Setup Content Updating

- Didn't do this before, but now it's setup: content will be updated on the DHT if a StoreContentMessage is sent with a newer version of the content

GetParameter
- Updated the GetParameter so that it can be constructed from a KadContent object or a StorageEntryMetadata object
- Move it to the DHT package

Others
- Added a few methods to StorageEntryMetadata, StorageEntryManager& DHT to simplify conversions between KadContent, GetParameter & StorageEntryMetadata

Tests
- Written a test to check content updating

src/kademlia/Kademlia.java

@@ -14,7 +14,7 @@ import java.util.NoSuchElementException;
 import java.util.Timer;
 import java.util.TimerTask;
 import kademlia.core.DefaultConfiguration;
-import kademlia.core.GetParameter;
+import kademlia.dht.GetParameter;
 import kademlia.core.KadConfiguration;
 import kademlia.core.KadServer;
 import kademlia.dht.DHT;

src/kademlia/dht/DHT.java

@@ -9,7 +9,6 @@ import java.io.FileOutputStream;
 import java.io.IOException;
 import java.util.List;
 import java.util.NoSuchElementException;
-import kademlia.core.GetParameter;
 import kademlia.core.KadConfiguration;
 import kademlia.exceptions.ContentExistException;
 import kademlia.exceptions.ContentNotFoundException;
@@ -77,13 +76,43 @@ public class DHT
      *
      * @param content The DHT content to store
      *
+     * @return boolean true if we stored the content, false if the content already exists and is up to date
+     *
      * @throws java.io.IOException
      */
-    public void store(StorageEntry content) throws IOException
+    public boolean store(StorageEntry content) throws IOException
     {
-        /* Keep track of this content in the entries manager */
+        /* Lets check if we have this content and it's the updated version */
+        if (this.entriesManager.contains(content.getContentMetadata()))
+        {
+            StorageEntryMetadata current = this.entriesManager.get(content.getContentMetadata());
+            if (current.getLastUpdatedTimestamp() >= content.getContentMetadata().getLastUpdatedTimestamp())
+            {
+                /* We have the current content, no need to update it! just leave this method now */
+                return false;
+            }
+            else
+            {
+                /* We have this content, but not the latest version, lets delete it so the new version will be added below */
                 try
                 {
+                    this.remove(content.getContentMetadata());
+                }
+                catch (ContentNotFoundException ex)
+                {
+                    /* @todo Log an error here */
+                }
+            }
+        }
+
+        /**
+         * If we got here means we don't have this content, or we need to update the content
+         * If we need to update the content, the code above would've already deleted it, so we just need to re-add it
+         */
+        try
+        {
+            System.out.println("Adding new content.");
+            /* Keep track of this content in the entries manager */
             StorageEntryMetadata sEntry = this.entriesManager.put(content.getContentMetadata());
 
             /* Now we store the content locally in a file */
@@ -94,16 +123,19 @@ public class DHT
             {
                 this.getSerializer().write(content, dout);
             }
+            return true;
         }
         catch (ContentExistException e)
         {
-            /* Content already exist on the DHT, no need to do anything here */
-        }
+            /* @todo Content already exist on the DHT, log an error here */
+            return false;
         }
 
-    public void store(KadContent content) throws IOException
+    }
+
+    public boolean store(KadContent content) throws IOException
     {
-        this.store(new StorageEntry(content));
+        return this.store(new StorageEntry(content));
     }
 
     /**

src/kademlia/dht/GetParameter.java

@@ -1,4 +1,4 @@
-package kademlia.core;
+package kademlia.dht;
 
 import kademlia.node.NodeId;
 
@@ -35,15 +35,55 @@ public class GetParameter
      * Construct a GetParameter to search for data by NodeId, owner, type
      *
      * @param key
-     * @param owner
      * @param type
+     * @param owner
      */
-    public GetParameter(NodeId key, String owner, String type)
+    public GetParameter(NodeId key, String type, String owner)
     {
         this(key, owner);
         this.type = type;
     }
 
