Scoring algorithm

pom.xml

@@ -5,7 +5,7 @@
 	<artifactId>libtorrent</artifactId>
 	<packaging>jar</packaging>
 	<name>libtorrent</name>
-	<version>1.0</version>
+	<version>1.0.0-alpha2</version>
 	<description>Java library used for downloading and uploading torrent files</description>
 	<url>http://code.google.com/p/libtorrent-java</url>
 
@@ -97,6 +97,34 @@
 					</execution>
 				</executions>
 			</plugin>
+			<plugin>
+				<groupId>org.apache.maven.plugins</groupId>
+				<artifactId>maven-pdf-plugin</artifactId>
+				<version>1.1</version>
+				<executions>
+					<execution>
+						<id>pdf</id>
+						<phase>package</phase>
+						<goals>
+							<goal>pdf</goal>
+						</goals>
+					</execution>
+				</executions>
+			</plugin>
+			<plugin>
+				<groupId>org.apache.maven.plugins</groupId>
+				<artifactId>maven-clean-plugin</artifactId>
+				<version>2.4.1</version>
+				<executions>
+					<execution>
+						<id>clean</id>
+						<phase>package</phase>
+						<goals>
+							<goal>clean</goal>
+						</goals>
+					</execution>
+				</executions>
+			</plugin>
 		</plugins>
 	</build>
 	<repositories>

src/main/java/net/torrent/protocol/algorithm/impl/TorrentStdAlgorithm.java

@@ -21,6 +21,8 @@ import net.torrent.protocol.algorithm.TorrentPeerAlgorithm;
 import net.torrent.protocol.algorithm.TorrentPieceDownloadAlgorithm;
 import net.torrent.protocol.algorithm.TorrentPieceUploadAlgorithm;
 import net.torrent.protocol.peerwire.manager.TorrentManager;
+import net.torrent.torrent.piece.PieceSelector;
+import net.torrent.torrent.piece.ScoredPieceSelector;
 
 /**
  * Standard torrent algorithm
@@ -28,15 +30,21 @@ import net.torrent.protocol.peerwire.manager.TorrentManager;
  * @author <a href="http://www.rogiel.com/">Rogiel Josias Sulzbach</a>
  */
 public class TorrentStdAlgorithm implements TorrentAlgorithm {
+	private final PieceSelector pieceSelector;
+
 	private final TorrentPeerAlgorithm peerAlgorithm;
 	private final TorrentInterestAlgorithm interestAlgorithm;
 	private final TorrentPieceDownloadAlgorithm downloadAlgorithm;
 	private final TorrentPieceUploadAlgorithm uploadAlgorithm;
 
 	public TorrentStdAlgorithm(final TorrentManager manager) {
+		pieceSelector = new ScoredPieceSelector(manager);
+		
 		peerAlgorithm = new TorrentStdPeerAlgorithm(manager);
-		interestAlgorithm = new TorrentStdInterestAlgorithm(manager);
+		interestAlgorithm = new TorrentStdInterestAlgorithm(manager,
-		downloadAlgorithm = new TorrentStdPieceDownloadAlgorithm(manager);
+				pieceSelector);
+		downloadAlgorithm = new TorrentStdPieceDownloadAlgorithm(manager,
+				pieceSelector);
 		uploadAlgorithm = new TorrentStdPieceUploadAlgorithm(manager);
 	}
 

src/main/java/net/torrent/protocol/algorithm/impl/TorrentStdInterestAlgorithm.java

@@ -20,6 +20,7 @@ import net.torrent.protocol.peerwire.manager.TorrentManager;
 import net.torrent.torrent.context.TorrentPeer;
 import net.torrent.torrent.context.TorrentPeer.ChokingState;
 import net.torrent.torrent.context.TorrentPeer.InterestState;
+import net.torrent.torrent.piece.PieceSelector;
 
 /**
  * Standard torrent interest algorithm
@@ -29,15 +30,29 @@ import net.torrent.torrent.context.TorrentPeer.InterestState;
 public class TorrentStdInterestAlgorithm implements TorrentInterestAlgorithm {
 	@SuppressWarnings("unused")
 	private final TorrentManager manager;
+	private final PieceSelector selector;
 
-	public TorrentStdInterestAlgorithm(TorrentManager manager) {
+	/**
+	 * Creates a new instance
+	 * 
+	 * @param manager
+	 *            the manager
+	 * @param pieceSelector
+	 *            the piece selector
+	 */
+	public TorrentStdInterestAlgorithm(TorrentManager manager,
+			PieceSelector pieceSelector) {
 		this.manager = manager;
+		this.selector = pieceSelector;
 	}
 
