357 lines
11 KiB
C++
357 lines
11 KiB
C++
#include <algorithm>
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#include <array>
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#include <cstring>
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#include <functional>
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#include <limits>
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#include <map>
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#include <set>
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#include <vector>
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#include <mpi.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <time.h>
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#include <unistd.h>
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#include <utility>
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#include <fmt/format.h>
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#include <fmt/ranges.h>
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#define TAG_SEND_NUM_EDGES 1001
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#define TAG_SEND_EDGES 1002
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#define TAG_SEND_FINAL_RESULT 1003
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typedef struct {
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int fst;
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int snd;
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} pair;
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void init_pair_type(MPI_Datatype *out);
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int main(int argc, char **argv) {
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MPI::Init(argc, argv);
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int rank = MPI::COMM_WORLD.Get_rank(), p = MPI::COMM_WORLD.Get_size();
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MPI_Datatype IntPairType;
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init_pair_type(&IntPairType);
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// One process reads the file and distributes the data to the other processes
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// using a 1D decomposition (each rank gets approx same number of vertices).
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#pragma region
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FILE *fp;
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char *line = NULL;
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size_t len;
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ssize_t read;
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pair params;
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if (rank == 0) {
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printf("Hello\n");
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fp = fopen(argv[1], "r");
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if ((read = getline(&line, &len, fp)) != -1)
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sscanf(line, "%d %d", ¶ms.fst, ¶ms.snd);
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}
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// Send the params
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MPI_Bcast(¶ms, 1, IntPairType, 0, MPI::COMM_WORLD);
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int total_num_nodes = params.fst;
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int total_num_edges = params.snd;
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int each_num_nodes = total_num_nodes / p;
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// Calculate exactly how many nodes my current process holds
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int num_my_nodes =
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rank == p - 1 ? total_num_nodes - rank * each_num_nodes : each_num_nodes;
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int my_nodes[num_my_nodes];
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std::function<std::pair<int, int>(int)> node_range =
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[p, total_num_nodes, each_num_nodes](int process) {
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int start = process * each_num_nodes;
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int end = process == p - 1 ? total_num_nodes : start + each_num_nodes;
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return std::make_pair(start, end);
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};
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// Read the edges
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int num_my_edges;
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pair *my_edges;
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int counts[p], displs[p];
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if (rank == 0) {
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line = NULL;
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pair all_edges[total_num_edges];
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// For the current process, what's the last node we're expecting to see?
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int current_process = 0;
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std::pair<int, int> current_node_range = node_range(current_process);
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int edge_counter = 0;
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for (int i = 0; i < total_num_edges; ++i) {
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getline(&line, &len, fp);
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int fst, snd;
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sscanf(line, "%d %d", &fst, &snd);
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if (fst >= current_node_range.second) {
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if (current_process == 0) {
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num_my_edges = edge_counter;
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my_edges = (pair *)calloc(num_my_edges, sizeof(pair));
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memcpy(my_edges, all_edges, edge_counter * sizeof(pair));
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} else {
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MPI_Send(&edge_counter, 1, MPI_INT, current_process,
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TAG_SEND_NUM_EDGES, MPI::COMM_WORLD);
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MPI_Send(all_edges, edge_counter, IntPairType, current_process,
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TAG_SEND_EDGES, MPI::COMM_WORLD);
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}
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// We're starting on the next process
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current_process += 1;
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current_node_range = node_range(current_process);
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edge_counter = 0;
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}
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all_edges[edge_counter].fst = fst;
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all_edges[edge_counter].snd = snd;
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edge_counter += 1;
