001    /*
002     * Copyright (C) 2008-2010 by Holger Arndt
003     *
004     * This file is part of the Universal Java Matrix Package (UJMP).
005     * See the NOTICE file distributed with this work for additional
006     * information regarding copyright ownership and licensing.
007     *
008     * UJMP is free software; you can redistribute it and/or modify
009     * it under the terms of the GNU Lesser General Public License as
010     * published by the Free Software Foundation; either version 2
011     * of the License, or (at your option) any later version.
012     *
013     * UJMP is distributed in the hope that it will be useful,
014     * but WITHOUT ANY WARRANTY; without even the implied warranty of
015     * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
016     * GNU Lesser General Public License for more details.
017     *
018     * You should have received a copy of the GNU Lesser General Public
019     * License along with UJMP; if not, write to the
020     * Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
021     * Boston, MA  02110-1301  USA
022     */
023    
024    package org.ujmp.core.util.concurrent;
025    
026    import java.util.concurrent.Callable;
027    import java.util.concurrent.Future;
028    import java.util.concurrent.ThreadPoolExecutor;
029    
030    import org.ujmp.core.util.UJMPSettings;
031    
032    public abstract class PFor {
033    
034            private final Object[] objects;
035    
036            public PFor(final int threads, final int first, final int last, final Object... objects) {
037                    this.objects = objects;
038    
039                    if (threads < 2) {
040                            for (int i = first; i <= last; i++) {
041                                    step(i);
042                            }
043                    } else {
044                            final ThreadPoolExecutor es = UJMPThreadPoolExecutor.getInstance(threads);
045    
046                            final Future<?>[] list = new Future[threads];
047                            final double stepsize = (double) (last + 1 - first) / threads;
048    
049                            for (int i = 0; i < threads; i++) {
050                                    int starti = (int) Math.ceil(first + i * stepsize);
051                                    int endi = (int) Math.ceil(first + (i + 1) * stepsize);
052                                    list[i] = es.submit(new StepCallable(starti, endi));
053                            }
054    
055                            for (Future<?> f : list) {
056                                    try {
057                                            f.get();
058                                    } catch (Exception e) {
059                                            e.printStackTrace();
060                                    }
061                            }
062                    }
063            }
064    
065            public PFor(final int first, final int last, final Object... objects) {
066                    this(UJMPSettings.getNumberOfThreads(), first, last, objects);
067            }
068    
069            public abstract void step(final int i);
070    
071            public final Object getObject(final int i) {
072                    return objects[i];
073            }
074    
075            class StepCallable implements Callable<Object> {
076                    private final int first;
077                    private final int last;
078    
079                    public StepCallable(final int first, final int last) {
080                            this.first = first;
081                            this.last = last;
082                    }
083    
084                    public final Void call() throws Exception {
085                            try {
086                                    for (int i = first; i < last; i++) {
087                                            step(i);
088                                    }
089                            } catch (Exception e) {
090                                    e.printStackTrace();
091                            }
092                            return null;
093                    }
094    
095            }
096    
097    }