+    /**
+     * Construct our get parameter from a Content
+     *
+     * @param c
+     */
+    public GetParameter(KadContent c)
+    {
+        this.key = c.getKey();
+
+        if (c.getType() != null)
+        {
+            this.type = c.getType();
+        }
+
+        if (c.getOwnerId() != null)
+        {
+            this.ownerId = c.getOwnerId();
+        }
+    }
+
+    /**
+     * Construct our get parameter from a StorageEntryMeta data
+     *
+     * @param md
+     */
+    public GetParameter(StorageEntryMetadata md)
+    {
+        this.key = md.getKey();
+
+        if (md.getType() != null)
+        {
+            this.type = md.getType();
+        }
+
+        if (md.getOwnerId() != null)
+        {
+            this.ownerId = md.getOwnerId();
+        }
+    }
+
     public NodeId getKey()
     {
         return this.key;

src/kademlia/dht/StorageEntryManager.java

@@ -5,7 +5,6 @@ import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.NoSuchElementException;
-import kademlia.core.GetParameter;
 import kademlia.exceptions.ContentExistException;
 import kademlia.exceptions.ContentNotFoundException;
 import kademlia.node.NodeId;
@@ -76,7 +75,6 @@ class StorageEntryManager
     {
         if (this.entries.containsKey(param.getKey()))
         {
-            System.out.println("Does contain the key");
             /* Content with this key exist, check if any match the rest of the search criteria */
             for (StorageEntryMetadata e : this.entries.get(param.getKey()))
             {
@@ -89,7 +87,6 @@ class StorageEntryManager
         }
         else
         {
-            System.out.println("Does not contain the key");
             System.out.println(this);
         }
         return false;
@@ -100,20 +97,15 @@ class StorageEntryManager
      */
     public boolean contains(KadContent content)
     {
-        return this.contains(new StorageEntryMetadata(content));
+        return this.contains(new GetParameter(content));
     }
 
     /**
      * Check if a StorageEntry exist on this DHT
      */
-    private boolean contains(StorageEntryMetadata entry)
+    public boolean contains(StorageEntryMetadata entry)
     {
-        if (this.entries.containsKey(entry.getKey()))
-        {
-            return this.entries.get(entry.getKey()).contains(entry);
-        }
-
-        return false;
+        return this.contains(new GetParameter(entry));
     }
 
     /**
@@ -148,6 +140,11 @@ class StorageEntryManager
         }
     }
 
+    public StorageEntryMetadata get(StorageEntryMetadata md)
+    {
+        return this.get(new GetParameter(md));
+    }
+
     /**
      * @return A list of all storage entries
      */

src/kademlia/dht/StorageEntryMetadata.java

@@ -1,7 +1,6 @@
 package kademlia.dht;
 
 import java.util.Objects;
-import kademlia.core.GetParameter;
 import kademlia.node.NodeId;
 
 /**
@@ -18,7 +17,7 @@ public class StorageEntryMetadata
     private final String ownerId;
     private final String type;
     private final int contentHash;
-    private final long lastUpdated;
+    private final long updatedTs;
 
     public StorageEntryMetadata(KadContent content)
     {
@@ -26,7 +25,7 @@ public class StorageEntryMetadata
         this.ownerId = content.getOwnerId();
         this.type = content.getType();
         this.contentHash = content.hashCode();
-        this.lastUpdated = content.getLastUpdatedTimestamp();
+        this.updatedTs = content.getLastUpdatedTimestamp();
     }
 
     public NodeId getKey()
@@ -49,6 +48,11 @@ public class StorageEntryMetadata
         return this.contentHash;
     }
     
+    public long getLastUpdatedTimestamp()
+    {
+        return this.updatedTs;
+    }
+
     /**
      * When a node is looking for content, he sends the search criteria in a GetParameter object
      * Here we take this GetParameter object and check if this StorageEntry satisfies the given parameters

src/kademlia/message/ContentLookupMessage.java

@@ -3,7 +3,7 @@ package kademlia.message;
 import java.io.DataInputStream;
 import java.io.DataOutputStream;
 import java.io.IOException;
-import kademlia.core.GetParameter;
+import kademlia.dht.GetParameter;
 import kademlia.node.Node;
 import kademlia.serializer.JsonSerializer;
 

src/kademlia/operation/ContentLookupOperation.java

@@ -9,7 +9,7 @@ import java.util.List;
 import java.util.Map;
 import java.util.SortedMap;
 import java.util.TreeMap;
-import kademlia.core.GetParameter;
+import kademlia.dht.GetParameter;
 import kademlia.core.KadConfiguration;
 import kademlia.core.KadServer;
 import kademlia.dht.StorageEntry;

