Package org.apache.catalina.tribes.tipis

Class LazyReplicatedMap<K,​V>

  • Type Parameters:
    K - The type of Key
    V - The type of Value
    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:
    • 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.

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

    TODO implement periodic sync/transfer thread
    See Also:
    Serialized Form

    • 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:
        owner - The map owner
        channel - The channel to use for communication
        timeout - long - timeout for RPC messages
        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
        cls - Class loaders

      • 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:
        owner - The map owner
        channel - The channel to use for communication
        timeout - long - timeout for RPC messages
        mapContextName - String - unique name for this map, to allow multiple maps per channel
        initialCapacity - int - the size of this map, see HashMap
        cls - Class loaders

      • LazyReplicatedMap

        public LazyReplicatedMap​(AbstractReplicatedMap.MapOwner owner,
                         Channel channel,
                         long timeout,
                         java.lang.String mapContextName,
                         java.lang.ClassLoader[] cls)
        Creates a new map
        Parameters:
        owner - The map owner
        channel - The channel to use for communication
        timeout - long - timeout for RPC messages
        mapContextName - String - unique name for this map, to allow multiple maps per channel
        cls - Class loaders

      • 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:
        owner - The map owner
        channel - The channel to use for communication
        timeout - long - timeout for RPC messages
        mapContextName - String - unique name for this map, to allow multiple maps per channel
        cls - Class loaders
        terminate - boolean - Flag for whether to terminate this map that failed to start.