/*
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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 2006-2010 Sun Microsystems, Inc.
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* Portions Copyright 2011-2013 ForgeRock AS
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*/
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package org.opends.server.replication.server;
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import org.opends.messages.Message;
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import org.opends.messages.MessageBuilder;
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import static org.opends.server.loggers.ErrorLogger.logError;
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import static org.opends.messages.ReplicationMessages.*;
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import static org.opends.server.util.StaticUtils.decodeUTF8;
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import static org.opends.server.util.StaticUtils.getBytes;
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import static org.opends.server.util.StaticUtils.stackTraceToSingleLineString;
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import java.util.List;
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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 java.util.concurrent.locks.ReentrantReadWriteLock;
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import com.sleepycat.je.*;
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/**
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* This class implements the interface between the underlying database
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* and the dbHandler class.
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* This is the only class that should have code using the BDB interfaces.
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*/
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public class ReplicationDB
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{
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private Database db = null;
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private ReplicationDbEnv dbenv = null;
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private ReplicationServer replicationServer;
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private int serverId;
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private String baseDn;
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// The lock used to provide exclusive access to the thread that
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// close the db (shutdown or clear).
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private ReentrantReadWriteLock dbCloseLock;
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// Change counter management
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// The Db itself does not allow to count records between a start and an end
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// change. And we cannot rely on the replication seqnum that is part of the
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// changenumber, since there can be holes (when an operation is canceled).
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// And traversing all the records from the start one to the end one works
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// fine but can be very long (ECL:lastChangeNumber).
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//
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// So we are storing special records in the DB (called counter records),
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// that contain the number of changes since the previous counter record.
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// One special record is :
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// - a special key : changetime , serverid=0 seqnum=0
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// - a counter value : count of changes since previous counter record.
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//
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// A counter record has to follow the order of the db, so it needs to have
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// a changenumber key that follow the order.
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// A counter record must have its own changenumber key since the Db does not
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// support duplicate key (it is a compatibility breaker character of the DB).
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//
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// We define 2 conditions to store a counter record :
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// 1/- at least 'counterWindowSize' changes have been stored in the Db
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// since the previous counter record
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// 2/- the change to be stored has a new timestamp - so that the counter
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// record is the first record for this timestamp.
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//
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private int counterCurrValue = 1;
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// Current value of the counter.
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private long counterTsLimit = 0;
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// When not null,
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// the next change with a ts different from tsForNewCounterRecord will lead
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// to store a new counterRecord.
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private int counterWindowSize = 1000;
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// The counter record will never be written to the db more often than each
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// counterWindowSize changes.
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/**
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* Creates a new database or open existing database that will be used
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* to store and retrieve changes from an LDAP server.
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* @param serverId The identifier of the LDAP server.
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* @param baseDn The baseDn of the replication domain.
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* @param replicationServer The ReplicationServer that needs to be shutdown.
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* @param dbenv The Db environment to use to create the db.
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* @throws DatabaseException If a database problem happened.
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*/
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public ReplicationDB(int serverId, String baseDn,
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ReplicationServer replicationServer,
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ReplicationDbEnv dbenv)
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throws DatabaseException
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{
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this.serverId = serverId;
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this.baseDn = baseDn;
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this.dbenv = dbenv;
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this.replicationServer = replicationServer;
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// Get or create the associated ReplicationServerDomain and Db.
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db = dbenv.getOrAddDb(serverId, baseDn,
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replicationServer.getReplicationServerDomain(baseDn,
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true).getGenerationId());
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dbCloseLock = new ReentrantReadWriteLock(true);
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//
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Cursor cursor;
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Transaction txn = null;
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DatabaseEntry key = new DatabaseEntry();
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DatabaseEntry data = new DatabaseEntry();
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OperationStatus status;
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int distBackToCounterRecord = 0;
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// Initialize counter
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this.counterCurrValue = 1;
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cursor = db.openCursor(txn, null);
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try
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{
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status = cursor.getLast(key, data, LockMode.DEFAULT);
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while (status == OperationStatus.SUCCESS)
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{
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ChangeNumber cn = new ChangeNumber(decodeUTF8(key.getData()));
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if (!ReplicationDB.isaCounter(cn))
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{
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status = cursor.getPrev(key, data, LockMode.DEFAULT);
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distBackToCounterRecord++;
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}
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else
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{
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// counter record
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counterCurrValue = decodeCounterValue(data.getData()) + 1;
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counterTsLimit = cn.getTime();
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break;
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}
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}
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counterCurrValue += distBackToCounterRecord;
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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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* add a list of changes to the underlying db.
