Coverage Report - org.apache.ojb.broker.util.sequence.SequenceManagerInMemoryImpl
 
Classes in this File Line Coverage Branch Coverage Complexity
SequenceManagerInMemoryImpl
N/A
N/A
2.2
 
 1  
 package org.apache.ojb.broker.util.sequence;
 2  
 
 3  
 /* Copyright 2002-2005 The Apache Software Foundation
 4  
  *
 5  
  * Licensed under the Apache License, Version 2.0 (the "License");
 6  
  * you may not use this file except in compliance with the License.
 7  
  * You may obtain a copy of the License at
 8  
  *
 9  
  *     http://www.apache.org/licenses/LICENSE-2.0
 10  
  *
 11  
  * Unless required by applicable law or agreed to in writing, software
 12  
  * distributed under the License is distributed on an "AS IS" BASIS,
 13  
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 14  
  * See the License for the specific language governing permissions and
 15  
  * limitations under the License.
 16  
  */
 17  
 
 18  
 import org.apache.ojb.broker.PersistenceBroker;
 19  
 import org.apache.ojb.broker.metadata.FieldDescriptor;
 20  
 
 21  
 import java.util.HashMap;
 22  
 import java.util.Map;
 23  
 
 24  
 /**
 25  
  * <p>
 26  
  * Very fast in memory sequence manager implementation, only the first
 27  
  * time an id was requested for a class, the manager query the database
 28  
  * for the max id in requested column - all following request were
 29  
  * performed in memory.
 30  
  * </p>
 31  
  * <b>Limitations:</b>
 32  
  * <ul type="disc">
 33  
  *        <li>do not use in clustered environments</li>
 34  
  *        <li>do not use if other applications generate id's for objects</li>
 35  
  * </ul>
 36  
  *
 37  
  *
 38  
  *
 39  
  * <p>
 40  
  * Implementation configuration properties:
 41  
  * </p>
 42  
  *
 43  
  * <table cellspacing="2" cellpadding="2" border="3" frame="box">
 44  
  * <tr>
 45  
  *     <td><strong>Property Key</strong></td>
 46  
  *     <td><strong>Property Values</strong></td>
 47  
  * </tr>
 48  
  * <tr>
 49  
  *     <td>seq.start</td>
 50  
  *     <td>
 51  
  *         Set the start index of used sequences (e.g. set 100000, id generation starts with 100001).
 52  
  *         Default start index is <em>1</em>.
 53  
  *    </td>
 54  
  * </tr>
 55  
  * <tr>
 56  
  *     <td>autoNaming</td>
 57  
  *     <td>
 58  
  *          Default was 'true'. If set 'true' OJB try to build a
 59  
  *          sequence name automatic if none found in field-descriptor
 60  
  *          and set this generated name as <code>sequence-name</code>
 61  
  *          in field-descriptor. If set 'false' OJB throws an exception
 62  
  *          if none sequence name was found in field-descriptor.
 63  
  *    </td>
 64  
  * </tr>
 65  
  * <tr>
 66  
  *     <td>sequenceStart</td>
 67  
  *     <td>
 68  
  *          <em>Deprecated, use property 'seq.start'.</em> Set the start index
 69  
  *          of used sequences (e.g. set 100000, id generation starts with 100001).
 70  
  *          Default start index is <em>1</em>.
 71  
  *    </td>
 72  
  * </tr>
 73  
  * </table>
 74  
  *
 75  
  * <br/>
 76  
  * <br/>
 77  
  * <br/>
 78  
  *
 79  
  * @see org.apache.ojb.broker.util.sequence.SequenceManager
 80  
  * @see org.apache.ojb.broker.util.sequence.SequenceManagerFactory
 81  
  * @see org.apache.ojb.broker.util.sequence.SequenceManagerHelper
 82  
  *
 83  
  *
 84  
  * @author <a href="mailto:armin@codeAuLait.de">Armin Waibel</a>
 85  
  * @version $Id: SequenceManagerInMemoryImpl.java,v 1.1 2007-08-24 22:17:29 ewestfal Exp $
 86  
  */
 87  
 public class SequenceManagerInMemoryImpl extends AbstractSequenceManager
 88  
 {
 89  
     protected static Map sequencesDBMap = new HashMap();
 90  
     private long sequenceStart;
 91  
 
