heterograph_capi.cc

/*!
 *  Copyright (c) 2020 by Contributors
 * \file graph/heterograph_capi.cc
 * \brief Heterograph CAPI bindings.
 */
#include <dgl/array.h>
#include <dgl/aten/coo.h>
#include <dgl/immutable_graph.h>
#include <dgl/packed_func_ext.h>
#include <dgl/runtime/c_runtime_api.h>
#include <dgl/runtime/container.h>
#include <dgl/runtime/parallel_for.h>

#include <set>

#include "../c_api_common.h"
#include "./heterograph.h"
#include "unit_graph.h"

using namespace dgl::runtime;

namespace dgl {

///////////////////////// Unitgraph functions /////////////////////////

// XXX(minjie): Ideally, Unitgraph should be invisible to python side

DGL_REGISTER_GLOBAL("heterograph_index._CAPI_DGLHeteroCreateUnitGraphFromCOO")
    .set_body([](DGLArgs args, DGLRetValue* rv) {
      int64_t nvtypes = args[0];
      int64_t num_src = args[1];
      int64_t num_dst = args[2];
      IdArray row = args[3];
      IdArray col = args[4];
      List<Value> formats = args[5];
      bool row_sorted = args[6];
      bool col_sorted = args[7];
      std::vector<SparseFormat> formats_vec;
      for (Value val : formats) {
        std::string fmt = val->data;
        formats_vec.push_back(ParseSparseFormat(fmt));
      }
      const auto code = SparseFormatsToCode(formats_vec);
      auto hgptr = CreateFromCOO(
          nvtypes, num_src, num_dst, row, col, row_sorted, col_sorted, code);
      *rv = HeteroGraphRef(hgptr);
    });

DGL_REGISTER_GLOBAL("heterograph_index._CAPI_DGLHeteroCreateUnitGraphFromCSR")
    .set_body([](DGLArgs args, DGLRetValue* rv) {
      int64_t nvtypes = args[0];
      int64_t num_src = args[1];
      int64_t num_dst = args[2];
      IdArray indptr = args[3];
      IdArray indices = args[4];
      IdArray edge_ids = args[5];
      List<Value> formats = args[6];
      bool transpose = args[7];
      std::vector<SparseFormat> formats_vec;
      for (Value val : formats) {
        std::string fmt = val->data;
        formats_vec.push_back(ParseSparseFormat(fmt));
      }
      const auto code = SparseFormatsToCode(formats_vec);
      if (!transpose) {
        auto hgptr = CreateFromCSR(
            nvtypes, num_src, num_dst, indptr, indices, edge_ids, code);
        *rv = HeteroGraphRef(hgptr);
      } else {
        auto hgptr = CreateFromCSC(
            nvtypes, num_src, num_dst, indptr, indices, edge_ids, code);
        *rv = HeteroGraphRef(hgptr);
      }
    });

DGL_REGISTER_GLOBAL("heterograph_index._CAPI_DGLHeteroCreateHeteroGraph")
    .set_body([](DGLArgs args, DGLRetValue* rv) {
      GraphRef meta_graph = args[0];
      List<HeteroGraphRef> rel_graphs = args[1];
      std::vector<HeteroGraphPtr> rel_ptrs;
      rel_ptrs.reserve(rel_graphs.size());
      for (const auto& ref : rel_graphs) {
        rel_ptrs.push_back(ref.sptr());
      }
      auto hgptr = CreateHeteroGraph(meta_graph.sptr(), rel_ptrs);
      *rv = HeteroGraphRef(hgptr);
    });

DGL_REGISTER_GLOBAL(
    "heterograph_index._CAPI_DGLHeteroCreateHeteroGraphWithNumNodes")
    .set_body([](DGLArgs args, DGLRetValue* rv) {
      GraphRef meta_graph = args[0];
      List<HeteroGraphRef> rel_graphs = args[1];
      IdArray num_nodes_per_type = args[2];
      std::vector<HeteroGraphPtr> rel_ptrs;
      rel_ptrs.reserve(rel_graphs.size());
      for (const auto& ref : rel_graphs) {
        rel_ptrs.push_back(ref.sptr());
      }
      auto hgptr = CreateHeteroGraph(
          meta_graph.sptr(), rel_ptrs, num_nodes_per_type.ToVector<int64_t>());
      *rv = HeteroGraphRef(hgptr);
    });

///////////////////////// HeteroGraph member functions /////////////////////////

DGL_REGISTER_GLOBAL("heterograph_index._CAPI_DGLHeteroGetMetaGraph")
    .set_body([](DGLArgs args, DGLRetValue* rv) {
      HeteroGraphRef hg = args[0];
      *rv = hg->meta_graph();
    });

