//
// $Id$
//
// Vilya library - tools for developing networked games
// Copyright (C) 2002-2012 Three Rings Design, Inc., All Rights Reserved
// http://code.google.com/p/vilya/
//
// This library is free software; you can redistribute it and/or modify it
// under the terms of the GNU Lesser General Public License as published
// by the Free Software Foundation; either version 2.1 of the License, or
// (at your option) any later version.
//
// This library 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
// Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
package com.threerings.whirled.server.persist;
import java.util.HashMap;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import com.google.common.collect.Maps;
import com.samskivert.io.PersistenceException;
import com.samskivert.util.HashIntMap;
import com.threerings.io.ObjectInputStream;
import com.threerings.io.ObjectOutputStream;
import com.threerings.whirled.data.SceneUpdate;
/**
* A utility class to assist the management of scene updates by a SceneRepository.
*/
public class SceneUpdateMarshaller
{
/**
* Create a SceneUpdateMarshaller that understands the update types specified.
*
* Note: Once a type is registered and in use by some SceneRepository that type id can never be
* used again. If you need to remove an update type, it should be replaced with null in the
* class list to reserve the old type id that it represented.
*/
public SceneUpdateMarshaller (Class<?> ... typesClasses)
{
for (Class<?> c : typesClasses) {
registerUpdateClass(c);
}
}
/**
* Returns the type code that is assigned to the specified SceneUpdate instance, or -1.
*/
public int getUpdateType (SceneUpdate update)
{
return (update == null) ? -1 : getUpdateType(update.getClass());
}
/**
* Returns the type code that is assigned to the specified SceneUpdate class, or -1.
*/
public int getUpdateType (Class<?> typeClass)
{
Integer type = _classToType.get(typeClass);
return (type == null) ? -1 : type.intValue();
}
/**
* Returns the update class associated with the specified type code, or null.
*/
public Class<?> getUpdateClass (int type)
{
return _typeToClass.get(type);
}
/**
* Persists the specified update to a new ByteArrayOutInputStream.
*/
public byte[] persistUpdate (SceneUpdate update)
throws PersistenceException
{
ByteArrayOutputStream out = new ByteArrayOutputStream();
try {
update.persistTo(new ObjectOutputStream(out));
} catch (IOException ioe) {
throw new PersistenceException("Error serializing update " + update, ioe);
}
return out.toByteArray();
}
/**
* Instantiates the appropriate update class and decodes the update from the data.
*/
public SceneUpdate decodeUpdate (int sceneId, int sceneVersion, int updateType, byte[] data)
throws PersistenceException
{
String errmsg = null;
Exception error = null;
try {
Class<?> updateClass = getUpdateClass(updateType);
if (updateClass == null) {
errmsg = "No class registered for update type [sceneId=" + sceneId +
", sceneVersion=" + sceneVersion + ", updateType=" + updateType + "].";
throw new PersistenceException(errmsg);
}
// create the update
SceneUpdate update = (SceneUpdate)updateClass.newInstance();
update.init(sceneId, sceneVersion);
// decode its contents from the serialized data
ByteArrayInputStream bin = new ByteArrayInputStream(data);
update.unpersistFrom(new ObjectInputStream(bin));
return update;
} catch (IOException ioe) {
error = ioe;
errmsg = "Unable to decode update";
} catch (ClassNotFoundException cnfe) {
error = cnfe;
errmsg = "Unable to instantiate update";
} catch (InstantiationException ie) {
error = ie;
errmsg = "Unable to instantiate update";
} catch (IllegalAccessException iae) {
error = iae;
errmsg = "Unable to instantiate update";
}
errmsg += " [sceneId=" + sceneId + ", sceneVersion=" + sceneVersion +
", updateType=" + updateType + "].";
throw new PersistenceException(errmsg, error);
}
/**
* Registers the update class with the update factory. This should be called below in the
* canonical list of update registrations.
*/
protected void registerUpdateClass (Class<?> typeClass)
{
// ensure that callers can't fuck up the reciprocal nature of our two maps.
if (_classToType.containsKey(typeClass)) {
throw new IllegalArgumentException("Class already registered: " + typeClass);
}
// always reserve the type Id
int type = ++_nextType;
// but only register non-null classes
if (typeClass != null) {
_typeToClass.put(type, typeClass);
_classToType.put(typeClass, Integer.valueOf(type));
}
}
/** The table mapping update types to classes. */
protected HashIntMap<Class<?>> _typeToClass = new HashIntMap<Class<?>>();
/** The table mapping update classes to types. */
protected HashMap<Class<?>, Integer> _classToType = Maps.newHashMap();
/** A counter used in assigning update types to classes. */
protected int _nextType = 0;
}