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*
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* @param changes The list of changes to add to the underlying db.
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*/
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public void addEntries(List<UpdateMsg> changes)
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{
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try
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{
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dbCloseLock.readLock().lock();
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try
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{
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// If the DB has been closed then return immediately.
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if (isDBClosed())
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{
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return;
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}
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for (UpdateMsg change : changes)
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{
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DatabaseEntry key = new ReplicationKey(
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change.getChangeNumber());
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DatabaseEntry data = new ReplicationData(change);
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if ((counterCurrValue != 0)
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&& (counterCurrValue % counterWindowSize == 0))
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{
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// enough changes to generate a counter record - wait for the next
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// change of time
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counterTsLimit = change.getChangeNumber().getTime();
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}
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if ((counterTsLimit != 0)
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&& (change.getChangeNumber().getTime() != counterTsLimit))
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{
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// Write the counter record
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DatabaseEntry counterKey = new ReplicationKey(
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new ChangeNumber(change.getChangeNumber().getTime(),
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0, 0));
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DatabaseEntry counterValue =
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encodeCounterValue(counterCurrValue - 1);
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db.put(null, counterKey, counterValue);
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counterTsLimit = 0;
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}
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db.put(null, key, data);
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counterCurrValue++;
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}
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}
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finally
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{
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dbCloseLock.readLock().unlock();
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}
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}
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catch (DatabaseException e)
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{
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replicationServer.handleUnexpectedDatabaseException(e);
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}
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}
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/**
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* Shutdown the database.
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*/
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public void shutdown()
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{
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try
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{
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dbCloseLock.writeLock().lock();
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try
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{
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db.close();
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db = null;
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}
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finally
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{
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dbCloseLock.writeLock().unlock();
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}
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}
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catch (DatabaseException e)
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{
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MessageBuilder mb = new MessageBuilder();
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mb.append(NOTE_EXCEPTION_CLOSING_DATABASE.get(this.toString()));
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mb.append(stackTraceToSingleLineString(e));
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logError(mb.toMessage());
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}
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}
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/**
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* Create a cursor that can be used to search or iterate on this
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* ReplicationServer DB.
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*
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* @param changeNumber The ChangeNumber from which the cursor must start.
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* @throws DatabaseException If a database error prevented the cursor
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* creation.
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* @throws Exception if the ReplServerDBCursor creation failed.
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* @return The ReplServerDBCursor.
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*/
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public ReplServerDBCursor openReadCursor(ChangeNumber changeNumber)
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throws DatabaseException, Exception
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{
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return new ReplServerDBCursor(changeNumber);
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}
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/**
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* Create a cursor that can be used to delete some record from this
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* ReplicationServer database.
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*
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* @throws DatabaseException If a database error prevented the cursor
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* creation.
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* @throws Exception if the ReplServerDBCursor creation failed.
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*
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* @return The ReplServerDBCursor.
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*/
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public ReplServerDBCursor openDeleteCursor()
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throws DatabaseException, Exception
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{
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return new ReplServerDBCursor();
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}
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private void closeLockedCursor(Cursor cursor)
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throws DatabaseException
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{
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try
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{
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if (cursor != null)
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{
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try
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{
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cursor.close();
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}
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catch (DatabaseException e)
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{
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// Ignore.
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}
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}
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}
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finally
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{
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dbCloseLock.readLock().unlock();
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}
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}
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/**
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* Read the first Change from the database.
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* @return the first ChangeNumber.
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*/
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public ChangeNumber readFirstChange()
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{
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Cursor cursor = null;
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ChangeNumber cn = null;
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try
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{
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dbCloseLock.readLock().lock();
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try
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{
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// If the DB has been closed then return immediately.
