/*
 * Copyright (C) 2008-2015 by Holger Arndt
 *
 * This file is part of the Universal Java Matrix Package (UJMP).
 * See the NOTICE file distributed with this work for additional
 * information regarding copyright ownership and licensing.
 *
 * UJMP 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
 * of the License, or (at your option) any later version.
 *
 * UJMP 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 UJMP; if not, write to the
 * Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
 * Boston, MA  02110-1301  USA
 */

package org.ujmp.core.util.concurrent;

import java.util.concurrent.Callable;
import java.util.concurrent.Future;
import java.util.concurrent.ThreadPoolExecutor;

import org.ujmp.core.util.UJMPSettings;

public abstract class PFor {

	private final Object[] objects;

	public PFor(final int threads, final int first, final int last) {
		this(threads, first, last, new Object[] {});
	}

	public PFor(final int threads, final int first, final int last, final Object... objects) {
		this.objects = objects;

		if (threads < 2) {
			for (int i = first; i <= last; i++) {
				step(i);
			}
		} else {
			final ThreadPoolExecutor es = UJMPThreadPoolExecutor.getInstance(threads);

			final Future[] list = new Future[threads];
			final double stepsize = (double) (last + 1 - first) / threads;

			for (int i = 0; i < threads; i++) {
				int starti = (int) Math.ceil(first + i * stepsize);
				int endi = (int) Math.ceil(first + (i + 1) * stepsize);
				list[i] = es.submit(new StepCallable(starti, endi));
			}

			for (Future f : list) {
				try {
					f.get();
				} catch (Exception e) {
					e.printStackTrace();
				}
			}
		}
	}

	public PFor(final int first, final int last) {
		this(first, last, new Object[] {});
	}

	public PFor(final int first, final int last, final Object... objects) {
		this(UJMPSettings.getInstance().getNumberOfThreads(), first, last, objects);
	}

	public abstract void step(final int i);

	public final Object getObject(final int i) {
		return objects[i];
	}

	class StepCallable implements Callable {
		private final int first;
		private final int last;

		public StepCallable(final int first, final int last) {
			this.first = first;
			this.last = last;
		}

		public final Void call() throws Exception {
			for (int i = first; i < last; i++) {
				step(i);
			}
			return null;
		}

	}

}

 
 


        
        

                    




        
      

      
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