/*
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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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* Portions Copyright 2006 Sun Microsystems, Inc.
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*/
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package org.opends.server.changelog;
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import static org.opends.server.messages.MessageHandler.getMessage;
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import static org.opends.server.synchronization.SynchMessages.*;
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import static org.opends.server.loggers.Error.logError;
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import static org.opends.server.util.StaticUtils.stackTraceToSingleLineString;
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import com.sleepycat.je.DatabaseException;
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import org.opends.server.types.DN;
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import org.opends.server.types.ErrorLogCategory;
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import org.opends.server.types.ErrorLogSeverity;
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import org.opends.server.synchronization.AckMessage;
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import org.opends.server.synchronization.ChangeNumber;
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import org.opends.server.synchronization.ServerState;
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import org.opends.server.synchronization.UpdateMessage;
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import java.io.IOException;
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import java.util.HashSet;
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import java.util.LinkedHashSet;
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import java.util.Map;
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import java.util.Set;
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import java.util.concurrent.ConcurrentHashMap;
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/**
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* This class define an in-memory cache that will be used to store
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* the messages that have been received from an LDAP server or
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* from another changelog server and that should be forwarded to
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* other servers.
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*
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* The size of the cache is set by configuration.
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* If the cache becomes bigger than the configured size, the older messages
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* are removed and should they be needed again must be read from the backing
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* file
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*
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*
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* it runs a thread that is responsible for saving the messages
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* received to the disk and for trimming them
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* Decision to trim can be based on disk space or age of the message
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*/
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public class ChangelogCache
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{
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private Object flowControlLock = new Object();
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private DN baseDn = null;
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/*
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* The following map contains one balanced tree for each replica ID
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* to which we are currently publishing
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* the first update in the balanced tree is the next change that we
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* must push to this particular server
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*
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* We add new TreeSet in the HashMap when a new server register
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* to this changelog server.
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*
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*/
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private Map<Short, ServerHandler> connectedServers =
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new ConcurrentHashMap<Short, ServerHandler>();
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/*
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* This map contains one ServerHandler for each changelog servers
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* with which we are connected (so normally all the changelogs)
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* the first update in the balanced tree is the next change that we
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* must push to this particular server
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*
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* We add new TreeSet in the HashMap when a new changelog server register
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* to this changelog server.
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*/
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private Map<Short, ServerHandler> changelogServers =
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new ConcurrentHashMap<Short, ServerHandler>();
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/*
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* This map contains the List of updates received from each
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* LDAP server
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*/
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private Map<Short, DbHandler> sourceDbHandlers =
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new ConcurrentHashMap<Short, DbHandler>();
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/**
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* Creates a new ChangelogCache associated to the DN baseDn.
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*
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* @param baseDn The baseDn associated to the ChangelogCache.
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*/
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public ChangelogCache(DN baseDn)
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{
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this.baseDn = baseDn;
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}
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/**
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* Add an update that has been received to the list of
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* updates that must be forwarded to all other servers.
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*
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* @param update The update that has been received.
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* @param sourceHandler The ServerHandler for the server from which the
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* update was received
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* @throws IOException When an IO exception happens during the update
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* processing.
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*/
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public void put(UpdateMessage update, ServerHandler sourceHandler)
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throws IOException
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{
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/*
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* TODO : In case that the source server is a LDAP server this method
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* should check that change did get pushed to at least one
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* other changelog server before pushing it to the LDAP servers
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*/
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sourceHandler.updateServerState(update);
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sourceHandler.incrementInCount();
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if (update.isAssured())
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{
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int count = this.NumServers();
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if (count > 1)
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{
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if (sourceHandler.isChangelogServer())
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ServerHandler.addWaitingAck(update, sourceHandler.getServerId(),
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this, count - 1);
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else
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sourceHandler.addWaitingAck(update, count - 1);
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}
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else
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{
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sourceHandler.sendAck(update.getChangeNumber());
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}
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}
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// look for the dbHandler that is responsible for the master server which
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// generated the change.
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DbHandler dbHandler = null;
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synchronized (sourceDbHandlers)
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{
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short id = update.getChangeNumber().getServerId();
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dbHandler = sourceDbHandlers.get(id);
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if (dbHandler == null)
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{
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try
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{
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dbHandler = new DbHandler(id, baseDn);
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} catch (DatabaseException e)
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{
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/*
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* Because of database problem we can't save any more changes
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* from at least one LDAP server.
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* This changelog therefore can't do it's job properly anymore
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* and needs to close all its connections and shutdown itself.
