Apache Tomcat 6.0.43

org.apache.catalina.tribes.tipis
Class LazyReplicatedMap<K,V>

java.lang.Object
  extended by org.apache.catalina.tribes.tipis.AbstractReplicatedMap<K,V>
      extended by org.apache.catalina.tribes.tipis.LazyReplicatedMap<K,V>
All Implemented Interfaces:
java.io.Serializable, java.util.Map<K,V>, ChannelListener, RpcCallback, Heartbeat, MembershipListener

public class LazyReplicatedMap<K,V>
extends AbstractReplicatedMap<K,V>

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.
A perfect usage for this map would be a session map for a session manager in a clustered environment.
The only way to modify this list is to use the put, putAll, remove methods. entrySet, entrySetFull, keySet, keySetFull, returns all non modifiable sets.

If objects (values) in the map change without invoking put() or remove() the data can be distributed using two different methods:
replicate(boolean) and replicate(Object, boolean)
These two methods are very important two understand. The map can work with two set of value objects:
1. Serializable - the entire object gets serialized each time it is replicated
2. ReplicatedMapEntry - this interface allows for a isDirty() flag and to replicate diffs if desired.
Implementing the ReplicatedMapEntry interface allows you to decide what objects get replicated and how much data gets replicated each time.
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.

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:

the boolean value in the replicate method used to decide whether to only replicate objects that implement the ReplicatedMapEntry interface or to replicate all objects. If an object doesn't implement the ReplicatedMapEntry interface each time the object gets replicated the entire object gets serialized, hence a call to replicate(true) will replicate all objects in this map that are using this node as primary.

REMBER TO CALL breakdown() or finalize() when you are done with the map to avoid memory leaks.

TODO implement periodic sync/transfer thread

Version:
1.0
Author:
Filip Hanik
See Also:
Serialized Form

Nested Class Summary
 
Nested classes/interfaces inherited from class org.apache.catalina.tribes.tipis.AbstractReplicatedMap
AbstractReplicatedMap.MapEntry<K,V>, AbstractReplicatedMap.MapMessage, AbstractReplicatedMap.MapOwner
 
Nested classes/interfaces inherited from interface java.util.Map
java.util.Map.Entry<K,V>
 
Field Summary
protected static Log log
           
 
Fields inherited from class org.apache.catalina.tribes.tipis.AbstractReplicatedMap
accessTimeout, channel, channelSendOptions, currentNode, DEFAULT_INITIAL_CAPACITY, DEFAULT_LOAD_FACTOR, externalLoaders, mapContextName, mapMembers, mapname, mapOwner, rpcChannel, rpcTimeout, stateMutex, stateTransferred
 
Constructor Summary
LazyReplicatedMap(AbstractReplicatedMap.MapOwner owner, Channel channel, long timeout, java.lang.String mapContextName, java.lang.ClassLoader[] cls)
          Creates a new map
LazyReplicatedMap(AbstractReplicatedMap.MapOwner owner, Channel channel, long timeout, java.lang.String mapContextName, java.lang.ClassLoader[] cls, boolean terminate)
          Creates a new map
LazyReplicatedMap(AbstractReplicatedMap.MapOwner owner, Channel channel, long timeout, java.lang.String mapContextName, int initialCapacity, java.lang.ClassLoader[] cls)
          Creates a new map
LazyReplicatedMap(AbstractReplicatedMap.MapOwner owner, Channel channel, long timeout, java.lang.String mapContextName, int initialCapacity, float loadFactor, java.lang.ClassLoader[] cls)
          Creates a new map
 
Method Summary
protected  int getStateMessageType()
           
protected  Member[] publishEntryInfo(java.lang.Object key, java.lang.Object value)
          publish info about a map pair (key/value) to other nodes in the cluster
 
Methods inherited from class org.apache.catalina.tribes.tipis.AbstractReplicatedMap
accept, breakdown, broadcast, clear, clear, clone, containsKey, containsValue, entrySet, entrySetFull, equals, excludeFromSet, finalize, get, getAccessTimeout, getChannel, getChannelSendOptions, getExternalLoaders, getInternal, getMapContextName, getMapMembers, getMapMembers, getMapMembersExcl, getMapOwner, getNextBackupIndex, getNextBackupNode, getRpcChannel, getRpcTimeout, getStateMutex, hashCode, heartbeat, init, inSet, isEmpty, isStateTransferred, keySet, keySetFull, leftOver, mapMemberAdded, memberAdded, memberAlive, memberDisappeared, messageReceived, ping, printMap, put, put, putAll, remove, remove, replicate, replicate, replyRequest, setAccessTimeout, setChannelSendOptions, setExternalLoaders, setMapOwner, size, sizeFull, transferState, values, wrap
 
Methods inherited from class java.lang.Object
getClass, notify, notifyAll, toString, wait, wait, wait
 

Field Detail

log

protected static Log log
Constructor Detail

LazyReplicatedMap

public LazyReplicatedMap(AbstractReplicatedMap.MapOwner owner,
                         Channel channel,
                         long timeout,
                         java.lang.String mapContextName,
                         int initialCapacity,
                         float loadFactor,
                         java.lang.ClassLoader[] cls)
Creates a new map

Parameters:
channel - The channel to use for communication
timeout - long - timeout for RPC messags
mapContextName - String - unique name for this map, to allow multiple maps per channel
initialCapacity - int - the size of this map, see HashMap
loadFactor - float - load factor, see HashMap

LazyReplicatedMap

public LazyReplicatedMap(AbstractReplicatedMap.MapOwner owner,
                         Channel channel,
                         long timeout,
                         java.lang.String mapContextName,
                         int initialCapacity,
                         java.lang.ClassLoader[] cls)
Creates a new map

Parameters:
channel - The channel to use for communication
timeout - long - timeout for RPC messags
mapContextName - String - unique name for this map, to allow multiple maps per channel
initialCapacity - int - the size of this map, see HashMap

LazyReplicatedMap

public LazyReplicatedMap(AbstractReplicatedMap.MapOwner owner,
                         Channel channel,
                         long timeout,
                         java.lang.String mapContextName,
                         java.lang.ClassLoader[] cls)
Creates a new map

Parameters:
channel - The channel to use for communication
timeout - long - timeout for RPC messags
mapContextName - String - unique name for this map, to allow multiple maps per channel

LazyReplicatedMap

public LazyReplicatedMap(AbstractReplicatedMap.MapOwner owner,
                         Channel channel,
                         long timeout,
                         java.lang.String mapContextName,
                         java.lang.ClassLoader[] cls,
                         boolean terminate)
Creates a new map

Parameters:
channel - The channel to use for communication
timeout - long - timeout for RPC messags
mapContextName - String - unique name for this map, to allow multiple maps per channel
terminate - boolean - Flag for whether to terminate this map that failed to start.
Method Detail

getStateMessageType

protected int getStateMessageType()
Specified by:
getStateMessageType in class AbstractReplicatedMap<K,V>

publishEntryInfo

protected Member[] publishEntryInfo(java.lang.Object key,
                                    java.lang.Object value)
                             throws ChannelException
publish info about a map pair (key/value) to other nodes in the cluster

Specified by:
publishEntryInfo in class AbstractReplicatedMap<K,V>
Parameters:
key - Object
value - Object
Returns:
Member - the backup node
Throws:
ChannelException

Apache Tomcat 6.0.43

Copyright © 2000-2014 Apache Software Foundation. All Rights Reserved.