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if (isDBClosed())
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{
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return null;
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}
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DatabaseEntry key = new DatabaseEntry();
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DatabaseEntry data = new DatabaseEntry();
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cursor = db.openCursor(null, null);
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OperationStatus status = cursor.getFirst(key, data,
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LockMode.DEFAULT);
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if (status != OperationStatus.SUCCESS)
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{
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/* database is empty */
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return null;
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}
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String str = decodeUTF8(key.getData());
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cn = new ChangeNumber(str);
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if (ReplicationDB.isaCounter(cn))
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{
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// First record is a counter record .. go next
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status = cursor.getNext(key, data, LockMode.DEFAULT);
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if (status != OperationStatus.SUCCESS)
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{
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// DB contains only a counter record
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return null;
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}
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else
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{
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cn = new ChangeNumber(decodeUTF8(key.getData()));
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}
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}
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}
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finally
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{
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closeLockedCursor(cursor);
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}
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}
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catch (DatabaseException e)
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{
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/* database is faulty */
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replicationServer.handleUnexpectedDatabaseException(e);
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cn = null;
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}
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return cn;
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}
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/**
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* Read the last Change from the database.
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*
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* @return the last ChangeNumber.
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*/
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public ChangeNumber readLastChange()
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{
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Cursor cursor = null;
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ChangeNumber cn = null;
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try
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{
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dbCloseLock.readLock().lock();
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try
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{
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// If the DB has been closed then return immediately.
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if (isDBClosed())
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{
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return null;
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}
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DatabaseEntry key = new DatabaseEntry();
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DatabaseEntry data = new DatabaseEntry();
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cursor = db.openCursor(null, null);
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OperationStatus status = cursor.getLast(key, data,
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LockMode.DEFAULT);
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if (status != OperationStatus.SUCCESS)
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{
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/* database is empty */
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return null;
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}
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String str = decodeUTF8(key.getData());
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cn = new ChangeNumber(str);
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if (ReplicationDB.isaCounter(cn))
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{
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if (cursor.getPrev(key, data, LockMode.DEFAULT)
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!= OperationStatus.SUCCESS)
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{
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/*
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* database only contain a counter record - don't know how much it
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* can be possible but ...
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*/
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cn = null;
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}
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else
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{
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str = decodeUTF8(key.getData());
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cn = new ChangeNumber(str);
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// There can't be 2 counter record next to each other
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}
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}
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}
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finally
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{
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closeLockedCursor(cursor);
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}
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}
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catch (DatabaseException e)
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{
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replicationServer.handleUnexpectedDatabaseException(e);
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cn = null;
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}
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return cn;
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}
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/**
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* Try to find in the DB, the change number right before the one
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* passed as a parameter.
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*
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* @param changeNumber
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* The changeNumber from which we start searching.
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* @return the changeNumber right before the one passed as a parameter.
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* Can return null if there is none.
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*/
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public ChangeNumber getPreviousChangeNumber(ChangeNumber changeNumber)
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{
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if (changeNumber == null)
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return null;
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Cursor cursor = null;
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ChangeNumber cn = null;
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DatabaseEntry key = new ReplicationKey(changeNumber);
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DatabaseEntry data = new DatabaseEntry();
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try
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{
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dbCloseLock.readLock().lock();
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try
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{
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// If the DB has been closed then return immediately.
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if (isDBClosed())
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{
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return null;
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}
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cursor = db.openCursor(null, null);
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if (cursor.getSearchKeyRange(key, data, LockMode.DEFAULT)
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== OperationStatus.SUCCESS)
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{
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// We can move close to the changeNumber.
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// Let's move to the previous change.
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if (cursor.getPrev(key, data, LockMode.DEFAULT)
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== OperationStatus.SUCCESS)
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{
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String str = decodeUTF8(key.getData());
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cn = new ChangeNumber(str);
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if (ReplicationDB.isaCounter(cn))
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{
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if (cursor.getPrev(key, data, LockMode.DEFAULT)
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!= OperationStatus.SUCCESS)
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{
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// database starts with a counter record.
