org.eclipse.persistence.descriptors

Class FetchGroupManager

java.lang.Object

org.eclipse.persistence.descriptors.FetchGroupManager

All Implemented Interfaces:

java.io.Serializable, java.lang.Cloneable

public class FetchGroupManager
extends java.lang.Object
implements java.lang.Cloneable, java.io.Serializable

Purpose: The fetch group manager controls the named fetch groups defined at the descriptor level. EclipseLink supports multiple, overlapped fetch groups, optionally with one of them as the default fetch group.

The domain object must implement org.eclipse.persistence.queries.FetchGroupTracker interface, in order to make use of the fetch group performance enhancement feature.

Please refer to FetchGroup class for the pros and cons of fetch group usage.

See Also:

FetchGroup, FetchGroupTracker, Serialized Form

Author:

King Wang, dclarke

Since:

TopLink 10.1.3.

Constructor Summary

Constructors

Constructor and Description
FetchGroupManager() Constructor

Method Summary

Modifier and Type	Method and Description
void	addFetchGroup(FetchGroup group) Add a named fetch group to the descriptor
void	addMinimalFetchGroup(FetchGroup fetchGroup) INTERNAL: Add primary key and version attributes to the passed fetch group.
java.lang.Object	clone() INTERNAL: Clone the fetch group manager.
void	copyAggregateFetchGroupInto(java.lang.Object source, java.lang.Object target, java.lang.Object rootEntity, org.eclipse.persistence.internal.sessions.AbstractSession session) INTERNAL: Copy fetch group reference from the source object to the target
void	copyFetchGroupInto(java.lang.Object source, java.lang.Object target, org.eclipse.persistence.internal.sessions.AbstractSession session) INTERNAL: Copy fetch group reference from the source object to the target
FetchGroup	createDefaultFetchGroup() PUBLIC: Returns clone of the default fetch group.
FetchGroup	createFullFetchGroup() PUBLIC: Returns clone of the full fetch group - contains all the attributes, no nesting.
FetchGroup	createMinimalFetchGroup() PUBLIC: Returns clone of the minimal fetch group.
org.eclipse.persistence.internal.queries.EntityFetchGroup	flatUnionFetchGroups(FetchGroup first, FetchGroup second, boolean shouldClone) INTERNAL: Union two fetch groups as EntityFetchGroups.
org.eclipse.persistence.internal.queries.EntityFetchGroup	getDefaultEntityFetchGroup() INTERNAL: Returns EntityFetchGroup corresponding to default FetchGroup.
FetchGroup	getDefaultFetchGroup() Return the descriptor-level default fetch group.
ClassDescriptor	getDescriptor() PUBLIC: Return the referenced descriptor.
org.eclipse.persistence.internal.queries.EntityFetchGroup	getEntityFetchGroup(FetchGroup fetchGroup) INTERNAL: Returns entity fetch group corresponding to the passed fetch group.
org.eclipse.persistence.internal.queries.EntityFetchGroup	getEntityFetchGroup(java.util.Set<java.lang.String> attributeNames) INTERNAL: Returns entity fetch group corresponding to the passed set of attributes.
FetchGroup	getFetchGroup(java.lang.String groupName) Return a pre-defined named fetch group.
FetchGroup	getFetchGroup(java.lang.String groupName, boolean useDefault) Lookup the FetchGroup to use given a name and a flag taking into consideration descriptor inheritance to ensure parent descriptors are searched for named and default FetchGroup.
java.util.Map<java.lang.String,FetchGroup>	getFetchGroups() Return the fetch group map: keyed by the group name, valued by the fetch group object.
org.eclipse.persistence.internal.queries.EntityFetchGroup	getIdEntityFetchGroup() INTERNAL: Returns EntityFetchGroup corresponding to primary key attribute(s).
org.eclipse.persistence.internal.queries.EntityFetchGroup	getNonReferenceEntityFetchGroup() INTERNAL: Returns EntityFetchGroup corresponding to non relational attributes intersected with defaultFetchGroup.
