/*******************************************************************************
 * Copyright (c) 2013 Association for Decentralized Information Management
 * in Industry THTH ry.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     VTT Technical Research Centre of Finland - initial API and implementation
 *     Semantum Oy - initial API and implementation
 *******************************************************************************/
package org.simantics.simulator.variable.impl;

import java.util.ArrayDeque;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.Semaphore;
import java.util.concurrent.TimeUnit;

import org.simantics.simulator.variable.Realm;

public class SimpleRealm implements Realm {

	private ArrayDeque<Runnable> tasks = new ArrayDeque<Runnable>();
	private Semaphore taskCount = new Semaphore(0);

	public void executeTasks() {		
		while(taskCount.tryAcquire()) {
			Runnable task;
			synchronized (tasks) {
				task = tasks.poll();
			}
			task.run();
		}
	}
	 
	public void waitTasks(long waitDuration) throws InterruptedException {
		taskCount.tryAcquire(waitDuration, TimeUnit.MILLISECONDS);
	}
	
	@Override
	public void syncExec(final Runnable runnable) throws InterruptedException {
		final CountDownLatch latch = new CountDownLatch(1);
		asyncExec(new Runnable() {
			@Override
			public void run() {
				runnable.run();
				latch.countDown();
			}			
		});
		latch.await();
	}

	@Override
	public void asyncExec(Runnable runnable) {
		synchronized (tasks) {
			tasks.add(runnable);			
		}
		taskCount.release();
	}

}