Fixed the bug that was causing replication of content files and StorageEntries. RefreshOperation working well!!

src/kademlia/core/Configuration.java

@@ -11,7 +11,7 @@ public class Configuration
     /**
      * Interval in milliseconds between execution of RestoreOperations.
      * */
-    public static long RESTORE_INTERVAL = 60 * 60 * 1000;
+    public static long RESTORE_INTERVAL = 60 * 1000;   // Default at 1 hour
 
     /**
      * If no reply received from a node in this period (in milliseconds)
@@ -37,7 +37,7 @@ public class Configuration
     /**
      * Bucket size.
      * */
-    public static int K = 5;
+    public static int K = 2;
 
     /**
      * Size of replacement cache.

src/kademlia/dht/DHT.java

@@ -11,6 +11,7 @@ import java.util.List;
 import java.util.NoSuchElementException;
 import kademlia.core.Configuration;
 import kademlia.core.GetParameter;
+import kademlia.exceptions.ContentExistException;
 import kademlia.node.NodeId;
 import kademlia.serializer.JsonSerializer;
 
@@ -54,12 +55,19 @@ public class DHT
     public void store(KadContent content) throws IOException
     {
         /* Keep track of this content in the entries manager */
-        this.entriesManager.put(content);
+        try
+        {
+            StorageEntry sEntry = this.entriesManager.put(content);
 
-        /* Now we store the content locally in a file */
+            /* Now we store the content locally in a file */
-        String contentStorageFolder = this.getContentStorageFolderName(content.getKey());
+            String contentStorageFolder = this.getContentStorageFolderName(content.getKey());
-        DataOutputStream dout = new DataOutputStream(new FileOutputStream(contentStorageFolder + File.separator + content.hashCode() + ".kct"));
+            DataOutputStream dout = new DataOutputStream(new FileOutputStream(contentStorageFolder + File.separator + sEntry.hashCode() + ".kct"));
-        contentSerializer.write(content, dout);
+            contentSerializer.write(content, dout);
+        }
+        catch (ContentExistException e)
+        {
+            /* Content already exist on the DHT, no need to do anything here */
+        }
     }
 
     /**
@@ -102,7 +110,7 @@ public class DHT
     {
         try
         {
-            return this.retrieve(entry.getKey(), entry.getContentHash());
+            return this.retrieve(entry.getKey(), entry.hashCode());
         }
         catch (FileNotFoundException e)
         {
@@ -133,7 +141,7 @@ public class DHT
         try
         {
             StorageEntry e = this.entriesManager.get(param);
-            return this.retrieve(e.getKey(), e.getContentHash());
+            return this.retrieve(e.getKey(), e.hashCode());
         }
         catch (FileNotFoundException e)
         {
@@ -201,7 +209,14 @@ public class DHT
     {
         for (StorageEntry e : ientries)
         {
-            this.entriesManager.put(e);
+            try
+            {
+                this.entriesManager.put(e);
+            }
+            catch (ContentExistException ex)
+            {
+                /* Entry already exist, no need to store it again */
+            }
         }
     }
 

src/kademlia/dht/KadContent.java

@@ -29,6 +29,14 @@ public interface KadContent
      */
     public long getCreatedTimestamp();
 
+    /**
+     * Each content will have an update timestamp
+     * This allows the DHT to keep only the latest version of a content
+     *
+     * @return long The timestamp of when this content was last updated
+     */
+    public long getLastUpdatedTimestamp();
+
     /**
      * @return The ID of the owner of this content
      */

src/kademlia/dht/StorageEntry.java

@@ -18,6 +18,7 @@ public class StorageEntry
     private final String ownerId;
     private final String type;
     private final int contentHash;
+    private final long lastUpdated;
 
     public StorageEntry(KadContent content)
     {
@@ -25,6 +26,7 @@ public class StorageEntry
         this.ownerId = content.getOwnerId();
         this.type = content.getType();
         this.contentHash = content.hashCode();
+        this.lastUpdated = content.getLastUpdatedTimestamp();
     }
 
     public NodeId getKey()
@@ -109,7 +111,7 @@ public class StorageEntry
         sb.append(this.type);
         sb.append("} ");
         sb.append("]");
-        
+
         return sb.toString();
     }
 }

src/kademlia/dht/StorageEntryManager.java

@@ -6,6 +6,7 @@ import java.util.List;
 import java.util.Map;
 import java.util.NoSuchElementException;
 import kademlia.core.GetParameter;
+import kademlia.exceptions.ContentExistException;
 import kademlia.node.NodeId;
 
 /**
@@ -31,10 +32,9 @@ class StorageEntryManager
      *
      * @param content The content to store a reference to
      */
-    public void put(KadContent content)
+    public StorageEntry put(KadContent content) throws ContentExistException
     {
-        StorageEntry entry = new StorageEntry(content);
+        return this.put(new StorageEntry(content));
-        this.put(entry);
     }
 
     /**
@@ -42,13 +42,24 @@ class StorageEntryManager
      *
      * @param entry The StorageEntry to store
      */
-    public void put(StorageEntry entry)
+    public StorageEntry put(StorageEntry entry) throws ContentExistException
     {
         if (!this.entries.containsKey(entry.getKey()))
         {
             this.entries.put(entry.getKey(), new ArrayList<StorageEntry>());
         }
-        this.entries.get(entry.getKey()).add(entry);
+
+        /* If this entry doesn't already exist, then we add it */
+        if (!this.contains(entry))
+        {
+            this.entries.get(entry.getKey()).add(entry);
+
+            return entry;
+        }
+        else
+        {
+            throw new ContentExistException("Content already exists on this DHT");
+        }
     }
 
