| /* |
| * Licensed to the Apache Software Foundation (ASF) under one or more |
| * contributor license agreements. See the NOTICE file distributed with |
| * this work for additional information regarding copyright ownership. |
| * The ASF licenses this file to You under the Apache License, Version 2.0 |
| * (the "License"); you may not use this file except in compliance with |
| * the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| package org.apache.catalina.tribes.tipis; |
| |
| import java.io.Serializable; |
| |
| import org.apache.catalina.tribes.Channel; |
| import org.apache.catalina.tribes.ChannelException; |
| import org.apache.catalina.tribes.ChannelListener; |
| import org.apache.catalina.tribes.Member; |
| import org.apache.catalina.tribes.MembershipListener; |
| import org.apache.catalina.tribes.group.RpcCallback; |
| import org.apache.catalina.tribes.util.Arrays; |
| import org.apache.catalina.tribes.UniqueId; |
| |
| /** |
| * A smart implementation of a stateful replicated map. uses primary/secondary backup strategy. |
| * One node is always the primary and one node is always the backup. |
| * This map is synchronized across a cluster, and only has one backup member.<br/> |
| * A perfect usage for this map would be a session map for a session manager in a clustered environment.<br/> |
| * The only way to modify this list is to use the <code>put, putAll, remove</code> methods. |
| * entrySet, entrySetFull, keySet, keySetFull, returns all non modifiable sets.<br><br> |
| * If objects (values) in the map change without invoking <code>put()</code> or <code>remove()</code> |
| * the data can be distributed using two different methods:<br> |
| * <code>replicate(boolean)</code> and <code>replicate(Object, boolean)</code><br> |
| * These two methods are very important two understand. The map can work with two set of value objects:<br> |
| * 1. Serializable - the entire object gets serialized each time it is replicated<br> |
| * 2. ReplicatedMapEntry - this interface allows for a isDirty() flag and to replicate diffs if desired.<br> |
| * Implementing the <code>ReplicatedMapEntry</code> interface allows you to decide what objects |
| * get replicated and how much data gets replicated each time.<br> |
| * If you implement a smart AOP mechanism to detect changes in underlying objects, you can replicate |
| * only those changes by implementing the ReplicatedMapEntry interface, and return true when isDiffable() |
| * is invoked.<br><br> |
| * |
| * This map implementation doesn't have a background thread running to replicate changes. |
| * If you do have changes without invoking put/remove then you need to invoke one of the following methods: |
| * <ul> |
| * <li><code>replicate(Object,boolean)</code> - replicates only the object that belongs to the key</li> |
| * <li><code>replicate(boolean)</code> - Scans the entire map for changes and replicates data</li> |
| * </ul> |
| * the <code>boolean</code> value in the <code>replicate</code> method used to decide |
| * whether to only replicate objects that implement the <code>ReplicatedMapEntry</code> interface |
| * or to replicate all objects. If an object doesn't implement the <code>ReplicatedMapEntry</code> interface |
| * each time the object gets replicated the entire object gets serialized, hence a call to <code>replicate(true)</code> |
| * will replicate all objects in this map that are using this node as primary. |
| * |
| * <br><br><b>REMBER TO CALL <code>breakdown()</code> or <code>finalize()</code> when you are done with the map to |
| * avoid memory leaks.<br><br> |
| * @todo implement periodic sync/transfer thread |
| * @author Filip Hanik |
| * @version 1.0 |
| */ |
| public class LazyReplicatedMap extends AbstractReplicatedMap |
| implements RpcCallback, ChannelListener, MembershipListener { |
| protected static org.apache.commons.logging.Log log = org.apache.commons.logging.LogFactory.getLog(LazyReplicatedMap.class); |
| |
| |
| |
| //------------------------------------------------------------------------------ |
| // CONSTRUCTORS / DESTRUCTORS |
| //------------------------------------------------------------------------------ |
| /** |
| * Creates a new map |
| * @param channel The channel to use for communication |
| * @param timeout long - timeout for RPC messags |
