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#pragma once
#include <array>
#include <vector>
#include "gsl/multi_span"
#include <mpi.h>
#include "Configuration.hpp"
#include "MpiEnvironment.hpp"
#include "Util.hpp"
#include "state.hpp"
class Communicator {
constexpr static std::size_t NoNeighbors{8};
std::vector<int> _neighbors;
std::vector<int> _sizes;
std::vector<MPI_Datatype> _sendTypes;
const std::vector<MPI_Datatype>& _recvTypes{_sendTypes};
std::vector<MPI_Aint> _sendDisplacements;
std::vector<MPI_Aint> _recvDisplacements;
MPI_Comm _commDistGraph{MPI_COMM_NULL};
MPI_Datatype _haloRowType;
MPI_Datatype _haloColumnType;
MPI_Datatype _haloCornerType{MPI_CHAR};
public:
Communicator(const MpiEnvironment& env, const Size& gridSize,
const Size& tileSize) {
// Begin definition of basic types
MPI_Type_contiguous(tileSize.Cols, MPI_CHAR, &_haloRowType);
MPI_Type_commit(&_haloRowType);
MPI_Type_vector(tileSize.Rows, 1, tileSize.Cols + 2, MPI_CHAR,
&_haloColumnType);
MPI_Type_commit(&_haloColumnType);
// End definition of basic types
// Begin definition of datastructures for a general cell
const auto& generalSendTypes = std::array<MPI_Datatype, NoNeighbors>{
_haloCornerType, _haloRowType, _haloCornerType, //
_haloColumnType, _haloColumnType, //
_haloCornerType, _haloRowType, _haloCornerType //
};
const auto& generalRecvTypes = generalSendTypes; // same
const auto& tCols = tileSize.Cols;
const auto& tRows = tileSize.Rows;
auto dp = [&](std::size_t x,
std::size_t y) { // character coordinates to displacement
return static_cast<MPI_Aint>(y * (tCols + 2) + x);
};
std::array<MPI_Aint, NoNeighbors> generalSendDisplacements{
dp(1, 1), dp(1, 1), dp(tCols, 1), //
dp(1, 1), dp(tCols, 1), //
dp(1, tRows), dp(1, tRows), dp(tCols, tRows) //
};
std::array<MPI_Aint, NoNeighbors> generalRecvDisplacements{
dp(0, 0), dp(1, 0), dp(tCols + 1, 0), //
dp(0, 1), dp(tCols + 1, 1), //
dp(0, tRows + 1), dp(1, tRows + 1), dp(tCols + 1, tRows + 1) //
};
std::array<int, NoNeighbors> generalSizes{
1, 1, 1, //
1, 1, //
1, 1, 1 //
};
// End definition of datastructures for a general cell
// Begin definition of datastructures for this particular cell
auto rank2coord = [&](std::size_t rank) {
return Coord{
rank % gridSize.Cols, //
rank / gridSize.Cols //
};
};
auto coord2rank = [&](Coord c) { return gridSize.Cols * c.Y + c.X; };
auto isInsideGrid = [&](Coord c) {
return c.X < gridSize.Cols && c.Y < gridSize.Rows;
};
const auto& myCoord = rank2coord(env.worldRank());
std::array<Coord, NoNeighbors> virtualNeighborCoords{{
{myCoord.X - 1, myCoord.Y - 1}, // intentional signed underflow
{myCoord.X + 0, myCoord.Y - 1}, //
{myCoord.X + 1, myCoord.Y - 1}, //
{myCoord.X - 1, myCoord.Y + 0}, //
{myCoord.X + 1, myCoord.Y + 0}, //
{myCoord.X - 1, myCoord.Y + 1}, //
{myCoord.X + 0, myCoord.Y + 1}, //
{myCoord.X + 1, myCoord.Y + 1} //
}};
// interate over all neighbors
for (std::size_t i{0}; i < NoNeighbors; ++i) {
const auto& nbrCoord = virtualNeighborCoords[i];
if (isInsideGrid(nbrCoord)) {
_neighbors.push_back(coord2rank(nbrCoord));
_sendTypes.push_back(generalSendTypes[i]);
_sendDisplacements.push_back(generalSendDisplacements[i]);
_recvDisplacements.push_back(generalRecvDisplacements[i]);
_sizes.push_back(generalSizes[i]);
}
}
// if (env.worldRank() == 0) {
// std::cout << "neighbors:\n";
// for (const auto i : neighbors) std::cout << i << ",\n";
// std::cout << '\n';
//}
MPI_Dist_graph_create_adjacent(
MPI_COMM_WORLD, // comm_old
_neighbors.size(), // indegree
_neighbors.data(), // sources
reinterpret_cast<int*>(MPI_UNWEIGHTED), // sourceweights
_neighbors.size(), // outdegree
_neighbors.data(), // destinations
reinterpret_cast<int*>(MPI_UNWEIGHTED), // destweights
MPI_INFO_NULL, // info
0, // reorder
&_commDistGraph // comm_dist_graph
);
// End definition of datastructures for this particular cell
}
~Communicator() {
MPI_Comm_free(&_commDistGraph);
MPI_Type_free(&_haloColumnType);
MPI_Type_free(&_haloRowType);
}
void Communicate(gsl::multi_span<State, -1, -1>& model) {
MPI_Neighbor_alltoallw(model.data(), // sendbuf
_sizes.data(), // sendcounts
_sendDisplacements.data(), // sdispl
_sendTypes.data(), // sendtypes
model.data(), // recvbuf
_sizes.data(), // recvcounts
_recvDisplacements.data(), // rdispls
_recvTypes.data(), // recvtypes
_commDistGraph // comm
);
}
};