Fixed the Distance Comparison bugs by using a new KeyComparator class of type Comparable<NodeId> and using BigIntegers to represent the keys and letting BigInteger do the comparisons

This commit is contained in:
Joshua Kissoon 2014-03-22 11:32:41 +05:30
parent 0cc24d42f3
commit 21053a16ff
7 changed files with 81 additions and 108 deletions

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@ -0,0 +1,44 @@
package kademlia.node;
import java.math.BigInteger;
import java.util.Comparator;
/**
* A Comparator to compare 2 keys to a given key
*
* @author Joshua Kissoon
* @since 20140322
*/
public class KeyComparator implements Comparator<Node>
{
private final BigInteger key;
/**
* @param key The NodeId relative to which the distance should be measured.
*/
public KeyComparator(NodeId key)
{
this.key = key.getInt();
}
/**
* Compare two objects which must both be of type <code>Node</code>
* and determine which is closest to the identifier specified in the
* constructor.
*
* @param n1 Node 1 to compare distance from the key
* @param n2 Node 2 to compare distance from the key
*/
@Override
public int compare(Node n1, Node n2)
{
BigInteger b1 = n1.getNodeId().getInt();
BigInteger b2 = n2.getNodeId().getInt();
b1 = b1.xor(key);
b2 = b2.xor(key);
return b1.abs().compareTo(b2.abs());
}
}

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@ -158,79 +158,4 @@ public class Node implements Streamable
{
return this.getNodeId().toString();
}
/**
* A DistanceComparator is used to compare Node objects based on their closeness
* */
public static class DistanceComparator implements Comparator
{
private final NodeId nid;
/**
* The NodeId relative to which the distance should be measured.
*
* @param nid
* */
public DistanceComparator(NodeId nid)
{
this.nid = nid;
}
/**
* Compare two objects which must both be of type <code>Node</code>
* and determine which is closest to the identifier specified in the
* constructor.
* */
@Override
public int compare(Object o1, Object o2)
{
Node n1 = (Node) o1;
Node n2 = (Node) o2;
// System.out.println("\nDistance Comparator: " + nodeId);
// System.out.println("Distance Comparator: " + n1.getNodeId());
// System.out.println("Distance Comparator: " + n2.getNodeId());
/* Check if they are equal and return 0 */
// if (n1.equals(n2))
// {
// //System.out.println("Distance Comparator: Return 0");
// return 0;
// }
//System.out.println("\n **************** Compare Starting **************** ");
//System.out.println("Comparing to: " + this.nodeId);
int distance1 = nid.getDistance(n1.getNodeId());
//System.out.println("Node " + n1.getNodeId() + " distance: " + index1);
int distance2 = nid.getDistance(n2.getNodeId());
//System.out.println("Node " + n2.getNodeId() + " distance: " + index2);
int retval;
if ((distance1 == distance2) && n1.equals(n2))
{
/**
* If the first node is farther to the given node, return 1
*
* @note -1 will also be returned if both nodes are the same distance away
* This really don't make a difference though, since they need to be sorted.
*/
//System.out.println("Distance Comparator: Return -1");
retval = 0;
}
else if (distance1 < distance2)
{
/* If the first node is closer to the given node, return 1 */
//System.out.println("Distance Comparator: Return 1");
retval = 1;
}
else
{
return -1;
}
//System.out.println("Returned: " + retval);
//System.out.println("**************** Compare Ended ***************** \n");
return retval;
}
}
}

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@ -74,6 +74,14 @@ public class NodeId implements Streamable
return this.keyBytes;
}
/**
* @return The BigInteger representation of the key
*/
public BigInteger getInt()
{
return new BigInteger(1, this.getBytes());
}
/**
* Compares a NodeId to this NodeId
*
@ -115,12 +123,10 @@ public class NodeId implements Streamable
for (int i = 0; i < ID_LENGTH / 8; i++)
{
result[i] = (byte) (this.keyBytes[i] ^ nidBytes[i]);
//System.out.println("XOR Result: " + result[i]);
}
NodeId resNid = new NodeId(result);
//System.out.println("Resulting Nid: " + resNid + " First set bit: " + resNid.getFirstSetBitIndex());
return resNid;
}

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@ -19,6 +19,7 @@ import kademlia.message.ContentLookupMessage;
import kademlia.message.ContentMessage;
import kademlia.message.Message;
import kademlia.message.NodeReplyMessage;
import kademlia.node.KeyComparator;
import kademlia.node.Node;
/**
@ -82,7 +83,7 @@ public class ContentLookupOperation implements Operation, Receiver
* We initialize a TreeMap to store nodes.
* This map will be sorted by which nodes are closest to the lookupId
*/
this.comparator = new Node.DistanceComparator(params.getKey());
this.comparator = new KeyComparator(params.getKey());
this.nodes = new TreeMap(this.comparator);
}

