//******************************************************************************
//
// File:    Test15.java
// Package: edu.rit.pj.test
// Unit:    Class edu.rit.pj.test.Test15
//
// 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.
//
// 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.test;

import edu.rit.mp.IntegerBuf;

import edu.rit.pj.Comm;

import edu.rit.util.Range;

/**
 * Class Test15 is a unit test main program for the all-gather collective
 * communication operation in class {@linkplain edu.rit.pj.Comm}. The program
 * runs on a number of processors in the cluster. Each process sets up an array
 * of data and fills in one slice; the processes all-gather the array slices
 * together; and each process prints its final array.
 * 

 * Usage: java -Dpj.np=K edu.rit.pj.test.Test15 N
 * 
K = Number of parallel processes
 * 
N = Array length
 *
 * @author  Alan Kaminsky
 * @version 18-Mar-2008
 */
public class Test15
	{

// Prevent construction.

	private Test15()
		{
		}

// Global variables.

	// World communicator.
	static Comm world;
	static int size;
	static int rank;

	// Command line arguments.
	static int N;

	// Array.
	static int[] data;

	// Communication buffers.
	static IntegerBuf[] buf;

// Main program.

	/**
	 * Unit test main program.
	 */
	public static void main
		(String[] args)
		throws Exception
		{
		// Initialize middleware.
		Comm.init (args);
		world = Comm.world();
		size = world.size();
		rank = world.rank();

		// Parse command line arguments.
		if (args.length != 1) usage();
		N = Integer.parseInt (args[0]);

		// Set up array.
		data = new int [N];
		for (int i = 0; i < N; ++ i)
			{
			data[i] = 100 * rank + i;
			}

		// Print array before all-gather.
		System.out.print (rank);
		System.out.print (" before:");
		for (int i = 0; i < N; ++ i)
			{
			System.out.print (' ');
			System.out.print (data[i]);
			}
		System.out.println();

		// Set up communication buffers.
		buf =
			IntegerBuf.sliceBuffers
				(data,
				 new Range (0, N-1) .subranges (size));

		// All-gather.
		world.allGather (buf[rank], buf);

		// Print array after all-gather.
		System.out.print (rank);
		System.out.print (" after:");
		for (int i = 0; i < N; ++ i)
			{
			System.out.print (' ');
			System.out.print (data[i]);
			}
		System.out.println();
		}

	/**
	 * Print a usage message and exit.
	 */
	private static void usage()
		{
		System.err.println ("Usage: java -Dpj.np= edu.rit.pj.test.Test15 ");
		System.err.println (" = Number of parallel processes");
		System.err.println (" = Array length");
		System.exit (1);
		}

	}