Route Length Computation

- Before we were doing this by just adding incrementing a value everytime we get a set of nodes as the reply of a FIND_NODE or FIND_VALUE RPC
-- This may be wrong since nodes the same distance away may reply and we'll still be incrementing for both
- Created a route length checker class to properly check route lengths

ContentLookupOperation
- Added the route length check to the CLO operation

Didn't add it to the NodeLookupOperation since I'm not sure we're using it anywhere... Though it can be useful there

src/kademlia/operation/ContentLookupOperation.java

@@ -24,6 +24,7 @@ import kademlia.message.Message;
 import kademlia.message.NodeReplyMessage;
 import kademlia.node.KeyComparator;
 import kademlia.node.Node;
+import kademlia.util.RouteLengthChecker;
 
 /**
  * Looks up a specified identifier and returns the value associated with it
@@ -57,13 +58,12 @@ public class ContentLookupOperation implements Operation, Receiver
     private final Comparator comparator;
 
     /* Statistical information */
-    private int routeLength;    // Length of the route to find this content
+    private RouteLengthChecker routeLengthChecker;
 
     
     {
         messagesTransiting = new HashMap<>();
         isContentFound = false;
-        routeLength = 1;
     }
 
     /**
@@ -105,7 +105,11 @@ public class ContentLookupOperation implements Operation, Receiver
              * We add all nodes here instead of the K-Closest because there may be the case that the K-Closest are offline
              * - The operation takes care of looking at the K-Closest.
              */
-            this.addNodes(this.localNode.getRoutingTable().getAllNodes());
+            List<Node> allNodes = this.localNode.getRoutingTable().getAllNodes();
+            this.addNodes(allNodes);
+            
+            /* Also add the initial set of nodes to the routeLengthChecker */
+            this.routeLengthChecker.addInitialNodes(allNodes);
 
             /**
              * If we haven't found the requested amount of content as yet,
@@ -254,9 +258,6 @@ public class ContentLookupOperation implements Operation, Receiver
         }
         else
         {
-            /* Our hop length is increased */
-            this.routeLength++;
-
             /* The reply received is a NodeReplyMessage with nodes closest to the content needed */
             NodeReplyMessage msg = (NodeReplyMessage) incoming;
 
@@ -270,6 +271,9 @@ public class ContentLookupOperation implements Operation, Receiver
             /* Remove this msg from messagesTransiting since it's completed now */
             this.messagesTransiting.remove(comm);
             
+            /* Add the received nodes to the routeLengthChecker */
+            this.routeLengthChecker.addNodes(msg.getNodes(), origin);
+
             /* Add the received nodes to our nodes list to query */
             this.addNodes(msg.getNodes());
             this.askNodesorFinish();
@@ -324,6 +328,6 @@ public class ContentLookupOperation implements Operation, Receiver
      */
     public int routeLength()
     {
-        return this.routeLength;
+        return this.routeLengthChecker.getRouteLength();
     }
 }

src/kademlia/routing/RoutingTable.java

@@ -124,7 +124,7 @@ public class RoutingTable implements KadRoutingTable
      * @return List A List of all Nodes in this RoutingTable
      */
     @Override
-    public synchronized final List getAllNodes()
+    public synchronized final List<Node> getAllNodes()
     {
         List<Node> nodes = new ArrayList<>();
 
@@ -143,7 +143,7 @@ public class RoutingTable implements KadRoutingTable
      * @return List A List of all Nodes in this RoutingTable
      */
     @Override
-    public final List getAllContacts()
+    public final List<Contact> getAllContacts()
     {
         List<Contact> contacts = new ArrayList<>();
 

src/kademlia/util/RouteLengthChecker.java

@@ -0,0 +1,92 @@
+package kademlia.util;
+
+import java.util.Collection;
+import java.util.HashMap;
+import kademlia.node.Node;
+
+/**
+ * Class that helps compute the route length taken to complete an operation.
+ *
+ * Only used for routing operations - mainly the NodeLookup and ContentLookup Operations.
+ *
+ * Idea:
+ * - Add the original set of nodes with route length 0;
+ * - When we get a node reply with a set of nodes, we add those nodes and set the route length to their sender route length + 1
+ *
+ * @author Joshua Kissoon
+ * @since 20140510
+ */
+public class RouteLengthChecker
+{
+
+    /* Store the nodes and their route length (RL) */
+    private final HashMap<Node, Integer> nodes;
+
+    /* Lets cache the max route length instead of having to go and search for it later */
+    private int maxRouteLength;
+
+    
+    {
+        this.nodes = new HashMap<>();
+        this.maxRouteLength = 1;
+    }
+
+    /**
+     * Add the initial nodes in the routing operation
+     *
+     * @param initialNodes The set of initial nodes
+     */
+    public void addInitialNodes(Collection<Node> initialNodes)
+    {
+        for (Node n : initialNodes)
+        {
+            this.nodes.put(n, 1);
+        }
+    }
+
+    /**
+     * Add any nodes that we get from a node reply.
+     *
+     * The route length of these nodes will be their sender + 1;
+     *
+     * @param inputSet The set of nodes we receive
+     * @param sender   The node who send the set
+     */
+    public void addNodes(Collection<Node> inputSet, Node sender)
+    {
+        if (!this.nodes.containsKey(sender))
+        {
+            return;
+        }
+
+        /* Get the route length of the input set - sender RL + 1 */
+        int inputSetRL = this.nodes.get(sender) + 1;
+
+        if (inputSetRL > this.maxRouteLength)
+        {
+            this.maxRouteLength = inputSetRL;
+        }
+
+        /* Add the nodes to our set */
+        for (Node n : inputSet)
+        {
+            /* We only add if the node is not already there... */
+            if (!this.nodes.containsKey(n))
+            {
+                this.nodes.put(n, inputSetRL);
+            }
+        }
+    }
+
+    /**
+     * Get the route length of the operation!
+     *
+     * It will be the max route length of all the nodes here.
+     *
+     * @return The route length
+     */
+    public int getRouteLength()
+    {
+        return this.maxRouteLength;
+    }
+}