DGL_REGISTER_GLOBAL("heterograph_index._CAPI_DGLHeteroIsMetaGraphUniBipartite")
    .set_body([](DGLArgs args, DGLRetValue* rv) {
      HeteroGraphRef hg = args[0];
      GraphPtr mg = hg->meta_graph();
      *rv = mg->IsUniBipartite();
    });

DGL_REGISTER_GLOBAL("heterograph_index._CAPI_DGLHeteroGetRelationGraph")
    .set_body([](DGLArgs args, DGLRetValue* rv) {
      HeteroGraphRef hg = args[0];
      dgl_type_t etype = args[1];
      CHECK_LE(etype, hg->NumEdgeTypes()) << "invalid edge type " << etype;
      auto unit_graph = hg->GetRelationGraph(etype);
      auto meta_graph = unit_graph->meta_graph();
      auto hgptr = CreateHeteroGraph(
          meta_graph, {unit_graph}, unit_graph->NumVerticesPerType());
      *rv = HeteroGraphRef(hgptr);
    });

DGL_REGISTER_GLOBAL("heterograph_index._CAPI_DGLHeteroGetFlattenedGraph")
    .set_body([](DGLArgs args, DGLRetValue* rv) {
      HeteroGraphRef hg = args[0];
      List<Value> etypes = args[1];
      std::vector<dgl_id_t> etypes_vec;
      for (Value val : etypes) {
        // (gq) have to decompose it into two statements because of a weird MSVC
        // internal error
        dgl_id_t id = val->data;
        etypes_vec.push_back(id);
      }

      *rv = FlattenedHeteroGraphRef(hg->Flatten(etypes_vec));
    });

DGL_REGISTER_GLOBAL("heterograph_index._CAPI_DGLHeteroAddVertices")
    .set_body([](DGLArgs args, DGLRetValue* rv) {
      HeteroGraphRef hg = args[0];
      dgl_type_t vtype = args[1];
      int64_t num = args[2];
      hg->AddVertices(vtype, num);
    });

DGL_REGISTER_GLOBAL("heterograph_index._CAPI_DGLHeteroAddEdge")
    .set_body([](DGLArgs args, DGLRetValue* rv) {
      HeteroGraphRef hg = args[0];
      dgl_type_t etype = args[1];
      dgl_id_t src = args[2];
      dgl_id_t dst = args[3];
      hg->AddEdge(etype, src, dst);
    });

DGL_REGISTER_GLOBAL("heterograph_index._CAPI_DGLHeteroAddEdges")
    .set_body([](DGLArgs args, DGLRetValue* rv) {
      HeteroGraphRef hg = args[0];
      dgl_type_t etype = args[1];
      IdArray src = args[2];
      IdArray dst = args[3];
      hg->AddEdges(etype, src, dst);
    });

DGL_REGISTER_GLOBAL("heterograph_index._CAPI_DGLHeteroClear")
    .set_body([](DGLArgs args, DGLRetValue* rv) {
      HeteroGraphRef hg = args[0];
      hg->Clear();
    });

DGL_REGISTER_GLOBAL("heterograph_index._CAPI_DGLHeteroDataType")
    .set_body([](DGLArgs args, DGLRetValue* rv) {
      HeteroGraphRef hg = args[0];
      *rv = hg->DataType();
    });

DGL_REGISTER_GLOBAL("heterograph_index._CAPI_DGLHeteroContext")
    .set_body([](DGLArgs args, DGLRetValue* rv) {
      HeteroGraphRef hg = args[0];
      *rv = hg->Context();
    });

DGL_REGISTER_GLOBAL("heterograph_index._CAPI_DGLHeteroIsPinned")
    .set_body([](DGLArgs args, DGLRetValue* rv) {
      HeteroGraphRef hg = args[0];
      *rv = hg->IsPinned();
    });

DGL_REGISTER_GLOBAL("heterograph_index._CAPI_DGLHeteroNumBits")
    .set_body([](DGLArgs args, DGLRetValue* rv) {
      HeteroGraphRef hg = args[0];
      *rv = hg->NumBits();
    });

DGL_REGISTER_GLOBAL("heterograph_index._CAPI_DGLHeteroIsMultigraph")
    .set_body([](DGLArgs args, DGLRetValue* rv) {
      HeteroGraphRef hg = args[0];
      *rv = hg->IsMultigraph();
    });

DGL_REGISTER_GLOBAL("heterograph_index._CAPI_DGLHeteroIsReadonly")
    .set_body([](DGLArgs args, DGLRetValue* rv) {
      HeteroGraphRef hg = args[0];
      *rv = hg->IsReadonly();
    });

DGL_REGISTER_GLOBAL("heterograph_index._CAPI_DGLHeteroNumVertices")
    .set_body([](DGLArgs args, DGLRetValue* rv) {
      HeteroGraphRef hg = args[0];
      dgl_type_t vtype = args[1];
      *rv = static_cast<int64_t>(hg->NumVertices(vtype));
    });

