sequencegeneratorbean.java~10~

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package shiponline;

import javax.ejb.*;

public class SequenceGeneratorBean implements SessionBean {
  SessionContext sessionContext;
  private class Entry {
   Sequence sequence;
   int first = 0;
   int last = Integer.MAX_VALUE;
 };

 private java.util.Hashtable entries = new java.util.Hashtable();
 private int blockSize;
 private int retryCount;
 private SequenceHome sequenceHome;
 public void ejbCreate() throws CreateException {
    /**@todo Complete this method*/
  }
  public void ejbRemove() {
    /**@todo Complete this method*/
  }
  public void ejbActivate() {
    /**@todo Complete this method*/
  }
  public void ejbPassivate() {
    /**@todo Complete this method*/
  }
  public void setSessionContext(SessionContext sessionContext) {
    try {
     javax.naming.Context context = new javax.naming.InitialContext();
     blockSize = ((Integer) context.lookup("java:comp/env/blockSize")).intValue();
     retryCount = ((Integer) context.lookup("java:comp/env/retryCount")).intValue();
     sequenceHome = (SequenceHome) context.lookup("java:comp/env/Sequence");
   }
   catch(javax.naming.NamingException e) {
     throw new javax.ejb.EJBException(e);
   }

  }
  public int nextSequenceNumber(String name) {
    try {
         Entry entry = (Entry) entries.get(name);
         if(entry == null) {
           // add an entry to the sequence table
           entry = new Entry();
           try {
             entry.sequence = sequenceHome.findByPrimaryKey(name);
           }
           catch(javax.ejb.FinderException e) {
             // if we couldn't find it, then create it...
             entry.sequence = sequenceHome.create(name);
           }
           entries.put(name, entry);
         }
         if(entry.last > entry.first + blockSize) {
           for(int retry = 0; true; retry++) {
             try {
               entry.first = entry.sequence.seqValueBeforeIncrementingBy(blockSize);
               entry.last = entry.first;
               break;
             }
             catch(Exception e) {
               if(retry < retryCount) {
                 // we hit a concurrency exception, so try again...
                 continue;
               }
               else {
                 // we tried too many times, so fail...
                 throw new javax.ejb.EJBException(e);
               }
             }
           }
         }
         return entry.last++;
       }
       catch(javax.ejb.CreateException e) {
         throw new javax.ejb.EJBException(e);
       }
       catch(Exception e) {
         throw new javax.ejb.EJBException(e);
       }

  }
}