/*
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* CDDL HEADER START
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*
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* The contents of this file are subject to the terms of the
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* Common Development and Distribution License, Version 1.0 only
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* (the "License"). You may not use this file except in compliance
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* with the License.
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*
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* You can obtain a copy of the license at
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* trunk/opends/resource/legal-notices/OpenDS.LICENSE
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* or https://OpenDS.dev.java.net/OpenDS.LICENSE.
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* See the License for the specific language governing permissions
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* and limitations under the License.
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*
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* When distributing Covered Code, include this CDDL HEADER in each
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* file and include the License file at
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* trunk/opends/resource/legal-notices/OpenDS.LICENSE. If applicable,
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* add the following below this CDDL HEADER, with the fields enclosed
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* by brackets "[]" replaced with your own identifying information:
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* Portions Copyright [yyyy] [name of copyright owner]
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*
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* CDDL HEADER END
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*
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*
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* Copyright 2006-2009 Sun Microsystems, Inc.
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*/
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package org.opends.server.replication.server;
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import org.opends.server.replication.common.ChangeNumber;
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import org.opends.server.replication.protocol.UpdateMsg;
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import org.opends.server.replication.server.ReplicationDB.ReplServerDBCursor;
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import com.sleepycat.je.DatabaseException;
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/**
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* This class allows to iterate through the changes received from a given
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* LDAP Server Identifier.
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*/
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public class ReplicationIterator
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{
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private UpdateMsg currentChange = null;
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private ReplServerDBCursor cursor = null;
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private DbHandler dbh;
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private ReplicationDB db;
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ChangeNumber lastNonNullCurrentCN;
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/**
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* Creates a new ReplicationIterator.
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* All created iterator must be released by the caller using the
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* releaseCursor() method.
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*
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* @param id the Identifier of the server on which the iterator applies.
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* @param db The db where the iterator must be created.
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* @param changeNumber The ChangeNumber after which the iterator must start.
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* @param dbh The associated DbHandler.
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* @throws Exception If there is no other change to push after change
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* with changeNumber number.
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* @throws DatabaseException if a database problem happened.
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*/
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public ReplicationIterator(
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short id, ReplicationDB db, ChangeNumber changeNumber, DbHandler dbh)
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throws Exception, DatabaseException
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{
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this.db = db;
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this.dbh = dbh;
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this.lastNonNullCurrentCN = changeNumber;
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try
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{
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cursor = db.openReadCursor(changeNumber);
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}
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catch(Exception e)
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{
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// we didn't find it in the db
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cursor = null;
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}
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if (cursor == null)
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{
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// flush the queue into the db
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dbh.flush();
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// look again in the db
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cursor = db.openReadCursor(changeNumber);
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if (cursor == null)
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{
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throw new Exception("no new change");
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}
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}
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}
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/**
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* Get the UpdateMsg where the iterator is currently set.
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* @return The UpdateMsg where the iterator is currently set.
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*/
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public UpdateMsg getChange()
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{
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return currentChange;
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}
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/**
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* Go to the next change in the ReplicationDB or in the server Queue.
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* @return false if the iterator is already on the last change before
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* this call.
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*/
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public boolean next()
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{
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boolean hasNext = false;
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currentChange = cursor.next(); // can return null
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if (currentChange != null)
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{
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lastNonNullCurrentCN = currentChange.getChangeNumber();
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hasNext = true;
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}
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else
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{
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synchronized (this)
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{
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if (cursor != null)
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{
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cursor.close();
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cursor = null;
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}
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dbh.flush();
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try
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{
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cursor = db.openReadCursor(lastNonNullCurrentCN);
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currentChange = cursor.next(); // can return null
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lastNonNullCurrentCN = currentChange.getChangeNumber();
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if (currentChange != null)
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{
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hasNext = true;
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}
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else
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{
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hasNext = false;
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}
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}
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catch(Exception e)
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{
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currentChange = null;
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hasNext = false;
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}
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}
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}
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return hasNext;
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}
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/**
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* Release the resources and locks used by this Iterator.
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* This method must be called when the iterator is no longer used.
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* Failure to do it could cause DB deadlock.
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*/
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public void releaseCursor()
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{
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synchronized (this)
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{
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if (cursor != null)
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{
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cursor.close();
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cursor = null;
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}
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this.dbh = null;
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this.db = null;
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}
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}
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/**
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* Called by the Gc when the object is garbage collected
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* Release the cursor in case the iterator was badly used and releaseCursor
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* was never called.
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*/
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protected void finalize()
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{
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releaseCursor();
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}
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}
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