1 /*

     2  * Copyright (c) 2007-2008 Nokia Corporation and/or its subsidiary(-ies).

     3  * All rights reserved.

     4  * This component and the accompanying materials are made available

     5  * under the terms of the License "Eclipse Public License v1.0"

     6  * which accompanies this distribution, and is available

     7  * at the URL "http://www.eclipse.org/legal/epl-v10.html".

     8  *

     9  * Initial Contributors:

    10  * Nokia Corporation - initial contribution.

    11  *

    12  * Contributors:

    13  *

    14  * Description:  

    15  *

    16  */

    17 package com.nokia.helium.metadata;

    18 

    19 import javax.persistence.EntityManager;

    20 import javax.persistence.EntityManagerFactory;

    21 

    22 

    23 /**

    24  * This class implements a simplified EntityManager

    25  * designed for batch committing.

    26  * Serial persists are committed and cleared each time

    27  * the limit is reached.  

    28  *

    29  */

    30 public class AutoCommitEntityManager {

    31     private EntityManager entityManager;

    32     private int count;

    33     private int maxCount = 750;

    34     

    35     /**

    36      * Creating a new AutoCommitEntityManager. The entityManagerFactory will be 

    37      * used to get a new EntityManager.

    38      * @param entityManagerFactory the entity manager to use to create a EntityManager.

    39      */

    40     public AutoCommitEntityManager(EntityManagerFactory entityManagerFactory) {

    41         this.entityManager = entityManagerFactory.createEntityManager();

    42         entityManager.getTransaction().begin();

    43     }

    44     

    45     /**

    46      * Persisting an object into the database.

    47      * @param o the object to persist

    48      */

    49     public synchronized void persist(Object o) {

    50         entityManager.persist(o);

    51         count++;

    52         if (count >= maxCount) {

    53             entityManager.getTransaction().commit();

    54             entityManager.clear();

    55             count = 0;

    56             entityManager.getTransaction().begin();

    57         }

    58     }

    59     

    60     /**

    61      * Closing the current entity manager. Committing any 

    62      * pending operation.

    63      */

    64     public synchronized void close() {

    65         if (entityManager.getTransaction().isActive()) {

    66             entityManager.getTransaction().commit();

    67             entityManager.clear();

    68         }

    69         entityManager.close();

    70         entityManager = null;

    71     }

    72 

    73     /**

    74      * Internal EntityManager used to

    75      * @param <T>

    76      * @return the merged entity.

    77      */

    78     public <T> T merge(T entity) {

    79         return entityManager.merge(entity);

    80     }

    81     

    82 }