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//******************************************************************************
//
// File: EmptyObjectBuf.java
// Package: edu.rit.mp.buf
// Unit: Class edu.rit.mp.buf.EmptyObjectBuf
//
// This Java source file is copyright (C) 2007 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.mp.buf;
import edu.rit.mp.Buf;
import edu.rit.mp.ObjectBuf;
import edu.rit.pj.reduction.ObjectOp;
import edu.rit.pj.reduction.Op;
import java.nio.ByteBuffer;
/**
* Class EmptyObjectBuf provides an object buffer that contains no items for
* messages using the Message Protocol (MP). When a message is sent from an
* EmptyObjectBuf, the message item type is Object and the message length is 0.
* When a message is received into an EmptyObjectBuf, the message item type must
* be Object, but all items in the message are discarded.
*
* @author Alan Kaminsky
* @version 03-Jul-2008
*/
public class EmptyObjectBuf
extends ObjectBuf<Object>
{
// Exported constructors.
/**
* Construct a new empty object buffer.
*/
public EmptyObjectBuf()
{
super (0);
}
// Exported operations.
/**
* Obtain the given item from this buffer.
* <P>
* The <TT>get()</TT> method must not block the calling thread; if it does,
* all message I/O in MP will be blocked.
*
* @param i Item index in the range 0 .. <TT>length()</TT>-1.
*
* @return Item at index <TT>i</TT>.
*/
public Object get
(int i)
{
throw new IndexOutOfBoundsException();
}
/**
* Store the given item in this buffer.
* <P>
* The <TT>put()</TT> method must not block the calling thread; if it does,
* all message I/O in MP will be blocked.
*
* @param i Item index in the range 0 .. <TT>length()</TT>-1.
* @param item Item to be stored at index <TT>i</TT>.
*/
public void put
(int i,
Object item)
{
throw new IndexOutOfBoundsException();
}
/**
* Copy items from the given buffer to this buffer. The number of items
* copied is this buffer's length or <TT>theSrc</TT>'s length, whichever is
* smaller. If <TT>theSrc</TT> is this buffer, the <TT>copy()</TT> method
* does nothing.
*
* @param theSrc Source of items to copy into this buffer.
*
* @exception ClassCastException
* (unchecked exception) Thrown if <TT>theSrc</TT>'s item data type is
* not the same as this buffer's item data type.
*/
public void copy
(Buf theSrc)
{
}
/**
* Create a buffer for performing parallel reduction using the given binary
* operation. The results of the reduction are placed into this buffer.
* <P>
* Operations performed on the returned reduction buffer have the same
* effect as operations performed on this buffer, except whenever a source
* item <I>S</I> is put into a destination item <I>D</I> in this buffer,
* <I>D</I> is set to <I>D op S</I>, that is, the reduction of <I>D</I> and
* <I>S</I> using the given binary operation (rather than just setting
* <I>D</I> to <I>S</I>).
*
* @param op Binary operation.
*
* @exception ClassCastException
* (unchecked exception) Thrown if this buffer's element data type and
* the given binary operation's argument data type are not the same.
*/
public Buf getReductionBuf
(Op op)
{
ObjectOp objectop = (ObjectOp) op;
return this;
}
}
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