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}
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// We have to send the last one again here, since it didn't get caught in
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// the loop above
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MPI_Send(&edge_counter, 1, MPI_INT, current_process, TAG_SEND_NUM_EDGES,
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MPI::COMM_WORLD);
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MPI_Send(all_edges, edge_counter, IntPairType, current_process,
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TAG_SEND_EDGES, MPI::COMM_WORLD);
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// int step = num_edges / p;
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// for (int i = 0; i < p; ++i) {
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// int start = i * step;
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// int end = i == p - 1 ? num_edges : start + step;
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// int count = end - start;
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// counts[i] = count;
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// displs[i] = start;
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// }
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} else {
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MPI_Recv(&num_my_edges, 1, MPI_INT, 0, TAG_SEND_NUM_EDGES, MPI::COMM_WORLD,
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NULL);
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my_edges = (pair *)calloc(num_my_edges, sizeof(pair));
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MPI_Recv(my_edges, num_my_edges, IntPairType, 0, TAG_SEND_EDGES,
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MPI::COMM_WORLD, NULL);
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}
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char *buf = (char *)calloc(sizeof(char), 1000);
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int offset = 0; // Keep track of the current position in the buffer
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for (int i = 0; i < std::min(num_my_edges, 5); i++) {
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offset +=
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sprintf(buf + offset, "(%d, %d)", my_edges[i].fst, my_edges[i].snd);
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if (i < len - 1) {
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// Add a separator (e.g., comma or space) if it's not the last
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offset += sprintf(buf + offset, " ");
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}
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}
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if (rank == 0) {
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fclose(fp);
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if (line)
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free(line);
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}
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#pragma endregion
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// Each process analyzes the non-local edges that are contained in its portion
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// of the graph.
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#pragma region
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std::map<int, int> node_label_assignment;
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std::pair<int, int> my_node_range = node_range(rank);
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// Initial node assignment
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for (int i = my_node_range.first; i < my_node_range.second; ++i) {
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node_label_assignment[i] = i;
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}
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std::map<int, std::set<int>> adj;
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std::set<int> non_local_nodes;
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std::set<std::pair<int, int>> non_local_edges;
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for (int i = 0; i < num_my_edges; ++i) {
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pair edge = my_edges[i];
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adj[edge.fst].insert(edge.snd);
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if (!(my_node_range.first <= edge.fst && edge.fst < my_node_range.second)) {
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non_local_nodes.insert(edge.fst);
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non_local_edges.insert(std::make_pair(edge.snd, edge.fst));
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}
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if (!(my_node_range.first <= edge.snd && edge.snd < my_node_range.second)) {
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non_local_nodes.insert(edge.snd);
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non_local_edges.insert(std::make_pair(edge.fst, edge.snd));
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}
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}
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#pragma endregion
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// Each process determines which processors stores the non-local vertices
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// corresponding to the non-local edges.
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#pragma region
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std::map<int, std::set<int>> send_map;
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std::map<int, std::set<int>> recv_map;
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for (auto entry : non_local_edges) {
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int local_node = entry.first, remote_node = entry.second;
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int corresponding_process = remote_node / each_num_nodes;
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// The last process gets some extra nodes
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if (corresponding_process >= p)
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corresponding_process = p - 1;
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send_map[corresponding_process].insert(local_node);
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recv_map[corresponding_process].insert(remote_node);
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}
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#pragma endregion
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// All the processes are communicating to figure out which process needs to
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// send what data to the other processes.
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#pragma region
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#pragma endregion
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// The processes perform the transfers of non-local labels and updates of
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// local labels until convergence.