 	@Override
 	public InterestState interested(TorrentPeer peer) {
-		// if(peer.getPort() == 25944)
+		int pieces = selector.countPieces(peer);
-		// return InterestState.UNINTERESTED;
+		if(pieces >= 5)
+			return InterestState.INTERESTED;
+		
+		
 		return InterestState.INTERESTED;
 	}
 

src/main/java/net/torrent/protocol/algorithm/impl/TorrentStdPieceDownloadAlgorithm.java

@@ -24,7 +24,6 @@ import net.torrent.torrent.TorrentPart;
 import net.torrent.torrent.TorrentPiece;
 import net.torrent.torrent.context.TorrentPeer;
 import net.torrent.torrent.piece.PieceSelector;
-import net.torrent.torrent.piece.RandomPieceSelector;
 
 /**
  * This standard implementation of {@link TorrentPieceDownloadAlgorithm} chooses
@@ -39,8 +38,6 @@ public class TorrentStdPieceDownloadAlgorithm implements
 	 * The torrent manager
 	 */
 	private final TorrentManager manager;
-	// private final TorrentContext context;
-	// private final Torrent torrent;
 
 	/**
 	 * This selector is used to find the next piece to be downloaded. Parts are
@@ -61,12 +58,13 @@ public class TorrentStdPieceDownloadAlgorithm implements
 	 * @param manager
 	 *            the torrent manager instance. With this object is possible to
 	 *            retrieve current downloads/uploads and connections.
+	 * @param pieceSelector
+	 *            the piece selector
 	 */
-	public TorrentStdPieceDownloadAlgorithm(TorrentManager manager) {
+	public TorrentStdPieceDownloadAlgorithm(TorrentManager manager,
+			PieceSelector pieceSelector) {
 		this.manager = manager;
-		// this.context = this.manager.getContext();
+		this.selector = pieceSelector;
-		// this.torrent = this.manager.getTorrent();
-		selector = new RandomPieceSelector(manager);
 	}
 
 	@Override

src/main/java/net/torrent/protocol/peerwire/handler/PeerWireAlgorithmHandler.java

@@ -45,7 +45,7 @@ import net.torrent.torrent.context.TorrentPeer;
 import net.torrent.torrent.context.TorrentPeer.ChokingState;
 import net.torrent.torrent.context.TorrentPeer.InterestState;
 import net.torrent.torrent.context.TorrentPeerCapabilities.TorrentPeerCapability;
-import net.torrent.util.PeerCallback;
+import net.torrent.util.PeerWirePeerCallback;
 
 import org.jboss.netty.channel.ChannelFuture;
 import org.jboss.netty.channel.ChannelHandlerContext;
@@ -343,7 +343,7 @@ public class PeerWireAlgorithmHandler extends IdleStateAwareChannelHandler {
 
 		if (datastore.checksum(part.getPiece())) {
 			manager.getContext().getBitfield().setPiece(part.getPiece(), true);
-			manager.getPeerManager().executeActive(new PeerCallback() {
+			manager.getPeerManager().executeActive(new PeerWirePeerCallback() {
 				@Override
 				public void callback(PeerWirePeer peer) {
 					peer.have(part.getPiece().getIndex());

src/main/java/net/torrent/protocol/peerwire/manager/PeerManager.java

@@ -25,7 +25,7 @@ import java.util.Set;
 import net.torrent.protocol.peerwire.PeerWirePeer;
 import net.torrent.torrent.context.TorrentContext;
 import net.torrent.torrent.context.TorrentPeer;
-import net.torrent.util.PeerCallback;
+import net.torrent.util.PeerWirePeerCallback;
 
 import org.jboss.netty.channel.Channel;
 
@@ -140,21 +140,21 @@ public class PeerManager implements Iterable<PeerWirePeer> {
 		return Collections.unmodifiableSet(inactivePeers.keySet());
 	}
 
-	public void executeActive(PeerCallback callback) {
+	public void executeActive(PeerWirePeerCallback callback) {
 		for (final Entry<Channel, PeerWirePeer> entry : this.activePeers
 				.entrySet()) {
 			callback.callback(entry.getValue());
 		}
 	}
 
-	public void executeInactive(PeerCallback callback) {
+	public void executeInactive(PeerWirePeerCallback callback) {
 		for (final Entry<Channel, PeerWirePeer> entry : this.inactivePeers
 				.entrySet()) {
 			callback.callback(entry.getValue());
 		}
 	}
 
