Mpi.hpp

/* Copyright 2022 Franz Poeschel
 *
 * This file is part of openPMD-api.
 *
 * openPMD-api is free software: you can redistribute it and/or modify
 * it under the terms of of either the GNU General Public License or
 * the GNU Lesser General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * openPMD-api is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License and the GNU Lesser General Public License
 * for more details.
 *
 * You should have received a copy of the GNU General Public License
 * and the GNU Lesser General Public License along with openPMD-api.
 * If not, see <http://www.gnu.org/licenses/>.
 */
#pragma once
 
#include "openPMD/config.hpp"
 
#include "openPMD/auxiliary/TypeTraits.hpp"
 
#if openPMD_HAVE_MPI
#include <mpi.h>
 
#include <string>
#include <vector>
#endif
 
#include <type_traits>
 
namespace openPMD::auxiliary
{
#if openPMD_HAVE_MPI
 
namespace
{
    template <typename T>
    constexpr MPI_Datatype openPMD_MPI_type()
    {
        using T_decay = std::decay_t<T>;
        if constexpr (std::is_same_v<T_decay, char>)
        {
            return MPI_CHAR;
        }
        else if constexpr (std::is_same_v<T_decay, signed char>)
        {
            return MPI_SIGNED_CHAR;
        }
        else if constexpr (std::is_same_v<T_decay, unsigned char>)
        {
            return MPI_UNSIGNED_CHAR;
        }
        else if constexpr (std::is_same_v<T_decay, short>)
        {
            return MPI_SHORT;
        }
        else if constexpr (std::is_same_v<T_decay, short unsigned>)
        {
            return MPI_UNSIGNED_SHORT;
        }
        else if constexpr (std::is_same_v<T_decay, unsigned>)
        {
            return MPI_UNSIGNED;
        }
        else if constexpr (std::is_same_v<T_decay, int>)
        {
            return MPI_INT;
        }
        else if constexpr (std::is_same_v<T_decay, long>)
        {
            return MPI_LONG;
        }
        else if constexpr (std::is_same_v<T_decay, long long>)
        {
            return MPI_LONG_LONG;
        }
        else if constexpr (std::is_same_v<T_decay, unsigned long>)
        {
            return MPI_UNSIGNED_LONG;
        }
        else if constexpr (std::is_same_v<T_decay, unsigned long long>)
        {
            return MPI_UNSIGNED_LONG_LONG;
        }
        else if constexpr (std::is_same_v<T_decay, float>)
        {
            return MPI_FLOAT;
        }
        else if constexpr (std::is_same_v<T_decay, double>)
        {
            return MPI_DOUBLE;
        }
        else if constexpr (std::is_same_v<T_decay, long double>)
        {
            return MPI_LONG_DOUBLE;
        }
        else
        {
            static_assert(
                dependent_false_v<T>, "openPMD_MPI_type: Unsupported type.");
        }
    }
} // namespace

struct StringMatrix
{
    std::vector<char> char_buffer;
    size_t line_length = 0;
    size_t num_lines = 0;
};
 
/*
 * These are mostly internal helper functions, so this defines only those that
 * we need.
 * Logically, these should be complemented by `collectStringsTo()` and
 * `distributeStringsAsMatrixToAllRanks()`, but we don't need them (yet).
 */

StringMatrix collectStringsAsMatrixTo(
    MPI_Comm communicator, int destRank, std::string const &thisRankString);

std::vector<std::string> distributeStringsToAllRanks(
    MPI_Comm communicator, std::string const &thisRankString);
#endif
} // namespace openPMD::auxiliary