DGL_REGISTER_GLOBAL("heterograph_index._CAPI_DGLHeteroNumEdges")
    .set_body([](DGLArgs args, DGLRetValue* rv) {
      HeteroGraphRef hg = args[0];
      dgl_type_t etype = args[1];
      *rv = static_cast<int64_t>(hg->NumEdges(etype));
    });

DGL_REGISTER_GLOBAL("heterograph_index._CAPI_DGLHeteroHasVertex")
    .set_body([](DGLArgs args, DGLRetValue* rv) {
      HeteroGraphRef hg = args[0];
      dgl_type_t vtype = args[1];
      dgl_id_t vid = args[2];
      *rv = hg->HasVertex(vtype, vid);
    });

DGL_REGISTER_GLOBAL("heterograph_index._CAPI_DGLHeteroHasVertices")
    .set_body([](DGLArgs args, DGLRetValue* rv) {
      HeteroGraphRef hg = args[0];
      dgl_type_t vtype = args[1];
      IdArray vids = args[2];
      *rv = hg->HasVertices(vtype, vids);
    });

DGL_REGISTER_GLOBAL("heterograph_index._CAPI_DGLHeteroHasEdgeBetween")
    .set_body([](DGLArgs args, DGLRetValue* rv) {
      HeteroGraphRef hg = args[0];
      dgl_type_t etype = args[1];
      dgl_id_t src = args[2];
      dgl_id_t dst = args[3];
      *rv = hg->HasEdgeBetween(etype, src, dst);
    });

DGL_REGISTER_GLOBAL("heterograph_index._CAPI_DGLHeteroHasEdgesBetween")
    .set_body([](DGLArgs args, DGLRetValue* rv) {
      HeteroGraphRef hg = args[0];
      dgl_type_t etype = args[1];
      IdArray src = args[2];
      IdArray dst = args[3];
      *rv = hg->HasEdgesBetween(etype, src, dst);
    });

DGL_REGISTER_GLOBAL("heterograph_index._CAPI_DGLHeteroPredecessors")
    .set_body([](DGLArgs args, DGLRetValue* rv) {
      HeteroGraphRef hg = args[0];
      dgl_type_t etype = args[1];
      dgl_id_t dst = args[2];
      *rv = hg->Predecessors(etype, dst);
    });

DGL_REGISTER_GLOBAL("heterograph_index._CAPI_DGLHeteroSuccessors")
    .set_body([](DGLArgs args, DGLRetValue* rv) {
      HeteroGraphRef hg = args[0];
      dgl_type_t etype = args[1];
      dgl_id_t src = args[2];
      *rv = hg->Successors(etype, src);
    });

DGL_REGISTER_GLOBAL("heterograph_index._CAPI_DGLHeteroEdgeId")
    .set_body([](DGLArgs args, DGLRetValue* rv) {
      HeteroGraphRef hg = args[0];
      dgl_type_t etype = args[1];
      dgl_id_t src = args[2];
      dgl_id_t dst = args[3];
      *rv = hg->EdgeId(etype, src, dst);
    });

DGL_REGISTER_GLOBAL("heterograph_index._CAPI_DGLHeteroEdgeIdsAll")
    .set_body([](DGLArgs args, DGLRetValue* rv) {
      HeteroGraphRef hg = args[0];
      dgl_type_t etype = args[1];
      IdArray src = args[2];
      IdArray dst = args[3];
      const auto& ret = hg->EdgeIdsAll(etype, src, dst);
      *rv = ConvertEdgeArrayToPackedFunc(ret);
    });

DGL_REGISTER_GLOBAL("heterograph_index._CAPI_DGLHeteroEdgeIdsOne")
    .set_body([](DGLArgs args, DGLRetValue* rv) {
      HeteroGraphRef hg = args[0];
      dgl_type_t etype = args[1];
      IdArray src = args[2];
      IdArray dst = args[3];
      *rv = hg->EdgeIdsOne(etype, src, dst);
    });

DGL_REGISTER_GLOBAL("heterograph_index._CAPI_DGLHeteroFindEdges")
    .set_body([](DGLArgs args, DGLRetValue* rv) {
      HeteroGraphRef hg = args[0];
      dgl_type_t etype = args[1];
      IdArray eids = args[2];
      const auto& ret = hg->FindEdges(etype, eids);
      *rv = ConvertEdgeArrayToPackedFunc(ret);
    });

DGL_REGISTER_GLOBAL("heterograph_index._CAPI_DGLHeteroInEdges_1")
    .set_body([](DGLArgs args, DGLRetValue* rv) {
      HeteroGraphRef hg = args[0];
      dgl_type_t etype = args[1];
      dgl_id_t vid = args[2];
      const auto& ret = hg->InEdges(etype, vid);
      *rv = ConvertEdgeArrayToPackedFunc(ret);
    });