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@ -15,6 +15,7 @@ import kademlia.exceptions.UnknownMessageException;
import kademlia.message.Message;
import kademlia.message.NodeLookupMessage;
import kademlia.message.NodeReplyMessage;
import kademlia.node.KeyComparator;
import kademlia.node.Node;
import kademlia.node.NodeId;
@ -72,9 +73,9 @@ public class NodeLookupOperation implements Operation, Receiver
* We initialize a TreeMap to store nodes.
* This map will be sorted by which nodes are closest to the lookupId
*/
this.comparator = new Node.DistanceComparator(lookupId);
//this.nodes = new TreeMap(this.comparator);
this.nodes = new HashMap<>();
this.comparator = new KeyComparator(lookupId);
this.nodes = new TreeMap(this.comparator);
//this.nodes = new HashMap<>();
}
/**

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@ -1,7 +1,5 @@
package kademlia.tests;
import java.io.IOException;
import kademlia.core.Configuration;
import kademlia.core.Kademlia;
import kademlia.node.NodeId;
@ -19,51 +17,51 @@ public class SaveStateTest
try
{
/* Setting up 2 Kad networks */
Kademlia kad1 = new Kademlia("JoshuaK", new NodeId("ASF45678947584567467"), 12049);
Kademlia kad2 = new Kademlia("Crystal", new NodeId("AfERTKdvHGVHERJHGFdh"), 4585);
Kademlia kad3 = new Kademlia("Shameer", new NodeId("ASERTKyrHGVHERfHGFsy"), 8104);
Kademlia kad4 = new Kademlia("Lokesh", new NodeId("AS3RTKJsdjVHERJHGF94"), 8335);
Kademlia kad5 = new Kademlia("Chandu", new NodeId("ASERT47kfeVHERJHGF15"), 13345);
Kademlia kad1 = new Kademlia("JoshuaK", new NodeId("ASF45678947584567463"), 12049);
Kademlia kad2 = new Kademlia("Crystal", new NodeId("ASF45678947584567464"), 4585);
Kademlia kad3 = new Kademlia("Shameer", new NodeId("ASF45678947584567465"), 8104);
Kademlia kad4 = new Kademlia("Lokesh", new NodeId("ASF45678947584567466"), 8335);
Kademlia kad5 = new Kademlia("Chandu", new NodeId("ASF45678947584567467"), 13345);
/* Connecting 2 to 1 */
System.out.println("Connecting Nodes 1 & 2");
kad2.bootstrap(kad1.getNode());
kad2.bootstrap(kad1.getNode());
System.out.println(kad1);
System.out.println(kad2);
kad3.bootstrap(kad2.getNode());
kad3.bootstrap(kad2.getNode());
System.out.println(kad1);
System.out.println(kad2);
System.out.println(kad3);
kad4.bootstrap(kad2.getNode());
System.out.println(kad3);
kad4.bootstrap(kad2.getNode());
System.out.println(kad1);
System.out.println(kad2);
System.out.println(kad3);
System.out.println(kad4);
kad5.bootstrap(kad4.getNode());
System.out.println(kad1);
System.out.println(kad2);
System.out.println(kad3);
System.out.println(kad4);
System.out.println(kad5);
synchronized (this)
{
System.out.println("\n\n\n\nSTORING CONTENT 1\n\n\n\n");
DHTContentImpl c = new DHTContentImpl(kad2.getOwnerId(), "Some Data");
System.out.println(c);
kad2.put(c);
kad2.put(c);
}
synchronized (this)
{
System.out.println("\n\n\n\nSTORING CONTENT 2\n\n\n\n");
DHTContentImpl c2 = new DHTContentImpl(kad2.getOwnerId(), "Some other Data");
System.out.println(c2);
kad4.put(c2);
kad4.put(c2);
}
System.out.println(kad1);
@ -71,7 +69,7 @@ public class SaveStateTest
System.out.println(kad3);
System.out.println(kad4);
System.out.println(kad5);
/* Shutting down kad1 and restarting it */
System.out.println("\n\n\nShutting down Kad instance");
System.out.println(kad2);
@ -80,11 +78,8 @@ public class SaveStateTest
System.out.println("\n\n\nReloading Kad instance from file");
Kademlia kadR2 = Kademlia.loadFromFile("JoshuaK");
System.out.println(kadR2);
}
// catch(RoutingException e)
// {
// System.err.println("Routing Exception");
// }
}
catch (Exception e)
{
e.printStackTrace();

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@ -6,6 +6,7 @@ import java.util.Map;
import java.util.SortedMap;
import java.util.TreeMap;
import kademlia.core.Kademlia;
import kademlia.node.KeyComparator;
import kademlia.node.Node;
import kademlia.node.NodeId;
@ -38,7 +39,7 @@ public class TreeMapTest
Kademlia kad4 = new Kademlia("Lokesh", new NodeId("AS3RTKJsdjVHERJHGF94"), 8891);
Kademlia kad5 = new Kademlia("Chandu", new NodeId("ASERT47kfeVHERJHGF15"), 8892);
this.comparator = new Node.DistanceComparator(kad1.getNode().getNodeId());
this.comparator = new KeyComparator(kad1.getNode().getNodeId());
this.nodes = new TreeMap(this.comparator);
/* Add all nodes as unasked */