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/*
* Copyright (c) 1998, 2024 Oracle and/or its affiliates. All rights reserved.
*
* This program and the accompanying materials are made available under the
* terms of the Eclipse Public License v. 2.0 which is available at
* http://www.eclipse.org/legal/epl-2.0,
* or the Eclipse Distribution License v. 1.0 which is available at
* http://www.eclipse.org/org/documents/edl-v10.php.
*
* SPDX-License-Identifier: EPL-2.0 OR BSD-3-Clause
*/
// Contributors:
// Oracle - initial API and implementation from Oracle TopLink
package org.eclipse.persistence.sessions;
import org.eclipse.persistence.exceptions.DatabaseException;
import org.eclipse.persistence.exceptions.OptimisticLockException;
import org.eclipse.persistence.sessions.changesets.UnitOfWorkChangeSet;
import java.util.Collection;
import java.util.Set;
import java.util.Vector;
/**
* Purpose: To allow object level transactions. This class represents the public API of the
* unit of work and should be used to maintain complete compatibility.
*
* Description: The unit of work is a session that implements all of the normal
* protocol of an EclipseLink session. It can be spawned from any other session including another unit of work.
* Objects can be brought into the unit of work through reading them or through registering them.
* The unit of work will operate on its own object space, that is the objects within the unit of work
* will be clones of the original objects. When the unit of work is committed, all changes to any objects
* registered within the unit of work will be committed to the database. A minimal commit/update will
* be performed and any foreign keys/circular reference/referential integrity will be resolved.
* If the commit to the database is successful the changed objects will be merged back into the unit of work
* parent session.
*
* Responsibilities:
*
* - Allow parallel transactions against a session's objects.
*
- Allow nested transactions.
*
- Not require the application to write objects that is changes, automatically determine what has changed.
*
- Perform a minimal commit/update of all changes that occurred.
*
- Resolve foreign keys for newly created objects and maintain referential integrity.
*
- Allow for the object transaction to use its own object space.
*
*/
public interface UnitOfWork extends Session {
/**
* Defines the ordering of updates and deletes of a set of the same entity type during a commit or flush operation.
* The commit order of entities is defined by their foreign key constraints, and then sorted alphabetically.
*
* By default the commit of a set of the same entity type is ordered by primary key.
*/
enum CommitOrderType {
/** Updates and deletes are ordered by the object's id. This can help avoid deadlocks on highly concurrent systems. */
ID,
/** Updates are ordered by the object's changes, then by id. This can improve batch writing efficiency. */
CHANGES,
/** No ordering is done. */
NONE
}
/**
* ADVANCED:
* Returns the set of read-only classes in this UnitOfWork.
*/
Set getReadOnlyClasses();
/**
* PUBLIC:
* Adds the given Java class to the receiver's set of read-only classes.
* Cannot be called after objects have been registered in the unit of work.
*/
void addReadOnlyClass(Class theClass);
/**
* PUBLIC:
* Adds the classes in the given Vector to the existing set of read-only classes.
* Cannot be called after objects have been registered in the unit of work.
*/
void addReadOnlyClasses(Collection classes);
/**
* ADVANCED:
* Assign sequence number to the object.
* This allows for an object's id to be assigned before commit.
* It can be used if the application requires to use the object id before the object exists on the database.
* Normally all ids are assigned during the commit automatically.
*/
void assignSequenceNumber(Object object) throws DatabaseException;
/**
* ADVANCED:
* Assign sequence numbers to all new objects registered in this unit of work,
* or any new objects reference by any objects registered.
* This allows for an object's id to be assigned before commit.
* It can be used if the application requires to use the object id before the object exists on the database.
* Normally all ids are assigned during the commit automatically.
*/
void assignSequenceNumbers() throws DatabaseException;
/**
* PUBLIC:
* Tell the unit of work to begin a transaction now.
* By default the unit of work will begin a transaction at commit time.
* The default is the recommended approach, however sometimes it is
* necessary to start the transaction before commit time. When the
* unit of work commits, this transaction will be committed.
*
* @see #commit()
* @see #release()
*/
void beginEarlyTransaction() throws DatabaseException;
/**
* PUBLIC:
* Commit the unit of work to its parent.