DGL_REGISTER_GLOBAL("heterograph_index._CAPI_DGLHeteroInEdges_2")
    .set_body([](DGLArgs args, DGLRetValue* rv) {
      HeteroGraphRef hg = args[0];
      dgl_type_t etype = args[1];
      IdArray vids = args[2];
      const auto& ret = hg->InEdges(etype, vids);
      *rv = ConvertEdgeArrayToPackedFunc(ret);
    });

DGL_REGISTER_GLOBAL("heterograph_index._CAPI_DGLHeteroOutEdges_1")
    .set_body([](DGLArgs args, DGLRetValue* rv) {
      HeteroGraphRef hg = args[0];
      dgl_type_t etype = args[1];
      dgl_id_t vid = args[2];
      const auto& ret = hg->OutEdges(etype, vid);
      *rv = ConvertEdgeArrayToPackedFunc(ret);
    });

DGL_REGISTER_GLOBAL("heterograph_index._CAPI_DGLHeteroOutEdges_2")
    .set_body([](DGLArgs args, DGLRetValue* rv) {
      HeteroGraphRef hg = args[0];
      dgl_type_t etype = args[1];
      IdArray vids = args[2];
      const auto& ret = hg->OutEdges(etype, vids);
      *rv = ConvertEdgeArrayToPackedFunc(ret);
    });

DGL_REGISTER_GLOBAL("heterograph_index._CAPI_DGLHeteroEdges")
    .set_body([](DGLArgs args, DGLRetValue* rv) {
      HeteroGraphRef hg = args[0];
      dgl_type_t etype = args[1];
      std::string order = args[2];
      const auto& ret = hg->Edges(etype, order);
      *rv = ConvertEdgeArrayToPackedFunc(ret);
    });

DGL_REGISTER_GLOBAL("heterograph_index._CAPI_DGLHeteroInDegree")
    .set_body([](DGLArgs args, DGLRetValue* rv) {
      HeteroGraphRef hg = args[0];
      dgl_type_t etype = args[1];
      dgl_id_t vid = args[2];
      *rv = static_cast<int64_t>(hg->InDegree(etype, vid));
    });

DGL_REGISTER_GLOBAL("heterograph_index._CAPI_DGLHeteroInDegrees")
    .set_body([](DGLArgs args, DGLRetValue* rv) {
      HeteroGraphRef hg = args[0];
      dgl_type_t etype = args[1];
      IdArray vids = args[2];
      *rv = hg->InDegrees(etype, vids);
    });

DGL_REGISTER_GLOBAL("heterograph_index._CAPI_DGLHeteroOutDegree")
    .set_body([](DGLArgs args, DGLRetValue* rv) {
      HeteroGraphRef hg = args[0];
      dgl_type_t etype = args[1];
      dgl_id_t vid = args[2];
      *rv = static_cast<int64_t>(hg->OutDegree(etype, vid));
    });

DGL_REGISTER_GLOBAL("heterograph_index._CAPI_DGLHeteroOutDegrees")
    .set_body([](DGLArgs args, DGLRetValue* rv) {
      HeteroGraphRef hg = args[0];
      dgl_type_t etype = args[1];
      IdArray vids = args[2];
      *rv = hg->OutDegrees(etype, vids);
    });

DGL_REGISTER_GLOBAL("heterograph_index._CAPI_DGLHeteroGetAdj")
    .set_body([](DGLArgs args, DGLRetValue* rv) {
      HeteroGraphRef hg = args[0];
      dgl_type_t etype = args[1];
      bool transpose = args[2];
      std::string fmt = args[3];
      *rv = ConvertNDArrayVectorToPackedFunc(hg->GetAdj(etype, transpose, fmt));
    });

DGL_REGISTER_GLOBAL("heterograph_index._CAPI_DGLHeteroVertexSubgraph")
    .set_body([](DGLArgs args, DGLRetValue* rv) {
      HeteroGraphRef hg = args[0];
      List<Value> vids = args[1];
      bool relabel_nodes = args[2];
      CHECK(relabel_nodes) << "Node subgraph only supports relabel_nodes=True.";
      std::vector<IdArray> vid_vec;
      vid_vec.reserve(vids.size());
      for (Value val : vids) {
        vid_vec.push_back(val->data);
      }
      std::shared_ptr<HeteroSubgraph> subg(
          new HeteroSubgraph(hg->VertexSubgraph(vid_vec)));
      *rv = HeteroSubgraphRef(subg);
    });

DGL_REGISTER_GLOBAL("heterograph_index._CAPI_DGLHeteroEdgeSubgraph")
    .set_body([](DGLArgs args, DGLRetValue* rv) {
      HeteroGraphRef hg = args[0];
      List<Value> eids = args[1];
      bool preserve_nodes = args[2];
      std::vector<IdArray> eid_vec;
      eid_vec.reserve(eids.size());
      for (Value val : eids) {
        eid_vec.push_back(val->data);
      }
      std::shared_ptr<HeteroSubgraph> subg(
          new HeteroSubgraph(hg->EdgeSubgraph(eid_vec, preserve_nodes)));
      *rv = HeteroSubgraphRef(subg);
    });

