/*
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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 legal-notices/CDDLv1_0.txt
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* or http://forgerock.org/license/CDDLv1.0.html.
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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 legal-notices/CDDLv1_0.txt.
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* If applicable, add the following below this CDDL HEADER, with the
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* fields enclosed by brackets "[]" replaced with your own identifying
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* 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 2009-2010 Sun Microsystems, Inc.
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* Portions Copyright 2011-2014 ForgeRock AS
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*/
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package org.opends.server.replication.server.changelog.je;
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import java.util.ArrayList;
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import java.util.List;
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import java.util.concurrent.atomic.AtomicBoolean;
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import java.util.concurrent.atomic.AtomicLong;
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import org.opends.server.admin.std.server.MonitorProviderCfg;
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import org.opends.server.api.MonitorProvider;
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import org.opends.server.config.ConfigException;
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import org.opends.server.core.DirectoryServer;
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import org.opends.server.loggers.debug.DebugTracer;
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import org.opends.server.replication.common.CSN;
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import org.opends.server.replication.server.changelog.api.*;
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import org.opends.server.replication.server.changelog.je.DraftCNDB.*;
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import org.opends.server.types.*;
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import static org.opends.server.loggers.debug.DebugLogger.*;
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/**
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* This class is used for managing the replicationServer database for each
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* server in the topology. It is responsible for efficiently saving the updates
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* that is received from each master server into stable storage. This class is
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* also able to generate a {@link DBCursor} that can be used to read all changes
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* from a given change number.
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* <p>
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* This class publishes some monitoring information below <code>
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* cn=monitor</code>.
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*/
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public class JEChangeNumberIndexDB implements ChangeNumberIndexDB
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{
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/**
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* The tracer object for the debug logger.
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*/
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private static final DebugTracer TRACER = getTracer();
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private static int NO_KEY = 0;
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private DraftCNDB db;
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/**
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* The newest changenumber stored in the DB. It is used to avoid purging the
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* record with the newest changenumber. The newest record in the changenumber
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* index DB is used to persist the {@link #lastGeneratedChangeNumber} which is
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* then retrieved on server startup.
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*/
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private volatile long newestChangeNumber = NO_KEY;
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/**
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* The last generated value for the change number. It is kept separate from
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* the {@link #newestChangeNumber} because there is an opportunity for a race
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* condition between:
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* <ol>
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* <li>this atomic long being incremented for a new record ('recordB')</li>
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* <li>the current newest record ('recordA') being purged from the DB</li>
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* <li>'recordB' failing to be inserted in the DB</li>
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* </ol>
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*/
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private final AtomicLong lastGeneratedChangeNumber;
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private DbMonitorProvider dbMonitor = new DbMonitorProvider();
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private final AtomicBoolean shutdown = new AtomicBoolean(false);
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/**
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* Creates a new JEChangeNumberIndexDB associated to a given LDAP server.
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*
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* @param dbEnv the Database Env to use to create the ReplicationServer DB.
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* server for this domain.
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* @throws ChangelogException If a database problem happened
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*/
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public JEChangeNumberIndexDB(ReplicationDbEnv dbEnv) throws ChangelogException
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{
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db = new DraftCNDB(dbEnv);
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final ChangeNumberIndexRecord newestRecord = db.readLastRecord();
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newestChangeNumber = getChangeNumber(newestRecord);
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// initialization of the lastGeneratedChangeNumber from the DB content
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// if DB is empty => last record does not exist => default to 0
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lastGeneratedChangeNumber = new AtomicLong(newestChangeNumber);
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// Monitoring registration
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DirectoryServer.deregisterMonitorProvider(dbMonitor);
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DirectoryServer.registerMonitorProvider(dbMonitor);
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}
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private long getChangeNumber(ChangeNumberIndexRecord record)
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throws ChangelogException
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{
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if (record != null)
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{
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return record.getChangeNumber();
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}
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return NO_KEY;
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}
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/** {@inheritDoc} */
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@Override
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public long addRecord(ChangeNumberIndexRecord record)
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throws ChangelogException
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{
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long changeNumber = nextChangeNumber();
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final ChangeNumberIndexRecord newRecord =
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new ChangeNumberIndexRecord(changeNumber, record.getPreviousCookie(),
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record.getBaseDN(), record.getCSN());
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db.addRecord(newRecord);
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newestChangeNumber = changeNumber;
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if (debugEnabled())
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{
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TRACER.debugInfo("In JEChangeNumberIndexDB.add, added: " + newRecord);
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}
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return changeNumber;
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}
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/** {@inheritDoc} */
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@Override
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public ChangeNumberIndexRecord getOldestRecord() throws ChangelogException
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{
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return db.readFirstRecord();
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}
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/** {@inheritDoc} */
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@Override
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public ChangeNumberIndexRecord getNewestRecord() throws ChangelogException
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{
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return db.readLastRecord();
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}
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private long nextChangeNumber()
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{
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return lastGeneratedChangeNumber.incrementAndGet();
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}
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/** {@inheritDoc} */
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@Override
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public long getLastGeneratedChangeNumber()
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{
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return lastGeneratedChangeNumber.get();
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}
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/**
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* Get the number of changes.
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* @return Returns the number of changes.
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*/
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public long count()
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{
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return db.count();
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}
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/**
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* Returns whether this database is empty.