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cn = null;
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}
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else
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{
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str = decodeUTF8(key.getData());
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cn = new ChangeNumber(str);
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// There can't be 2 counter record next to each other
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}
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}
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}
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// else, there was no change previous to our changeNumber.
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}
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else
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{
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// We could not move the cursor past to the changeNumber
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// Check if the last change is older than changeNumber
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if (cursor.getLast(key, data, LockMode.DEFAULT)
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== OperationStatus.SUCCESS)
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{
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String str = decodeUTF8(key.getData());
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cn = new ChangeNumber(str);
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if (ReplicationDB.isaCounter(cn))
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{
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if (cursor.getPrev(key, data, LockMode.DEFAULT)
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!= OperationStatus.SUCCESS)
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{
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/*
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* database only contain a counter record, should not be
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* possible, but Ok, let's just say no change Number
|
*/
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cn = null;
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}
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else
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{
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str = decodeUTF8(key.getData());
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cn = new ChangeNumber(str);
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// There can't be 2 counter record next to each other
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}
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}
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}
|
}
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}
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finally
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{
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closeLockedCursor(cursor);
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}
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}
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catch (DatabaseException e)
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{
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replicationServer.handleUnexpectedDatabaseException(e);
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cn = null;
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}
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return cn;
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}
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|
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/**
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* {@inheritDoc}
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*/
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@Override
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public String toString()
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{
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return serverId + baseDn;
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}
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/**
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* This Class implements a cursor that can be used to browse a
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* replicationServer database.
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*/
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public class ReplServerDBCursor
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{
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// The transaction that will protect the actions done with the cursor
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// Will be let null for a read cursor
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// Will be set non null for a write cursor
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private final Transaction txn;
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private final Cursor cursor;
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private final DatabaseEntry key;
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private final DatabaseEntry data;
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private boolean isClosed = false;
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/**
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* Creates a ReplServerDBCursor that can be used for browsing a
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* replicationServer db.
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*
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* @param startingChangeNumber
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* The ChangeNumber from which the cursor must start.
|
* @throws Exception
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* When the startingChangeNumber does not exist.
|
*/
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private ReplServerDBCursor(ChangeNumber startingChangeNumber)
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throws Exception
|
{
|
if (startingChangeNumber != null)
|
{
|
key = new ReplicationKey(startingChangeNumber);
|
}
|
else
|
{
|
key = new DatabaseEntry();
|
}
|
data = new DatabaseEntry();
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|
txn = null;
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// Take the lock. From now on, whatever error that happen in the life
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// of this cursor should end by unlocking that lock. We must also
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// unlock it when throwing an exception.
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dbCloseLock.readLock().lock();
|
|
Cursor localCursor = null;
|
try
|
{
|
// If the DB has been closed then create empty cursor.
|
if (isDBClosed())
|
{
|
isClosed = true;
|
cursor = null;
|
return;
|
}
|
|
localCursor = db.openCursor(txn, null);
|
if (startingChangeNumber != null)
|
{
|
if (localCursor.getSearchKey(key, data, LockMode.DEFAULT) !=
|
OperationStatus.SUCCESS)
|
{
|
// We could not move the cursor to the expected startingChangeNumber
|
if (localCursor.getSearchKeyRange(key, data, LockMode.DEFAULT) !=
|
OperationStatus.SUCCESS)
|
{
|
// We could not even move the cursor closed to it => failure
|
throw new Exception("ChangeNumber not available");
|
}
|
else
|
{
|
// We can move close to the startingChangeNumber.
|
// Let's create a cursor from that point.
|
DatabaseEntry aKey = new DatabaseEntry();
|
DatabaseEntry aData = new DatabaseEntry();
|
if (localCursor.getPrev(aKey, aData, LockMode.DEFAULT) !=
|
OperationStatus.SUCCESS)
|
{
|
localCursor.close();
|
localCursor = db.openCursor(txn, null);
|
}
|
}
|
}
|
}
|
cursor = localCursor;
|
}
|
catch (Exception e)
|
{
|
// Unlocking is required before throwing any exception
|
closeLockedCursor(localCursor);
|
throw e;
|
}
|
}
|
|
private ReplServerDBCursor() throws Exception
|
{
|
key = new DatabaseEntry();
|
data = new DatabaseEntry();
|
|
// We'll go on only if no close or no clear is running
|
dbCloseLock.readLock().lock();
|
|
Transaction localTxn = null;
|
Cursor localCursor = null;
|
try
|
{
|
// If the DB has been closed then create empty cursor.