* For a nested unit of work this will merge any changes to its objects
* with its parents.
* For a first level unit of work it will commit all changes to its objects
* to the database as a single transaction. If successful the changes to its
* objects will be merged to its parent's objects. If the commit fails the database
* transaction will be rolledback, and the unit of work will be released.
* If the commit is successful the unit of work is released, and a new unit of work
* must be acquired if further changes are desired.
*
* @see #commitAndResumeOnFailure()
* @see #commitAndResume()
* @see #release()
*/
void commit() throws DatabaseException, OptimisticLockException;
/**
* PUBLIC:
* Commit the unit of work to its parent.
* For a nested unit of work this will merge any changes to its objects
* with its parents.
* For a first level unit of work it will commit all changes to its objects
* to the database as a single transaction. If successful the changes to its
* objects will be merged to its parent's objects. If the commit fails the database
* transaction will be rolledback, and the unit of work will be released.
* The normal commit releases the unit of work, forcing a new one to be acquired if further changes are desired.
* The resuming feature allows for the same unit of work (and working copies) to be continued to be used.
*
* @see #commitAndResumeOnFailure()
* @see #commit()
* @see #release()
*/
void commitAndResume() throws DatabaseException, OptimisticLockException;
/**
* PUBLIC:
* Commit the unit of work to its parent.
* For a nested unit of work this will merge any changes to its objects
* with its parents.
* For a first level unit of work it will commit all changes to its objects
* to the database as a single transaction. If successful the changes to its
* objects will be merged to its parent's objects. If the commit fails the database
* transaction will be rolledback, but the unit of work will remain active.
* It can then be retried or released.
* The normal commit failure releases the unit of work, forcing a new one to be acquired if further changes are desired.
* The resuming feature allows for the same unit of work (and working copies) to be continued to be used if an error occurs.
* The UnitOfWork will also remain active if the commit is successful.
*
* @see #commit()
* @see #release()
*/
void commitAndResumeOnFailure() throws DatabaseException, OptimisticLockException;
/**
* PUBLIC:
* Merge the attributes of the clone into the unit of work copy.
* This can be used for objects that are returned from the client through
* RMI serialization or other serialization mechanisms, because the RMI object will
* be a clone this will merge its attributes correctly to preserve object identity
* within the unit of work and record its changes.
* Everything connected to this object (i.e. the entire object tree where rmiClone
* is the root) is also merged.
*
* @return the registered version for the clone being merged.
* @see #mergeClone(Object)
* @see #shallowMergeClone(Object)
*/
Object deepMergeClone(Object rmiClone);
/**
* PUBLIC:
* Revert the object's attributes from the parent.
* This reverts everything the object references.
*
* @return the object reverted.
* @see #revertObject(Object)
* @see #shallowRevertObject(Object)
*/
Object deepRevertObject(Object clone);
/**
* ADVANCED:
* Unregister the object with the unit of work.
* This can be used to delete an object that was just created and is not yet persistent.
* Delete object can also be used, but will result in inserting the object and then deleting it.
* The method should be used carefully because it will delete all the reachable parts.
*/
void deepUnregisterObject(Object clone);
/**
* PUBLIC:
* Delete all of the objects and all of their privately owned parts in the database.
* Delete operations are delayed in a unit of work until commit.
*/
void deleteAllObjects(Collection domainObjects);
/**
* PUBLIC:
* Delete the object and all of their privately owned parts in the database.
* Delete operations are delayed in a unit of work until commit.
*/
Object deleteObject(Object domainObject);
/**
* ADVANCED:
* The unit of work performs validations such as,
* ensuring multiple copies of the same object don't exist in the same unit of work,
* ensuring deleted objects are not referred after commit,
* ensures that objects from the parent cache are not referred in the unit of work cache.
* The level of validation can be increased or decreased for debugging purposes or under
* advanced situation where the application requires/desires to violate clone identity in the unit of work.
* It is strongly suggested that clone identity not be violate in the unit of work.
*/
void dontPerformValidation();
/**
* ADVANCED:
* Set optimistic read lock on the object. This feature is override by normal optimistic lock.
