ostore.dtree
Class DTreeNode

java.lang.Object
  |
  +--ostore.dtree.DTreeNode

All Implemented Interfaces:

EventHandlerIF, SingleThreadedEventHandlerIF

public class DTreeNode

extends Object

implements SingleThreadedEventHandlerIF, EventHandlerIF

The stage responsible for fulfilling the server's roles in various dissemination trees.

Stages (e.g. the inner ring) send updates, invalidations, and other responses to secondary replicas and clients via a multicast dissemination tree. This stage implements the protocols required for the server to participate in these trees as a parent, child, or both.

USAGE

To send a message down the dissemination tree, dispatch a DownDTreeMsg containing the message and the GUID for the tree. That GUID will usually (always?) be the A-GUID for the data object which the message concerns.

The local DTreeNode stage will receive the DownDTreeMsg, extract the content message, and forward it down the tree inside a DTreeMsg using DD.

Conversely, to send a message up the dissemination tree, dispatch a UpDTreeMsg containing the message and the GUID for the tree.

To join a dissemination tree, dispatch a JoinTreeReq containing the GUID for the tree. The DTreeNode will attempt to locate a current member of the tree (including the inner ring), using a DTreeLocateMsg requesting that member to tie the local node into its tree. The remote node will return a JoinTreeResp with the result (success or failure), which this DTreeNode will dispatch locally.

If the local server wishes to publish itself as an available secondary replica for a data object, it should set the JoinTreeReq.publish flag on its request to true. The DTreeNode stage will then publish the appropriate tag in DD.

Version:

$Id: DTreeNode.java,v 1.72 2004/05/13 20:13:52 hweather Exp $

Author:

Dennis Geels

See Also:

DownDTreeMsg, UpDTreeMsg, JoinTreeReq, JoinTreeResp, DTreeMsg, DTreeLocateMsg

Field Summary

protected static Double	DEFAULT_DISTANCE_GUESS The latency estimate to use for peers that don't appear in the RoutingTable.
protected Map	engines A QSSignature->Signature map for storing verification engines for the various signature algorithms used.
protected static long	MSG_TIMEOUT The number of milliseconds to wait before resending messages.
protected String	name The name by which to refer to this stage.
protected Map	node_states A GUID->NodeState map storing the information for tree.
protected static int	NORMAL_LEASE The length of a link lease, in bytes.
protected Map	pending_joins A SecureHash->DTreeServiceReq map storing join requests, indexed by their digests.
protected static double	REJOIN_DISTANCE_FACTOR The factor by which a single tree rejoin action can increase this node's total latency from the tree root.
protected static int	RETRIES The number of times to retry any message.
protected static boolean	USE_DISTANCE_METRIC A flag that determines whether to rejoin trees using the depth metric (tree hops) or distance metric (latency in ms).

Constructor Summary

DTreeNode()
Initializes internal data structures.

Method Summary

void	destroy()
void	handleEvent(QueueElementIF elem)
void	handleEvents(QueueElementIF[] elemarr)
void	init(ConfigDataIF config)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

MSG_TIMEOUT

protected static final long MSG_TIMEOUT

The number of milliseconds to wait before resending messages. For now, use the same timeout for all message types. Currently 1000 (1 second).

See Also:

Constant Field Values

RETRIES

protected static final int RETRIES

The number of times to retry any message.

See Also:

Constant Field Values

NORMAL_LEASE

protected static final int NORMAL_LEASE

The length of a link lease, in bytes. Default: 1GB (almost infinite). TODO: should be much more flexible.

See Also:

Constant Field Values

DEFAULT_DISTANCE_GUESS

protected static final Double DEFAULT_DISTANCE_GUESS

The latency estimate to use for peers that don't appear in the RoutingTable.

USE_DISTANCE_METRIC

protected static final boolean USE_DISTANCE_METRIC

A flag that determines whether to rejoin trees using the depth metric (tree hops) or distance metric (latency in ms).

See Also:

Constant Field Values

REJOIN_DISTANCE_FACTOR

protected static final double REJOIN_DISTANCE_FACTOR

The factor by which a single tree rejoin action can increase this node's total latency from the tree root. Larger factors may produce slower trees, but they should be more efficient.

See Also:

Constant Field Values

name

protected String name

The name by which to refer to this stage. It should be the name of the corresponding StageIF.

node_states

protected Map node_states

A GUID->NodeState map storing the information for tree.

engines

protected Map engines

A QSSignature->Signature map for storing verification engines for the various signature algorithms used.

pending_joins

protected Map pending_joins

A SecureHash->DTreeServiceReq map storing join requests, indexed by their digests.

Constructor Detail

DTreeNode

public DTreeNode()

Initializes internal data structures.

Method Detail

handleEvent

public void handleEvent(QueueElementIF elem)
                 throws UnknownEventException

Specified by:

handleEvent in interface EventHandlerIF

UnknownEventException

handleEvents

public void handleEvents(QueueElementIF[] elemarr)
                  throws UnknownEventException

Specified by:

handleEvents in interface EventHandlerIF

UnknownEventException

init

public void init(ConfigDataIF config)
          throws Exception

Specified by:

init in interface EventHandlerIF

Exception

destroy

public void destroy()

Specified by:

destroy in interface EventHandlerIF