/*
//@HEADER
// ************************************************************************
// 
//                        Kokkos v. 2.0
//              Copyright (2014) Sandia Corporation
// 
// Under the terms of Contract DE-AC04-94AL85000 with Sandia Corporation,
// the U.S. Government retains certain rights in this software.
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// Questions? Contact  H. Carter Edwards (hcedwar@sandia.gov)
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*/

#ifndef PARALLELCOMM_HPP
#define PARALLELCOMM_HPP

//------------------------------------------------------------------------

#include <Kokkos_Macros.hpp>

//------------------------------------------------------------------------

#if defined( KOKKOS_HAVE_MPI )

#include <mpi.h>
#include <string>

namespace comm {

struct Machine {
  MPI_Comm mpi_comm ;

  Machine() : mpi_comm( MPI_COMM_NULL ) {}

  Machine( const Machine & rhs )
    : mpi_comm( rhs.mpi_comm ) {}

  Machine( MPI_Comm c ) : mpi_comm( c ) {}

  static Machine init( int * argc , char *** argv )
  {
    MPI_Init( argc , argv );
    return Machine( MPI_COMM_WORLD );
  }

  static void finalize() { MPI_Finalize(); }
};

inline
unsigned  size( Machine machine )
{
  int np ; MPI_Comm_size( machine.mpi_comm , & np ); return np ;
}

inline
unsigned  rank( Machine machine )
{
  int ip ; MPI_Comm_rank( machine.mpi_comm , & ip ); return ip ;
}

inline
double max( Machine machine , double local )
{
  double global = 0;
  MPI_Allreduce( & local , & global , 1 , MPI_DOUBLE , MPI_MAX , machine.mpi_comm );
  return global ;
}

inline
std::string command_line( Machine machine , const int argc , const char * const * const argv )
{
  std::string argline ;

  if ( 0 == rank( machine ) ) {
    for ( int i = 1 ; i < argc ; ++i ) {
      argline.append(" ").append( argv[i] );
    }
  }

  int length = argline.length();
  MPI_Bcast( & length , 1 , MPI_INT , 0 , machine.mpi_comm );
  argline.resize( length , ' ' );
  MPI_Bcast( (void*) argline.data() , length , MPI_CHAR , 0 , machine.mpi_comm );

  return argline ;
}

}

#else /* ! defined( KOKKOS_HAVE_MPI ) */

#include <string>

namespace comm {

// Stub for non-parallel

struct Machine {
  static Machine init( int * , char *** )
  { return Machine(); }

  static void finalize() {}
};

inline
unsigned  size( Machine ) { return 1 ; }

inline
unsigned  rank( Machine ) { return 0 ; }

inline
double max( Machine , double local )
{ return local ; }

inline
std::string command_line( Machine machine , const int argc , const char * const * const argv )
{
  std::string argline ;

  if ( 0 == rank( machine ) ) {
    for ( int i = 1 ; i < argc ; ++i ) {
      argline.append(" ").append( argv[i] );
    }
  }

  return argline ;
}

}

#endif /* ! defined( KOKKOS_HAVE_MPI ) */

//------------------------------------------------------------------------

#endif /* #ifndef PARALLELCOMM_HPP */