* when the object is changed in UnitOfWork. The cloneFromUOW must be the clone of from this
* UnitOfWork and it must implements version locking or timestamp locking.
* The SQL would look like the followings.
*
* If shouldModifyVersionField is true,
* "UPDATE EMPLOYEE SET VERSION = 2 WHERE EMP_ID = 9 AND VERSION = 1"
*
* If shouldModifyVersionField is false,
* "UPDATE EMPLOYEE SET VERSION = 1 WHERE EMP_ID = 9 AND VERSION = 1"
*/
void forceUpdateToVersionField(Object cloneFromUOW, boolean shouldModifyVersionField);
/**
* ADVANCED:
* This method will calculate the changes for the UnitOfWork. Without assigning sequence numbers.
* This is a computationaly intensive operation and should be avoided unless necessary.
* A valid changeSet, with sequence numbers can be collected from the UnitOfWork after the commit
* is complete by calling unitOfWork.getUnitOfWorkChangeSet().
*/
UnitOfWorkChangeSet getCurrentChanges();
/**
* ADVANCED:
* Return the original version of the object(clone) from the parent's identity map.
*/
Object getOriginalVersionOfObject(Object workingClone);
/**
* PUBLIC:
* Return the parent.
* This is a unit of work if nested, otherwise a database session or client session.
*/
org.eclipse.persistence.internal.sessions.AbstractSession getParent();
/**
* ADVANCED:
* Returns the currentChangeSet from the UnitOfWork.
* This is only valid after the UnitOfWork has committed successfully
*/
org.eclipse.persistence.sessions.changesets.UnitOfWorkChangeSet getUnitOfWorkChangeSet();
/**
* ADVANCED:
* The unit of work performs validations such as,
* ensuring multiple copies of the same object don't exist in the same unit of work,
* ensuring deleted objects are not referred after commit,
* ensures that objects from the parent cache are not referred in the unit of work cache.
* The level of validation can be increased or decreased for debugging purposes or under
* advanced situation where the application requires/desires to violate clone identity in the unit of work.
* It is strongly suggested that clone identity not be violate in the unit of work.
*/
int getValidationLevel();
/**
* ADVANCED:
* The Unit of work is capable of preprocessing to determine if any on the clone have been changed.
* This is computationally expensive and should be avoided on large object graphs.
*/
boolean hasChanges();
/**
* PUBLIC:
* Return if the unit of work is active (has not been released).
*/
boolean isActive();
/**
* PUBLIC:
* Checks to see if the specified class is read-only or not in this UnitOfWork.
*
* @return true if the class is read-only, false otherwise.
*/
boolean isClassReadOnly(Class theClass);
/**
* ADVANCED:
* Return whether the clone object is already registered.
*/
boolean isObjectRegistered(Object clone);
/**
* ADVANCED:
* Return if this session is a nested unit of work.
*/
boolean isNestedUnitOfWork();
/**
* PUBLIC:
* Merge the attributes of the clone into the unit of work copy.
* This can be used for objects that are returned from the client through
* RMI serialization (or another serialization mechanism), because the RMI object
* will be a clone this will merge its attributes correctly to preserve object
* identity within the unit of work and record its changes.
*
* The object and its private owned parts are merged.
*
* @return the registered version for the clone being merged.
* @see #shallowMergeClone(Object)
* @see #deepMergeClone(Object)
*/
Object mergeClone(Object rmiClone);
/**
* PUBLIC:
* Merge the attributes of the clone into the unit of work copy.
* This can be used for objects that are returned from the client through
* RMI serialization (or another serialization mechanism), because the RMI object
* will be a clone this will merge its attributes correctly to preserve object
* identity within the unit of work and record its changes.
*
* The object and its private owned parts are merged. This will include
* references from this clone to independent objects.
*
* @return the registered version for the clone being merged.
* @see #shallowMergeClone(Object)
* @see #deepMergeClone(Object)
*/
Object mergeCloneWithReferences(Object rmiClone);
/**
* PUBLIC:
* Return a new instance of the class registered in this unit of work.
* This can be used to ensure that new objects are registered correctly.
