/*
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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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* Copyright 2006-2010 Sun Microsystems, Inc.
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*/
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package org.opends.server.replication.server;
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import org.opends.messages.MessageBuilder;
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import static org.opends.server.loggers.ErrorLogger.logError;
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import static org.opends.messages.ReplicationMessages.*;
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import static org.opends.server.util.StaticUtils.stackTraceToSingleLineString;
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import java.util.ArrayList;
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import java.util.Date;
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import java.util.List;
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import java.util.LinkedList;
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import org.opends.server.admin.std.server.MonitorProviderCfg;
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import org.opends.server.api.DirectoryThread;
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import org.opends.server.api.MonitorProvider;
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import org.opends.server.config.ConfigException;
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import org.opends.server.types.Attribute;
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import org.opends.server.types.Attributes;
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import org.opends.server.types.InitializationException;
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import org.opends.server.util.TimeThread;
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import org.opends.server.core.DirectoryServer;
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import org.opends.server.replication.common.ChangeNumber;
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import org.opends.server.replication.protocol.UpdateMsg;
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import org.opends.server.replication.server.ReplicationDB.ReplServerDBCursor;
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import com.sleepycat.je.DatabaseException;
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import com.sleepycat.je.LockConflictException;
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/**
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* This class is used for managing the replicationServer database for each
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* server in the topology.
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* It is responsible for efficiently saving the updates that is received from
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* each master server into stable storage.
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* This class is also able to generate a ReplicationIterator that can be
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* used to read all changes from a given ChangeNUmber.
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*
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* This class publish some monitoring information below cn=monitor.
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*
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*/
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public class DbHandler implements Runnable
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{
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// The msgQueue holds all the updates not yet saved to stable storage.
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// This list is only used as a temporary placeholder so that the write
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// in the stable storage can be grouped for efficiency reason.
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// Adding an update synchronously add the update to this list.
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// A dedicated thread loops on flush() and trim().
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// flush() : get a number of changes from the in memory list by block
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// and write them to the db.
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// trim() : deletes from the DB a number of changes that are older than a
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// certain date.
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//
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// Changes are not read back by replicationServer threads that are responsible
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// for pushing the changes to other replication server or to LDAP server
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//
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private final LinkedList<UpdateMsg> msgQueue =
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new LinkedList<UpdateMsg>();
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// The High and low water mark for the max size of the msgQueue.
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// the threads calling add() method will be blocked if the size of
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// msgQueue becomes larger than the queueHimark and will resume
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// only when the size of the msgQueue goes below queueLowmark.
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int queueMaxSize = 5000;
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int queueLowmark = 1000;
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int queueHimark = 4000;
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// The queue himark and lowmark in bytes, this is set to 100 times the
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// himark and lowmark in number of updates.
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int queueMaxBytes = 100 * queueMaxSize;
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int queueLowmarkBytes = 100 * queueLowmark;
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int queueHimarkBytes = 100 * queueHimark;
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// The number of bytes currently in the queue
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int queueByteSize = 0;
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private ReplicationDB db;
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private ChangeNumber firstChange = null;
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private ChangeNumber lastChange = null;
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private int serverId;
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private String baseDn;
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private DbMonitorProvider dbMonitor = new DbMonitorProvider();
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private boolean shutdown = false;
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private boolean done = false;
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private DirectoryThread thread = null;
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private final Object flushLock = new Object();
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private ReplicationServer replicationServer;
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// The maximum number of retries in case of DatabaseDeadlock Exception.
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private static final int DEADLOCK_RETRIES = 10;
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private long latestTrimDate = 0;
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/**
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*
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* The trim age in milliseconds. Changes record in the change DB that
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* are older than this age are removed.
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*
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*/
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private long trimage;
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/**
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* Creates a new dbHandler associated to a given LDAP server.
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*
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* @param id Identifier of the DB.
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* @param baseDn the baseDn for which this DB was created.
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* @param replicationServer The ReplicationServer that creates this dbHandler.
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* @param dbenv the Database Env to use to create the ReplicationServer DB.
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* server for this domain.
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* @param queueSize The queueSize to use when creating the dbHandler.