-	public void execute(PeerCallback callback) {
+	public void execute(PeerWirePeerCallback callback) {
 		executeActive(callback);
 		executeInactive(callback);
 	}

src/main/java/net/torrent/torrent/context/TorrentContext.java

@@ -40,7 +40,7 @@ public class TorrentContext {
 	private final TorrentPeerCapabilities capabilites = new TorrentPeerCapabilities(
 			TorrentPeerCapability.DHT, TorrentPeerCapability.FAST_PEERS);
 
-	private final Set<TorrentPeer> peers = new HashSet<TorrentPeer>();
+	private final TorrentSwarm swarm = new TorrentSwarm(this);
 	/**
 	 * Unknown peers does not have their IDs, consequently they cannot be
 	 * queried using their Id and must be done through IP.
@@ -103,8 +103,8 @@ public class TorrentContext {
 	 * 
 	 * @return the list of peers
 	 */
-	public Set<TorrentPeer> getPeers() {
+	public TorrentSwarm getSwarm() {
-		return Collections.unmodifiableSet(peers);
+		return swarm;
 	}
 
 	/**
@@ -116,73 +116,15 @@ public class TorrentContext {
 		return Collections.unmodifiableSet(unknownPeers);
 	}
 
-	/**
-	 * Get an peer by its PeerID
-	 * 
-	 * @param peerId
-	 *            the peer id
-	 * @return the found peer. Null if not found.
-	 */
 	public TorrentPeer getPeer(TorrentPeerID peerId) {
-		for (final TorrentPeer peer : peers) {
+		return swarm.getPeer(peerId);
-			if (peer.getPeerID().equals(peerId))
-				return peer;
-		}
-		return null;
 	}
 
-	/**
-	 * Get an peer by its address
-	 * 
-	 * @param address
-	 *            the address
-	 * @return the found peer. Null if not found.
-	 */
 	public TorrentPeer getPeer(InetSocketAddress address) {
-		for (final TorrentPeer peer : peers) {
+		return swarm.getPeer(address);
-			if (peer.getSocketAddress().equals(address))
-				return peer;
-		}
-		return null;
 	}
 
-	/**
-	 * Lookup for a peer first by its id, then by address, if still not found,
-	 * creates a new entry.
-	 * 
-	 * @param id
-	 *            the peer id
-	 * @param address
-	 *            the address
-	 * @return the found or newly created peer
-	 */
 	public TorrentPeer getPeer(TorrentPeerID id, InetSocketAddress address) {
-		TorrentPeer peer = getPeer(id);
+		return swarm.getPeer(id, address);
-		if (peer == null) {
-			peer = getPeer(address);
-			if (peer != null) {
-				if (peers.remove(peer))
-					peer = peer.createWithID(id);
-			} else {
-				peer = new TorrentPeer(this, id, null);
-			}
-			peers.add(peer);
-		}
-		return peer;
-	}
-
-	/**
-	 * If this peer already exists, will update its IP.
-	 * 
-	 * @param peerInfo
-	 *            the peer info object, returned from the tracker
-	 */
-	public TorrentPeer addPeerByPeerInfo(PeerInfo peerInfo) {
-		final TorrentPeerID id = TorrentPeerID.create(peerInfo.getPeerId());
-		final InetSocketAddress address = new InetSocketAddress(
-				peerInfo.getIp(), peerInfo.getPort());
-		TorrentPeer peer = getPeer(id, address);
-		peer.setSocketAddress(address);
-		return peer;
 	}
 }

