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//******************************************************************************
//
// File: FixedLongSchedule.java
// Package: edu.rit.pj
// Unit: Class edu.rit.pj.FixedLongSchedule
//
// This Java source file is copyright (C) 2010 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.pj;
import edu.rit.util.LongRange;
/**
* Class FixedLongSchedule provides a fixed schedule object. The loop index
* is type <TT>long</TT>. The loop iterations are apportioned among the parallel
* team threads once at the beginning of the parallel for loop, with each thread
* getting a fixed number of iterations, the same number of iterations for each
* thread (plus or minus one).
*
* @author Alan Kaminsky
* @version 27-Jan-2010
*/
class FixedLongSchedule
extends LongSchedule
{
// Hidden data members.
// Chunk for each thread.
private LongRange[] myChunk;
// Exported constructors.
/**
* Construct a new fixed schedule object.
*/
public FixedLongSchedule()
{
super();
}
/**
* Construct a new fixed schedule object. This constructor is for use by the
* <TT>LongSchedule.parse()</TT> method.
*
* @param args Array of argument strings.
*/
public FixedLongSchedule
(String[] args)
{
super();
throw new IllegalArgumentException
("FixedLongSchedule(): Usage: -Dpj.schedule=fixed");
}
// Exported operations.
/**
* Determine if this schedule is a fixed schedule. For a parallel team with
* <I>K</I> threads, a fixed schedule partitions the loop index range into
* exactly <I>K</I> chunks, one chunk for each thread, each chunk with
* predetermined upper and lower bounds.
*
* @return True if this is a fixed schedule, false otherwise.
*/
public boolean isFixedSchedule()
{
return true;
}
// Hidden operations.
/**
* Start generating chunks of iterations for a parallel for loop using this
* schedule.
* <P>
* The <TT>start()</TT> method is only called by a single thread in the
* Parallel Java middleware.
*
* @param K Number of threads in the parallel team.
* @param theLoopRange Range of iterations for the entire parallel for
* loop. The stride may be 1 or greater.
*/
public void start
(int K,
LongRange theLoopRange)
{
myChunk = theLoopRange.subranges (K);
for (int i = 0; i < K; ++ i)
{
if (myChunk[i].length() == 0) myChunk[i] = null;
}
}
/**
* Obtain the next chunk of iterations for the given thread index. If there
* are more iterations, a range object is returned whose lower bound, upper
* bound, and stride specify the chunk of iterations to perform. The
* returned range object's stride is the same as that given to the
* <TT>start()</TT> method. The returned range object's lower bound and
* upper bound are contained within the range given to the <TT>start()</TT>
* method. If there are no more iterations, null is returned.
* <P>
* The <TT>next()</TT> method is called by multiple parallel team threads in
* the Parallel Java middleware. The <TT>next()</TT> method must be multiple
* thread safe.
*
* @param theThreadIndex Thread index in the range 0 .. <I>K</I>-1.
*
* @return Chunk of iterations, or null if no more iterations.
*/
public LongRange next
(int theThreadIndex)
{
LongRange chunk = myChunk[theThreadIndex];
myChunk[theThreadIndex] = null;
return chunk;
}
}
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