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* @throws DatabaseException If a database problem happened
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*/
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public DbHandler(
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int id, String baseDn, ReplicationServer replicationServer,
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ReplicationDbEnv dbenv, int queueSize)
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throws DatabaseException
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{
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this.replicationServer = replicationServer;
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serverId = id;
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this.baseDn = baseDn;
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trimage = replicationServer.getTrimage();
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queueMaxSize = queueSize;
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queueLowmark = queueSize * 1 / 5;
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queueHimark = queueSize * 4 / 5;
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queueMaxBytes = 200 * queueMaxSize;
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queueLowmarkBytes = 200 * queueLowmark;
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queueHimarkBytes = 200 * queueLowmark;
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db = new ReplicationDB(id, baseDn, replicationServer, dbenv);
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firstChange = db.readFirstChange();
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lastChange = db.readLastChange();
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thread = new DirectoryThread(this,
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"Replication Server db for DS " + id + " and " + baseDn + " in RS " +
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replicationServer.getServerId());
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thread.start();
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DirectoryServer.deregisterMonitorProvider(
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dbMonitor.getMonitorInstanceName());
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DirectoryServer.registerMonitorProvider(dbMonitor);
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}
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/**
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* Add an update to the list of messages that must be saved to the db
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* managed by this db handler.
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* This method is blocking if the size of the list of message is larger
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* than its maximum.
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*
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* @param update The update that must be saved to the db managed by this db
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* handler.
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*/
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public void add(UpdateMsg update)
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{
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synchronized (msgQueue)
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{
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int size = msgQueue.size();
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if ((size > queueHimark) || (queueByteSize > queueHimarkBytes))
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msgQueue.notify();
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while ((size > queueMaxSize) || (queueByteSize > queueMaxBytes))
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{
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try
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{
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msgQueue.wait(500);
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} catch (InterruptedException e)
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{
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// simply loop to try again.
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}
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size = msgQueue.size();
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}
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queueByteSize += update.size();
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msgQueue.add(update);
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if (lastChange == null || lastChange.older(update.getChangeNumber()))
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{
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lastChange = update.getChangeNumber();
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}
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if (firstChange == null)
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firstChange = update.getChangeNumber();
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}
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}
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/**
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* Get some changes out of the message queue of the LDAP server.
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* (from the beginning of the queue)
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* @param number the maximum number of messages to extract.
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* @return a List containing number changes extracted from the queue.
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*/
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private List<UpdateMsg> getChanges(int number)
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{
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int current = 0;
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LinkedList<UpdateMsg> changes = new LinkedList<UpdateMsg>();
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synchronized (msgQueue)
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{
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int size = msgQueue.size();
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while ((current < number) && (current < size))
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{
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UpdateMsg msg = msgQueue.get(current);
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current++;
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changes.add(msg);
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}
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}
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return changes;
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}
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/**
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* Get the firstChange.
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* @return Returns the firstChange.
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*/
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public ChangeNumber getFirstChange()
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{
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return firstChange;
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}
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/**
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* Get the lastChange.
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* @return Returns the lastChange.
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*/
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public ChangeNumber getLastChange()
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{
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return lastChange;
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}
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/**
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* Get the number of changes.
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*
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* @return Returns the number of changes.
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*/
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public long getChangesCount()
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{
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try
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{
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return lastChange.getSeqnum() - firstChange.getSeqnum() + 1;
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}
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catch (Exception e)
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{
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return 0;
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}
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}
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/**
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* Generate a new ReplicationIterator that allows to browse the db
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* managed by this dbHandler and starting at the position defined
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* by a given changeNumber.
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*
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* @param changeNumber The position where the iterator must start.
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*
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* @return a new ReplicationIterator that allows to browse the db
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* managed by this dbHandler and starting at the position defined
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* by a given changeNumber.
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*
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* @throws DatabaseException if a database problem happened.
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* @throws Exception If there is no other change to push after change
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* with changeNumber number.
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*/
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public ReplicationIterator generateIterator(ChangeNumber changeNumber)
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throws DatabaseException, Exception
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{
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if (changeNumber == null)
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{
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flush();
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}
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ReplicationIterator it =
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new ReplicationIterator(serverId, db, changeNumber, this);
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return it;
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}
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/**
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* Return the number of changes between 2 provided change numbers.
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* @param from The lower (older) change number.
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* @param to The upper (newer) change number.
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* @return The computed number of changes.
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*/
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public int traverseAndCount(ChangeNumber from, ChangeNumber to)
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{
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int count = 0;
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flush();
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ReplServerDBCursor cursor = null;
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try
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{
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try
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{
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cursor = db.openReadCursor(from);
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}
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catch(Exception e)
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{
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return 0;
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}
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ChangeNumber curr = null;
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while ((curr = cursor.nextChangeNumber())!=null)
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{
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if (curr.newerOrEquals(to))
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break;
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count++;
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}
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}
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finally
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{
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if (cursor != null)
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cursor.abort();
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}
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return count;
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}
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/**
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* Removes the provided number of messages from the beginning of the msgQueue.
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*
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* @param number the number of changes to be removed.