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* TODO : log error
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*/
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int msgID = MSGID_CHANGELOG_SHUTDOWN_DATABASE_ERROR;
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String message = getMessage(msgID) + stackTraceToSingleLineString(e);
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logError(ErrorLogCategory.SYNCHRONIZATION,
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ErrorLogSeverity.SEVERE_ERROR,
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message, msgID);
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Changelog.shutdown();
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return;
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}
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sourceDbHandlers.put(id, dbHandler);
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}
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}
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// Publish the messages to the source handler
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dbHandler.add(update);
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/*
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* Push the message to the changelog servers
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*/
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HashSet<ServerHandler> saturatedHandler = new HashSet<ServerHandler>();
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if (!sourceHandler.isChangelogServer())
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{
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for (ServerHandler handler : changelogServers.values())
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{
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handler.add(update);
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if (handler.isSaturated(update.getChangeNumber(), sourceHandler))
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saturatedHandler.add(handler);
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}
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}
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/*
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* Push the message to the LDAP servers
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*/
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for (ServerHandler handler : connectedServers.values())
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{
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// don't forward the change to the server that just sent it
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if (handler == sourceHandler)
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{
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continue;
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}
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handler.add(update);
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if (handler.isSaturated(update.getChangeNumber(), sourceHandler))
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saturatedHandler.add(handler);
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}
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/*
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* Check if some flow control must be done.
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* Flow control is done by stopping the reader thread of this
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* server. The messages will therefore accumulate in the TCP socket
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* and will block the writer thread(s) on the other side.
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*/
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while (!saturatedHandler.isEmpty())
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{
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HashSet<ServerHandler> restartedHandler = new HashSet<ServerHandler>();
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for (ServerHandler handler : saturatedHandler)
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{
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if (handler.restartAfterSaturation(sourceHandler))
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{
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restartedHandler.add(handler);
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}
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}
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for (ServerHandler handler : restartedHandler)
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saturatedHandler.remove(handler);
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synchronized(flowControlLock)
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{
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if (!saturatedHandler.isEmpty())
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{
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try
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{
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flowControlLock.wait(100);
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} catch (Exception e)
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{
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// just loop
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}
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}
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}
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}
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}
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/**
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* Create initialize context necessary for finding the changes
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* that must be sent to a given LDAP or changelog server.
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*
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* @param handler handler for the server that must be started
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* @throws Exception when method has failed
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*/
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public void startServer(ServerHandler handler) throws Exception
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{
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/*
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* create the balanced tree that will be used to forward changes
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* TODO initialize it will all the previous changes that this replicaID
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* has not seen
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*/
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synchronized (connectedServers)
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{
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if (connectedServers.containsKey(handler.getServerId()))
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{
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/* TODO : handle error properly */
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throw new Exception("serverId already registered");
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}
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connectedServers.put(handler.getServerId(), handler);
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}
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}
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/**
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* Stop operations with a given server.
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*
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* @param handler the server for which we want to stop operations
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*/
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public void stopServer(ServerHandler handler)
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{
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handler.stopHandler();
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if (handler.isChangelogServer())
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changelogServers.remove(handler.getServerId());
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else
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connectedServers.remove(handler.getServerId());
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}
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/**
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* Create initialize context necessary for finding the changes
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* that must be sent to a given changelog server.
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*
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* @param handler the server ID to which we want to forward changes
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* @throws Exception in case of errors
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*/
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public void startChangelog(ServerHandler handler) throws Exception
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{
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/*
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* create the balanced tree that will be used to forward changes
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* TODO initialize it will all the previous changes that this replicaID
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* has not seen
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* TODO throw proper exception
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*/
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synchronized (changelogServers)
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{
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if (changelogServers.containsKey(handler.getServerId()))
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{
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throw new Exception("changelog Id already registered");
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}
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changelogServers.put(handler.getServerId(), handler);
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}
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}
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/**
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* Get the next update that need to be sent to a given LDAP server.
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* This call is blocking when no update is available or when dependencies
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* do not allow to send the next available change
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*
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* @param handler The server handler for the target directory server.
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*
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* @return the update that must be forwarded
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*/
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public UpdateMessage take(ServerHandler handler)
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{
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UpdateMessage msg;
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/*
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* Get the balanced tree that we use to sort the changes to be
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* sent to the replica from the cookie
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*
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* The next change to send is always the first one in the tree
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* So this methods simply need to check that dependencies are OK
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* and update this replicaId RUV
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*
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* TODO : dependency :
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* before forwarding change, we should check that the dependency
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* that is indicated in this change is OK (change already in the RUV)
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*/
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msg = handler.take();
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synchronized (flowControlLock)
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{
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if (handler.restartAfterSaturation(null))
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flowControlLock.notifyAll();
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}
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return msg;
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}
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/**
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* Return a Set of String containing the lists of Changelog servers
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* connected to this server.
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* @return the set of connected servers
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*/
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public Set<String> getChangelogs()
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{
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LinkedHashSet<String> mySet = new LinkedHashSet<String>();
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for (ServerHandler handler : changelogServers.values())
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{
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mySet.add(handler.getServerURL());
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}
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return mySet;
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}
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/**
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* Return a Set containing the servers known by this changelog.
