#include <stdlib.h>
#include "mpi.h"
#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/types.h>
#include <time.h>
#include <limits.h>

#define VERSION "mpi_spawn"

int main(int argc, char* argv[]){
  int nchild, my_rank, universe_size = 0,flag;
  MPI_Comm parent;
  
  MPI_Init(&argc, &argv);
  MPI_Comm_rank(MPI_COMM_WORLD, &my_rank);

  MPI_Comm_get_attr(MPI_COMM_WORLD, MPI_UNIVERSE_SIZE,  
               &universe_size, &flag);  

  fprintf(stderr, "universe=%d\n", universe_size);

  if(!flag){
    fprintf(stderr, "We're Screwed.\n");
    MPI_Finalize();
    exit(0);
  }
  if(universe_size == 1){
    MPI_Comm intercomm;
    int errcodes[10];
    if((argc < 2) || (nchild = atoi(argv[1]) <= 0)){
      if(my_rank == 0){
        fprintf(stderr, "Usage: %s <nchild> %d\n", argv[0], argc);
        MPI_Finalize();
        exit(0);
      }
    }
    //  if(MPI_Comm_get_parent(&parent) != MPI_SUCCESS){

    fprintf(stderr, "Master has rank=%d\n", my_rank);
    if(MPI_Comm_spawn(VERSION, argv, nchild, MPI_INFO_NULL, my_rank, MPI_COMM_WORLD, &intercomm, errcodes) != MPI_SUCCESS)
      fprintf(stderr, "Spawn failed!\n");
    else
      fprintf(stderr, "Spawn was successful\n");
    sleep(10);
  }
  else{
    fprintf(stderr, "Spawned child has rank=%d\n", my_rank);
    sleep(10);
  }
  MPI_Finalize();
  exit(0);
}