lib_mpi_split.h

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/*****************************************************************************
* Multiscale Universal Interface Code Coupling Library                       *
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* Copyright (C) 2019 Y. H. Tang, S. Kudo, X. Bian, Z. Li, G. E. Karniadakis  *
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#ifndef LIB_MPI_SPLIT_H_
#define LIB_MPI_SPLIT_H_
 
#include <exception>
namespace mui {
 
  inline void mpi_finalize_after_split() {
    int flag;
    MPI_Finalized(&flag);
    if (!flag) MPI_Finalize();
  }
 
  inline MPI_Comm mpi_split_by_app( int argc=0, char **argv=NULL, int threadType=-1, int *thread_support=NULL )
  {
    {
    int flag;
    MPI_Initialized(&flag);
    if( !flag ) {
        if(threadType != -1) {
          MPI_Init_thread( &argc, &argv, threadType, thread_support );
        }
        else {
          MPI_Init( &argc, &argv );
        }
        atexit( mpi_finalize_after_split );
      }
    }
    void* v;
    int flag;
    MPI_Comm_get_attr(MPI_COMM_WORLD,MPI_APPNUM,&v,&flag);
    if (!flag) {
        std::cout << "MUI Info [lib_mpi_split.h]: Calling mpi_split_by_app() when run as a single application" << std::endl;
    }
    int appnum = *static_cast<int*>(v);
    int rank;
    MPI_Comm_rank(MPI_COMM_WORLD,&rank);
    MPI_Comm domain;
    MPI_Comm_split(MPI_COMM_WORLD,appnum,rank,&domain);
    return domain;
  }
}
 
#endif /* LIB_MPI_SPLIT_H_ */