/*
* 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 2006-2010 Sun Microsystems, Inc.
* Portions Copyright 2011-2015 ForgeRock AS
*/
package org.opends.server.replication.common;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Date;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.ConcurrentMap;
import java.util.concurrent.ConcurrentSkipListMap;
import org.forgerock.opendj.io.ASN1Writer;
import org.forgerock.opendj.ldap.ByteString;
import org.opends.server.replication.protocol.ProtocolVersion;
/**
* This class is used to associate serverIds with {@link CSN}s.
* <p>
* For example, it is exchanged with the replication servers at connection
* establishment time to communicate "which CSNs was last seen by a serverId".
*/
public class ServerState implements Iterable<CSN>
{
/** Associates a serverId with a CSN. */
private final ConcurrentMap<Integer, CSN> serverIdToCSN = new ConcurrentSkipListMap<>();
/**
* Whether the state has been saved to persistent storage. It starts at true,
* and moves to false when an update is made to the current object.
*/
private volatile boolean saved = true;
/**
* Creates a new empty ServerState.
*/
public ServerState()
{
super();
}
/**
* Empty the ServerState.
* After this call the Server State will be in the same state
* as if it was just created.
*/
public void clear()
{
serverIdToCSN.clear();
}
/**
* Forward update the Server State with a CSN. The provided CSN will be put on
* the current object only if it is newer than the existing CSN for the same
* serverId or if there is no existing CSN.
*
* @param csn
* The committed CSN.
* @return a boolean indicating if the update was meaningful.
*/
public boolean update(CSN csn)
{
if (csn == null)
{
return false;
}
saved = false;
final int serverId = csn.getServerId();
while (true)
{
final CSN existingCSN = serverIdToCSN.get(serverId);
if (existingCSN == null)
{
if (serverIdToCSN.putIfAbsent(serverId, csn) == null)
{
return true;
}
// oops, a concurrent modification happened, run the same process again
continue;
}
else if (csn.isNewerThan(existingCSN))
{
if (serverIdToCSN.replace(serverId, existingCSN, csn))
{
return true;
}
// oops, a concurrent modification happened, run the same process again
continue;
}
return false;
}
}
/**
* Update the Server State with a Server State. Every CSN of this object is
* updated with the CSN of the passed server state if it is newer.
*
* @param serverState the server state to use for the update.
* @return a boolean indicating if the update was meaningful.
*/
public boolean update(ServerState serverState)
{
if (serverState == null)
{
return false;
}
boolean updated = false;
for (CSN csn : serverState.serverIdToCSN.values())
{
if (update(csn))
{
updated = true;
}
}
return updated;
}
/**
* Removes the mapping to the provided CSN if it is present in this
* ServerState.
*
* @param expectedCSN
* the CSN to be removed
* @return true if the CSN could be removed, false otherwise.
*/
public boolean removeCSN(CSN expectedCSN)
{
if (expectedCSN == null)
{
return false;
}
if (serverIdToCSN.remove(expectedCSN.getServerId(), expectedCSN))
{
saved = false;
return true;
}
return false;
}
/**
* Replace the Server State with another ServerState.
*
* @param serverState The ServerState.
*
* @return a boolean indicating if the update was meaningful.
*/
public boolean reload(ServerState serverState) {
if (serverState == null) {
return false;
}
clear();
return update(serverState);
}
/**
* Return a Set of String usable as a textual representation of
* a Server state.
* format : time seqnum id
*
* example :
* 1 00000109e4666da600220001
* 2 00000109e44567a600220002
*
* @return the representation of the Server state
*/
public Set<String> toStringSet()
{
final Set<String> result = new HashSet<>();
for (CSN change : serverIdToCSN.values())
{
Date date = new Date(change.getTime());
result.add(change + " " + date + " " + change.getTime());
}
return result;
}
/**
* Return an ArrayList of ANS1OctetString encoding the CSNs
* contained in the ServerState.
* @return an ArrayList of ANS1OctetString encoding the CSNs
* contained in the ServerState.
*/
public ArrayList<ByteString> toASN1ArrayList()
{
final ArrayList<ByteString> values = new ArrayList<>(0);
for (CSN csn : serverIdToCSN.values())
{
values.add(ByteString.valueOfUtf8(csn.toString()));
}
return values;
}
/**
* Encodes this server state to the provided ASN1 writer.
*
* @param writer
* The ASN1 writer.
* @param protocolVersion
* The replication protocol version.
* @throws IOException
* If an error occurred during encoding.