///////////////////////// HeteroSubgraph members /////////////////////////

DGL_REGISTER_GLOBAL("heterograph_index._CAPI_DGLHeteroSubgraphGetGraph")
    .set_body([](DGLArgs args, DGLRetValue* rv) {
      HeteroSubgraphRef subg = args[0];
      *rv = HeteroGraphRef(subg->graph);
    });

DGL_REGISTER_GLOBAL(
    "heterograph_index._CAPI_DGLHeteroSubgraphGetInducedVertices")
    .set_body([](DGLArgs args, DGLRetValue* rv) {
      HeteroSubgraphRef subg = args[0];
      List<Value> induced_verts;
      for (IdArray arr : subg->induced_vertices) {
        induced_verts.push_back(Value(MakeValue(arr)));
      }
      *rv = induced_verts;
    });

DGL_REGISTER_GLOBAL("heterograph_index._CAPI_DGLHeteroSubgraphGetInducedEdges")
    .set_body([](DGLArgs args, DGLRetValue* rv) {
      HeteroSubgraphRef subg = args[0];
      List<Value> induced_edges;
      for (IdArray arr : subg->induced_edges) {
        induced_edges.push_back(Value(MakeValue(arr)));
      }
      *rv = induced_edges;
    });

///////////////////////// Global functions and algorithms
////////////////////////////

DGL_REGISTER_GLOBAL("heterograph_index._CAPI_DGLHeteroAsNumBits")
    .set_body([](DGLArgs args, DGLRetValue* rv) {
      HeteroGraphRef hg = args[0];
      int bits = args[1];
      HeteroGraphPtr bhg_ptr = hg.sptr();
      auto hg_ptr = std::dynamic_pointer_cast<HeteroGraph>(bhg_ptr);
      HeteroGraphPtr hg_new;
      if (hg_ptr) {
        hg_new = HeteroGraph::AsNumBits(hg_ptr, bits);
      } else {
        hg_new = UnitGraph::AsNumBits(bhg_ptr, bits);
      }
      *rv = HeteroGraphRef(hg_new);
    });

DGL_REGISTER_GLOBAL("heterograph_index._CAPI_DGLHeteroCopyTo")
    .set_body([](DGLArgs args, DGLRetValue* rv) {
      HeteroGraphRef hg = args[0];
      int device_type = args[1];
      int device_id = args[2];
      DGLContext ctx;
      ctx.device_type = static_cast<DGLDeviceType>(device_type);
      ctx.device_id = device_id;
      HeteroGraphPtr hg_new = HeteroGraph::CopyTo(hg.sptr(), ctx);
      *rv = HeteroGraphRef(hg_new);
    });

DGL_REGISTER_GLOBAL("heterograph_index._CAPI_DGLHeteroPinMemory_")
    .set_body([](DGLArgs args, DGLRetValue* rv) {
      HeteroGraphRef hg = args[0];
      auto hgindex = std::dynamic_pointer_cast<HeteroGraph>(hg.sptr());
      hgindex->PinMemory_();
      *rv = hg;
    });

DGL_REGISTER_GLOBAL("heterograph_index._CAPI_DGLHeteroUnpinMemory_")
    .set_body([](DGLArgs args, DGLRetValue* rv) {
      HeteroGraphRef hg = args[0];
      auto hgindex = std::dynamic_pointer_cast<HeteroGraph>(hg.sptr());
      hgindex->UnpinMemory_();
      *rv = hg;
    });

DGL_REGISTER_GLOBAL("heterograph_index._CAPI_DGLHeteroRecordStream")
    .set_body([](DGLArgs args, DGLRetValue* rv) {
      HeteroGraphRef hg = args[0];
      DGLStreamHandle stream = args[1];
      auto hgindex = std::dynamic_pointer_cast<HeteroGraph>(hg.sptr());
      hgindex->RecordStream(stream);
      *rv = hg;
    });

DGL_REGISTER_GLOBAL("heterograph_index._CAPI_DGLHeteroCopyToSharedMem")
    .set_body([](DGLArgs args, DGLRetValue* rv) {
      HeteroGraphRef hg = args[0];
      std::string name = args[1];
      List<Value> ntypes = args[2];
      List<Value> etypes = args[3];
      List<Value> fmts = args[4];
      auto ntypes_vec = ListValueToVector<std::string>(ntypes);
      auto etypes_vec = ListValueToVector<std::string>(etypes);
      std::set<std::string> fmts_set;
      for (const auto& fmt : fmts) {
        std::string fmt_data = fmt->data;
        fmts_set.insert(fmt_data);
      }
      auto hg_share = HeteroGraph::CopyToSharedMem(
          hg.sptr(), name, ntypes_vec, etypes_vec, fmts_set);
      *rv = HeteroGraphRef(hg_share);
    });

