vector.hpp

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// Copyright (c) 2019-2024 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, Olivier Parcollet, Nils Wentzell
 
#pragma once
 
#include "./communicator.hpp"
#include "./generic_communication.hpp"
#include "./ranges.hpp"
#include "./utils.hpp"
 
#include <mpi.h>
 
#include <vector>
 
namespace mpi {
 
  template <typename T> void mpi_broadcast(std::vector<T> &v, communicator c = {}, int root = 0) {
    auto bsize = v.size();
    broadcast(bsize, c, root);
    if (c.rank() != root) v.resize(bsize);
    broadcast_range(v, c, root);
  }
 
  template <typename T> void mpi_reduce_in_place(std::vector<T> &v, communicator c = {}, int root = 0, bool all = false, MPI_Op op = MPI_SUM) {
    reduce_in_place_range(v, c, root, all, op);
  }
 
  template <typename T>
  auto mpi_reduce(std::vector<T> const &v, communicator c = {}, int root = 0, bool all = false, MPI_Op op = MPI_SUM) {
    std::vector<regular_t<T>> res(c.rank() == root || all ? v.size() : 0);
    reduce_range(v, res, c, root, all, op);
    return res;
  }
 
  template <typename T> auto mpi_scatter(std::vector<T> const &v, communicator c = {}, int root = 0) {
    auto bsize = v.size();
    broadcast(bsize, c, root);
    std::vector<T> res(chunk_length(bsize, c.size(), c.rank()));
    scatter_range(v, res, bsize, c, root);
    return res;
  }
 
  template <typename T> auto mpi_gather(std::vector<T> const &v, communicator c = {}, int root = 0, bool all = false) {
    long bsize = mpi::all_reduce(v.size(), c);
    std::vector<T> res(c.rank() == root || all ? bsize : 0);
    gather_range(v, res, bsize, c, root, all);
    return res;
  }
 
} // namespace mpi