org.eclipse.persistence.internal.queries.EntityFetchGroup	getNonReferenceEntityFetchGroup(boolean addPk, boolean addVersion) INTERNAL: Returns EntityFetchGroup corresponding to non relational attributes intersected with defaultFetchGroup.
org.eclipse.persistence.internal.queries.EntityFetchGroup	getObjectEntityFetchGroup(java.lang.Object domainObject) INTERNAL: Return FetchGroup held by the object.
FetchGroup	getObjectFetchGroup(java.lang.Object domainObject) INTERNAL: Return FetchGroup held by the object.
boolean	hasFetchGroup(java.lang.String groupName) Return true if a fetch group exists for the given group name.
void	initialize(org.eclipse.persistence.internal.sessions.AbstractSession session) INTERNAL: Initialize the fetch groups.
protected void	initNonReferenceEntityFetchGroup()
boolean	isAttributeFetched(java.lang.Object entity, java.lang.String attributeName) Return true if the attribute of the object has already been fetched
boolean	isFullFetchGroup(FetchGroup fetchGroup) PUBLIC: Indicates whether the passed fetch group contains all the attributes, no nesting.
boolean	isMinimalFetchGroup(FetchGroup fetchGroup) PUBLIC: Indicates whether the passed fetch group is minimal.
boolean	isObjectValidForFetchGroup(java.lang.Object object, FetchGroup fetchGroup) INTERNAL: Return if the cached object data is sufficiently valid against a fetch group
boolean	isPartialObject(java.lang.Object domainObject) INTERNAL: Return true if the object is partially fetched and cached.
void	postInitialize(org.eclipse.persistence.internal.sessions.AbstractSession session) INTERNAL: postInitialize called for inheritance children first.
void	prepareAndVerify(FetchGroup fetchGroup) PUBLIC: Add primary key and version attributes to the passed fetch group and all the fetch group it contains.
protected void	prepareAndVerifyInternal(FetchGroup fetchGroup, java.lang.String attributePrefix) INTERNAL: Add primary key and version attributes to the passed fetch group and all the fetch group it contains.
void	reset(java.lang.Object source) INTERNAL: Reset object attributes to the default values.
void	setDefaultFetchGroup(FetchGroup newDefaultFetchGroup) Set the descriptor-level default fetch group.
void	setDescriptor(ClassDescriptor descriptor) Set the referenced descriptor.
void	setObjectFetchGroup(java.lang.Object source, FetchGroup fetchGroup, org.eclipse.persistence.internal.sessions.AbstractSession session) INTERNAL: Set fetch group into the object.
void	setRefreshOnFetchGroupToObject(java.lang.Object source, boolean shouldRefreshOnFetchgroup) INTERNAL: Set if the tracked object is fetched from executing a query with or without refresh.
void	setShouldUseInheritedDefaultFetchGroup(boolean shouldUseInheritedDefaultFetchGroup) PUBLIC: Set whether defaultFetchGroup should be copied from the parent if not set.
boolean	shouldUseInheritedDefaultFetchGroup() PUBLIC: Indicates whether defaultFetchGroup should be copied from the parent if not set.
boolean	shouldWriteInto(java.lang.Object cachedObject, java.lang.Object clone) INTERNAL: Return true if the cached object data should be written in clone.
void	unionEntityFetchGroupIntoObject(java.lang.Object source, org.eclipse.persistence.internal.queries.EntityFetchGroup newEntityFetchGroup, org.eclipse.persistence.internal.sessions.AbstractSession session, boolean shouldClone) INTERNAL: Union the fetch group of the domain object with the new fetch group.
FetchGroup	unionFetchGroups(FetchGroup first, FetchGroup second) INTERNAL: Union two fetch groups.
void	writePartialIntoClones(java.lang.Object partialObject, java.lang.Object workingClone, java.lang.Object backupClone, org.eclipse.persistence.internal.sessions.UnitOfWorkImpl uow) INTERNAL: Write data of the partially fetched object into the working and backup clones

