https://github.com/javaee/jpa-spec: Java(TM) Persistence API 
Copyright (c) 2008 - 2013 Oracle Corporation. All rights reserved.
This program and the accompanying materials are made available under the
terms of the Eclipse Public License v1.0 and Eclipse Distribution License v. 1.0
which accompanies this distribution.
The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v10.html
and the Eclipse Distribution License is available at
http://www.eclipse.org/org/documents/edl-v10.php.
Contributors:
    Linda DeMichiel - Java Persistence 2.1
    Linda DeMichiel - Java Persistence 2.0

/*******************************************************************************
 * Copyright (c) 2008 - 2013 Oracle Corporation. All rights reserved.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v1.0 and Eclipse Distribution License v. 1.0
 * which accompanies this distribution.
 * The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v10.html
 * and the Eclipse Distribution License is available at
 * http://www.eclipse.org/org/documents/edl-v10.php.
 *
 * Contributors:
 *     Linda DeMichiel - Java Persistence 2.1
 *     Linda DeMichiel - Java Persistence 2.0
 *
 ******************************************************************************/ 
package javax.persistence;


Defines the values of the javax.persistence.lock.scope property for pessimistic locking. This property may be passed as an argument to the methods of the EntityManager, Query, and TypedQuery interfaces that allow lock modes to be specified or used with the NamedQuery annotation. 
Since:Java Persistence 2.0
/**
 * Defines the values of the <code>javax.persistence.lock.scope</code>
 * property for pessimistic locking.  This property may be passed as
 * an argument to the methods of the {@link EntityManager},
 * {@link Query}, and {@link TypedQuery} interfaces that
 * allow lock modes to be specified or used with the
 * {@link NamedQuery} annotation.
 *
 * @since Java Persistence 2.0
 */
public enum PessimisticLockScope {

    
This value defines the default behavior for pessimistic locking.

The persistence provider must lock the database row(s) that
correspond to the non-collection-valued persistent state of
that instance.  If a joined inheritance strategy is used, or if
the entity is otherwise mapped to a secondary table, this
entails locking the row(s) for the entity instance in the
additional table(s).  Entity relationships for which the locked
entity contains the foreign key will also be locked, but not
the state of the referenced entities (unless those entities are
explicitly locked).  Element collections and relationships for
which the entity does not contain the foreign key (such as
relationships that are mapped to join tables or unidirectional
one-to-many relationships for which the target entity contains
the foreign key) will not be locked by default.

/**
     * This value defines the default behavior for pessimistic locking.
     *
     * <p>The persistence provider must lock the database row(s) that
     * correspond to the non-collection-valued persistent state of
     * that instance.  If a joined inheritance strategy is used, or if
     * the entity is otherwise mapped to a secondary table, this
     * entails locking the row(s) for the entity instance in the
     * additional table(s).  Entity relationships for which the locked
     * entity contains the foreign key will also be locked, but not
     * the state of the referenced entities (unless those entities are
     * explicitly locked).  Element collections and relationships for
     * which the entity does not contain the foreign key (such as
     * relationships that are mapped to join tables or unidirectional
     * one-to-many relationships for which the target entity contains
     * the foreign key) will not be locked by default.
     */
    NORMAL,

    
In addition to the behavior for
PessimisticLockScope.NORMAL, element collections
and relationships owned by the entity that are contained in
join tables will be locked if the
javax.persistence.lock.scope property is specified
with a value of PessimisticLockScope.EXTENDED.
The state of entities referenced by such relationships will not
be locked (unless those entities are explicitly locked).
Locking such a relationship or element collection generally locks only
the rows in the join table or collection table for that
relationship or collection.  This means that phantoms will be
possible.

/**
     * In addition to the behavior for
     * <code>PessimisticLockScope.NORMAL</code>, element collections
     * and relationships owned by the entity that are contained in
     * join tables will be locked if the
     * <code>javax.persistence.lock.scope</code> property is specified
     * with a value of <code>PessimisticLockScope.EXTENDED</code>.
     * The state of entities referenced by such relationships will not
     * be locked (unless those entities are explicitly locked).
     * Locking such a relationship or element collection generally locks only
     * the rows in the join table or collection table for that
     * relationship or collection.  This means that phantoms will be
     * possible.
     */
    EXTENDED
}