viceroy
Class PapersPlusAlgorithm

java.lang.Object
  |
  +--viceroy.PapersAlgorithm
        |
        +--viceroy.PapersPlusAlgorithm

All Implemented Interfaces:

LookupAlgorithm

public class PapersPlusAlgorithm

extends PapersAlgorithm

resembles the paper's algorithm but has a small extra check: in the Traverse Tree phase, before doing anything, i check if the left child or the right is responsible for the value. if so then without any other check, goto the ring phase with the child that is responsible.

Since:

1.92

Author:

Anat Talmy

, Oren Dobzinski

Field Summary

private static org.apache.log4j.Logger

logger logger for debug

Fields inherited from class viceroy.PapersAlgorithm

messagePath, state

Constructor Summary

PapersPlusAlgorithm(AuthorizedViceroyPeer first)
Empty Ctor to avoid duplication.

Method Summary

protected ViceroyPeer	lookupTraverseTree(AuthorizedViceroyPeer peer, Resource valueToLook) Performs the traverse tree phase in the lookup algorithm.
LookupAlgorithm	newLookupAlgorithm(AuthorizedViceroyPeer peer) creates a fresh new lookup algorithm, with empty path

Methods inherited from class viceroy.PapersAlgorithm

getLookupState, getMessagePath, goToLeftChild, goToParent, goToPredecessor, goToRightChild, goToSuccessor, howOvershoots, lookupProceedToRoot, lookupTraverseRing, nextOnLookup, overshoots

Methods inherited from class java.lang.Object

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

Field Detail

logger

private static final org.apache.log4j.Logger logger

logger for debug

Constructor Detail

PapersPlusAlgorithm

public PapersPlusAlgorithm(AuthorizedViceroyPeer first)

Empty Ctor to avoid duplication.

Method Detail

newLookupAlgorithm

public LookupAlgorithm newLookupAlgorithm(AuthorizedViceroyPeer peer)

creates a fresh new lookup algorithm, with empty path

Specified by:

newLookupAlgorithm in interface LookupAlgorithm

Overrides:

newLookupAlgorithm in class PapersAlgorithm

Parameters:

peer - starting point of the new algorithm

Returns:

a fresh new lookup algorithm, with empty path

lookupTraverseTree

protected ViceroyPeer lookupTraverseTree(AuthorizedViceroyPeer peer,
                                         Resource valueToLook)
                                  throws ResourceNotFoundException

Performs the traverse tree phase in the lookup algorithm. This phase is as follows:

 if( leftChild && leftChild.isResponsible(val) )
	   goto leftChild
 if( rightChild && rightChild.isResponsible(val) )
     goto rightChild		
 
 if( clockwiseDist(this,val) < 1/2^level &&
     leftChild &&
     !overshoot(leftChild,val) )
   goto leftChild
 
 else if ( clockwiseDist(this,val) >=1/2^level &&
           rightChild &&
           !overshoot(rightChild,val) )
        goto rightChild
 
 else goto traverse ring phase
 

Overrides:

lookupTraverseTree in class PapersAlgorithm

Parameters:

peer - the current peer

valueToLook -

Returns:

the next peer to go to according the lookup algorithm

Throws:

ResourceNotFoundException