DGL_REGISTER_GLOBAL("heterograph_index._CAPI_DGLHeteroCreateFromSharedMem")
    .set_body([](DGLArgs args, DGLRetValue* rv) {
      std::string name = args[0];
      HeteroGraphPtr hg;
      std::vector<std::string> ntypes;
      std::vector<std::string> etypes;
      std::tie(hg, ntypes, etypes) = HeteroGraph::CreateFromSharedMem(name);
      List<Value> ntypes_list;
      List<Value> etypes_list;
      for (const auto& ntype : ntypes)
        ntypes_list.push_back(Value(MakeValue(ntype)));
      for (const auto& etype : etypes)
        etypes_list.push_back(Value(MakeValue(etype)));
      List<ObjectRef> ret;
      ret.push_back(HeteroGraphRef(hg));
      ret.push_back(ntypes_list);
      ret.push_back(etypes_list);
      *rv = ret;
    });

DGL_REGISTER_GLOBAL("heterograph_index._CAPI_DGLHeteroJointUnion")
    .set_body([](DGLArgs args, DGLRetValue* rv) {
      GraphRef meta_graph = args[0];
      List<HeteroGraphRef> component_graphs = args[1];
      CHECK(component_graphs.size() > 1)
          << "Expect graph list to have at least two graphs";
      std::vector<HeteroGraphPtr> component_ptrs;
      component_ptrs.reserve(component_graphs.size());
      const int64_t bits = component_graphs[0]->NumBits();
      const DGLContext ctx = component_graphs[0]->Context();
      for (const auto& component : component_graphs) {
        component_ptrs.push_back(component.sptr());
        CHECK_EQ(component->NumBits(), bits)
            << "Expect graphs to joint union have the same index dtype(int"
            << bits << "), but got int" << component->NumBits();
        CHECK_EQ(component->Context(), ctx)
            << "Expect graphs to joint union have the same context" << ctx
            << "), but got " << component->Context();
      }

      auto hgptr = JointUnionHeteroGraph(meta_graph.sptr(), component_ptrs);
      *rv = HeteroGraphRef(hgptr);
    });

DGL_REGISTER_GLOBAL("heterograph_index._CAPI_DGLHeteroDisjointUnion_v2")
    .set_body([](DGLArgs args, DGLRetValue* rv) {
      GraphRef meta_graph = args[0];
      List<HeteroGraphRef> component_graphs = args[1];
      CHECK(component_graphs.size() > 0)
          << "Expect graph list has at least one graph";
      std::vector<HeteroGraphPtr> component_ptrs;
      component_ptrs.reserve(component_graphs.size());
      const int64_t bits = component_graphs[0]->NumBits();
      const DGLContext ctx = component_graphs[0]->Context();
      for (const auto& component : component_graphs) {
        component_ptrs.push_back(component.sptr());
        CHECK_EQ(component->NumBits(), bits)
            << "Expect graphs to batch have the same index dtype(int" << bits
            << "), but got int" << component->NumBits();
        CHECK_EQ(component->Context(), ctx)
            << "Expect graphs to batch have the same context" << ctx
            << "), but got " << component->Context();
      }

      auto hgptr = DisjointUnionHeteroGraph2(meta_graph.sptr(), component_ptrs);
      *rv = HeteroGraphRef(hgptr);
    });

DGL_REGISTER_GLOBAL(
    "heterograph_index._CAPI_DGLHeteroDisjointPartitionBySizes_v2")
    .set_body([](DGLArgs args, DGLRetValue* rv) {
      HeteroGraphRef hg = args[0];
      const IdArray vertex_sizes = args[1];
      const IdArray edge_sizes = args[2];
      std::vector<HeteroGraphPtr> ret;
      ret = DisjointPartitionHeteroBySizes2(
          hg->meta_graph(), hg.sptr(), vertex_sizes, edge_sizes);
      List<HeteroGraphRef> ret_list;
      for (HeteroGraphPtr hgptr : ret) {
        ret_list.push_back(HeteroGraphRef(hgptr));
      }
      *rv = ret_list;
    });

DGL_REGISTER_GLOBAL("heterograph_index._CAPI_DGLHeteroDisjointPartitionBySizes")
    .set_body([](DGLArgs args, DGLRetValue* rv) {
      HeteroGraphRef hg = args[0];
      const IdArray vertex_sizes = args[1];
      const IdArray edge_sizes = args[2];
      const int64_t bits = hg->NumBits();
      std::vector<HeteroGraphPtr> ret;
      ATEN_ID_BITS_SWITCH(bits, IdType, {
        ret = DisjointPartitionHeteroBySizes<IdType>(
            hg->meta_graph(), hg.sptr(), vertex_sizes, edge_sizes);
      });
      List<HeteroGraphRef> ret_list;
      for (HeteroGraphPtr hgptr : ret) {
        ret_list.push_back(HeteroGraphRef(hgptr));
      }
      *rv = ret_list;
    });