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*
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* @return <code>true</code> if this database is empty, <code>false</code>
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* otherwise
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* @throws ChangelogException
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* if a database problem occurs.
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*/
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public boolean isEmpty() throws ChangelogException
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{
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return getNewestRecord() == null;
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}
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/** {@inheritDoc} */
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@Override
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public DBCursor<ChangeNumberIndexRecord> getCursorFrom(long startChangeNumber)
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throws ChangelogException
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{
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return new JEChangeNumberIndexDBCursor(db, startChangeNumber);
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}
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/**
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* Shutdown this DB.
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*/
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public void shutdown()
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{
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if (shutdown.compareAndSet(false, true))
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{
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db.shutdown();
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DirectoryServer.deregisterMonitorProvider(dbMonitor);
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}
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}
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/**
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* Synchronously purges the change number index DB up to and excluding the
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* provided timestamp.
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*
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* @param purgeCSN
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* the timestamp up to which purging must happen
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* @return the oldest non purged CSN.
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* @throws ChangelogException
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* if a database problem occurs.
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*/
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public CSN purgeUpTo(CSN purgeCSN) throws ChangelogException
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{
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if (isEmpty() || purgeCSN == null)
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{
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return null;
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}
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final DraftCNDBCursor cursor = db.openDeleteCursor();
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try
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{
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while (!mustShutdown(shutdown) && cursor.next())
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{
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final ChangeNumberIndexRecord record = cursor.currentRecord();
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if (record.getChangeNumber() != newestChangeNumber
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&& record.getCSN().isOlderThan(purgeCSN))
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{
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cursor.delete();
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}
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else
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{
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// 1- Current record is not old enough to purge.
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// 2- Do not purge the newest record to avoid having the last
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// generated changenumber dropping back to 0 when the server restarts
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return record.getCSN();
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}
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}
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return null;
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}
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catch (ChangelogException e)
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{
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cursor.abort();
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throw e;
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}
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catch (Exception e)
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{
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cursor.abort();
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throw new ChangelogException(e);
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}
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finally
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{
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cursor.close();
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}
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}
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/**
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* Clear the changes from this DB (from both memory cache and DB storage) for
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* the provided baseDN.
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*
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* @param baseDNToClear
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* The baseDN for which we want to remove all records from this DB,
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* null means all.
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* @throws ChangelogException
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* if a database problem occurs.
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*/
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public void removeDomain(DN baseDNToClear) throws ChangelogException
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{
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if (isEmpty())
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{
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return;
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}
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final DraftCNDBCursor cursor = db.openDeleteCursor();
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try
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{
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while (!mustShutdown(shutdown) && cursor.next())
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{
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final ChangeNumberIndexRecord record = cursor.currentRecord();
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if (record.getChangeNumber() == newestChangeNumber)
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{
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// do not purge the newest record to avoid having the last generated
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// changenumber dropping back to 0 if the server restarts
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return;
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}
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if (baseDNToClear == null || record.getBaseDN().equals(baseDNToClear))
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{
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cursor.delete();
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}
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}
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}
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catch (ChangelogException e)
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{
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cursor.abort();
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throw e;
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}
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finally
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{
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cursor.close();
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}
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}
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private boolean mustShutdown(AtomicBoolean shutdown)
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{
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return shutdown != null && shutdown.get();
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}
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/**
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* This internal class is used to implement the Monitoring capabilities of the
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* JEChangeNumberIndexDB.
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*/
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private class DbMonitorProvider extends MonitorProvider<MonitorProviderCfg>
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{
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/** {@inheritDoc} */
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@Override
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public List<Attribute> getMonitorData()
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{
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List<Attribute> attributes = new ArrayList<Attribute>();
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attributes.add(createChangeNumberAttribute(true));
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attributes.add(createChangeNumberAttribute(false));
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attributes.add(Attributes.create("count", Long.toString(count())));
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return attributes;
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}
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private Attribute createChangeNumberAttribute(boolean isFirst)
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{
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final String attributeName =
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isFirst ? "first-draft-changenumber" : "last-draft-changenumber";
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final String changeNumber = String.valueOf(readChangeNumber(isFirst));
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return Attributes.create(attributeName, changeNumber);
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}
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private long readChangeNumber(boolean isFirst)
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{
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try
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{
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return getChangeNumber(
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isFirst ? db.readFirstRecord() : db.readLastRecord());
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}
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catch (ChangelogException e)
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{
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if (debugEnabled())
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{
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TRACER.debugCaught(DebugLogLevel.WARNING, e);
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}
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return NO_KEY;
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}
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}
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/** {@inheritDoc} */
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@Override
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public String getMonitorInstanceName()
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{
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return "ChangeNumber Index Database";
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}
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/** {@inheritDoc} */
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@Override
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public void initializeMonitorProvider(MonitorProviderCfg configuration)
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throws ConfigException,InitializationException
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{
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// Nothing to do for now
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}
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}
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/** {@inheritDoc} */
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@Override
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public String toString()
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{
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return getClass().getSimpleName() + ", newestChangeNumber="
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+ newestChangeNumber;
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}
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/**
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* Clear the changes from this DB (from both memory cache and DB storage).
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*
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* @throws ChangelogException
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* if a database problem occurs.
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*/
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public void clear() throws ChangelogException
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{
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db.clear();
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newestChangeNumber = NO_KEY;
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}
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}
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