com.threerings.whirled.data.SceneUpdate Maven / Gradle / Ivy
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//
// $Id$
//
// 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.data;
import java.io.IOException;
import com.samskivert.util.StringUtil;
import com.threerings.io.ObjectInputStream;
import com.threerings.io.ObjectOutputStream;
import com.threerings.io.Streamable;
import com.threerings.util.ActionScript;
import static com.threerings.whirled.Log.log;
/**
* Used to encapsulate updates to scenes in such a manner that updates can be stored persistently
* and sent to clients to update their own local copies of scenes.
*/
public class SceneUpdate
implements Streamable, Cloneable
{
/**
* Initializes this scene update such that it will operate on a scene with the specified target
* scene and version number.
*
* @param targetId the id of the scene on which we are to operate.
* @param targetVersion the version of the scene on which we are to operate.
*/
public void init (int targetId, int targetVersion)
{
_targetId = targetId;
_targetVersion = targetVersion;
}
/**
* Returns the scene id for which this update is appropriate.
*/
public int getSceneId ()
{
return _targetId;
}
/**
* Returns the scene version for which this update is appropriate.
*/
public int getSceneVersion ()
{
return _targetVersion;
}
/**
* Returns the amount by which this update increments the scene version.
*/
public int getVersionIncrement ()
{
return 1;
}
/**
* Called to ensure that the scene is in the appropriate state prior to applying the update.
*
* @exception IllegalStateException thrown if the update cannot be applied to the scene because
* it is not in a valid state (appropriate previous updates were not applied, it's the wrong
* kind of scene, etc.).
*/
public void validate (SceneModel model)
throws IllegalStateException
{
if (model.sceneId != _targetId) {
String errmsg = "Wrong target scene, expected id " + _targetId +
" got id " + model.sceneId;
throw new IllegalStateException(errmsg);
}
if (model.version != _targetVersion) {
String errmsg = "Target scene not proper version, expected " + _targetVersion +
" got " + model.version;
throw new IllegalStateException(errmsg);
}
}
/**
* Applies this update to the specified scene model. Derived classes will want to override this
* method and apply updates of their own, being sure to call super.apply.
*/
public void apply (SceneModel model)
{
// increment the version; disallowing integer overflow
model.version = Math.max(_targetVersion + getVersionIncrement(), model.version);
// sanity check for the amazing two billion updates
if (model.version == _targetVersion) {
log.warning("Egads! This scene has been updated two billion times [model=" + model +
", update=" + this + "].");
}
}
/**
* Writes our custom streamable fields.
*/
public void writeObject (ObjectOutputStream out)
throws IOException
{
if (null == _dbSer.get()) {
out.writeInt(_targetId);
out.writeInt(_targetVersion);
}
out.defaultWriteObject();
}
/**
* Reads our custom streamable fields.
*/
public void readObject (ObjectInputStream in)
throws IOException, ClassNotFoundException
{
if (null == _dbSer.get()) {
_targetId = in.readInt();
_targetVersion = in.readInt();
}
in.defaultReadObject();
}
/**
* Serializes the bare representation of this instance without the scene id and version fields.
* Useful when storing updates in a database where the scene id and version fields are stored
* in separate columns and the rest if the representation is contained in an opaque blob.
*/
@ActionScript(omit=true)
public void persistTo (ObjectOutputStream out)
throws IOException
{
_dbSer.set(Boolean.TRUE);
try {
out.writeBareObject(this);
} finally {
_dbSer.set(null);
}
}
/**
* Unserializes this instance from the bare representation created by {@link #persistTo}.
*/
@ActionScript(omit=true)
public void unpersistFrom (ObjectInputStream in)
throws IOException, ClassNotFoundException
{
_dbSer.set(Boolean.TRUE);
try {
in.readBareObject(this);
} finally {
_dbSer.set(null);
}
}
@Override
public String toString ()
{
StringBuilder buf = new StringBuilder("[");
toString(buf);
return buf.append("]").toString();
}
/**
* An extensible mechanism for generating a string representation of this instance.
*/
@ActionScript(name="toStringBuilder")
protected void toString (StringBuilder buf)
{
buf.append("sceneId=").append(_targetId);
buf.append(", version=").append(_targetVersion);
buf.append(", ");
StringUtil.fieldsToString(buf, this);
}
/** The version number of the scene on which we operate. */
protected transient int _targetId;
/** The version number of the scene on which we operate. */
protected transient int _targetVersion;
/** Used when serializing this update for storage in the database. */
@ActionScript(omit=true)
protected static ThreadLocal _dbSer = new ThreadLocal();
}