Finished DHT content storage and retrieval

Started working on Content lookup and sending content

src/kademlia/core/GetParameter.java

@@ -16,7 +16,7 @@ public class GetParameter
 {
 
     private NodeId key;
-    private String owner = null;
+    private String ownerId = null;
     private String type = null;
 
     public GetParameter(NodeId key)
@@ -27,7 +27,7 @@ public class GetParameter
     public GetParameter(NodeId key, String owner)
     {
         this(key);
-        this.owner = owner;
+        this.ownerId = owner;
     }
 
     public GetParameter(NodeId key, String owner, String type)
@@ -36,4 +36,18 @@ public class GetParameter
         this.type = type;
     }
 
+    public NodeId getKey()
+    {
+        return this.key;
+    }
+
+    public String getOwnerId()
+    {
+        return this.ownerId;
+    }
+
+    public String getType()
+    {
+        return this.type;
+    }
 }

src/kademlia/core/Kademlia.java

@@ -2,6 +2,8 @@ package kademlia.core;
 
 import java.io.IOException;
 import java.net.InetAddress;
+import java.util.List;
+import java.util.NoSuchElementException;
 import java.util.Timer;
 import java.util.TimerTask;
 import kademlia.dht.DHT;
@@ -24,6 +26,7 @@ import kademlia.operation.StoreOperation;
  * @todo When we receive a store message - if we have a newer version of the content, re-send this newer version to that node so as to update their version
  * @todo Handle IPv6 Addresses
  * @todo Handle compressing data
+ * @todo Allow optional storing of content locally using the put method
  */
 public class Kademlia
 {
@@ -138,13 +141,23 @@ public class Kademlia
      * The content returned is a JSON String in byte format; this string is parsed into a class
      *
      * @param param The parameters used to search for the content
-     * @param c     The class to cast the returned object to
      *
      * @return DHTContent The content
+     *
+     * @throws java.io.IOException
      */
-    public KadContent get(GetParameter param, Class c)
+    public List<KadContent> get(GetParameter param) throws NoSuchElementException, IOException
     {
-        return null;
+        if (this.dht.contains(param))
+        {
+            /* If the content exist in our own DHT, then return it. */
+            return this.dht.get(param);
+        }
+        else
+        {
+            /* Seems like it doesn't exist in our DHT, get it from other Nodes */
+            return new DataLookupOperation().execute().getContent();
+        }
     }
 
     /**

src/kademlia/dht/DHT.java

@@ -1,10 +1,18 @@
 package kademlia.dht;
 
+import java.io.DataInputStream;
 import java.io.DataOutputStream;
 import java.io.File;
+import java.io.FileInputStream;
+import java.io.FileNotFoundException;
 import java.io.FileOutputStream;
 import java.io.IOException;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.NoSuchElementException;
 import kademlia.core.Configuration;
+import kademlia.core.GetParameter;
+import kademlia.node.NodeId;
 import kademlia.serializer.JsonSerializer;
 
 /**
@@ -33,10 +41,90 @@ public class DHT
     public void store(KadContent content) throws IOException
     {
         /* Keep track of this content in the entries manager */
-        this.entriesManager.put(new StorageEntry(content));
+        this.entriesManager.put(content);
+
+        /* Now we store the content locally in a file */
+        String contentStorageFolder = this.getContentStorageFolderName(content.getKey());
+        DataOutputStream dout = new DataOutputStream(new FileOutputStream(contentStorageFolder + File.separator + content.hashCode() + ".kct"));
+        new JsonSerializer().write(content, dout);
+    }
 
