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//******************************************************************************
//
// File: PixelSchedule.java
// Package: edu.rit.mri
// Unit: Class edu.rit.mri.PixelSchedule
//
// This Java source file is copyright (C) 2008 by Alan Kaminsky. All rights
// reserved. For further information, contact the author, Alan Kaminsky, at
// ark@cs.rit.edu.
//
// This Java source file is part of the Parallel Java Library ("PJ"). PJ is free
// software; you can redistribute it and/or modify it under the terms of the GNU
// General Public License as published by the Free Software Foundation; either
// version 3 of the License, or (at your option) any later version.
//
// PJ 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 General Public License for more details.
//
// Linking this library statically or dynamically with other modules is making a
// combined work based on this library. Thus, the terms and conditions of the
// GNU General Public License cover the whole combination.
//
// As a special exception, the copyright holders of this library give you
// permission to link this library with independent modules to produce an
// executable, regardless of the license terms of these independent modules, and
// to copy and distribute the resulting executable under terms of your choice,
// provided that you also meet, for each linked independent module, the terms
// and conditions of the license of that module. An independent module is a
// module which is not derived from or based on this library. If you modify this
// library, you may extend this exception to your version of the library, but
// you are not obligated to do so. If you do not wish to do so, delete this
// exception statement from your version.
//
// A copy of the GNU General Public License is provided in the file gpl.txt. You
// may also obtain a copy of the GNU General Public License on the World Wide
// Web at http://www.gnu.org/licenses/gpl.html.
//
//******************************************************************************
package edu.rit.mri;
import java.io.File;
import java.io.IOException;
/**
* Class PixelSchedule provides a load balancing schedule object used by class
* {@linkplain SpinRelaxometryClu} for partitioning the pixels of the input spin
* signal data sets among the workers. The data sets are divided into chunks of
* a fixed size.
*
* @author Alan Kaminsky
* @version 25-Jun-2008
*/
public class PixelSchedule
{
// Hidden data members.
// Chunk size.
private int chunkSize;
// Spin signal data set file names.
private String[] signalFileName;
// Index of current file.
private int fileIndex;
// Index of current pixel.
private int pixelIndex;
// Number of pixels remaining in current file.
private int pixelsRemaining;
// Exported constructors.
/**
* Construct a new pixel schedule object.
*
* @param chunkSize Maximum number of pixels in each chunk.
* @param signalFileName Array of spin signal data set file names.
*/
public PixelSchedule
(int chunkSize,
String[] signalFileName)
{
this.chunkSize = chunkSize;
this.signalFileName = signalFileName;
this.fileIndex = -1;
this.pixelIndex = 0;
this.pixelsRemaining = 0;
}
// Exported operations.
/**
* Get the next chunk of pixels to analyze. If there are no more chunks,
* null is returned.
*
* @return Chunk, or null.
*
* @exception IOException
* Thrown if an I/O error occurred.
*/
public PixelChunk next()
throws IOException
{
// Finished with current file?
if (pixelsRemaining == 0)
{
// Yes. Go to next file.
fileIndex = Math.min (fileIndex+1, signalFileName.length);
// More files?
if (fileIndex == signalFileName.length)
{
// No more files.
return null;
}
// Get number of pixels in current file.
SignalDataSetReader reader =
new SignalDataSetReader
(new File (signalFileName[fileIndex]));
pixelIndex = 0;
pixelsRemaining = reader.getPixelCount();
reader.close();
}
// Carve next chunk out of current file.
int n = Math.min (chunkSize, pixelsRemaining);
PixelChunk chunk = new PixelChunk (fileIndex, pixelIndex, n);
pixelIndex += n;
pixelsRemaining -= n;
return chunk;
}
}
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