optimize the data structure to speed up sampling in graph engine. (#37315)

* optimize the data structure from c++ to python to speed up sampling in graph engine

* update test

paddle/fluid/distributed/service/graph_py_service.cc

@@ -289,10 +289,12 @@ void GraphPyClient::load_node_file(std::string name, std::string filepath) {
     status.wait();
   }
 }
-std::vector<std::vector<std::pair<uint64_t, float>>>
+
+std::pair<std::vector<std::vector<uint64_t>>, std::vector<float>>
 GraphPyClient::batch_sample_neighbors(std::string name,
                                       std::vector<uint64_t> node_ids,
-                                      int sample_size) {
+                                      int sample_size, bool return_weight,
+                                      bool return_edges) {
   std::vector<std::vector<std::pair<uint64_t, float>>> v;
   if (this->table_id_map.count(name)) {
     uint32_t table_id = this->table_id_map[name];
@@ -300,7 +302,31 @@ GraphPyClient::batch_sample_neighbors(std::string name,
         worker_ptr->batch_sample_neighbors(table_id, node_ids, sample_size, v);
     status.wait();
   }
-  return v;
+
+  // res.first[0]: neighbors (nodes)
+  // res.first[1]: slice index
+  // res.first[2]: src nodes
+  // res.second: edges weight
+  std::pair<std::vector<std::vector<uint64_t>>, std::vector<float>> res;
+  res.first.push_back({});
+  res.first.push_back({});
+  if (return_edges) res.first.push_back({});
+  for (size_t i = 0; i < v.size(); i++) {
+    for (size_t j = 0; j < v[i].size(); j++) {
+      res.first[0].push_back(v[i][j].first);
+      if (return_edges) res.first[2].push_back(node_ids[i]);
+      if (return_weight) res.second.push_back(v[i][j].second);
+    }
+    if (i == v.size() - 1) break;
+
+    if (i == 0) {
+      res.first[1].push_back(v[i].size());
+    } else {
+      res.first[1].push_back(v[i].size() + res.first[1].back());
+    }
+  }
+
+  return res;
 }
 
 void GraphPyClient::use_neighbors_sample_cache(std::string name,

paddle/fluid/distributed/service/graph_py_service.h

@@ -148,8 +148,10 @@ class GraphPyClient : public GraphPyService {
   int get_client_id() { return client_id; }
   void set_client_id(int client_id) { this->client_id = client_id; }
   void start_client();
-  std::vector<std::vector<std::pair<uint64_t, float>>> batch_sample_neighbors(
-      std::string name, std::vector<uint64_t> node_ids, int sample_size);
+  std::pair<std::vector<std::vector<uint64_t>>, std::vector<float>>
+  batch_sample_neighbors(std::string name, std::vector<uint64_t> node_ids,
+                         int sample_size, bool return_weight,
+                         bool return_edges);
   std::vector<uint64_t> random_sample_nodes(std::string name, int server_index,
                                             int sample_size);
   std::vector<std::vector<std::string>> get_node_feat(

paddle/fluid/distributed/table/common_graph_table.cc

@@ -193,7 +193,6 @@ int32_t GraphTable::load_nodes(const std::string &path, std::string node_type) {
     std::ifstream file(path);
     std::string line;
     while (std::getline(file, line)) {
-      count++;
       auto values = paddle::string::split_string<std::string>(line, "\t");
       if (values.size() < 2) continue;
       auto id = std::stoull(values[1]);
@@ -207,7 +206,9 @@ int32_t GraphTable::load_nodes(const std::string &path, std::string node_type) {
 
       if (count % 1000000 == 0) {
         VLOG(0) << count << " nodes are loaded from filepath";
+        VLOG(0) << line;
       }
+      count++;
 
       std::string nt = values[0];
       if (nt != node_type) {
@@ -273,6 +274,7 @@ int32_t GraphTable::load_edges(const std::string &path, bool reverse_edge) {
       }
       if (count % 1000000 == 0) {
         VLOG(0) << count << " edges are loaded from filepath";
+        VLOG(0) << line;
       }
 
       size_t index = src_shard_id - shard_start;

paddle/fluid/distributed/test/graph_node_test.cc

@@ -556,15 +556,17 @@ void RunBrpcPushSparse() {
     ASSERT_EQ(count_item_nodes.size(), 12);
   }
 
-  vs = client1.batch_sample_neighbors(std::string("user2item"),
-                                      std::vector<uint64_t>(1, 96), 4);
-  ASSERT_EQ(vs[0].size(), 3);
+  std::pair<std::vector<std::vector<uint64_t>>, std::vector<float>> res;
+  res = client1.batch_sample_neighbors(
+      std::string("user2item"), std::vector<uint64_t>(1, 96), 4, true, false);
+  ASSERT_EQ(res.first[0].size(), 3);
   std::vector<uint64_t> node_ids;
   node_ids.push_back(96);
   node_ids.push_back(37);
-  vs = client1.batch_sample_neighbors(std::string("user2item"), node_ids, 4);
+  res = client1.batch_sample_neighbors(std::string("user2item"), node_ids, 4,
+                                       true, false);
 
-  ASSERT_EQ(vs.size(), 2);
+  ASSERT_EQ(res.first[1].size(), 1);
   std::vector<uint64_t> nodes_ids = client2.random_sample_nodes("user", 0, 6);
   ASSERT_EQ(nodes_ids.size(), 2);
   ASSERT_EQ(true, (nodes_ids[0] == 59 && nodes_ids[1] == 37) ||
@@ -693,4 +695,4 @@ void testGraphToBuffer() {
   VLOG(0) << s1.get_feature(0);
 }
 
-TEST(RunBrpcPushSparse, Run) { RunBrpcPushSparse(); }
\ No newline at end of file
+TEST(RunBrpcPushSparse, Run) { RunBrpcPushSparse(); }

paddle/fluid/pybind/fleet_py.cc

@@ -209,6 +209,8 @@ void BindGraphPyClient(py::module* m) {
       .def("start_client", &GraphPyClient::start_client)
       .def("batch_sample_neighboors", &GraphPyClient::batch_sample_neighbors)
       .def("batch_sample_neighbors", &GraphPyClient::batch_sample_neighbors)
+      .def("use_neighbors_sample_cache",
+           &GraphPyClient::use_neighbors_sample_cache)
       .def("remove_graph_node", &GraphPyClient::remove_graph_node)
       .def("random_sample_nodes", &GraphPyClient::random_sample_nodes)
       .def("stop_server", &GraphPyClient::stop_server)