     /**
-         * Now we store the content locally in a file
+     * Retrieves a Content from local storage
+     *
+     * @param key      The Key of the content to retrieve
+     * @param hashCode The hash code of the content to retrieve
+     *
+     * @return A KadContent object
+     */
+    private KadContent retrieve(NodeId key, int hashCode) throws FileNotFoundException, IOException, ClassNotFoundException
+    {
+        String folder = this.getContentStorageFolderName(key);
+        DataInputStream in = new DataInputStream(new FileInputStream(folder + File.separator + hashCode + ".kct"));
+        return new JsonSerializer().read(in);
+    }
+
+    /**
+     * Check if any content for the given criteria exists in this DHT
+     *
+     * @param param The content search criteria
+     *
+     * @return boolean Whether any content exist that satisfy the criteria
+     */
+    public boolean contains(GetParameter param)
+    {
+        return this.entriesManager.contains(param);
+    }
+
+    /**
+     * Get the List<StorageEntry> for the content if any exist,
+     * retrieve the content from the storage system and return it
+     *
+     * @param param The parameters used to filter the content needed
+     *
+     * @return List<KadContent> A list with the content found on the DHT satisfying the given criteria
+     *
+     * @throws java.io.IOException
+     */
+    public List<KadContent> get(GetParameter param) throws NoSuchElementException, IOException
+    {
+        /* Load all KadContent for the entries if any exist */
+        List<KadContent> values = new ArrayList<>();
+
+        try
+        {
+            for (StorageEntry e : this.entriesManager.get(param))
+            {
+                values.add(this.retrieve(e.getKey(), e.getContentHash()));
+            }
+        }
+        catch (FileNotFoundException e)
+        {
+            System.err.println("Error while loading file for content.");
+        }
+        catch (ClassNotFoundException e)
+        {
+            System.err.println("The class for some content was not found.");
+        }
+
+        if (values.isEmpty())
+        {
+            throw new NoSuchElementException();
+        }
+
+        return values;
+    }
+
+    /**
+     * Get the name of the folder for which a content should be stored
+     *
+     * @param key The key of the content
+     *
+     * @return String The name of the folder
+     */
+    private String getContentStorageFolderName(NodeId key)
+    {
+        /**
          * Each content is stored in a folder named after the first 10 characters of the NodeId
          *
          * The name of the file containing the content is the hash of this content
@@ -44,23 +132,21 @@ public class DHT
         String storagePath = System.getProperty("user.home") + File.separator + Configuration.localFolder;
         File mainStorageFolder = new File(storagePath);
 
-        /* Create the folder if it doesn't exist */
+        /* Create the main storage folder if it doesn't exist */
         if (!mainStorageFolder.isDirectory())
         {
             mainStorageFolder.mkdir();
         }
 
-        /* Check if a folder after the first 10 characters of Hex(nodeId) exist, if not, create it */
-        String folderName = content.getKey().hexRepresentation().substring(0, 20);
+        String folderName = key.hexRepresentation().substring(0, 10);
         File contentStorageFolder = new File(mainStorageFolder + File.separator + folderName);
+
+        /* Create the content folder if it doesn't exist */
         if (!contentStorageFolder.isDirectory())
         {
             contentStorageFolder.mkdir();
         }
 
-        /* Write the content to a file and store it in the folder */
-        File contentFile = new File(String.valueOf(content.hashCode()) + ".kct");
-        DataOutputStream dout = new DataOutputStream(new FileOutputStream(contentStorageFolder + File.separator + contentFile));
-        new JsonSerializer().write(content, dout);
+        return mainStorageFolder + File.separator + folderName;
     }
 }

src/kademlia/dht/StorageEntry.java

@@ -1,6 +1,7 @@
 package kademlia.dht;
 
 import java.util.Objects;
+import kademlia.core.GetParameter;
 import kademlia.node.NodeId;
 
 /**
@@ -16,12 +17,14 @@ public class StorageEntry
     private final NodeId key;
     private final String ownerId;
     private final String type;
+    private final int contentHash;
 
     public StorageEntry(KadContent content)
     {
         this.key = content.getKey();
         this.ownerId = content.getOwnerId();
         this.type = content.getType();
+        this.contentHash = content.hashCode();
     }
 
     public NodeId getKey()
@@ -29,6 +32,52 @@ public class StorageEntry
         return this.key;
     }
 