|
if (isDBClosed())
|
{
|
isClosed = true;
|
txn = null;
|
cursor = null;
|
return;
|
}
|
|
// Create the transaction that will protect whatever done with this
|
// write cursor.
|
localTxn = dbenv.beginTransaction();
|
localCursor = db.openCursor(localTxn, null);
|
|
txn = localTxn;
|
cursor = localCursor;
|
}
|
catch (Exception e)
|
{
|
closeLockedCursor(localCursor);
|
|
if (localTxn != null)
|
{
|
try
|
{
|
localTxn.abort();
|
}
|
catch (DatabaseException ignore)
|
{
|
// Ignore.
|
}
|
}
|
throw e;
|
}
|
}
|
|
/**
|
* Close the ReplicationServer Cursor.
|
*/
|
public void close()
|
{
|
synchronized (this)
|
{
|
if (isClosed)
|
{
|
return;
|
}
|
isClosed = true;
|
}
|
|
closeLockedCursor(cursor);
|
if (txn != null)
|
{
|
try
|
{
|
// No need for durability when purging.
|
txn.commit(Durability.COMMIT_NO_SYNC);
|
}
|
catch (DatabaseException e)
|
{
|
replicationServer.handleUnexpectedDatabaseException(e);
|
}
|
}
|
}
|
|
/**
|
* Abort the Cursor after a Deadlock Exception.
|
* This method catch and ignore the DeadlockException because
|
* this must be done when aborting a cursor after a DeadlockException
|
* (per the Cursor documentation).
|
* This should not be used in any other case.
|
*/
|
public void abort()
|
{
|
synchronized (this)
|
{
|
if (isClosed)
|
{
|
return;
|
}
|
isClosed = true;
|
}
|
|
closeLockedCursor(cursor);
|
|
if (txn != null)
|
{
|
try
|
{
|
txn.abort();
|
}
|
catch (DatabaseException e)
|
{
|
replicationServer.handleUnexpectedDatabaseException(e);
|
}
|
}
|
}
|
|
/**
|
* Get the next ChangeNumber in the database from this Cursor.
|
*
|
* @return The next ChangeNumber in the database from this cursor.
|
* @throws DatabaseException In case of underlying database problem.
|
*/
|
public ChangeNumber nextChangeNumber() throws DatabaseException
|
{
|
if (isClosed)
|
{
|
return null;
|
}
|
|
OperationStatus status = cursor.getNext(key, data, LockMode.DEFAULT);
|
|
if (status != OperationStatus.SUCCESS)
|
{
|
return null;
|
}
|
String csnString = decodeUTF8(key.getData());
|
return new ChangeNumber(csnString);
|
}
|
|
/**
|
* Get the next UpdateMsg from this cursor.
|
*
|
* @return the next UpdateMsg.
|
*/
|
public UpdateMsg next()
|
{
|
if (isClosed)
|
{
|
return null;
|
}
|
|
UpdateMsg currentChange = null;
|
while (currentChange == null)
|
{
|
try
|
{
|
OperationStatus status = cursor.getNext(key, data, LockMode.DEFAULT);
|
if (status != OperationStatus.SUCCESS)
|
{
|
return null;
|
}
|
} catch (DatabaseException e)
|
{
|
return null;
|
}
|
|
ChangeNumber cn = null;
|
try
|
{
|
cn = new ChangeNumber(
|
decodeUTF8(key.getData()));
|
if (ReplicationDB.isaCounter(cn))
|
{
|
// counter record
|
continue;
|
}
|
currentChange = ReplicationData.generateChange(data
|
.getData());
|
}
|
catch (Exception e)
|
{
|
/*
|
* An error happening trying to convert the data from the
|
* replicationServer database to an Update Message. This can only
|
* happen if the database is corrupted. There is not much more that we
|
* can do at this point except trying to continue with the next
|
* record. In such case, it is therefore possible that we miss some
|
* changes.