src/main/java/net/torrent/torrent/context/TorrentSwarm.java

@@ -0,0 +1,175 @@
+/**
+ * 
+ */
+package net.torrent.torrent.context;
+
+import java.net.InetSocketAddress;
+import java.util.ArrayList;
+import java.util.Iterator;
+import java.util.List;
+
+import net.torrent.protocol.tracker.message.PeerListMessage.PeerInfo;
+import net.torrent.torrent.TorrentPiece;
+import net.torrent.util.SwarmCallback;
+
+/**
+ * An torrent swarm is an set of all connected peers.
+ * 
+ * @author <a href="http://www.rogiel.com/">Rogiel Josias Sulzbach</a>
+ */
+public class TorrentSwarm implements Iterable<TorrentPeer> {
+	/**
+	 * The torrent context
+	 */
+	private final TorrentContext context;
+
+	/**
+	 * The list of active peers
+	 */
+	private List<TorrentPeer> peers = new ArrayList<TorrentPeer>();
+
+	/**
+	 * Creates a new instance
+	 * 
+	 * @param context
+	 *            the torrent context
+	 */
+	public TorrentSwarm(final TorrentContext context) {
+		this.context = context;
+	}
+
+	/**
+	 * Add an given peer to the swarm
+	 * 
+	 * @param peer
+	 *            the peer
+	 * @return true if was not present in swarm
+	 */
+	public boolean add(TorrentPeer peer) {
+		return this.peers.add(peer);
+	}
+
+	/**
+	 * Removes an given peer from the swarm
+	 * 
+	 * @param peer
+	 *            the peer
+	 * @return true if peer was in swarm
+	 */
+	public boolean remove(TorrentPeer peer) {
+		return this.peers.remove(peer);
+	}
+
+	/**
+	 * Executes an callback on each peer in the swarm
+	 * 
+	 * @param callback
+	 *            the callback
+	 */
+	public void execute(SwarmCallback callback) {
+		for (final TorrentPeer peer : this) {
+			callback.callback(peer);
+		}
+	}
+
+	/**
+	 * Select the peers which have the <tt>piece</tt>
+	 * 
+	 * @param piece
+	 *            the piece
+	 * @return list of peers with piece
+	 */
+	public List<TorrentPeer> getPeersWithPiece(TorrentPiece piece) {
+		final List<TorrentPeer> hasPieces = new ArrayList<TorrentPeer>();
+		for (final TorrentPeer peer : peers) {
+			if (!peer.getBitfield().hasPiece(piece))
+				continue;
+			hasPieces.add(peer);
+		}
+		return hasPieces;
+	}
+
+	/**
+	 * Get an peer by its PeerID
+	 * 
+	 * @param peerId
+	 *            the peer id
+	 * @return the found peer. Null if not found.
+	 */
+	public TorrentPeer getPeer(TorrentPeerID peerId) {
+		for (final TorrentPeer peer : peers) {
+			if (peer.getPeerID().equals(peerId))
+				return peer;
+		}
+		return null;
+	}
+
+	/**
+	 * Get an peer by its address
+	 * 
+	 * @param address
+	 *            the address
+	 * @return the found peer. Null if not found.
+	 */
+	public TorrentPeer getPeer(InetSocketAddress address) {
+		for (final TorrentPeer peer : peers) {
+			if (peer.getSocketAddress().equals(address))
+				return peer;
+		}
+		return null;
+	}
+
+	/**
+	 * Lookup for a peer first by its id, then by address, if still not found,
+	 * creates a new entry.
+	 * 
+	 * @param id
+	 *            the peer id
+	 * @param address
+	 *            the address
+	 * @return the found or newly created peer
+	 */
+	public TorrentPeer getPeer(TorrentPeerID id, InetSocketAddress address) {
+		TorrentPeer peer = getPeer(id);
+		if (peer == null) {
+			peer = getPeer(address);
+			if (peer != null) {
+				if (remove(peer))
+					peer = peer.createWithID(id);
+			} else {
+				peer = new TorrentPeer(context, id, null);
+			}
+			add(peer);
+		}
+		return peer;
+	}
+
+	/**
+	 * If this peer already exists, will update its IP.
+	 * 
+	 * @param peerInfo
+	 *            the peer info object, returned from the tracker
+	 */
+	public TorrentPeer addPeerByPeerInfo(PeerInfo peerInfo) {
+		final TorrentPeerID id = TorrentPeerID.create(peerInfo.getPeerId());
+		final InetSocketAddress address = new InetSocketAddress(
+				peerInfo.getIp(), peerInfo.getPort());
+		TorrentPeer peer = getPeer(id, address);
+		peer.setSocketAddress(address);
+		return peer;
+	}
+
+	@Override
+	public Iterator<TorrentPeer> iterator() {
+		return peers.iterator();
+	}
+
+	/**
+	 * Get the torrent context
+	 * 
+	 * @return the torrent context
+	 */
+	public TorrentContext getContext() {
+		return context;
+	}
+}

src/main/java/net/torrent/torrent/piece/PieceSelector.java

@@ -34,4 +34,11 @@ public interface PieceSelector {
 	 * @return the {@link TorrentPiece piece} selected for download.
 	 */
 	public TorrentPiece select(TorrentPeer peer);
+
+	/**
+	 * Return the amount of pieces available to select
+	 * 
+	 * @return the amount of pieces available
+	 */
+	public int countPieces(TorrentPeer peer);
 }