+    public String getOwnerId()
+    {
+        return this.ownerId;
+    }
+
+    public String getType()
+    {
+        return this.type;
+    }
+
+    public int getContentHash()
+    {
+        return this.contentHash;
+    }
+
+    /**
+     * 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
+     *
+     * @param params
+     *
+     * @return boolean Whether this content satisfies the parameters
+     */
+    public boolean satisfiesParameters(GetParameter params)
+    {
+        /* Check that owner id matches */
+        if ((params.getOwnerId() != null) && (!params.getOwnerId().equals(this.ownerId)))
+        {
+            return false;
+        }
+
+        /* Check that type matches */
+        if ((params.getType() != null) && (!params.getType().equals(this.type)))
+        {
+            return false;
+        }
+
+        /* Check that key matches */
+        if ((params.getKey() != null) && (!params.getKey().equals(this.key)))
+        {
+            return false;
+        }
+
+        return true;
+    }
+
     @Override
     public boolean equals(Object o)
     {

src/kademlia/dht/StorageEntryManager.java

@@ -4,6 +4,8 @@ import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
+import java.util.NoSuchElementException;
+import kademlia.core.GetParameter;
 import kademlia.node.NodeId;
 
 /**
@@ -27,10 +29,11 @@ public class StorageEntryManager
     /**
      * Add a new entry to our storage
      *
-     * @param entry
+     * @param content The content to store a reference to
      */
-    public void put(StorageEntry entry)
+    public void put(KadContent content)
     {
+        StorageEntry entry = new StorageEntry(content);
         if (!this.entries.containsKey(entry.getKey()))
         {
             this.entries.put(entry.getKey(), new ArrayList<StorageEntry>());
@@ -44,27 +47,65 @@ public class StorageEntryManager
      *
      * @todo Add searching for content by type and ownerID
      *
-     * @param key
+     * @param param The parameters used to search for a content
      *
      * @return boolean
      */
-    public boolean contains(NodeId key)
+    public boolean contains(GetParameter param)
     {
-        return this.entries.containsKey(key);
+        if (this.entries.containsKey(param.getKey()))
+        {
+            /* Content with this key exist, check if any match the rest of the search criteria */
+            for (StorageEntry e : this.entries.get(param.getKey()))
+            {
+                /* If any entry satisfies the given parameters, return true */
+                if (e.satisfiesParameters(param))
+                {
+                    return true;
+                }
+            }
+        }
+        return false;
     }
 
     /**
      * Checks if our DHT has a Content for the given criteria
      *
-     * @todo Add finding for content by type and ownerID
+     * @param param The parameters used to search for a content
      *
-     * @param key
+     * @todo Add finding for content by type and ownerID
      *
      * @return List of content for the specific search parameters
      */
-    public List<StorageEntry> get(NodeId key)
+    public List<StorageEntry> get(GetParameter param) throws NoSuchElementException
     {
-        return this.entries.get(key);
+        if (this.entries.containsKey(param.getKey()))
+        {
+            /* Content with this key exist, check if any match the rest of the search criteria */
+            List<StorageEntry> results = new ArrayList<>();
+
+            for (StorageEntry e : this.entries.get(param.getKey()))
+            {
+                /* If any entry satisfies the given parameters, return true */
+                if (e.satisfiesParameters(param))
+                {
+                    results.add(e);
+                }
+            }
+
+            if (results.size() > 0)
+            {
+                return results;
+            }
+            else
+            {
+                throw new NoSuchElementException();
+            }
+        }
+        else
+        {
+            throw new NoSuchElementException("No content exist for the given parameters");
+        }
     }
 
 }

src/kademlia/operation/ContentLookupOperation.java

@@ -0,0 +1,31 @@
+package kademlia.operation;
+
+import kademlia.core.KadServer;
+import kademlia.node.Node;
+import kademlia.node.NodeId;
+
+/**
+ * Looks up a specified identifier and returns the value associated with it
+ *
+ * @author Joshua Kissoon
+ * @since 20140226
+ */
+public class ContentLookupOperation implements Operation
+{
+
+    private final KadServer server;
+    private final Node localNode;
+    private final NodeId key;
+
+    /**
+     * @param server
+     * @param localNode
+     * @param key       The key for the content which we need to find
+     */
+    public ContentLookupOperation(KadServer server, Node localNode, NodeId key)
+    {
+        this.server = server;
+        this.localNode = localNode;
+        this.key = key;
+    }
+}