/*
* Mojito Distributed Hash Table (Mojito DHT)
* Copyright (C) 2006-2007 LimeWire LLC
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
package org.limewire.mojito.db;
import java.io.IOException;
import java.io.OutputStream;
import java.io.Serializable;
import org.limewire.mojito.routing.Version;
/**
* Defines an interface for a DHT value encapsulating the {@link DHTValueType},
* {@link Version} and value.
*/
public interface DHTValue extends Serializable {
/**
* An empty value is a value without an actual payload
* and storing an empty value in the DHT will remove an
* existing value from the DHT.
*/
public static final DHTValue EMPTY_VALUE = new EmptyValue();
/**
* Returns the type of the value.
*/
public DHTValueType getValueType();
/**
* Returns the version of the value.
*/
public Version getVersion();
/**
* Returns the actual value (a copy) as bytes.
*/
public byte[] getValue();
/**
* Writes the value to the <code>OutputStream</code>.
*/
public void write(OutputStream out) throws IOException;
/**
* Returns the size of the value payload in byte.
*/
public int size();
/**
* An implementation of <code>DHTValue</code> that has no payload.
*/
static final class EmptyValue implements DHTValue {
private static final long serialVersionUID = 4690500560328936523L;
private static final byte[] EMPTY = new byte[0];
private EmptyValue() {
}
public byte[] getValue() {
return EMPTY;
}
public void write(OutputStream out) throws IOException {
}
public DHTValueType getValueType() {
return DHTValueType.BINARY;
}
public Version getVersion() {
return Version.ZERO;
}
public int size() {
return 0;
}
@Override
public String toString() {
return "This is an empty DHTValue";
}
}
}