src/main/java/net/torrent/torrent/piece/ScoredPieceSelector.java

@@ -0,0 +1,77 @@
+/*
+ * Copyright 2011 Rogiel Josias Sulzbach
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package net.torrent.torrent.piece;
+
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.List;
+
+import net.torrent.protocol.peerwire.manager.TorrentManager;
+import net.torrent.torrent.TorrentPiece;
+import net.torrent.torrent.context.TorrentPeer;
+import net.torrent.torrent.piece.score.PieceRarenessScoreAlgorithm;
+import net.torrent.torrent.piece.score.ScoredPieceComparator;
+
+/**
+ * Select pieces in sequential order. Can be used for streaming purposes.
+ * 
+ * @author <a href="http://www.rogiel.com/">Rogiel Josias Sulzbach</a>
+ */
+public class ScoredPieceSelector extends SortedListPieceSelector {
+	/**
+	 * Sort again the list each <tt>n</tt> calls to {@link #select(TorrentPeer)}
+	 */
+	private static final int SORT_INTERVAL = 10;
+
+	/**
+	 * Call counter. Used to sort the list.
+	 */
+	private int calls = 0;
+
+	/**
+	 * The piece comparator
+	 */
+	private final ScoredPieceComparator comparator;
+
+	/**
+	 * Creates a new instance
+	 * 
+	 * @param manager
+	 *            the torrent manager
+	 */
+	public ScoredPieceSelector(TorrentManager manager) {
+		super(manager, Arrays.asList(manager.getTorrent().getPieces()));
+		this.comparator = new ScoredPieceComparator(manager.getContext()
+				.getSwarm(), new PieceRarenessScoreAlgorithm());
+		// initial sort will be skipped because comparator is null.
+		this.sort(pieces);
+	}
+
+	@Override
+	protected void sort(List<TorrentPiece> pieces) {
+		if (comparator != null)
+			Collections.sort(pieces, comparator);
+		System.out.println(pieces);
+	}
+
+	@Override
+	public synchronized TorrentPiece select(TorrentPeer peer) {
+		if (calls % SORT_INTERVAL == 0)
+			this.sort(pieces);
+		calls++;
+		return super.select(peer);
+	}
+}

src/main/java/net/torrent/torrent/piece/SortedListPieceSelector.java

@@ -32,11 +32,11 @@ public abstract class SortedListPieceSelector implements PieceSelector {
 	/**
 	 * The torrent manager
 	 */
-	private final TorrentManager manager;
+	protected final TorrentManager manager;
 	/**
 	 * The sorted list of pieces
 	 */
-	private final List<TorrentPiece> pieces;
+	protected final List<TorrentPiece> pieces;
 
 	/**
 	 * Creates a new instance
@@ -53,6 +53,14 @@ public abstract class SortedListPieceSelector implements PieceSelector {
 		this.sort(this.pieces);
 	}
 
+	/**
+	 * Sorts the set using an implementation specific algorithm.
+	 * 
+	 * @param pieces
+	 *            the unsorted pieces list that will be sorted.
+	 */
+	protected abstract void sort(List<TorrentPiece> pieces);
+
 	@Override
 	public synchronized TorrentPiece select(TorrentPeer peer) {
 		for (int index = 0; index < pieces.size(); index++) {
@@ -68,11 +76,19 @@ public abstract class SortedListPieceSelector implements PieceSelector {
 		return null;
 	}
 
-	/**
+	@Override
-	 * Sorts the set using an implementation specific algorithm.
+	public int countPieces(TorrentPeer peer) {
-	 * 
+		int count = 0;
-	 * @param pieces
+		for (int index = 0; index < pieces.size(); index++) {
-	 *            the unsorted pieces list that will be sorted.
+			final TorrentPiece piece = pieces.get(index);
-	 */
+			if (manager.getContext().getBitfield().hasPiece(piece))
-	protected abstract void sort(List<TorrentPiece> pieces);
+				continue;
+			if (!peer.getBitfield().hasPiece(piece))
+				continue;
+			if (manager.getDownloadManager().isDownloading(piece))
+				continue;
+			count++;
+		}
+		return count;
+	}
 }

