/*
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* The contents of this file are subject to the terms of the Common Development and
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* Distribution License (the License). You may not use this file except in compliance with the
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* License.
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*
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* You can obtain a copy of the License at legal/CDDLv1.0.txt. See the License for the
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* specific language governing permission and limitations under the License.
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*
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* When distributing Covered Software, include this CDDL Header Notice in each file and include
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* the License file at legal/CDDLv1.0.txt. If applicable, add the following below the CDDL
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* Header, with the fields enclosed by brackets [] replaced by your own identifying
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* information: "Portions Copyright [year] [name of copyright owner]".
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*
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* Copyright 2006-2010 Sun Microsystems, Inc.
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* Portions Copyright 2011-2016 ForgeRock AS.
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*/
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package org.opends.server.replication.common;
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import java.io.IOException;
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import java.util.ArrayList;
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import java.util.Collections;
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import java.util.Date;
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import java.util.HashMap;
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import java.util.HashSet;
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import java.util.Iterator;
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import java.util.List;
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import java.util.Map;
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import java.util.Set;
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import java.util.concurrent.ConcurrentMap;
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import java.util.concurrent.ConcurrentSkipListMap;
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import org.forgerock.opendj.io.ASN1Writer;
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import org.forgerock.opendj.ldap.ByteString;
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import org.opends.server.replication.protocol.ProtocolVersion;
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/**
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* This class is used to associate serverIds with {@link CSN}s.
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* <p>
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* For example, it is exchanged with the replication servers at connection
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* establishment time to communicate "which CSNs was last seen by a serverId".
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*/
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public class ServerState implements Iterable<CSN>
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{
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/** Associates a serverId with a CSN. */
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private final ConcurrentMap<Integer, CSN> serverIdToCSN = new ConcurrentSkipListMap<>();
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/**
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* Whether the state has been saved to persistent storage. It starts at true,
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* and moves to false when an update is made to the current object.
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*/
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private volatile boolean saved = true;
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/** Creates a new empty ServerState. */
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public ServerState()
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{
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super();
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}
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/**
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* Empty the ServerState.
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* After this call the Server State will be in the same state
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* as if it was just created.
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*/
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public void clear()
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{
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serverIdToCSN.clear();
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}
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/**
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* Forward update the Server State with a CSN. The provided CSN will be put on
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* the current object only if it is newer than the existing CSN for the same
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* serverId or if there is no existing CSN.
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*
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* @param csn
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* The committed CSN.
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* @return a boolean indicating if the update was meaningful.
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*/
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public boolean update(CSN csn)
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{
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if (csn == null)
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{
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return false;
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}
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saved = false;
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final int serverId = csn.getServerId();
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while (true)
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{
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final CSN existingCSN = serverIdToCSN.get(serverId);
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if (existingCSN == null)
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{
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if (serverIdToCSN.putIfAbsent(serverId, csn) == null)
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{
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return true;
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}
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// oops, a concurrent modification happened, run the same process again
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continue;
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}
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else if (csn.isNewerThan(existingCSN))
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{
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if (serverIdToCSN.replace(serverId, existingCSN, csn))
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{
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return true;
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}
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// oops, a concurrent modification happened, run the same process again
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continue;
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}
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return false;
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}
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}
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/**
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* Update the Server State with a Server State. Every CSN of this object is
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* updated with the CSN of the passed server state if it is newer.
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*
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* @param serverState the server state to use for the update.
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* @return a boolean indicating if the update was meaningful.
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*/
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public boolean update(ServerState serverState)
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{
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if (serverState == null)
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{
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return false;
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}
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boolean updated = false;
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for (CSN csn : serverState.serverIdToCSN.values())
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{
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if (update(csn))
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{
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updated = true;
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}
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}
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return updated;
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}
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/**
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* Removes the mapping to the provided CSN if it is present in this
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* ServerState.
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*
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* @param expectedCSN
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* the CSN to be removed
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* @return true if the CSN could be removed, false otherwise.
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*/
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public boolean removeCSN(CSN expectedCSN)
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{
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if (expectedCSN == null)
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{
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return false;
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}
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if (serverIdToCSN.remove(expectedCSN.getServerId(), expectedCSN))
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{
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saved = false;
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return true;
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}
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return false;
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}
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/**
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* Return a Set of String usable as a textual representation of
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* a Server state.
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* format : time seqnum id
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*
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* example :
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* 1 00000109e4666da600220001
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* 2 00000109e44567a600220002
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*
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* @return the representation of the Server state
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*/
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public Set<String> toStringSet()
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{
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final Set<String> result = new HashSet<>();
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for (CSN change : serverIdToCSN.values())
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{
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Date date = new Date(change.getTime());
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result.add(change + " " + date + " " + change.getTime());
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}
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return result;
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}
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/**
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* Return an ArrayList of ANS1OctetString encoding the CSNs
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* contained in the ServerState.
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* @return an ArrayList of ANS1OctetString encoding the CSNs
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* contained in the ServerState.
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*/
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public ArrayList<ByteString> toASN1ArrayList()
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{
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final ArrayList<ByteString> values = new ArrayList<>(0);
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for (CSN csn : serverIdToCSN.values())
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{
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values.add(ByteString.valueOfUtf8(csn.toString()));
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}
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return values;
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}
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/**
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* Encodes this server state to the provided ASN1 writer.
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*
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* @param writer
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* The ASN1 writer.