DGL_REGISTER_GLOBAL("heterograph_index._CAPI_DGLHeteroSlice")
    .set_body([](DGLArgs args, DGLRetValue* rv) {
      HeteroGraphRef hg = args[0];
      const IdArray num_nodes_per_type = args[1];
      const IdArray start_nid_per_type = args[2];
      const IdArray num_edges_per_type = args[3];
      const IdArray start_eid_per_type = args[4];
      auto hgptr = SliceHeteroGraph(
          hg->meta_graph(), hg.sptr(), num_nodes_per_type, start_nid_per_type,
          num_edges_per_type, start_eid_per_type);
      *rv = HeteroGraphRef(hgptr);
    });

DGL_REGISTER_GLOBAL("heterograph_index._CAPI_DGLHeteroGetCreatedFormats")
    .set_body([](DGLArgs args, DGLRetValue* rv) {
      HeteroGraphRef hg = args[0];
      List<Value> format_list;
      dgl_format_code_t code = hg->GetRelationGraph(0)->GetCreatedFormats();
      for (auto format : CodeToSparseFormats(code)) {
        format_list.push_back(Value(MakeValue(ToStringSparseFormat(format))));
      }
      *rv = format_list;
    });

DGL_REGISTER_GLOBAL("heterograph_index._CAPI_DGLHeteroGetAllowedFormats")
    .set_body([](DGLArgs args, DGLRetValue* rv) {
      HeteroGraphRef hg = args[0];
      List<Value> format_list;
      dgl_format_code_t code = hg->GetRelationGraph(0)->GetAllowedFormats();
      for (auto format : CodeToSparseFormats(code)) {
        format_list.push_back(Value(MakeValue(ToStringSparseFormat(format))));
      }
      *rv = format_list;
    });

DGL_REGISTER_GLOBAL("heterograph_index._CAPI_DGLHeteroCreateFormat")
    .set_body([](DGLArgs args, DGLRetValue* rv) {
      HeteroGraphRef hg = args[0];
      dgl_format_code_t code = hg->GetRelationGraph(0)->GetAllowedFormats();
      auto get_format_f = [&](size_t etype_b, size_t etype_e) {
        for (auto etype = etype_b; etype < etype_e; ++etype) {
          auto bg =
              std::dynamic_pointer_cast<UnitGraph>(hg->GetRelationGraph(etype));
          for (auto format : CodeToSparseFormats(code)) bg->GetFormat(format);
        }
      };

#if !(defined(DGL_USE_CUDA))
      runtime::parallel_for(0, hg->NumEdgeTypes(), get_format_f);
#else
      get_format_f(0, hg->NumEdgeTypes());
#endif
    });

DGL_REGISTER_GLOBAL("heterograph_index._CAPI_DGLHeteroGetFormatGraph")
    .set_body([](DGLArgs args, DGLRetValue* rv) {
      HeteroGraphRef hg = args[0];
      List<Value> formats = args[1];
      std::vector<SparseFormat> formats_vec;
      for (Value val : formats) {
        std::string fmt = val->data;
        formats_vec.push_back(ParseSparseFormat(fmt));
      }
      auto hgptr = hg->GetGraphInFormat(SparseFormatsToCode(formats_vec));
      *rv = HeteroGraphRef(hgptr);
    });

DGL_REGISTER_GLOBAL("subgraph._CAPI_DGLInSubgraph")
    .set_body([](DGLArgs args, DGLRetValue* rv) {
      HeteroGraphRef hg = args[0];
      const auto& nodes = ListValueToVector<IdArray>(args[1]);
      bool relabel_nodes = args[2];
      std::shared_ptr<HeteroSubgraph> ret(new HeteroSubgraph);
      *ret = InEdgeGraph(hg.sptr(), nodes, relabel_nodes);
      *rv = HeteroGraphRef(ret);
    });

DGL_REGISTER_GLOBAL("subgraph._CAPI_DGLOutSubgraph")
    .set_body([](DGLArgs args, DGLRetValue* rv) {
      HeteroGraphRef hg = args[0];
      const auto& nodes = ListValueToVector<IdArray>(args[1]);
      bool relabel_nodes = args[2];
      std::shared_ptr<HeteroSubgraph> ret(new HeteroSubgraph);
      *ret = OutEdgeGraph(hg.sptr(), nodes, relabel_nodes);
      *rv = HeteroGraphRef(ret);
    });

DGL_REGISTER_GLOBAL("transform._CAPI_DGLAsImmutableGraph")
    .set_body([](DGLArgs args, DGLRetValue* rv) {
      HeteroGraphRef hg = args[0];
      *rv = GraphRef(hg->AsImmutableGraph());
    });