*/
Object newInstance(Class theClass);
/**
* ADVANCED:
* The unit of work performs validations such as,
* ensuring multiple copies of the same object don't exist in the same unit of work,
* ensuring deleted objects are not referred after commit,
* ensures that objects from the parent cache are not referred in the unit of work cache.
* The level of validation can be increased or decreased for debugging purposes or under
* advanced situation where the application requires/desires to violate clone identity in the unit of work.
* It is strongly suggested that clone identity not be violate in the unit of work.
*/
void performFullValidation();
/**
* ADVANCED:
* The unit of work performs validations such as,
* ensuring multiple copies of the same object don't exist in the same unit of work,
* ensuring deleted objects are not referred after commit,
* ensures that objects from the parent cache are not referred in the unit of work cache.
* The level of validation can be increased or decreased for debugging purposes or under
* advanced situation where the application requires/desires to violate clone identity in the unit of work.
* It is strongly suggested that clone identity not be violate in the unit of work.
*/
void performPartialValidation();
/**
* PUBLIC:
* Print the objects in the unit of work.
*/
void printRegisteredObjects();
/**
* PUBLIC:
* Refresh the attributes of the object and of all of its private parts from the database.
* The object will be pessimistically locked on the database for the duration of the transaction.
* If the object is already locked this method will wait until the lock is released.
* A no wait option is available through setting the lock mode.
* @see #refreshAndLockObject(Object, short)
*/
Object refreshAndLockObject(Object object);
/**
* PUBLIC:
* Refresh the attributes of the object and of all of its private parts from the database.
* The object will be pessimistically locked on the database for the duration of the transaction.
*
Lock Modes: ObjectBuildingQuery.NO_LOCK, LOCK, LOCK_NOWAIT
*/
Object refreshAndLockObject(Object object, short lockMode);
/**
* PUBLIC:
* Register the objects with the unit of work.
* All newly created root domain objects must be registered to be inserted on commit.
* Also any existing objects that will be edited and were not read from this unit of work
* must also be registered.
* Once registered any changes to the objects will be committed to the database on commit.
*
* @return is the clones of the original objects, the return value must be used for editing,
* editing the original is not allowed in the unit of work.
*/
Vector registerAllObjects(Collection domainObjects);
/**
* ADVANCED:
* Register the existing object with the unit of work.
* This is a advanced API that can be used if the application can guaranteed the object exists on the database.
* When registerObject is called the unit of work determines existence through the descriptor's doesExist setting.
*
* @return The clone of the original object, the return value must be used for editing.
* Editing the original is not allowed in the unit of work.
*/
Object registerExistingObject(Object existingObject);
/**
* ADVANCED:
* Register the new object with the unit of work.
* This will register the new object without cloning.
* Normally the registerObject method should be used for all registration of new and existing objects.
* This version of the register method can only be used for new objects.
* This method should only be used if a new object is desired to be registered without cloning.
*
* @see #registerObject(Object)
*/
Object registerNewObject(Object newObject);
/**
* PUBLIC:
* Register the object with the unit of work.
* All newly created root domain objects must be registered to be inserted on commit.
* Also any existing objects that will be edited and were not read from this unit of work
* must also be registered.
* Once registered any changes to the objects will be committed to the database on commit.
*
* @return the clone of the original object, the return value must be used for editing,
*
* ** Editing the original is not allowed in the unit of work. **
*/
Object registerObject(Object domainObject);
/**
* PUBLIC:
* Release the unit of work.
* This terminates this unit of work.
* Because the unit of work operates on its own object space (clones) no work is required.
* The unit of work should no longer be used or referenced by the application beyond this point
* so that it can garbage collect.
*
* @see #commit()
*/
@Override void release();
/**
* PUBLIC:
* Empties the set of read-only classes.
* It is illegal to call this method on nested UnitOfWork objects. A nested UnitOfWork
* cannot have a subset of its parent's set of read-only classes.
*/
void removeAllReadOnlyClasses();
/**
* ADVANCED:
* Remove optimistic read lock from the object
* See forceUpdateToVersionField(Object)
*/
void removeForceUpdateToVersionField(Object cloneFromUOW);
/**
* PUBLIC:
* Removes a Class from the receiver's set of read-only classes.
