org.apache.catalina.tribes.tipis

Class LazyReplicatedMap

public class LazyReplicatedMap extends AbstractReplicatedMap implements RpcCallback, ChannelListener, MembershipListener

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.

Version: 1.0

Author: Filip Hanik

UNKNOWN: implement periodic sync/transfer thread

Field Summary
protected static Loglog
Constructor Summary
LazyReplicatedMap(AbstractReplicatedMap.MapOwner owner, Channel channel, long timeout, String mapContextName, int initialCapacity, float loadFactor, ClassLoader[] cls)
Creates a new map
LazyReplicatedMap(AbstractReplicatedMap.MapOwner owner, Channel channel, long timeout, String mapContextName, int initialCapacity, ClassLoader[] cls)
Creates a new map
LazyReplicatedMap(AbstractReplicatedMap.MapOwner owner, Channel channel, long timeout, String mapContextName, ClassLoader[] cls)
Creates a new map
Method Summary
protected intgetStateMessageType()
protected Member[]publishEntryInfo(Object key, Object value)
publish info about a map pair (key/value) to other nodes in the cluster

Field Detail

log

protected static Log log

Constructor Detail

LazyReplicatedMap

public LazyReplicatedMap(AbstractReplicatedMap.MapOwner owner, Channel channel, long timeout, String mapContextName, int initialCapacity, float loadFactor, 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, String mapContextName, int initialCapacity, 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, String mapContextName, 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

Method Detail

getStateMessageType

protected int getStateMessageType()

publishEntryInfo

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

Parameters: key Object value Object

Returns: Member - the backup node

Throws: ChannelException

Copyright © 2000-2011 Apache Software Foundation. All Rights Reserved.