/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License, Version 1.0 only
* (the "License"). You may not use this file except in compliance
* with the License.
*
* You can obtain a copy of the license at legal-notices/CDDLv1_0.txt
* or http://forgerock.org/license/CDDLv1.0.html.
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at legal-notices/CDDLv1_0.txt.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information:
* Portions Copyright [yyyy] [name of copyright owner]
*
* CDDL HEADER END
*
* Copyright 2014-2015 ForgeRock AS
*/
package org.opends.server.replication.server.changelog.file;
import java.util.concurrent.atomic.AtomicReference;
import org.opends.server.replication.common.CSN;
import org.opends.server.replication.protocol.ReplicaOfflineMsg;
import org.opends.server.replication.protocol.UpdateMsg;
import org.opends.server.replication.server.changelog.api.ChangelogException;
import org.opends.server.replication.server.changelog.api.DBCursor;
import org.opends.server.replication.server.changelog.api.ReplicaId;
import org.opends.server.replication.server.changelog.api.ReplicationDomainDB;
/**
* {@link DBCursor} over a replica returning {@link UpdateMsg}s.
* <p>
* It decorates an existing {@link DBCursor} on a replicaDB and can possibly
* return replica offline messages when the decorated DBCursor is exhausted and
* the offline CSN is newer than the last returned update CSN.
*/
public class ReplicaCursor implements DBCursor<UpdateMsg>
{
/** @NonNull */
private final DBCursor<UpdateMsg> cursor;
private final AtomicReference<ReplicaOfflineMsg> replicaOfflineMsg = new AtomicReference<>();
private UpdateMsg currentRecord;
private final ReplicaId replicaId;
private final ReplicationDomainDB domainDB;
/**
* Creates a ReplicaCursor object with a cursor to decorate
* and an offlineCSN to return as part of a ReplicaOfflineMsg.
*
* @param cursor
* the non-null underlying cursor that needs to be exhausted before
* we return a ReplicaOfflineMsg
* @param offlineCSN
* the offline CSN from which to builder the
* {@link ReplicaOfflineMsg} to return
* @param replicaId
* the replica identifier
* @param domainDB
* the DB for the provided replication domain
*/
public ReplicaCursor(DBCursor<UpdateMsg> cursor, CSN offlineCSN, ReplicaId replicaId, ReplicationDomainDB domainDB)
{
this.cursor = cursor;
this.replicaId = replicaId;
this.domainDB = domainDB;
setOfflineCSN(offlineCSN);
}
/**
* Sets the offline CSN to be returned by this cursor.
*
* @param offlineCSN
* The offline CSN to be returned by this cursor.
* If null, it will unset any previous offlineCSN and never return a ReplicaOfflineMsg
*/
public void setOfflineCSN(CSN offlineCSN)
{
this.replicaOfflineMsg.set(
offlineCSN != null ? new ReplicaOfflineMsg(offlineCSN) : null);
}
/** {@inheritDoc} */
@Override
public UpdateMsg getRecord()
{
return currentRecord;
}
/**
* Returns the replica identifier that this cursor is associated to.
*
* @return the replica identifier that this cursor is associated to
*/
public ReplicaId getReplicaId()
{
return replicaId;
}
/** {@inheritDoc} */
@Override
public boolean next() throws ChangelogException
{
final ReplicaOfflineMsg offlineMsg1 = replicaOfflineMsg.get();
if (isReplicaOfflineMsgOutdated(offlineMsg1, currentRecord))
{
replicaOfflineMsg.compareAndSet(offlineMsg1, null);
}
// now verify if new changes have been added to the DB
// (cursors are automatically restarted)
final UpdateMsg lastUpdate = cursor.getRecord();
final boolean hasNext = cursor.next();
if (hasNext)
{
currentRecord = cursor.getRecord();
return true;
}
// replicaDB just happened to be exhausted now
final ReplicaOfflineMsg offlineMsg2 = replicaOfflineMsg.get();
if (isReplicaOfflineMsgOutdated(offlineMsg2, lastUpdate))
{
replicaOfflineMsg.compareAndSet(offlineMsg2, null);
currentRecord = null;
return false;
}
currentRecord = offlineMsg2;
return currentRecord != null;
}
/** It could also mean that the replica offline message has already been consumed. */
private boolean isReplicaOfflineMsgOutdated(
final ReplicaOfflineMsg offlineMsg, final UpdateMsg updateMsg)
{
return offlineMsg != null
&& updateMsg != null
&& offlineMsg.getCSN().isOlderThanOrEqualTo(updateMsg.getCSN());
}
/** {@inheritDoc} */
@Override
public void close()
{
cursor.close();
domainDB.unregisterCursor(this);
}
/** {@inheritDoc} */
@Override
public String toString()
{
final ReplicaOfflineMsg msg = replicaOfflineMsg.get();
return getClass().getSimpleName()
+ " currentRecord=" + currentRecord
+ " offlineCSN=" + (msg != null ? msg.getCSN().toStringUI() : null)
+ " cursor=" + cursor.toString().split("", 2)[1];
}
}