// ==================================================================
// Author: Jean-Michel Richer
// Email: jean-michel.richer@univ-angers.fr
// Date: Aug 2016
// Purpose: Demonstrate basic functionnalities of MPI with C++
// ==================================================================
#include <iostream>
#include <cstdlib>
#include <unistd.h> // for sleep
using namespace std;
#include <mpi.h>

// ==================================================================
// C++ version
// ==================================================================

int main(int argc, char ** argv) {
	// maximum number of CPUs
	int max_cpus;
	// cpu identifier (called rank)
	int cpu_rank;
	// C-string to store name of the host
	char cpu_name[MPI::MAX_PROCESSOR_NAME];
	// length of the C-string
	int length;

	// initialization also using command line parameters
	MPI::Init(argc, argv);
	
	// get number of programs running
	max_cpus = MPI::COMM_WORLD.Get_size();
	
	// get program identifier
	cpu_rank = MPI::COMM_WORLD.Get_rank();
	
	// get cpu name
	memset(cpu_name, 0, MPI::MAX_PROCESSOR_NAME);
	MPI::Get_processor_name(cpu_name, length);
  
  	// sleep
	sleep(cpu_rank);
  	
	cerr << "running on " << cpu_name << " with id=" << cpu_rank << "/";
	cerr << max_cpus << endl;
    
    // free resources, don't forget !
	MPI::Finalize();

	exit(EXIT_SUCCESS);
}