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*/
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private void clearQueue(int number)
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{
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synchronized (msgQueue)
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{
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int current = 0;
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while ((current < number) && (!msgQueue.isEmpty()))
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{
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UpdateMsg msg = msgQueue.remove(); // remove first
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queueByteSize -= msg.size();
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current++;
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}
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if ((msgQueue.size() < queueLowmark) &&
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(queueByteSize < queueLowmarkBytes))
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msgQueue.notifyAll();
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}
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}
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/**
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* Shutdown this dbHandler.
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*/
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public void shutdown()
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{
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if (shutdown == true)
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{
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return;
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}
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shutdown = true;
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synchronized (msgQueue)
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{
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msgQueue.notifyAll();
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}
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synchronized (this)
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{
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while (done == false)
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{
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try
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{
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this.wait();
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} catch (Exception e)
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{}
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}
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}
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while (msgQueue.size() != 0)
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flush();
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db.shutdown();
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DirectoryServer.deregisterMonitorProvider(
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dbMonitor.getMonitorInstanceName());
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}
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/**
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* Run method for this class.
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* Periodically Flushes the ReplicationServerDomain cache from memory to the
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* stable storage and trims the old updates.
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*/
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public void run()
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{
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while (shutdown == false)
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{
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try
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{
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flush();
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trim();
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synchronized (msgQueue)
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{
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if ((msgQueue.size() < queueLowmark) &&
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(queueByteSize < queueLowmarkBytes))
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{
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try
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{
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msgQueue.wait(1000);
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} catch (InterruptedException e)
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{ }
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}
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}
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} catch (Exception end)
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{
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MessageBuilder mb = new MessageBuilder();
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mb.append(ERR_EXCEPTION_CHANGELOG_TRIM_FLUSH.get());
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mb.append(stackTraceToSingleLineString(end));
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logError(mb.toMessage());
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synchronized (this)
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{
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// set the done variable to true so that this thread don't
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// get stuck in this dbHandler.shutdown() when it get called
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// by replicationServer.shutdown();
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done = true;
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}
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if (replicationServer != null)
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replicationServer.shutdown();
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break;
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}
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}
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// call flush a last time before exiting to make sure that
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// no change was forgotten in the msgQueue
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flush();
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synchronized (this)
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{
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done = true;
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this.notifyAll();
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}
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}
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/**
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* Retrieves the latest trim date.
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* @return the latest trim date.
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*/
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public long getLatestTrimDate()
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{
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return latestTrimDate;
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}
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/**
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* Trim old changes from this replicationServer database.
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* @throws DatabaseException In case of database problem.
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*/
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private void trim() throws DatabaseException, Exception
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{
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if (trimage == 0)
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return;
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int size = 0;
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boolean finished = false;
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boolean done = false;
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latestTrimDate = TimeThread.getTime() - trimage;
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ChangeNumber trimDate = new ChangeNumber(latestTrimDate, 0, 0);
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// In case of deadlock detection by the Database, this thread can
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// by aborted by a DeadlockException. This is a transient error and
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// the transaction should be attempted again.
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// We will try DEADLOCK_RETRIES times before failing.
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int tries = 0;
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while ((tries++ < DEADLOCK_RETRIES) && (!done))
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{
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synchronized (flushLock)
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{
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/* the trim is done by group in order to save some CPU and IO bandwidth
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* start the transaction then do a bunch of remove then commit
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*/
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ReplServerDBCursor cursor;
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cursor = db.openDeleteCursor();
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try
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{
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while ((size < 5000 ) && (!finished))
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{
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ChangeNumber changeNumber = cursor.nextChangeNumber();
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if (changeNumber != null)
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{
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if ((!changeNumber.equals(lastChange))
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&& (changeNumber.older(trimDate)))
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{
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size++;
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cursor.delete();
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}
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else
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{
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firstChange = changeNumber;
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finished = true;
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}
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}
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else
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finished = true;
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}
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cursor.close();
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done = true;
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}
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catch (LockConflictException e)
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{
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cursor.abort();
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if (tries == DEADLOCK_RETRIES)
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{
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// could not handle the Deadlock after DEADLOCK_RETRIES tries.
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// shutdown the ReplicationServer.
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shutdown = true;
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throw (e);
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}
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}
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catch (DatabaseException e)
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{
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// mark shutdown for this db so that we don't try again to
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// stop it from cursor.close() or methods called by cursor.close()
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shutdown = true;
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cursor.abort();
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throw (e);
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}
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}
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}
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}
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/**
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* Flush a number of updates from the memory list to the stable storage.