|
* TODO : This should be handled by the repair functionality.
|
*/
|
Message message = ERR_REPLICATIONDB_CANNOT_PROCESS_CHANGE_RECORD
|
.get(replicationServer.getServerId(),
|
(cn == null ? "" : cn.toString()),
|
e.getMessage());
|
logError(message);
|
}
|
}
|
return currentChange;
|
}
|
|
/**
|
* Delete the record at the current cursor position.
|
*
|
* @throws DatabaseException In case of database problem.
|
*/
|
public void delete() throws DatabaseException
|
{
|
if (isClosed)
|
{
|
throw new IllegalStateException("ReplServerDBCursor already closed");
|
}
|
|
cursor.delete();
|
}
|
} // ReplServerDBCursor
|
|
/**
|
* Clears this change DB from the changes it contains.
|
*
|
* @throws Exception Throws an exception it occurs.
|
* @throws DatabaseException Throws a DatabaseException when it occurs.
|
*/
|
public void clear() throws Exception, DatabaseException
|
{
|
// The coming users will be blocked until the clear is done
|
dbCloseLock.writeLock().lock();
|
try
|
{
|
// If the DB has been closed then return immediately.
|
if (isDBClosed())
|
{
|
return;
|
}
|
|
String dbName = db.getDatabaseName();
|
|
// Clears the reference to this serverID
|
dbenv.clearServerId(baseDn, serverId);
|
|
// Closing is requested by the Berkeley DB before truncate
|
db.close();
|
db = null; // In case there's a failure between here and recreation.
|
|
// Clears the changes
|
dbenv.clearDb(dbName);
|
|
// RE-create the db
|
db = dbenv.getOrAddDb(serverId, baseDn, (long)-1);
|
}
|
catch(Exception e)
|
{
|
MessageBuilder mb = new MessageBuilder();
|
mb.append(ERR_ERROR_CLEARING_DB.get(this.toString(),
|
e.getMessage() + " " +
|
stackTraceToSingleLineString(e)));
|
logError(mb.toMessage());
|
}
|
finally
|
{
|
// Relax the waiting users
|
dbCloseLock.writeLock().unlock();
|
}
|
}
|
/**
|
* Count the number of changes between 2 changes numbers (inclusive).
|
* @param start The lower limit of the count.
|
* @param stop The higher limit of the count.
|
* @return The number of changes between provided start and stop changeNumber.
|
* Returns 0 when an error occurs.
|
*/
|
public int count(ChangeNumber start, ChangeNumber stop)
|
{
|
int counterRecord1 = 0;
|
int counterRecord2 = 0;
|
int distToCounterRecord1 = 0;
|
int distBackToCounterRecord2 = 0;
|
int count=0;
|
OperationStatus status;
|
|
try
|
{
|
dbCloseLock.readLock().lock();
|
|
Cursor cursor = null;
|
try
|
{
|
// If the DB has been closed then return immediately.
|
if (isDBClosed())
|
{
|
return 0;
|
}
|
|
ChangeNumber cn ;
|
|
if ((start==null)&&(stop==null))
|
return (int)db.count();
|
|
// Step 1 : from the start point, traverse db to the next counter record
|
// or to the stop point.
|
DatabaseEntry key = new DatabaseEntry();
|
DatabaseEntry data = new DatabaseEntry();
|
cursor = db.openCursor(null, null);
|
if (start != null)
|
{
|
key = new ReplicationKey(start);
|
status = cursor.getSearchKey(key, data, LockMode.DEFAULT);
|
if (status == OperationStatus.NOTFOUND)
|
status = cursor.getSearchKeyRange(key, data, LockMode.DEFAULT);
|
}
|
else
|
{
|
status = cursor.getNext(key, data, LockMode.DEFAULT);
|
}
|
|
while (status == OperationStatus.SUCCESS)
|
{
|
// test whether the record is a regular change or a counter
|
String csnString = decodeUTF8(key.getData());
|
cn = new ChangeNumber(csnString);
|
if (cn.getServerId() != 0)
|
{
|
// reached a regular change record
|
// test whether we reached the 'stop' target
|
if (!cn.newer(stop))
|
{
|
// let's loop
|
distToCounterRecord1++;
|
status = cursor.getNext(key, data, LockMode.DEFAULT);
|
}
|
else
|
{
|
// reached the end
|
break;
|
}
|
}
|
else
|
{
|
// counter record
|
counterRecord1 = decodeCounterValue(data.getData());
|
break;
|
}
|
}
|
cursor.close();
|
|
// cases
|
//
|
if (counterRecord1==0)
|
return distToCounterRecord1;
|
|
// Step 2 : from the stop point, traverse db to the next counter record
|
// or to the start point.