 92  
     public SequenceManagerInMemoryImpl(PersistenceBroker broker)
 93  
     {
 94  
         super(broker);
 95  
         Long start = SequenceManagerHelper.getSeqStart(getConfigurationProperties());
 96  
         sequenceStart = start != null ? start.longValue() : 1;
 97  
     }
 98  
 
 99  
     protected long getUniqueLong(FieldDescriptor field) throws SequenceManagerException
 100  
     {
 101  
         String seqName = calculateSequenceName(field);
 102  
         // we have to be threadsafe
 103  
         synchronized (SequenceManagerInMemoryImpl.class)
 104  
         {
 105  
             // get id for given seq name
 106  
             Long currentId = getSequence(seqName);
 107  
             // check - first time we search for sequence name
 108  
             if (currentId == null)
 109  
             {
 110  
                 long maxKey = SequenceManagerHelper.getMaxForExtent(getBrokerForClass(), field);
 111  
                 maxKey = sequenceStart > maxKey ? sequenceStart : maxKey;
 112  
                 currentId = new Long(maxKey);
 113  
             }
 114  
             currentId = new Long(currentId.longValue() + 1);
 115  
             // put new id back to map
 116  
             addSequence(seqName, currentId);
 117  
             return currentId.intValue();
 118  
         }
 119  
     }
 120  
 
 121  
     /**
 122  
      * Returns last used sequence value or <code>null</code> if no sequence
 123  
      * was add for given sequence name.
 124  
      *
 125  
      * @param sequenceName Name of the sequence.
 126  
      * @return Last used sequence value or <code>null</code>
 127  
      */
 128  
     private Long getSequence(String sequenceName)
 129  
     {
 130  
         Long result = null;
 131  
         // now lookup the sequence map for calling DB
 132  
         Map mapForDB = (Map) sequencesDBMap.get(getBrokerForClass()
 133  
                 .serviceConnectionManager().getConnectionDescriptor().getJcdAlias());
 134  
         if(mapForDB != null)
 135  
         {
 136  
             result = (Long) mapForDB.get(sequenceName);
 137  
         }
 138  
         return result;
 139  
     }
 140  
 
 141  
     /**
 142  
      * Add new sequence value for sequence name.
 143  
      * @param sequenceName Name of the sequence.
 144  
      * @param seq The sequence value to add.
 145  
      */
 146  
     private void addSequence(String sequenceName, Long seq)
 147  
     {
 148  
         // lookup the sequence map for calling DB
 149  
         String jcdAlias = getBrokerForClass()
 150  
                 .serviceConnectionManager().getConnectionDescriptor().getJcdAlias();
 151  
         Map mapForDB = (Map) sequencesDBMap.get(jcdAlias);
 152  
         if(mapForDB == null)
 153  
         {
 154  
             mapForDB = new HashMap();
 155  
         }
 156  
         mapForDB.put(sequenceName, seq);
 157  
         sequencesDBMap.put(jcdAlias, mapForDB);
 158  
     }
 159  
 
 160  
     /**
 161  
      * Remove the sequence for given sequence name.
 162  
      *
 163  
      * @param sequenceName Name of the sequence to remove.
 164  
      */
 165  
     protected void removeSequence(String sequenceName)
 166  
     {
 167  
         // lookup the sequence map for calling DB
 168  
         Map mapForDB = (Map) sequencesDBMap.get(getBrokerForClass()
 169  
                 .serviceConnectionManager().getConnectionDescriptor().getJcdAlias());
 170  
         if(mapForDB != null)
 171  
         {
 172  
             synchronized(SequenceManagerInMemoryImpl.class)
 173  
             {
 174  
                 mapForDB.remove(sequenceName);
 175  
             }
 176  
         }
 177  
     }
 178  
 }