DistributedReference.java

/*
 * Galaxy
 * Copyright (c) 2012-2014, Parallel Universe Software Co. All rights reserved.
 * 
 * This program and the accompanying materials are dual-licensed under
 * either the terms of the Eclipse Public License v1.0 as published by
 * the Eclipse Foundation
 *  
 *   or (per the licensee's choosing)
 *  
 * under the terms of the GNU Lesser General Public License version 3.0
 * as published by the Free Software Foundation.
 */
package co.paralleluniverse.galaxy.objects;

import co.paralleluniverse.common.io.ByteBufferInputStream;
import co.paralleluniverse.common.io.Persistable;
import co.paralleluniverse.galaxy.Cache;
import co.paralleluniverse.galaxy.CacheListener;
import co.paralleluniverse.galaxy.Grid;
import co.paralleluniverse.io.serialization.Serialization;
import java.io.IOException;
import java.io.InputStream;
import java.nio.ByteBuffer;

/**
 * Wraps T and implements Distributed interface
 *
 * @author eitan
 * @param <T>
 */
public class DistributedReference<T> implements CacheListener, Persistable, java.io.Serializable {
    private final long id;
    private transient volatile T obj;
    private transient volatile long version;
    private transient byte[] tmpBuffer;

    public DistributedReference(long id, T obj) {
        this.obj = obj;
        this.id = id;
        this.version = -1;
    }

    @Override
    public String toString() {
        return getClass().getSimpleName() + "[" + Long.toHexString(id) + " (" + version + "): " + (obj != null ? (obj.getClass().getName() + "@" + System.identityHashCode(obj)) : "null") + "]";
    }

    public T get() {
        return obj;
    }

    public long getId() {
        return id;
    }

    protected void clear() {
        this.obj = null;
    }

    @Override
    public void invalidated(Cache cache, long id) {
    }

    @Override
    public void evicted(Cache cache, long id) {
        clear();
    }

    @Override
    public void killed(Cache cache, long id) {
    }
    
    @Override
    public void received(Cache cache, long id, long version, ByteBuffer data) {
        if (version > this.version) {
            read(data);
            this.version = version;
        }
    }

    /**
     * This method is not thread safe!
     *
     * @return
     */
    @Override
    public int size() {
//        if (obj instanceof Persistable)
//            return ((Persistable) obj).size();
//        else
        return obj != null ? getSerialized().length : 0;
    }

    /**
     * This method is not thread safe!
     */
    @Override
    public void write(ByteBuffer buffer) {
//        if (obj instanceof Persistable)
//            ((Persistable) obj).write(buffer);
//        else {
        if (obj != null)
            buffer.put(getSerialized());
        tmpBuffer = null;
//        }
    }

    byte[] getSerialized() {
        if (tmpBuffer == null)
            tmpBuffer = serialize(obj);
        return tmpBuffer;
    }

    @Override
    public void read(ByteBuffer buffer) {
//        if (obj instanceof Persistable)
//            ((Persistable) obj).read(buffer);
//        else
        /*
         * IMPORTANT:
         * We need to take care of the situation where a simple set is invoked (w/o getx beforehand).
         * The returned PUTX will call received which will overwrite the object (which we wanted to set as the value
         * for the line)
         */
        this.obj = deserialize(new ByteBufferInputStream(buffer));
    }

    @Override
    public void messageReceived(byte[] message) {
    }

    protected void set(T obj) {
        this.obj = obj;
    }

    protected byte[] serialize(T obj) {
        return obj != null ? Serialization.getInstance().write(obj) : null;
    }

    protected T deserialize(InputStream is) {
        try {
            return (T) Serialization.getInstance().read(is);
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
    }

    protected Object writeReplace() {
        return new SerializedDistributedRef(id);
    }

    protected static class SerializedDistributedRef implements java.io.Serializable {
        final long id;

        public SerializedDistributedRef(long id) {
            this.id = id;
        }

        Object readResolve() {
            try {
                return DistributedReferenceStore.getOrCreateRef(Grid.getInstance().store(), id);
            } catch (InterruptedException e) {
                throw new RuntimeException(e);
            }
        }
    }
}