DGL_REGISTER_GLOBAL("transform._CAPI_DGLHeteroSortOutEdges")
    .set_body([](DGLArgs args, DGLRetValue* rv) {
      HeteroGraphRef hg = args[0];
      NDArray tag = args[1];
      int64_t num_tag = args[2];

      CHECK_EQ(hg->Context().device_type, kDGLCPU)
          << "Only support sorting by tag on cpu";
      CHECK(aten::IsValidIdArray(tag));
      CHECK_EQ(tag->ctx.device_type, kDGLCPU)
          << "Only support sorting by tag on cpu";

      const auto csr = hg->GetCSRMatrix(0);

      NDArray tag_pos = aten::NullArray();
      aten::CSRMatrix output;
      std::tie(output, tag_pos) = aten::CSRSortByTag(csr, tag, num_tag);
      HeteroGraphPtr output_hg =
          CreateFromCSR(hg->NumVertexTypes(), output, ALL_CODE);
      List<ObjectRef> ret;
      ret.push_back(HeteroGraphRef(output_hg));
      ret.push_back(Value(MakeValue(tag_pos)));
      *rv = ret;
    });

DGL_REGISTER_GLOBAL("transform._CAPI_DGLHeteroSortInEdges")
    .set_body([](DGLArgs args, DGLRetValue* rv) {
      HeteroGraphRef hg = args[0];
      NDArray tag = args[1];
      int64_t num_tag = args[2];

      CHECK_EQ(hg->Context().device_type, kDGLCPU)
          << "Only support sorting by tag on cpu";
      CHECK(aten::IsValidIdArray(tag));
      CHECK_EQ(tag->ctx.device_type, kDGLCPU)
          << "Only support sorting by tag on cpu";

      const auto csc = hg->GetCSCMatrix(0);

      NDArray tag_pos = aten::NullArray();
      aten::CSRMatrix output;
      std::tie(output, tag_pos) = aten::CSRSortByTag(csc, tag, num_tag);

      HeteroGraphPtr output_hg =
          CreateFromCSC(hg->NumVertexTypes(), output, ALL_CODE);
      List<ObjectRef> ret;
      ret.push_back(HeteroGraphRef(output_hg));
      ret.push_back(Value(MakeValue(tag_pos)));
      *rv = ret;
    });

DGL_REGISTER_GLOBAL("heterograph._CAPI_DGLFindSrcDstNtypes")
    .set_body([](DGLArgs args, DGLRetValue* rv) {
      GraphRef metagraph = args[0];
      std::unordered_set<uint64_t> dst_set;
      std::unordered_set<uint64_t> src_set;

      for (uint64_t eid = 0; eid < metagraph->NumEdges(); ++eid) {
        auto edge = metagraph->FindEdge(eid);
        auto src = edge.first;
        auto dst = edge.second;
        dst_set.insert(dst);
        src_set.insert(src);
      }

      List<Value> srclist, dstlist;
      List<List<Value>> ret_list;
      for (uint64_t nid = 0; nid < metagraph->NumVertices(); ++nid) {
        auto is_dst = dst_set.count(nid);
        auto is_src = src_set.count(nid);
        if (is_dst && is_src)
          return;
        else if (is_dst)
          dstlist.push_back(Value(MakeValue(static_cast<int64_t>(nid))));
        else
          // If a node type is isolated, put it in srctype as defined in the
          // Python docstring.
          srclist.push_back(Value(MakeValue(static_cast<int64_t>(nid))));
      }
      ret_list.push_back(srclist);
      ret_list.push_back(dstlist);
      *rv = ret_list;
    });

DGL_REGISTER_GLOBAL("heterograph_index._CAPI_DGLHeteroReverse")
    .set_body([](DGLArgs args, DGLRetValue* rv) {
      HeteroGraphRef hg = args[0];
      CHECK_GT(hg->NumEdgeTypes(), 0);
      auto g = std::dynamic_pointer_cast<HeteroGraph>(hg.sptr());
      std::vector<HeteroGraphPtr> rev_ugs;
      const auto& ugs = g->relation_graphs();
      rev_ugs.resize(ugs.size());

      for (size_t i = 0; i < ugs.size(); ++i) {
        const auto& rev_ug = ugs[i]->Reverse();
        rev_ugs[i] = rev_ug;
      }
      // node types are not changed
      const auto& num_nodes = g->NumVerticesPerType();
      const auto& meta_edges = hg->meta_graph()->Edges("eid");
      // reverse the metagraph
      const auto& rev_meta = ImmutableGraph::CreateFromCOO(
          hg->meta_graph()->NumVertices(), meta_edges.dst, meta_edges.src);
      *rv = CreateHeteroGraph(rev_meta, rev_ugs, num_nodes);
    });
}  // namespace dgl