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* @return a set containing the servers known by this changelog.
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*/
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public Set<Short> getServers()
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{
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return sourceDbHandlers.keySet();
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}
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/**
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* Creates and returns an iterator.
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*
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* @param serverId Identifier of the server for which the iterator is created.
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* @param changeNumber Starting point for the iterator.
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* @return the created ChangelogIterator.
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*/
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public ChangelogIterator getChangelogIterator(short serverId,
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ChangeNumber changeNumber)
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{
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DbHandler handler = sourceDbHandlers.get(serverId);
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if (handler == null)
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return null;
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try
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{
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return handler.generateIterator(changeNumber);
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}
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catch (Exception e) {
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return null;
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}
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}
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/**
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* Get the baseDn.
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* @return Returns the baseDn.
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*/
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public DN getBaseDn()
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{
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return baseDn;
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}
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/**
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* creates a new ChangelogDB with specified identifier.
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* @param id the identifier of the new ChangelogDB.
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* @param baseDn the baseDn of the new ChangelogDB.
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* @throws DatabaseException If a database error happened.
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*/
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public void newDb(short id, DN baseDn) throws DatabaseException
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{
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synchronized (sourceDbHandlers)
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{
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sourceDbHandlers.put(id , new DbHandler(id, baseDn));
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}
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}
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/**
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* Get the number of currently connected servers.
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*
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* @return the number of currently connected servers.
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*/
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private int NumServers()
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{
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return changelogServers.size() + connectedServers.size();
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}
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/**
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* Add an ack to the list of ack received for a given change.
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*
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* @param message The ack message received.
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* @param fromServerId The identifier of the server that sent the ack.
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*/
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public void ack(AckMessage message, short fromServerId)
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{
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ServerHandler handler = connectedServers.get(
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message.getChangeNumber().getServerId());
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if (handler != null)
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handler.ack(message, fromServerId);
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else
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{
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ServerHandler.ackChangelog(message, fromServerId);
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}
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}
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/**
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* Send back an ack to the server that sent the change.
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*
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* @param changeNumber The ChangeNumber of the change that must be acked.
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* @param isLDAPserver This boolean indicates if the server that sent the
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* change was an LDAP server or a Changelog server.
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*/
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public void sendAck(ChangeNumber changeNumber, boolean isLDAPserver)
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{
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short serverId = changeNumber.getServerId();
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sendAck(changeNumber, isLDAPserver, serverId);
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}
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/**
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*
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* Send back an ack to a server that sent the change.
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*
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* @param changeNumber The ChangeNumber of the change that must be acked.
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* @param isLDAPserver This boolean indicates if the server that sent the
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* change was an LDAP server or a Changelog server.
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* @param serverId The identifier of the server from which we
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* received the change..
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*/
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public void sendAck(ChangeNumber changeNumber, boolean isLDAPserver,
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short serverId)
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{
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// TODO Auto-generated method stub
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ServerHandler handler;
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if (isLDAPserver)
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handler = connectedServers.get(serverId);
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else
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handler = changelogServers.get(serverId);
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// TODO : check for null handler and log error
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try
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{
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handler.sendAck(changeNumber);
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} catch (IOException e)
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{
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/*
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* An error happened trying the send back an ack to this server.
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* Log an error and close the connection to this server.
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*/
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int msgID = MSGID_CHANGELOG_ERROR_SENDING_ACK;
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String message = getMessage(msgID, this.toString())
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+ stackTraceToSingleLineString(e);
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logError(ErrorLogCategory.SYNCHRONIZATION,
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ErrorLogSeverity.SEVERE_ERROR,
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message, msgID);
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handler.shutdown();
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}
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}
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/**
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* Shutdown this ChangelogCache.
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*/
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public void shutdown()
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{
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// Close session with other changelogs
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for (ServerHandler serverHandler : changelogServers.values())
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{
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serverHandler.shutdown();
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}
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// Close session with other LDAP servers
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for (ServerHandler serverHandler : connectedServers.values())
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{
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serverHandler.shutdown();
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}
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// Shutdown the dbHandlers
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for (DbHandler dbHandler : sourceDbHandlers.values())
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{
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dbHandler.shutdown();
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}
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}
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/**
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* Returns the ServerState describing the last change from this replica.
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*
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* @return The ServerState describing the last change from this replica.
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*/
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public ServerState getDbServerState()
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{
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ServerState serverState = new ServerState(baseDn);
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for (DbHandler db : sourceDbHandlers.values())
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{
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serverState.update(db.getLastChange());
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}
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return serverState;
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}
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/**
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* {@inheritDoc}
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*/
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@Override
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public String toString()
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{
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return "ChangelogCache " + baseDn;
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}
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}
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