappings from the specified Map to this MergeContext. The key and value for each entry in map is subject to the same restrictions as put(Object mergeEntity, Object managedEntity). This method assumes that the merge process is not yet operating on any merge entity

Specified by:

putAll in interface Map<Object,Object>

Parameters:

map - keys and values must be non-null

Throws:

NullPointerException - if any key or value is null

IllegalArgumentException - if a key in map was already in this MergeContext but associated value in map is different from the previous value in this MergeContext.

IllegalStateException - if internal cross-references are out of sync,

remove

public Object remove(Object mergeEntity)

The remove operation is not supported.

Specified by:

remove in interface Map<Object,Object>

Parameters:

mergeEntity - the merge entity.

Throws:

UnsupportedOperationException - if called.

size

public int size()

Returns the number of merge-to-managed entity cross-references in this MergeContext

Specified by:

size in interface Map<Object,Object>

Returns:

the number of merge-to-managed entity cross-references in this MergeContext

values

public Collection<Object> values()

Returns an unmodifiable Set view of managed entities contained in this MergeContext.

Specified by:

values in interface Map<Object,Object>

Returns:

an unmodifiable Set view of managed entities contained in this MergeContext

See Also:

Collections.unmodifiableSet(Set)

isOperatedOn

public boolean isOperatedOn(Object mergeEntity)

Returns true if the listener is performing the merge operation on the specified merge entity.

Parameters:

mergeEntity - the merge entity; must be non-null

Returns:

true if the listener is performing the merge operation on the specified merge entity; false, if there is no mapping for mergeEntity.

Throws:

NullPointerException - if mergeEntity is null

setOperatedOn

public void setOperatedOn(Object mergeEntity,
                          boolean isOperatedOn)

Set flag to indicate if the listener is performing the merge operation on the specified merge entity.

Parameters:

mergeEntity - must be non-null and this MergeContext must contain a cross-reference for mergeEntity to a managed entity

Throws:

NullPointerException - if mergeEntity is null

IllegalStateException - if this MergeContext does not contain a a cross-reference for mergeEntity

invertMap

public Map<Object,Object> invertMap()

Returns an unmodifiable map view of the managed-to-merge entity cross-references. The returned Map will contain a cross-reference from each managed entity to the most recently associated merge entity that was most recently put in the MergeContext.

Returns:

an unmodifiable map view of the managed-to-merge entity cross-references.

See Also:

Collections.unmodifiableMap(Map)