src/kademlia/tests/ContentSendingTest.java

@@ -2,7 +2,7 @@ package kademlia.tests;
 
 import java.io.IOException;
 import java.util.List;
-import kademlia.core.GetParameter;
+import kademlia.dht.GetParameter;
 import kademlia.Kademlia;
 import kademlia.dht.StorageEntry;
 import kademlia.node.NodeId;

src/kademlia/tests/ContentUpdatingTest.java

@@ -0,0 +1,64 @@
+package kademlia.tests;
+
+import java.io.IOException;
+import java.util.List;
+import kademlia.dht.GetParameter;
+import kademlia.Kademlia;
+import kademlia.dht.StorageEntry;
+import kademlia.node.NodeId;
+
+/**
+ * Testing sending and receiving content between 2 Nodes on a network
+ *
+ * @author Joshua Kissoon
+ * @since 20140224
+ */
+public class ContentUpdatingTest
+{
+
+    public static void main(String[] args)
+    {
+        try
+        {
+            /* Setting up 2 Kad networks */
+            Kademlia kad1 = new Kademlia("JoshuaK", new NodeId("ASF45678947584567467"), 7574);
+            System.out.println("Created Node Kad 1: " + kad1.getNode().getNodeId());
+            Kademlia kad2 = new Kademlia("Crystal", new NodeId("ASERTKJDHGVHERJHGFLK"), 7572);
+            System.out.println("Created Node Kad 2: " + kad2.getNode().getNodeId());
+            kad2.bootstrap(kad1.getNode());
+
+            /* Lets create the content and share it */
+            DHTContentImpl c = new DHTContentImpl(kad2.getOwnerId(), "Some Data");
+            kad2.put(c);
+
+            /* Lets retrieve the content */
+            System.out.println("Retrieving Content");
+            GetParameter gp = new GetParameter(c.getKey(), DHTContentImpl.TYPE, c.getOwnerId());
+            System.out.println("Get Parameter: " + gp);
+            List<StorageEntry> conte = kad2.get(gp, 4);
+            for (StorageEntry cc : conte)
+            {
+                System.out.println("Content Found: " + new DHTContentImpl().fromBytes(cc.getContent()));
+                System.out.println("Content Metadata: " + cc.getContentMetadata());
+            }
+
+            /* Lets update the content and put it again */
+            c.setData("Some New Data");
+            kad2.put(c);
+
+            /* Lets retrieve the content */
+            System.out.println("Retrieving Content Again");
+            conte = kad2.get(gp, 4);
+            for (StorageEntry cc : conte)
+            {
+                System.out.println("Content Found: " + new DHTContentImpl().fromBytes(cc.getContent()));
+                System.out.println("Content Metadata: " + cc.getContentMetadata());
+            }
+
+        }
+        catch (IOException e)
+        {
+            e.printStackTrace();
+        }
+    }
+}

src/kademlia/tests/DHTContentImpl.java

@@ -18,7 +18,8 @@ public class DHTContentImpl implements KadContent
     private NodeId key;
     private String data;
     private String ownerId;
-    private long createTs, updateTs;
+    private final long createTs;
+    private long updateTs;
 
     
     {
@@ -46,6 +47,7 @@ public class DHTContentImpl implements KadContent
     public void setData(String newData)
     {
         this.data = newData;
+        this.setUpdated();
     }
 
     @Override
@@ -66,6 +68,14 @@ public class DHTContentImpl implements KadContent
         return this.ownerId;
     }
 
+    /**
+     * Set the content as updated
+     */
+    public void setUpdated()
+    {
+        this.updateTs = System.currentTimeMillis() / 1000L;
+    }
+
     @Override
     public long getCreatedTimestamp()
     {

src/kademlia/tests/RefreshOperationTest.java

@@ -2,7 +2,7 @@ package kademlia.tests;
 
 import java.io.IOException;
 import java.util.List;
-import kademlia.core.GetParameter;
+import kademlia.dht.GetParameter;
 import kademlia.Kademlia;
 import kademlia.dht.StorageEntry;
 import kademlia.node.NodeId;

src/kademlia/tests/SaveStateTest2.java

@@ -2,7 +2,7 @@ package kademlia.tests;
 
 import java.util.List;
 import kademlia.Kademlia;
-import kademlia.core.GetParameter;
+import kademlia.dht.GetParameter;
 import kademlia.dht.StorageEntry;
 import kademlia.node.NodeId;