src/main/java/net/torrent/torrent/piece/score/PieceRarenessScoreAlgorithm.java

@@ -0,0 +1,34 @@
+/**
+ * 
+ */
+package net.torrent.torrent.piece.score;
+
+import java.util.concurrent.atomic.AtomicInteger;
+
+import net.torrent.torrent.TorrentPiece;
+import net.torrent.torrent.context.TorrentPeer;
+import net.torrent.torrent.context.TorrentSwarm;
+import net.torrent.util.SwarmCallback;
+
+/**
+ * @author <a href="http://www.rogiel.com/">Rogiel Josias Sulzbach</a>
+ */
+public class PieceRarenessScoreAlgorithm implements PieceScoreAlgorithm {
+	@Override
+	public int calculate(TorrentSwarm swarm, final TorrentPiece piece) {
+		final AtomicInteger score = new AtomicInteger();
+		swarm.execute(new SwarmCallback() {
+			@Override
+			public void callback(TorrentPeer peer) {
+				int peerScore = (int) (Math.random() * 10); // bit of randomness
+				if (!peer.isAccessible()) {
+					peerScore += 100;
+				}
+				if (!peer.getBitfield().hasPiece(piece))
+					peerScore += 1000;
+				score.addAndGet(peerScore);
+			}
+		});
+		return score.get();
+	}
+}

src/main/java/net/torrent/torrent/piece/score/PieceScoreAlgorithm.java

@@ -0,0 +1,23 @@
+/**
+ * 
+ */
+package net.torrent.torrent.piece.score;
+
+import net.torrent.torrent.TorrentPiece;
+import net.torrent.torrent.context.TorrentSwarm;
+
+/**
+ * Computes the score of an piece inside the swarm.
+ * <p>
+ * Pieces with higher scores will be more suitable to download than others.
+ * 
+ * @author <a href="http://www.rogiel.com/">Rogiel Josias Sulzbach</a>
+ */
+public interface PieceScoreAlgorithm {
+	/**
+	 * Computes the score of an piece inside an swarm.
+	 * 
+	 * @return
+	 */
+	int calculate(TorrentSwarm swarm, TorrentPiece piece);
+}

src/main/java/net/torrent/torrent/piece/score/ScoredPieceComparator.java

@@ -0,0 +1,27 @@
+/**
+ * 
+ */
+package net.torrent.torrent.piece.score;
+
+import java.util.Comparator;
+
+import net.torrent.torrent.TorrentPiece;
+import net.torrent.torrent.context.TorrentSwarm;
+
+/**
+ * @author <a href="http://www.rogiel.com/">Rogiel Josias Sulzbach</a>
+ */
+public class ScoredPieceComparator implements Comparator<TorrentPiece> {
+	private final PieceScoreAlgorithm score;
+	private final TorrentSwarm swarm;
+
+	public ScoredPieceComparator(TorrentSwarm swarm, PieceScoreAlgorithm score) {
+		this.swarm = swarm;
+		this.score = score;
+	}
+
+	@Override
+	public int compare(TorrentPiece piece1, TorrentPiece piece2) {
+		return score.calculate(swarm, piece1) - score.calculate(swarm, piece2);
+	}
+}

src/main/java/net/torrent/util/PeerWirePeerCallback.java

@@ -0,0 +1,34 @@
+/*
+ * Copyright 2011 Rogiel Josias Sulzbach
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package net.torrent.util;
+
+import net.torrent.protocol.peerwire.PeerWirePeer;
+import net.torrent.protocol.peerwire.manager.PeerManager;
+
+/**
+ * Callback used in {@link PeerManager#execute(PeerCallback)}
+ * 
+ * @author <a href="http://www.rogiel.com/">Rogiel Josias Sulzbach</a>
+ */
+public interface PeerWirePeerCallback {
+	/**
+	 * Execute the desired action for <tt>peer</tt>
+	 * 
+	 * @param peer
+	 *            the peer
+	 */
+	void callback(PeerWirePeer peer);
+}

src/main/java/net/torrent/util/SwarmCallback.java

@@ -0,0 +1,22 @@
+/**
+ * 
+ */
+package net.torrent.util;
+
+import net.torrent.torrent.context.TorrentPeer;
+import net.torrent.torrent.context.TorrentSwarm;
+
+/**
+ * Callback used in {@link TorrentSwarm#execute(SwarmCallback)}
+ * 
+ * @author <a href="http://www.rogiel.com/">Rogiel Josias Sulzbach</a>
+ */
+public interface SwarmCallback {
+	/**
+	 * Execute the desired action for <tt>peer</tt>
+	 * 
+	 * @param peer
+	 *            the peer
+	 */
+	void callback(TorrentPeer peer);
+}