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* @param protocolVersion
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* The replication protocol version.
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* @throws IOException
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* If an error occurred during encoding.
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*/
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public void writeTo(ASN1Writer writer, short protocolVersion)
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throws IOException
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{
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if (protocolVersion >= ProtocolVersion.REPLICATION_PROTOCOL_V7)
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{
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for (CSN csn : serverIdToCSN.values())
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{
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writer.writeOctetString(csn.toByteString());
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}
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}
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else
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{
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for (CSN csn : serverIdToCSN.values())
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{
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writer.writeOctetString(csn.toString());
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}
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}
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}
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/**
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* Returns a snapshot of this object.
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*
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* @return an unmodifiable List representing a snapshot of this object.
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*/
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public List<CSN> getSnapshot()
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{
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if (serverIdToCSN.isEmpty())
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{
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return Collections.emptyList();
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}
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return Collections.unmodifiableList(new ArrayList<CSN>(serverIdToCSN.values()));
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}
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/**
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* Return the text representation of ServerState.
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* @return the text representation of ServerState
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*/
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@Override
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public String toString()
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{
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final StringBuilder buffer = new StringBuilder();
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toString(buffer);
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return buffer.toString();
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}
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/**
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* Appends the text representation of ServerState.
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* @param buffer The buffer to which the information should be appended.
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*/
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void toString(final StringBuilder buffer)
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{
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boolean first = true;
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for (CSN csn : serverIdToCSN.values())
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{
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if (!first)
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{
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buffer.append(" ");
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}
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csn.toString(buffer);
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first = false;
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}
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}
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/**
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* Returns the {@code CSN} contained in this server state which corresponds to
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* the provided server ID.
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*
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* @param serverId
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* The server ID.
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* @return The {@code CSN} contained in this server state which
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* corresponds to the provided server ID.
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*/
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public CSN getCSN(int serverId)
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{
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return serverIdToCSN.get(serverId);
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}
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/**
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* Returns a copy of this ServerState's content as a Map of serverId => CSN.
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*
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* @return a copy of this ServerState's content as a Map of serverId => CSN.
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*/
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public Map<Integer, CSN> getServerIdToCSNMap()
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{
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// copy to protect from concurrent updates
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// that could change the number of elements in the Map
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return new HashMap<>(serverIdToCSN);
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}
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@Override
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public Iterator<CSN> iterator()
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{
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return serverIdToCSN.values().iterator();
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}
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/**
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* Check that all the CSNs in the covered serverState are also in this
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* serverState.
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*
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* @param covered The ServerState that needs to be checked.
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* @return A boolean indicating if this ServerState covers the ServerState
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* given in parameter.
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*/
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public boolean cover(ServerState covered)
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{
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for (CSN coveredChange : covered.serverIdToCSN.values())
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{
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if (!cover(coveredChange))
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{
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return false;
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}
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}
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return true;
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}
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/**
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* Checks that the CSN given as a parameter is in this ServerState.
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*
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* @param covered The CSN that should be checked.
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* @return A boolean indicating if this ServerState contains the CSN given in
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* parameter.
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*/
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public boolean cover(CSN covered)
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{
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final CSN csn = this.serverIdToCSN.get(covered.getServerId());
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return csn != null && !csn.isOlderThan(covered);
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}
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/**
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* Tests if the state is empty.
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*
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* @return True if the state is empty.
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*/
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public boolean isEmpty()
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{
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return serverIdToCSN.isEmpty();
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}
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/**
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* Make a duplicate of this state.
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* @return The duplicate of this state.
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*/
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public ServerState duplicate()
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{
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final ServerState newState = new ServerState();
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newState.serverIdToCSN.putAll(serverIdToCSN);
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return newState;
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}
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/**
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* Computes the number of changes a first server state has in advance
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* compared to a second server state.
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* @param ss1 The server state supposed to be newer than the second one
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* @param ss2 The server state supposed to be older than the first one
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* @return The difference of changes (sum of the differences for each server
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* id changes). 0 If no gap between 2 states.
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* @throws IllegalArgumentException If one of the passed state is null
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*/
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public static int diffChanges(ServerState ss1, ServerState ss2)
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throws IllegalArgumentException
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{
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if (ss1 == null || ss2 == null)
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{
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throw new IllegalArgumentException("Null server state(s)");
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}
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int diff = 0;
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for (Map.Entry<Integer, CSN> entry : ss1.serverIdToCSN.entrySet())
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{
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Integer serverId = entry.getKey();
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CSN csn1 = entry.getValue();
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if (csn1 != null)
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{
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CSN csn2 = ss2.serverIdToCSN.get(serverId);
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if (csn2 != null)
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{
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diff += CSN.diffSeqNum(csn1, csn2);
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}
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else
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{
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// ss2 does not have a change for this server id but ss1, so the
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// server holding ss1 has every changes represented in csn1 in advance
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// compared to server holding ss2, add this amount
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diff += csn1.getSeqnum();
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}
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}
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}
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return diff;
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}
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/**
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* Set the saved status of this ServerState.
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*
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* @param b A boolean indicating if the State has been safely stored.
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*/
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public void setSaved(boolean b)
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{
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saved = b;
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}
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/**
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* Get the saved status of this ServerState.
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*
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* @return The saved status of this ServerState.
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*/
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public boolean isSaved()
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{
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return saved;
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}
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}
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