* It is illegal to try to send this method to a nested UnitOfWork.
*/
void removeReadOnlyClass(Class theClass);
/**
* PUBLIC:
* Revert all changes made to any registered object.
* Clear all deleted and new objects.
* Revert should not be confused with release which it the normal compliment to commit.
* Revert is more similar to commit and resume, however reverts all changes and resumes.
* If you do not require to resume the unit of work release should be used instead.
*
* @see #commitAndResume()
* @see #release()
*/
void revertAndResume();
/**
* PUBLIC:
* Revert the object's attributes from the parent.
* This also reverts the object privately-owned parts.
*
* @return the object reverted.
* @see #shallowRevertObject(Object)
* @see #deepRevertObject(Object)
*/
Object revertObject(Object clone);
/**
* ADVANCED:
* By default new objects are not cached until the exist on the database.
* Occasionally if mergeClone is used on new objects and is required to allow multiple merges
* on the same new object, then if the new objects are not cached, each mergeClone will be
* interpreted as a different new object.
* By setting new objects to be cached mergeClone can be performed multiple times before commit.
* New objects cannot be cached unless they have a valid assigned primary key before being registered.
* New object with non-null invalid primary keys such as 0 or '' can cause problems and should not be used with this option.
*/
void setShouldNewObjectsBeCached(boolean shouldNewObjectsBeCached);
/**
* ADVANCED:
* By default deletes are performed last in a unit of work.
* Sometimes you may want to have the deletes performed before other actions.
*/
void setShouldPerformDeletesFirst(boolean shouldPerformDeletesFirst);
/**
* ADVANCED:
* Conforming queries can be set to provide different levels of detail about the
* exceptions they encounter
* There are two levels:
* DO_NOT_THROW_CONFORM_EXCEPTIONS = 0;
* THROW_ALL_CONFORM_EXCEPTIONS = 1;
*/
void setShouldThrowConformExceptions(int shouldThrowExceptions);
/**
* ADVANCED:
* The unit of work performs validations such as,
* ensuring multiple copies of the same object don't exist in the same unit of work,
* ensuring deleted objects are not referred after commit,
* ensures that objects from the parent cache are not referred in the unit of work cache.
* The level of validation can be increased or decreased for debugging purposes or under
* advanced situation where the application requires/desires to violate clone identity in the unit of work.
* It is strongly suggested that clone identity not be violate in the unit of work.
*/
void setValidationLevel(int validationLevel);
/**
* PUBLIC:
* Merge the attributes of the clone into the unit of work copy.
* This can be used for objects that are returned from the client through
* RMI serialization (or other serialization mechanisms), because the RMI object will
* be a clone this will merge its attributes correctly to preserve object identity
* within the unit of work and record its changes.
*
* Only direct attributes are merged.
*
* @return the registered version for the clone being merged.
* @see #mergeClone(Object)
* @see #deepMergeClone(Object)
*/
Object shallowMergeClone(Object rmiClone);
/**
* PUBLIC:
* Revert the object's attributes from the parent.
* This only reverts the object's direct attributes.
*
* @return the object reverted.
* @see #revertObject(Object)
* @see #deepRevertObject(Object)
*/
Object shallowRevertObject(Object clone);
/**
* ADVANCED:
* Unregister the object with the unit of work.
* This can be used to delete an object that was just created and is not yet persistent.
* Delete object can also be used, but will result in inserting the object and then deleting it.
* The method will only unregister the clone, none of its parts.
*/
void shallowUnregisterObject(Object clone);
/**
* ADVANCED:
* By default new objects are not cached until the exist on the database.
* Occasionally if mergeClone is used on new objects and is required to allow multiple merges
* on the same new object, then if the new objects are not cached, each mergeClone will be
* interpreted as a different new object.
* By setting new objects to be cached mergeClone can be performed multiple times before commit.
* New objects cannot be cached unless they have a valid assigned primary key before being registered.
* New object with non-null invalid primary keys such as 0 or '' can cause problems and should not be used with this option.
