org.apache.catalina.tribes.tipis
Class LazyReplicatedMap

java.lang.Object
  java.util.AbstractMap<K,V>
      java.util.concurrent.ConcurrentHashMap
          org.apache.catalina.tribes.tipis.AbstractReplicatedMap
              org.apache.catalina.tribes.tipis.LazyReplicatedMap

All Implemented Interfaces:

Serializable, ConcurrentMap, Map, ChannelListener, RpcCallback, Heartbeat, MembershipListener

public class LazyReplicatedMap
extends AbstractReplicatedMap

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:

• replicate(Object,boolean) - replicates only the object that belongs to the key
• replicate(boolean) - Scans the entire map for changes and replicates data

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, AbstractReplicatedMap.MapMessage, AbstractReplicatedMap.MapOwner

Nested classes/interfaces inherited from class java.util.AbstractMap

AbstractMap.SimpleEntry<K,V>, AbstractMap.SimpleImmutableEntry<K,V>

Nested classes/interfaces inherited from interface java.util.Map

Map.Entry<K,V>

Field Summary

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, String mapContextName, 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, int initialCapacity, float loadFactor, ClassLoader[] cls)
Creates a new map

Method Summary

protected int	getStateMessageType()
protected Member[]	publishEntryInfo(Object key, 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.util.concurrent.ConcurrentHashMap

contains, elements, keys, putIfAbsent, remove, replace, replace

Methods inherited from class java.util.AbstractMap

toString

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

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()

Specified by:

getStateMessageType in class AbstractReplicatedMap

publishEntryInfo

protected Member[] publishEntryInfo(Object key,
                                    Object value)
                             throws ChannelException

publish info about a map pair (key/value) to other nodes in the cluster

Specified by:

publishEntryInfo in class AbstractReplicatedMap

Parameters:

key - Object

value - Object

Returns:

Member - the backup node

Throws:

ChannelException