package be.ac.vub.ir.mpi;

import java.util.Random;

import mpi.MPI;

public class MPITest {

	//======================== PROGRAM  ===========================//
	public static void main(String[] args) throws InterruptedException {
		// ** Start up **
		MPI.Init(args);
		final int MY_TAG=1;
		
		if (MPI.COMM_WORLD.Size() != 2 ){
			System.err.println("Only use this program by running 2 processes and not "+MPI.COMM_WORLD.Size());
			MPI.Finalize(); // Don't forget!!
			return;
		}

		int myRank = MPI.COMM_WORLD.Rank();
		
		// ** Master process **
		if (myRank == 0){ 
			int random = new Random().nextInt();
			System.out.println("Process "+myRank+" sends random number "+random+" to my brother process.");
			MPI.COMM_WORLD.Send(random, 0, 1, MPI.INT, 1, MY_TAG);

		} 
		// ** Slave process **
		else { 

			int buffer[] = new int[1];
			MPI.COMM_WORLD.Recv(buffer, 0, 1, MPI.CHAR, 0, MY_TAG);
			System.out.println("Process "+myRank+" received random number: "+buffer[0]);
		}
		
		// ** Finalize **
		MPI.Finalize(); // Don't forget!!
	}
}