core/plugins/org.eclipse.hawk.timeaware/src/org/eclipse/hawk/timeaware/graph/TimeAwareGraphNodeWrapper.java

/*******************************************************************************
 * Copyright (c) 2020 Aston University.
 * 
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License 2.0 which is available at
 * http://www.eclipse.org/legal/epl-2.0.
 *
 * This Source Code may also be made available under the following Secondary
 * Licenses when the conditions for such availability set forth in the Eclipse
 * Public License, v. 2.0 are satisfied: GNU General Public License, version 3.
 *
 * SPDX-License-Identifier: EPL-2.0 OR GPL-3.0
 *
 * Contributors:
 *     Antonio Garcia-Dominguez - initial API and implementation
 ******************************************************************************/
package org.eclipse.hawk.timeaware.graph;

import java.lang.ref.WeakReference;

import org.eclipse.hawk.core.graph.IGraphNode;
import org.eclipse.hawk.core.graph.timeaware.ITimeAwareGraphNode;
import org.eclipse.hawk.epsilon.emc.wrappers.GraphNodeWrapper;
import org.eclipse.hawk.timeaware.queries.TimeAwareEOLQueryEngine;

/**
 * Wraps a standalone node while remembering its original time, so we can
 * retrieve the exact same node later if the weak reference has been GC'ed.
 */
public class TimeAwareGraphNodeWrapper extends GraphNodeWrapper {

	private long time;

	public TimeAwareGraphNodeWrapper(IGraphNode n, TimeAwareEOLQueryEngine containerModel) {
		super(n, containerModel);
		this.time = ((ITimeAwareGraphNode) n).getTime();
	}

	@Override
	public IGraphNode getNode() {
		IGraphNode ret = node.get();
		if (ret == null) {
			TimeAwareEOLQueryEngine taQuery = (TimeAwareEOLQueryEngine)containerModel;
			ret = taQuery.getBackend().getNodeById(id).travelInTime(time);
			node = new WeakReference<IGraphNode>(ret);
		}
		return ret;
	}

	
}