|
data = new DatabaseEntry();
|
key = new ReplicationKey(stop);
|
cursor = db.openCursor(null, null);
|
status = cursor.getSearchKey(key, data, LockMode.DEFAULT);
|
if (status == OperationStatus.SUCCESS)
|
{
|
cn = new ChangeNumber(decodeUTF8(key.getData()));
|
}
|
else
|
{
|
key = new DatabaseEntry();
|
data = new DatabaseEntry();
|
status = cursor.getLast(key, data, LockMode.DEFAULT);
|
if (status != OperationStatus.SUCCESS)
|
{
|
/* database is empty */
|
return 0;
|
}
|
}
|
while (status == OperationStatus.SUCCESS)
|
{
|
cn = new ChangeNumber(decodeUTF8(key.getData()));
|
if (!ReplicationDB.isaCounter(cn))
|
{
|
// regular change record
|
if (!cn.older(start))
|
{
|
distBackToCounterRecord2++;
|
status = cursor.getPrev(key, data, LockMode.DEFAULT);
|
}
|
else
|
break;
|
}
|
else
|
{
|
// counter record
|
counterRecord2 = decodeCounterValue(data.getData());
|
break;
|
}
|
}
|
cursor.close();
|
|
// Step 3 : Now consolidates the result
|
if (counterRecord1!=0)
|
{
|
if (counterRecord1 == counterRecord2)
|
{
|
// only one cp between from and to - no need to use it
|
count = distToCounterRecord1 + distBackToCounterRecord2;
|
}
|
else
|
{
|
// 2 cp between from and to
|
count = distToCounterRecord1 + (counterRecord2-counterRecord1)
|
+ distBackToCounterRecord2;
|
}
|
}
|
}
|
finally
|
{
|
closeLockedCursor(cursor);
|
}
|
}
|
catch (DatabaseException e)
|
{
|
replicationServer.handleUnexpectedDatabaseException(e);
|
}
|
return count;
|
}
|
|
/**
|
* Test if a provided changeNumber represents a counter record.
|
* @param cn The provided changeNumber.
|
* @return True if the provided changenumber is a counter.
|
*/
|
static private boolean isaCounter(ChangeNumber cn)
|
{
|
return ((cn.getServerId()== 0) && (cn.getSeqnum()==0));
|
}
|
|
/**
|
* Decode the provided database entry as a the value of a counter.
|
* @param entry The provided entry.
|
* @return The counter value.
|
*/
|
private static int decodeCounterValue(byte[] entry)
|
{
|
String numAckStr = decodeUTF8(entry);
|
return Integer.parseInt(numAckStr);
|
}
|
|
/**
|
* Encode the provided counter value in a database entry.
|
* @return The database entry with the counter value encoded inside.
|
*/
|
static private DatabaseEntry encodeCounterValue(int value)
|
{
|
DatabaseEntry entry = new DatabaseEntry();
|
entry.setData(getBytes(String.valueOf(value)));
|
return entry;
|
}
|
|
/**
|
* Set the counter writing window size (public method for unit tests only).
|
* @param size Size in number of record.
|
*/
|
public void setCounterWindowSize(int size)
|
{
|
this.counterWindowSize = size;
|
}
|
|
|
|
// Returns {@code true} if the DB is closed. This method assumes that either
|
// the db read/write lock has been taken.
|
private boolean isDBClosed()
|
{
|
return db == null;
|
}
|
|
}
|