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* Flush is done by chunk sized to 500 messages, starting from the
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* beginning of the list.
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*/
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public void flush()
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{
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int size;
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int chunksize = (500 < queueMaxSize ? 500 : queueMaxSize);
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do
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{
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synchronized(flushLock)
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{
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// get N (or less) messages from the queue to save to the DB
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// (from the beginning of the queue)
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List<UpdateMsg> changes = getChanges(chunksize);
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// if no more changes to save exit immediately.
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if ((changes == null) || ((size = changes.size()) == 0))
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return;
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// save the change to the stable storage.
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db.addEntries(changes);
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// remove the changes from the list of changes to be saved
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// (remove from the beginning of the queue)
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clearQueue(changes.size());
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}
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} while (size >= chunksize);
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}
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/**
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* This internal class is used to implement the Monitoring capabilities
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* of the dbHandler.
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*/
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private class DbMonitorProvider extends MonitorProvider<MonitorProviderCfg>
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{
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private DbMonitorProvider()
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{
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super("ReplicationServer Database");
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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 ArrayList<Attribute> getMonitorData()
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{
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ArrayList<Attribute> attributes = new ArrayList<Attribute>();
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attributes.add(Attributes.create("replicationServer-database",
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String.valueOf(serverId)));
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attributes.add(Attributes.create("domain-name", baseDn.toString()));
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if (firstChange != null)
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{
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Date firstTime = new Date(firstChange.getTime());
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attributes.add(Attributes.create("first-change", firstChange
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.toString()
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+ " " + firstTime.toString()));
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}
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if (lastChange != null)
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{
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Date lastTime = new Date(lastChange.getTime());
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attributes.add(Attributes.create("last-change", lastChange
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.toString()
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+ " " + lastTime.toString()));
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}
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attributes.add(
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Attributes.create("queue-size", String.valueOf(msgQueue.size())));
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attributes.add(
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Attributes.create("queue-size-bytes", String.valueOf(queueByteSize)));
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return attributes;
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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 getMonitorInstanceName()
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{
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ReplicationServerDomain domain =
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replicationServer.getReplicationServerDomain(baseDn, false);
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return "ReplicationServer database " + String.valueOf(serverId) +
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",cn=" + domain.getMonitorInstanceName();
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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 long getUpdateInterval()
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{
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/* we don't wont to do polling on this monitor */
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return 0;
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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 void initializeMonitorProvider(MonitorProviderCfg configuration)
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throws ConfigException,InitializationException
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{
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// Nothing to do for now
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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 void updateMonitorData()
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{
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// As long as getUpdateInterval() returns 0, this will never get called
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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(baseDn + " " + serverId + " " + firstChange + " " + lastChange);
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}
|
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/**
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* Set the Purge delay for this db Handler.
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* @param delay The purge delay in Milliseconds.
|
*/
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public void setPurgeDelay(long delay)
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{
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trimage = delay;
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}
|
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/**
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* Clear the changes from this DB (from both memory cache and DB storage).
|
* @throws DatabaseException When an exception occurs while removing the
|
* changes from the DB.
|
* @throws Exception When an exception occurs while accessing a resource
|
* from the DB.
|
*
|
*/
|
public void clear() throws DatabaseException, Exception
|
{
|
synchronized(flushLock)
|
{
|
msgQueue.clear();
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queueByteSize = 0;
|
|
db.clear();
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firstChange = db.readFirstChange();
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lastChange = db.readLastChange();
|
}
|
}
|
|
/**
|
* Getter fot the serverID of the server for which this database is managed.
|
*
|
* @return the serverId.
|
*/
|
public int getServerId()
|
{
|
return this.serverId;
|
}
|
|
/**
|
* Return the size of the msgQueue (the memory cache of the DbHandler).
|
* For test purpose.
|
* @return The memory queue size.
|
*/
|
public int getQueueSize()
|
{
|
return this.msgQueue.size();
|
}
|
|
/**
|
* Set the counter writing window size (public for unit tests only).
|
* @param size Size in number of record.
|
*/
|
public void setCounterWindowSize(int size)
|
{
|
db.setCounterWindowSize(size);
|
}
|
|
/**
|
* Return the number of changes between 2 provided change numbers.
|
* This a alternative to traverseAndCount, expected to be much more efficient
|
* when there is a huge number of changes in the Db.
|
* @param from The lower (older) change number.
|
* @param to The upper (newer) change number.
|
* @return The computed number of changes.
|
*/
|
public int getCount(ChangeNumber from, ChangeNumber to)
|
{
|
int c=0;
|
flush();
|
c = db.count(from, to);
|
return c;
|
}
|
|
}
|
