EclipseLink 2.2.0, build 'v20110202-r8913' API Reference

org.eclipse.persistence.descriptors
Class FetchGroupManager

java.lang.Object
  extended by org.eclipse.persistence.descriptors.FetchGroupManager
All Implemented Interfaces:
java.lang.Cloneable

public class FetchGroupManager
extends java.lang.Object
implements java.lang.Cloneable

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
Author:
King Wang, dclarke
Since:
TopLink 10.1.3.

Constructor Summary
FetchGroupManager()
          Constructor
 
Method Summary
 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 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)
          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)
          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, 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,
                                   org.eclipse.persistence.internal.sessions.UnitOfWorkImpl uow)
INTERNAL: Write data of the partially fetched object into the working and backup clones


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)
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)
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.


EclipseLink 2.2.0, build 'v20110202-r8913' API Reference