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#ifndef LIBRARY_SRC_MPI_INIT_SINGLETON_HPP_
#define LIBRARY_SRC_MPI_INIT_SINGLETON_HPP_

#include <mpi.h>

#include <memory>

/**
 * @file mpi_init_singleton.hpp
 *
 * @brief Contains MPI library initialization code
 */

namespace rocshmem {

class MPIInitSingleton {
 private:
  /**
   * @brief Primary constructor
   */
  MPIInitSingleton();

 public:
  /**
   * @brief Destructor
   */
  ~MPIInitSingleton();

  /**
   * @brief Invoke singleton construction or return handle
   *
   * @return Initialized handle to singleton
   */
  static MPIInitSingleton* GetInstance();

  /**
   * @brief Accessor for my COMM_WORLD rank identifier
   *
   * @return My COMM_WORLD rank identifier
   */
  int get_rank();

  /**
   * @brief Accessor for number or processes in COMM_WORLD
   *
   * @return Number of processes in COMM_WORLD
   */
  int get_nprocs();

 private:
  /**
   * @brief My MPI rank identifier
   */
  int my_rank_{-1};

  /**
   * @brief Number of MPI processes
   */
  int nprocs_{-1};

  /**
   * @brief Was MPI initialized before rocshmem_init call
   */
  int pre_init_done{0};

  /**
   * @brief Refers to global variable
   */
  static MPIInitSingleton* instance;
};

}  // namespace rocshmem

#endif  // LIBRARY_SRC_MPI_INIT_SINGLETON_HPP_