     /**
@@ -77,6 +88,27 @@ class StorageEntryManager
         return false;
     }
 
+    /**
+     * Check if a content exist in the DHT
+     */
+    public boolean contains(KadContent content)
+    {
+        return this.contains(new StorageEntry(content));
+    }
+
+    /**
+     * Check if a StorageEntry exist on this DHT
+     */
+    private boolean contains(StorageEntry entry)
+    {
+        if (this.entries.containsKey(entry.getKey()))
+        {
+            return this.entries.get(entry.getKey()).contains(entry);
+        }
+
+        return false;
+    }
+
     /**
      * Checks if our DHT has a Content for the given criteria
      *

src/kademlia/exceptions/ContentExistException.java

@@ -0,0 +1,21 @@
+package kademlia.exceptions;
+
+/**
+ * An exception used to indicate that a content already exist on the DHT
+ *
+ * @author Joshua Kissoon
+ * @created 20140322
+ */
+public class ContentExistException extends Exception
+{
+
+    public ContentExistException()
+    {
+        super();
+    }
+
+    public ContentExistException(String message)
+    {
+        super(message);
+    }
+}

src/kademlia/tests/AutoRefreshOperationTest.java

@@ -1,5 +1,9 @@
 package kademlia.tests;
 
+import java.io.IOException;
+import java.util.Timer;
+import java.util.TimerTask;
+import kademlia.core.Configuration;
 import kademlia.core.Kademlia;
 import kademlia.node.NodeId;
 
@@ -17,31 +21,22 @@ public class AutoRefreshOperationTest
         try
         {
             /* Setting up 2 Kad networks */
-            Kademlia kad1 = new Kademlia("JoshuaK", new NodeId("ASF45678947584567463"), 12049);
+            final Kademlia kad1 = new Kademlia("JoshuaK", new NodeId("ASF45678947584567463"), 12049);
-            Kademlia kad2 = new Kademlia("Crystal", new NodeId("ASF45678947584567464"), 4585);
+            final Kademlia kad2 = new Kademlia("Crystal", new NodeId("ASF45678947584567464"), 4585);
-            Kademlia kad3 = new Kademlia("Shameer", new NodeId("ASF45678947584567465"), 8104);
+            final Kademlia kad3 = new Kademlia("Shameer", new NodeId("ASF45678947584567465"), 8104);
-            Kademlia kad4 = new Kademlia("Lokesh", new NodeId("ASF45678947584567466"), 8335);
+            final Kademlia kad4 = new Kademlia("Lokesh", new NodeId("ASF45678947584567466"), 8335);
-            Kademlia kad5 = new Kademlia("Chandu", new NodeId("ASF45678947584567467"), 13345);
+            final Kademlia kad5 = new Kademlia("Chandu", new NodeId("ASF45678947584567467"), 13345);
 
             /* Connecting nodes */
-            System.out.println("Connecting Nodes 1 & 2");
+            System.out.println("Connecting Nodes");
             kad2.bootstrap(kad1.getNode());
             kad3.bootstrap(kad2.getNode());
             kad4.bootstrap(kad2.getNode());
             kad5.bootstrap(kad4.getNode());
 
-            System.out.println(kad1);
+            DHTContentImpl c = new DHTContentImpl(kad1.getOwnerId(), "Some Data");
-            System.out.println(kad2);
+            kad1.putLocally(c);
-            System.out.println(kad3);
+            System.out.println("\nSTORING CONTENT 1 locally on " + kad1.getOwnerId() + "\n\n\n\n");
-            System.out.println(kad4);
-            System.out.println(kad5);
-
-            DHTContentImpl c = new DHTContentImpl(kad2.getOwnerId(), "Some Data");
-            kad2.put(c);
-            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);
 
             System.out.println(kad1);
             System.out.println(kad2);
@@ -49,14 +44,24 @@ public class AutoRefreshOperationTest
             System.out.println(kad4);
             System.out.println(kad5);
 
-            /* Shutting down kad1 and restarting it */
+            /* Print the node states every few minutes */
-            System.out.println("\n\n\nShutting down Kad instance");
+            Timer timer = new Timer(true);
-            System.out.println(kad2);
+            timer.schedule(
-            kad1.shutdown();
+                    new TimerTask()
-
+                    {
-            System.out.println("\n\n\nReloading Kad instance from file");
+                        @Override
-            Kademlia kadR2 = Kademlia.loadFromFile("JoshuaK");
+                        public void run()
-            System.out.println(kadR2);
+                        {
+                            System.out.println(kad1);
+                            System.out.println(kad2);
+                            System.out.println(kad3);
+                            System.out.println(kad4);
+                            System.out.println(kad5);
+                        }
+                    },
+                    // Delay                        // Interval
+                    Configuration.RESTORE_INTERVAL, Configuration.RESTORE_INTERVAL
+            );
         }
 
         catch (Exception e)

src/kademlia/tests/DHTContentImpl.java

@@ -15,13 +15,13 @@ public class DHTContentImpl implements KadContent
     private final NodeId key;
     private String data;
     private final String ownerId;
-    private final long createTs;
+    private final long createTs, updateTs;
 
     public static final String TYPE = "DHTContentImpl";
 
     
     {
-        this.createTs = System.currentTimeMillis() / 1000L;
+        this.createTs = this.updateTs = System.currentTimeMillis() / 1000L;
     }
 
     public DHTContentImpl(String ownerId, String data)
@@ -71,6 +71,13 @@ public class DHTContentImpl implements KadContent
         return this.createTs;
     }
 
+    @Override
+    public long getLastUpdatedTimestamp()
+    {
+        return this.updateTs;
+    }
+
+    @Override
     public String toString()
     {
         return "DHTContentImpl[{data=" + this.data + "{ {key:" + this.key + "}]";