Methods inherited from class java.lang.Object

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

Constructor Detail

FetchGroupManager

public FetchGroupManager()

Constructor

Method Detail

addFetchGroup

public void addFetchGroup(FetchGroup group)

Add a named fetch group to the descriptor

getFetchGroups

public java.util.Map<java.lang.String,FetchGroup> getFetchGroups()

Return the fetch group map: keyed by the group name, valued by the fetch group object.

getDefaultFetchGroup

public FetchGroup getDefaultFetchGroup()

Return the descriptor-level default fetch group. All read object and read all queries would use the default fetch group if no fetch group is explicitly defined for the query, unless setShouldUseDefaultFetchGroup(false); is also called on the query. Default fetch group should be used carefully. It would be beneficial if most of the system queries are for the subset of the object, so un-needed attributes data would not have to be read, and the users do not have to setup every query for the given fetch group, as default one is always used. However, if queries on object are mostly use case specific and not systematic, using default fetch group could cause undesirable extra round-trip and performance degradation.

See Also:

ObjectLevelReadQuery.setShouldUseDefaultFetchGroup(boolean)

getDefaultEntityFetchGroup

public org.eclipse.persistence.internal.queries.EntityFetchGroup getDefaultEntityFetchGroup()

INTERNAL: Returns EntityFetchGroup corresponding to default FetchGroup.

createMinimalFetchGroup

public FetchGroup createMinimalFetchGroup()

PUBLIC: Returns clone of the minimal fetch group. Could be used as a starting point for a new user-defined fetch group.

isMinimalFetchGroup

public boolean isMinimalFetchGroup(FetchGroup fetchGroup)

PUBLIC: Indicates whether the passed fetch group is minimal.

getIdEntityFetchGroup

public org.eclipse.persistence.internal.queries.EntityFetchGroup getIdEntityFetchGroup()

INTERNAL: Returns EntityFetchGroup corresponding to primary key attribute(s).

getNonReferenceEntityFetchGroup

public org.eclipse.persistence.internal.queries.EntityFetchGroup getNonReferenceEntityFetchGroup()

INTERNAL: Returns EntityFetchGroup corresponding to non relational attributes intersected with defaultFetchGroup.

getNonReferenceEntityFetchGroup

public org.eclipse.persistence.internal.queries.EntityFetchGroup getNonReferenceEntityFetchGroup(boolean addPk,
                                                                                                 boolean addVersion)

INTERNAL: Returns EntityFetchGroup corresponding to non relational attributes intersected with defaultFetchGroup.

addMinimalFetchGroup

public void addMinimalFetchGroup(FetchGroup fetchGroup)

INTERNAL: Add primary key and version attributes to the passed fetch group.

prepareAndVerify

public void prepareAndVerify(FetchGroup fetchGroup)

PUBLIC: Add primary key and version attributes to the passed fetch group and all the fetch group it contains. Also verifies that all the attributes have corresponding mappings. Could be used for fetch group preparation and validation. Called by ObjectLevelReadQuery prepareFetchgroup method.

prepareAndVerifyInternal

protected void prepareAndVerifyInternal(FetchGroup fetchGroup,
                                        java.lang.String attributePrefix)

INTERNAL: Add primary key and version attributes to the passed fetch group and all the fetch group it contains. Also verifies that all the attributes have corresponding mappings.

createDefaultFetchGroup

public FetchGroup createDefaultFetchGroup()

PUBLIC: Returns clone of the default fetch group. Could be used as a starting point for a new user-defined fetch group.

createFullFetchGroup

public FetchGroup createFullFetchGroup()

PUBLIC: Returns clone of the full fetch group - contains all the attributes, no nesting. Could be used as a starting point for a new user-defined fetch group.

isFullFetchGroup

public boolean isFullFetchGroup(FetchGroup fetchGroup)

PUBLIC: Indicates whether the passed fetch group contains all the attributes, no nesting.

getEntityFetchGroup

public org.eclipse.persistence.internal.queries.EntityFetchGroup getEntityFetchGroup(java.util.Set<java.lang.String> attributeNames)

INTERNAL: Returns entity fetch group corresponding to the passed set of attributes.

getEntityFetchGroup

public org.eclipse.persistence.internal.queries.EntityFetchGroup getEntityFetchGroup(FetchGroup fetchGroup)

INTERNAL: Returns entity fetch group corresponding to the passed fetch group.

getFetchGroup

public FetchGroup getFetchGroup(java.lang.String groupName)

Return a pre-defined named fetch group. Lookup the FetchGroup to use given a name taking into consideration descriptor inheritance to ensure parent descriptors are searched for named FetchGroups.

getFetchGroup

public FetchGroup getFetchGroup(java.lang.String groupName,
                                boolean useDefault)

Lookup the FetchGroup to use given a name and a flag taking into consideration descriptor inheritance to ensure parent descriptors are searched for named and default FetchGroup. This is used to determine the FetchGroup to use in a query's prepare.

setDefaultFetchGroup

public void setDefaultFetchGroup(FetchGroup newDefaultFetchGroup)

Set the descriptor-level default fetch group. All read object and read all queries would use the default fetch group if no fetch group is explicitly defined for the query, unless setShouldUseDefaultFetchGroup(false); is also called on the query. Default fetch group should be used carefully. It would be beneficial if most of the system queries are for the subset of the object, so un-needed attributes data would not have to be read, and the users do not have to setup every query for the given fetch group, as default one is always used. However, if queries on object are mostly use case specific and not systematic, using default fetch group could cause undesirable extra round-trip and performance degradation.

