/*
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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 2013 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.*;
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import org.opends.server.replication.common.CSN;
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import org.opends.server.replication.protocol.UpdateMsg;
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import org.opends.server.replication.server.changelog.api.ChangelogException;
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import org.opends.server.replication.server.changelog.api.DBCursor;
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import org.opends.server.util.StaticUtils;
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/**
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* {@link DBCursor} implementation that iterates across a Collection of
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* {@link DBCursor}s, advancing from the oldest to the newest change cross all
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* cursors.
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*/
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final class CompositeDBCursor implements DBCursor<UpdateMsg>
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{
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private UpdateMsg currentChange;
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private final List<DBCursor<UpdateMsg>> exhaustedCursors =
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new ArrayList<DBCursor<UpdateMsg>>();
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/**
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* The cursors are sorted based on the current change of each cursor to
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* consider the next change across all available cursors.
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*/
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private final NavigableSet<DBCursor<UpdateMsg>> cursors =
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new TreeSet<DBCursor<UpdateMsg>>(new Comparator<DBCursor<UpdateMsg>>()
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{
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@Override
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public int compare(DBCursor<UpdateMsg> o1, DBCursor<UpdateMsg> o2)
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{
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final CSN csn1 = o1.getRecord().getCSN();
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final CSN csn2 = o2.getRecord().getCSN();
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return CSN.compare(csn1, csn2);
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}
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});
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/**
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* Builds a CompositeDBCursor using the provided collection of cursors.
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*
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* @param cursors
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* the cursors that will be iterated upon.
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*/
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public CompositeDBCursor(Collection<DBCursor<UpdateMsg>> cursors)
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{
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for (DBCursor<UpdateMsg> cursor : cursors)
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{
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add(cursor);
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}
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}
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/** {@inheritDoc} */
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@Override
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public boolean next() throws ChangelogException
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{
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// try to recycle empty cursors in case the underlying ReplicaDBs received
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// new changes. Copy the List to avoid ConcurrentModificationExceptions.
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DBCursor<UpdateMsg>[] copy =
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exhaustedCursors.toArray(new DBCursor[exhaustedCursors.size()]);
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exhaustedCursors.clear();
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for (DBCursor<UpdateMsg> cursor : copy)
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{
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cursor.next();
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add(cursor);
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}
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if (cursors.isEmpty())
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{
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// no cursors are left with changes.
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currentChange = null;
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return false;
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}
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// To keep consistent the cursors' order in the SortedSet, it is necessary
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// to remove and eventually add again a cursor (after moving it forward).
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final DBCursor<UpdateMsg> cursor = cursors.pollFirst();
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currentChange = cursor.getRecord();
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cursor.next();
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add(cursor);
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return true;
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}
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private void add(DBCursor<UpdateMsg> cursor)
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{
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if (cursor.getRecord() != null)
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{
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this.cursors.add(cursor);
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}
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else
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{
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this.exhaustedCursors.add(cursor);
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}
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}
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/** {@inheritDoc} */
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@Override
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public UpdateMsg getRecord()
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{
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return currentChange;
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}
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/** {@inheritDoc} */
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@Override
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public void close()
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{
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StaticUtils.close(cursors);
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StaticUtils.close(exhaustedCursors);
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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() + " currentChange=" + currentChange
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+ " open cursors=" + cursors + " exhausted cursors=" + exhaustedCursors;
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}
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}
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