/*
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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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* Copyright 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.concurrent.atomic.AtomicReference;
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import org.opends.server.replication.common.CSN;
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import org.opends.server.replication.protocol.ReplicaOfflineMsg;
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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.replication.server.changelog.api.ReplicationDomainDB;
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import org.opends.server.types.DN;
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import com.forgerock.opendj.util.Pair;
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/**
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* {@link DBCursor} over a replica returning {@link UpdateMsg}s.
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* <p>
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* It decorates an existing {@link DBCursor} on a replicaDB and can possibly
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* return replica offline messages when the decorated DBCursor is exhausted and
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* the offline CSN is newer than the last returned update CSN.
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*/
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public class ReplicaCursor implements DBCursor<UpdateMsg>
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{
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/** @NonNull */
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private final DBCursor<UpdateMsg> cursor;
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private final AtomicReference<ReplicaOfflineMsg> replicaOfflineMsg =
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new AtomicReference<ReplicaOfflineMsg>();
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private UpdateMsg currentRecord;
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private final Pair<DN, Integer> replicaID;
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private final ReplicationDomainDB domainDB;
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/**
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* Creates a ReplicaCursor object with a cursor to decorate
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* and an offlineCSN to return as part of a ReplicaOfflineMsg.
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*
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* @param cursor
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* the non-null underlying cursor that needs to be exhausted before
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* we return a ReplicaOfflineMsg
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* @param offlineCSN
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* the offline CSN from which to builder the
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* {@link ReplicaOfflineMsg} to return
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* @param replicaID
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* the baseDN => serverId pair to uniquely identify the replica
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* @param domainDB
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* the DB for the provided replication domain
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*/
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public ReplicaCursor(DBCursor<UpdateMsg> cursor, CSN offlineCSN,
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Pair<DN, Integer> replicaID, ReplicationDomainDB domainDB)
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{
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this.cursor = cursor;
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this.replicaID = replicaID;
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this.domainDB = domainDB;
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setOfflineCSN(offlineCSN);
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}
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/**
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* Sets the offline CSN to be returned by this cursor.
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*
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* @param offlineCSN
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* The offline CSN to be returned by this cursor.
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* If null, it will unset any previous offlineCSN and never return a ReplicaOfflineMsg
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*/
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public void setOfflineCSN(CSN offlineCSN)
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{
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this.replicaOfflineMsg.set(
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offlineCSN != null ? new ReplicaOfflineMsg(offlineCSN) : null);
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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 currentRecord;
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}
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/**
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* Returns the replica identifier that this cursor is associated to.
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*
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* @return the replica identifier that this cursor is associated to
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*/
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public Pair<DN, Integer> getReplicaID()
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{
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return replicaID;
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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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final ReplicaOfflineMsg offlineMsg1 = replicaOfflineMsg.get();
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if (isReplicaOfflineMsgOutdated(offlineMsg1, currentRecord))
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{
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replicaOfflineMsg.compareAndSet(offlineMsg1, null);
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}
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// now verify if new changes have been added to the DB
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// (cursors are automatically restarted)
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final UpdateMsg lastUpdate = cursor.getRecord();
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final boolean hasNext = cursor.next();
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if (hasNext)
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{
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currentRecord = cursor.getRecord();
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return true;
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}
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// replicaDB just happened to be exhausted now
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final ReplicaOfflineMsg offlineMsg2 = replicaOfflineMsg.get();
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if (isReplicaOfflineMsgOutdated(offlineMsg2, lastUpdate))
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{
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replicaOfflineMsg.compareAndSet(offlineMsg2, null);
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currentRecord = null;
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return false;
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}
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currentRecord = offlineMsg2;
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return currentRecord != null;
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}
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/** It could also mean that the replica offline message has already been consumed. */
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private boolean isReplicaOfflineMsgOutdated(
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final ReplicaOfflineMsg offlineMsg, final UpdateMsg updateMsg)
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{
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return offlineMsg != null
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&& updateMsg != null
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&& offlineMsg.getCSN().isOlderThanOrEqualTo(updateMsg.getCSN());
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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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cursor.close();
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domainDB.unregisterCursor(this);
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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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final ReplicaOfflineMsg msg = replicaOfflineMsg.get();
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return getClass().getSimpleName()
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+ " currentRecord=" + currentRecord
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+ " offlineCSN=" + (msg != null ? msg.getCSN().toStringUI() : null)
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+ " cursor=" + cursor.toString().split("", 2)[1];
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}
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}
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