package org.apache.ojb.broker.util.sequence;

 /* Copyright 2002-2005 The Apache Software Foundation

  *

  * Licensed under the Apache License, Version 2.0 (the "License");

  * you may not use this file except in compliance with the License.

  * You may obtain a copy of the License at

  *

  *     http://www.apache.org/licenses/LICENSE-2.0

  *

  * Unless required by applicable law or agreed to in writing, software

  * distributed under the License is distributed on an "AS IS" BASIS,

  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

  * See the License for the specific language governing permissions and

  * limitations under the License.

  */

 import org.apache.ojb.broker.PersistenceBroker;

 import org.apache.ojb.broker.PersistenceBrokerException;

 import org.apache.ojb.broker.metadata.SequenceDescriptor;

 import org.apache.ojb.broker.util.ClassHelper;

 import org.apache.ojb.broker.util.logging.Logger;

 import org.apache.ojb.broker.util.logging.LoggerFactory;

 /**

  * Threadsafe factory class, creates <code>SequenceManager</code> instances.

  * The implementation class is configured by the OJB.properties file.

  */

 public class SequenceManagerFactory

 {

     private static Logger log = LoggerFactory.getLogger(SequenceManagerFactory.class);

     private static SequenceManagerFactory singleton;

     private Class defaultSeqManagerClass;

     public SequenceManagerFactory()

     {

         defaultSeqManagerClass = SequenceManagerHighLowImpl.class;

         if(log.isDebugEnabled()) log.debug("Default sequence manager class was " + defaultSeqManagerClass.getName());

     }

     public synchronized static SequenceManager getSequenceManager(PersistenceBroker broker)

     {

         if (singleton == null)

         {

             singleton = new SequenceManagerFactory();

         }

         return singleton.createNewSequenceManager(broker);

     }

     private SequenceManager createNewSequenceManager(PersistenceBroker broker)

     {

         synchronized (singleton)

         {

             if (log.isDebugEnabled()) log.debug("create new sequence manager for broker " + broker);

             try

             {

                 // first we use seqMan defined in the OJB.properties

                 Class seqManClass = defaultSeqManagerClass;

                 SequenceDescriptor sd = broker.serviceConnectionManager().getConnectionDescriptor().getSequenceDescriptor();

                 if (sd != null && sd.getSequenceManagerClass() != null)

                 {

                     // if a seqMan was defined in repository, use that

                     seqManClass = sd.getSequenceManagerClass();

                     if (log.isDebugEnabled())

                     {

                         log.debug("Jdbc-Connection-Descriptor '" +

                                 broker.serviceConnectionManager().getConnectionDescriptor().getJcdAlias() +

                                 "' use sequence manager: " + seqManClass);

                     }

                 }

                 return (SequenceManager) ClassHelper.newInstance(seqManClass, PersistenceBroker.class, broker);

             }

             catch (Exception ex)

             {

                 log.error("Could not create sequence manager for broker " + broker, ex);

                 throw new PersistenceBrokerException(ex);

             }

         }

     }

 }