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#pragma region
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while (true) {
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// First, exchange the data that needs to be exchanged
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std::vector<int> sendbuf;
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std::vector<int> send_counts;
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std::vector<int> send_displs;
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std::vector<int> recv_counts;
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std::vector<int> recv_displs;
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int recv_total;
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{
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int offset = 0;
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for (int i = 0; i < p; ++i) {
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int count = send_map[i].size();
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// std::sort(send_map[i].begin(), send_map[i].end());
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for (auto k : send_map[i]) {
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sendbuf.push_back(node_label_assignment[k]);
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}
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send_counts.push_back(count);
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send_displs.push_back(offset);
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offset += count;
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}
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offset = 0;
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for (int i = 0; i < p; ++i) {
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int count = recv_map[i].size();
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// std::sort(recv_map[i].begin(), recv_map[i].end());
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recv_counts.push_back(count);
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recv_displs.push_back(offset);
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offset += count;
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}
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recv_total = offset;
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}
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std::vector<int> recvbuf(recv_total, 0);
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// std::cout << fmt::format("[{}] {} \t|| \t{}", rank,
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// fmt::join(send_counts, ", "),
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// fmt::join(recv_counts, ", "))
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// << std::endl;
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MPI::COMM_WORLD.Alltoallv(sendbuf.data(), send_counts.data(),
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send_displs.data(), MPI_INT, recvbuf.data(),
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recv_counts.data(), recv_displs.data(), MPI_INT);
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std::map<int, int> total_node_label_assignment(node_label_assignment);
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for (int i = 0; i < p; ++i) {
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std::vector<int> ouais(recv_map[i].begin(), recv_map[i].end());
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for (int j = 0; j < recv_counts[i]; ++j) {
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int remote_node = ouais[j];
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int remote_value = recvbuf[recv_displs[i] + j];
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total_node_label_assignment[remote_node] = remote_value;
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}
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}
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// For each local node, determine the minimum label out of its neighbors
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std::map<int, int> new_labels;
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for (int i = my_node_range.first; i < my_node_range.second; ++i) {
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int current_value = total_node_label_assignment[i];
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int min = current_value;
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for (auto neighbor : adj[i]) {
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if (total_node_label_assignment[neighbor] < min)
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min = total_node_label_assignment[neighbor];
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}
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if (min < current_value) {
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new_labels[i] = min;
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}
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}
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// std::cout << fmt::format("[{}] Helloge {}", rank,
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// fmt::join(new_labels, ", "))
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// << std::endl;
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// Have there been any changes in the labels?
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int num_changes = new_labels.size();
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int total_changes;
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MPI::COMM_WORLD.Allreduce(&num_changes, &total_changes, 1, MPI_INT,
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MPI::SUM);
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std::cout << fmt::format("[{}] # updates: {} ({})", rank, num_changes,
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total_changes)
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<< std::endl;
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if (total_changes == 0) {
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break;
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}
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// Update the original node assignment
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for (auto entry : new_labels) {
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node_label_assignment[entry.first] = entry.second;
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}
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}
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#pragma endregion
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// The results are gathered to a single process, which writes them to the
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// disk.
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#pragma region
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if (rank == 0) {
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std::vector<int> all_assignments(total_num_nodes);
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std::map<int, int> label_count;
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int ctr = 0;
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for (int i = 0; i < p; ++i) {
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std::pair<int, int> this_node_range = node_range(i);
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int count = this_node_range.second - this_node_range.first;
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if (i == 0) {
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for (int j = 0; j < count; ++j) {
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all_assignments[this_node_range.first + j] =
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node_label_assignment[this_node_range.first + j];
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label_count[all_assignments[this_node_range.first + j]]++;
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}
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} else {
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MPI::COMM_WORLD.Recv(&all_assignments[this_node_range.first], count,
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MPI::INT, i, TAG_SEND_FINAL_RESULT);
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for (int j = 0; j < count; ++j) {
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label_count[all_assignments[this_node_range.first + j]]++;
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}
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}
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}
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std::cout << "Done! " << label_count.size() << std::endl;
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} else {
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std::vector<int> flat_assignments;
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for (int i = my_node_range.first; i < my_node_range.second; ++i) {
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flat_assignments.push_back(node_label_assignment[i]);
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}
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MPI::COMM_WORLD.Send(flat_assignments.data(), flat_assignments.size(),
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MPI::INT, 0, TAG_SEND_FINAL_RESULT);
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}
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#pragma endregion
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MPI::Finalize();
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return 0;
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}
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void init_pair_type(MPI_Datatype *out) {
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int blocklengths[2] = {1, 1};
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MPI_Datatype types[2] = {MPI_INT, MPI_INT};
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MPI_Aint offsets[2];
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offsets[0] = offsetof(pair, fst);
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offsets[1] = offsetof(pair, snd);
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MPI_Type_create_struct(2, blocklengths, offsets, types, out);
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MPI_Type_commit(out);
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} |