*/
public void writeTo(ASN1Writer writer, short protocolVersion)
throws IOException
{
if (protocolVersion >= ProtocolVersion.REPLICATION_PROTOCOL_V7)
{
for (CSN csn : serverIdToCSN.values())
{
writer.writeOctetString(csn.toByteString());
}
}
else
{
for (CSN csn : serverIdToCSN.values())
{
writer.writeOctetString(csn.toString());
}
}
}
/**
* Returns a snapshot of this object.
*
* @return an unmodifiable List representing a snapshot of this object.
*/
public List<CSN> getSnapshot()
{
if (serverIdToCSN.isEmpty())
{
return Collections.emptyList();
}
return Collections.unmodifiableList(new ArrayList<CSN>(serverIdToCSN.values()));
}
/**
* Return the text representation of ServerState.
* @return the text representation of ServerState
*/
@Override
public String toString()
{
final StringBuilder buffer = new StringBuilder();
toString(buffer);
return buffer.toString();
}
/**
* Appends the text representation of ServerState.
* @param buffer The buffer to which the information should be appended.
*/
void toString(final StringBuilder buffer)
{
boolean first = true;
for (CSN csn : serverIdToCSN.values())
{
if (!first)
{
buffer.append(" ");
}
csn.toString(buffer);
first = false;
}
}
/**
* Returns the {@code CSN} contained in this server state which corresponds to
* the provided server ID.
*
* @param serverId
* The server ID.
* @return The {@code CSN} contained in this server state which
* corresponds to the provided server ID.
*/
public CSN getCSN(int serverId)
{
return serverIdToCSN.get(serverId);
}
/**
* Returns a copy of this ServerState's content as a Map of serverId => CSN.
*
* @return a copy of this ServerState's content as a Map of serverId => CSN.
*/
public Map<Integer, CSN> getServerIdToCSNMap()
{
// copy to protect from concurrent updates
// that could change the number of elements in the Map
return new HashMap<>(serverIdToCSN);
}
/** {@inheritDoc} */
@Override
public Iterator<CSN> iterator()
{
return serverIdToCSN.values().iterator();
}
/**
* Check that all the CSNs in the covered serverState are also in this
* serverState.
*
* @param covered The ServerState that needs to be checked.
* @return A boolean indicating if this ServerState covers the ServerState
* given in parameter.
*/
public boolean cover(ServerState covered)
{
for (CSN coveredChange : covered.serverIdToCSN.values())
{
if (!cover(coveredChange))
{
return false;
}
}
return true;
}
/**
* Checks that the CSN given as a parameter is in this ServerState.
*
* @param covered The CSN that should be checked.
* @return A boolean indicating if this ServerState contains the CSN given in
* parameter.
*/
public boolean cover(CSN covered)
{
final CSN csn = this.serverIdToCSN.get(covered.getServerId());
return csn != null && !csn.isOlderThan(covered);
}
/**
* Tests if the state is empty.
*
* @return True if the state is empty.
*/
public boolean isEmpty()
{
return serverIdToCSN.isEmpty();
}
/**
* Make a duplicate of this state.
* @return The duplicate of this state.
*/
public ServerState duplicate()
{
final ServerState newState = new ServerState();
newState.serverIdToCSN.putAll(serverIdToCSN);
return newState;
}
/**
* Computes the number of changes a first server state has in advance
* compared to a second server state.
* @param ss1 The server state supposed to be newer than the second one
* @param ss2 The server state supposed to be older than the first one
* @return The difference of changes (sum of the differences for each server
* id changes). 0 If no gap between 2 states.
* @throws IllegalArgumentException If one of the passed state is null
*/
public static int diffChanges(ServerState ss1, ServerState ss2)
throws IllegalArgumentException
{
if (ss1 == null || ss2 == null)
{
throw new IllegalArgumentException("Null server state(s)");
}
int diff = 0;
for (Integer serverId : ss1.serverIdToCSN.keySet())
{
CSN csn1 = ss1.serverIdToCSN.get(serverId);
if (csn1 != null)
{
CSN csn2 = ss2.serverIdToCSN.get(serverId);
if (csn2 != null)
{
diff += CSN.diffSeqNum(csn1, csn2);
}
else
{
// ss2 does not have a change for this server id but ss1, so the
// server holding ss1 has every changes represented in csn1 in advance
// compared to server holding ss2, add this amount
diff += csn1.getSeqnum();
}
}
}
return diff;
}
/**
* Set the saved status of this ServerState.
*
* @param b A boolean indicating if the State has been safely stored.
*/
public void setSaved(boolean b)
{
saved = b;
}
/**
* Get the saved status of this ServerState.
*
* @return The saved status of this ServerState.
*/
public boolean isSaved()
{
return saved;
}
}