*/
boolean shouldNewObjectsBeCached();
/**
* ADVANCED:
* By default all objects are inserted and updated in the database before
* any object is deleted. If this flag is set to true, deletes will be
* performed before inserts and updates
*/
boolean shouldPerformDeletesFirst();
/**
* ADVANCED:
* The unit of work performs validations such as,
* ensuring multiple copies of the same object don't exist in the same unit of work,
* ensuring deleted objects are not referred after commit,
* ensures that objects from the parent cache are not referred in the unit of work cache.
* The level of validation can be increased or decreased for debugging purposes or under
* advanced situation where the application requires/desires to violate clone identity in the unit of work.
* It is strongly suggested that clone identity not be violate in the unit of work.
*/
boolean shouldPerformFullValidation();
/**
* ADVANCED:
* The unit of work performs validations such as,
* ensuring multiple copies of the same object don't exist in the same unit of work,
* ensuring deleted objects are not referred after commit,
* ensures that objects from the parent cache are not referred in the unit of work cache.
* The level of validation can be increased or decreased for debugging purposes or under
* advanced situation where the application requires/desires to violate clone identity in the unit of work.
* It is strongly suggested that clone identity not be violate in the unit of work.
*/
boolean shouldPerformNoValidation();
/**
* ADVANCED:
* The unit of work performs validations such as,
* ensuring multiple copies of the same object don't exist in the same unit of work,
* ensuring deleted objects are not referred after commit,
* ensures that objects from the parent cache are not referred in the unit of work cache.
* The level of validation can be increased or decreased for debugging purposes or under
* advanced situation where the application requires/desires to violate clone identity in the unit of work.
* It is strongly suggested that clone identity not be violate in the unit of work.
*/
boolean shouldPerformPartialValidation();
/**
* ADVANCED:
* Unregister the object with the unit of work.
* This can be used to delete an object that was just created and is not yet persistent.
* Delete object can also be used, but will result in inserting the object and then deleting it.
* The method will only unregister private owned parts
*/
void unregisterObject(Object clone);
/**
* ADVANCED:
* This can be used to help debugging an object-space corruption.
* An object-space corruption is when your application has incorrectly related a clone to an original object.
* This method will validate that all registered objects are in a correct state and throw
* an error if not, it will contain the full stack of object references in the error message.
* If you call this method after each register or change you perform it will pin-point where the error was made.
*/
void validateObjectSpace();
/**
* ADVANCED: Writes all changes now before commit().
* The commit process will begin and all changes will be written out to the datastore, but the datastore transaction will not
* be committed, nor will changes be merged into the global cache.
*
* A subsequent commit (on UnitOfWork or global transaction) will be required to finalize the commit process.
*
* As the commit process has begun any attempt to register objects, or execute object-level queries will
* generate an exception. Report queries, non-caching queries, and data read/modify queries are allowed.
*
* On exception any global transaction will be rolled marked or marked rollback only. No recovery of this UnitOfWork will be possible.
*
* Can only be called once. It can not be used to write out changes in an incremental fashion.
*
* Use to partially commit a transaction outside of a JTA transaction's callbacks. Allows you to get back any exception directly.
*
* Use to commit a UnitOfWork in two stages.
*/
void writeChanges();
/**
* Get an entity instance, whose state may be lazily fetched.
* If the requested instance does not exist in the database, null is returned, or the object will fail when accessed.
* The instance will be lazy when it does not exist in the cache, and supports fetch groups.
*
* @param theClass instance class
* @param primaryKey the primary key of the object, either as a List, singleton, IdClass or an instance of the object
* @param the entity type
*
* @return a reference to the entity instance
*/
T getReference(Class theClass, Object primaryKey);
/**
* Get an entity instance, whose state may be lazily fetched.
* If the requested instance does not exist in the database, null is returned, or the object will fail when accessed.
* The instance will be lazy when it does not exist in the cache, and supports fetch groups.
*
* @param entity persistent or detached entity instance
* @param the entity type
* @return a reference to the entity instance
*/
T getReference(T entity);
/**
* ADVANCED:
* Return the commit order.
*/
CommitOrderType getCommitOrder();
/**
* ADVANCED:
* Set the commit order.
*/
void setCommitOrder(CommitOrderType order);
}