environment.hpp

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// Copyright (c) 2024 Simons Foundation
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0.txt
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
// Authors: Thomas Hahn, Alexander Hampel, Olivier Parcollet, Nils Wentzell
 
#pragma once
 
#include "./utils.hpp"
 
#include <mpi.h>
 
#include <cstdlib>
 
namespace mpi {
 
  [[nodiscard]] inline bool is_initialized() noexcept {
    int flag = 0;
    check_mpi_call(MPI_Initialized(&flag), "MPI_Initialized");
    return flag;
  }
 
  static const bool has_env = []() {
    if (std::getenv("OMPI_COMM_WORLD_RANK") != nullptr or std::getenv("PMI_RANK") != nullptr or std::getenv("CRAY_MPICH_VERSION") != nullptr
        or std::getenv("FORCE_MPI_INIT") != nullptr)
      return true;
    else
      return false;
  }();
 
  struct environment {
    environment(int argc, char *argv[]) { //  NOLINT (C-style array is wanted here)
      if (has_env && !is_initialized()) check_mpi_call(MPI_Init(&argc, &argv), "MPI_Init");
    }
 
    ~environment() {
      if (has_env) check_mpi_call(MPI_Finalize(), "MPI_Finalize");
    }
  };
 
} // namespace mpi