See Also:

ObjectLevelReadQuery.setShouldUseDefaultFetchGroup(boolean)

isPartialObject

public boolean isPartialObject(java.lang.Object domainObject)

INTERNAL: Return true if the object is partially fetched and cached. It applies to the query with fetch group.

isObjectValidForFetchGroup

public boolean isObjectValidForFetchGroup(java.lang.Object object,
                                          FetchGroup fetchGroup)

INTERNAL: Return if the cached object data is sufficiently valid against a fetch group

shouldWriteInto

public boolean shouldWriteInto(java.lang.Object cachedObject,
                               java.lang.Object clone)

INTERNAL: Return true if the cached object data should be written in clone. It is used in Fetch Group case when filling in the clone from the cached object.

writePartialIntoClones

public void writePartialIntoClones(java.lang.Object partialObject,
                                   java.lang.Object workingClone,
                                   java.lang.Object backupClone,
                                   org.eclipse.persistence.internal.sessions.UnitOfWorkImpl uow)

INTERNAL: Write data of the partially fetched object into the working and backup clones

copyAggregateFetchGroupInto

public void copyAggregateFetchGroupInto(java.lang.Object source,
                                        java.lang.Object target,
                                        java.lang.Object rootEntity,
                                        org.eclipse.persistence.internal.sessions.AbstractSession session)

INTERNAL: Copy fetch group reference from the source object to the target

copyFetchGroupInto

public void copyFetchGroupInto(java.lang.Object source,
                               java.lang.Object target,
                               org.eclipse.persistence.internal.sessions.AbstractSession session)

INTERNAL: Copy fetch group reference from the source object to the target

unionEntityFetchGroupIntoObject

public void unionEntityFetchGroupIntoObject(java.lang.Object source,
                                            org.eclipse.persistence.internal.queries.EntityFetchGroup newEntityFetchGroup,
                                            org.eclipse.persistence.internal.sessions.AbstractSession session,
                                            boolean shouldClone)

INTERNAL: Union the fetch group of the domain object with the new fetch group.

unionFetchGroups

public FetchGroup unionFetchGroups(FetchGroup first,
                                   FetchGroup second)

INTERNAL: Union two fetch groups.

flatUnionFetchGroups

public org.eclipse.persistence.internal.queries.EntityFetchGroup flatUnionFetchGroups(FetchGroup first,
                                                                                      FetchGroup second,
                                                                                      boolean shouldClone)

INTERNAL: Union two fetch groups as EntityFetchGroups. Ignores all nested attributes.

reset

public void reset(java.lang.Object source)

INTERNAL: Reset object attributes to the default values.

getObjectFetchGroup

public FetchGroup getObjectFetchGroup(java.lang.Object domainObject)

INTERNAL: Return FetchGroup held by the object.

getObjectEntityFetchGroup

public org.eclipse.persistence.internal.queries.EntityFetchGroup getObjectEntityFetchGroup(java.lang.Object domainObject)

INTERNAL: Return FetchGroup held by the object.

setObjectFetchGroup

public void setObjectFetchGroup(java.lang.Object source,
                                FetchGroup fetchGroup,
                                org.eclipse.persistence.internal.sessions.AbstractSession session)

INTERNAL: Set fetch group into the object.

setRefreshOnFetchGroupToObject

public void setRefreshOnFetchGroupToObject(java.lang.Object source,
                                           boolean shouldRefreshOnFetchgroup)

INTERNAL: Set if the tracked object is fetched from executing a query with or without refresh.

isAttributeFetched

public boolean isAttributeFetched(java.lang.Object entity,
                                  java.lang.String attributeName)

Return true if the attribute of the object has already been fetched

getDescriptor

public ClassDescriptor getDescriptor()

PUBLIC: Return the referenced descriptor.

setDescriptor

public void setDescriptor(ClassDescriptor descriptor)

Set the referenced descriptor.

hasFetchGroup

public boolean hasFetchGroup(java.lang.String groupName)

Return true if a fetch group exists for the given group name.

initialize

public void initialize(org.eclipse.persistence.internal.sessions.AbstractSession session)
                throws DescriptorException

INTERNAL: Initialize the fetch groups. XXX-dclarke: added support for reinit the query manager's queries if they exist

Throws:

DescriptorException

postInitialize

public void postInitialize(org.eclipse.persistence.internal.sessions.AbstractSession session)
                    throws DescriptorException

INTERNAL: postInitialize called for inheritance children first. That allows to copy defaultFetchGroup from the parent only in case it has been set by user (not automatically generated).

Throws:

DescriptorException

initNonReferenceEntityFetchGroup

protected void initNonReferenceEntityFetchGroup()

clone

public java.lang.Object clone()

INTERNAL: Clone the fetch group manager.

Overrides:

clone in class java.lang.Object

setShouldUseInheritedDefaultFetchGroup

public void setShouldUseInheritedDefaultFetchGroup(boolean shouldUseInheritedDefaultFetchGroup)

PUBLIC: Set whether defaultFetchGroup should be copied from the parent if not set.

shouldUseInheritedDefaultFetchGroup

public boolean shouldUseInheritedDefaultFetchGroup()

PUBLIC: Indicates whether defaultFetchGroup should be copied from the parent if not set.