| * @param mapContextName String - unique name for this map, to allow multiple maps per channel |
| * @param initialCapacity int - the size of this map, see HashMap |
| * @param loadFactor float - load factor, see HashMap |
| */ |
| public LazyReplicatedMap(Object owner, Channel channel, long timeout, String mapContextName, int initialCapacity, float loadFactor, ClassLoader[] cls) { |
| super(owner,channel,timeout,mapContextName,initialCapacity,loadFactor, Channel.SEND_OPTIONS_DEFAULT,cls); |
| } |
| |
| /** |
| * Creates a new map |
| * @param channel The channel to use for communication |
| * @param timeout long - timeout for RPC messags |
| * @param mapContextName String - unique name for this map, to allow multiple maps per channel |
| * @param initialCapacity int - the size of this map, see HashMap |
| */ |
| public LazyReplicatedMap(Object owner, Channel channel, long timeout, String mapContextName, int initialCapacity, ClassLoader[] cls) { |
| super(owner, channel,timeout,mapContextName,initialCapacity, LazyReplicatedMap.DEFAULT_LOAD_FACTOR, Channel.SEND_OPTIONS_DEFAULT, cls); |
| } |
| |
| /** |
| * Creates a new map |
| * @param channel The channel to use for communication |
| * @param timeout long - timeout for RPC messags |
| * @param mapContextName String - unique name for this map, to allow multiple maps per channel |
| */ |
| public LazyReplicatedMap(Object owner, Channel channel, long timeout, String mapContextName, ClassLoader[] cls) { |
| super(owner, channel,timeout,mapContextName, LazyReplicatedMap.DEFAULT_INITIAL_CAPACITY,LazyReplicatedMap.DEFAULT_LOAD_FACTOR,Channel.SEND_OPTIONS_DEFAULT, cls); |
| } |
| |
| |
| |
| |
| |
| //------------------------------------------------------------------------------ |
| // METHODS TO OVERRIDE |
| //------------------------------------------------------------------------------ |
| /** |
| * publish info about a map pair (key/value) to other nodes in the cluster |
| * @param key Object |
| * @param value Object |
| * @return Member - the backup node |
| * @throws ChannelException |
| */ |
| protected Member[] publishEntryInfo(Object key, Object value) throws ChannelException { |
| if (! (key instanceof Serializable && value instanceof Serializable) ) return new Member[0]; |
| Member[] members = getMapMembers(); |
| int firstIdx = getNextBackupIndex(); |
| int nextIdx = firstIdx; |
| Member[] backup = new Member[0]; |
| |
| //there are no backups |
| if ( members.length == 0 || firstIdx == -1 ) return backup; |
| |
| boolean success = false; |
| do { |
| //select a backup node |
| Member next = members[firstIdx]; |
| |
| //increment for the next round of back up selection |
| nextIdx = firstIdx + 1; |
| if ( nextIdx >= members.length ) nextIdx = 0; |
| |
| if (next == null) { |
| continue; |
| } |
| MapMessage msg = null; |
| try { |
| backup = wrap(next); |
| //publish the backup data to one node |
| msg = new MapMessage(getMapContextName(), MapMessage.MSG_BACKUP, false, |
| (Serializable) key, (Serializable) value, null, backup); |
| if ( log.isTraceEnabled() ) |
| log.trace("Publishing backup data:"+msg+" to: "+next.getName()); |
| UniqueId id = getChannel().send(backup, msg, getChannelSendOptions()); |
| if ( log.isTraceEnabled() ) |
| log.trace("Data published:"+msg+" msg Id:"+id); |
| //we published out to a backup, mark the test success |
| success = true; |
| }catch ( ChannelException x ) { |
| log.error("Unable to replicate backup key:"+key+" to backup:"+next+". Reason:"+x.getMessage(),x); |
| } |
| try { |
| //publish the data out to all nodes |
| Member[] proxies = excludeFromSet(backup, getMapMembers()); |
| if (success && proxies.length > 0 ) { |
| msg = new MapMessage(getMapContextName(), MapMessage.MSG_PROXY, false, |
| (Serializable) key, null, null, backup); |
| if ( log.isTraceEnabled() ) |
| log.trace("Publishing proxy data:"+msg+" to: "+Arrays.toNameString(proxies)); |
| getChannel().send(proxies, msg, getChannelSendOptions()); |
| } |
| }catch ( ChannelException x ) { |
| //log the error, but proceed, this should only happen if a node went down, |
| //and if the node went down, then it can't receive the message, the others |
| //should still get it. |
| log.error("Unable to replicate proxy key:"+key+" to backup:"+next+". Reason:"+x.getMessage(),x); |
| } |
| } while ( !success && (firstIdx!=nextIdx)); |
| return backup; |
| } |
| |
| |
| |
| |
| |
| } |
