[graphbolt] Add const for const reference. (#5744)

Co-authored-by: Ubuntu <ubuntu@ip-172-31-28-63.ap-northeast-1.compute.internal>

graphbolt/include/graphbolt/csc_sampling_graph.h

@@ -46,7 +46,7 @@ class CSCSamplingGraph : public torch::CustomClassHolder {
    * present.
    */
   CSCSamplingGraph(
-      torch::Tensor& indptr, torch::Tensor& indices,
+      const torch::Tensor& indptr, const torch::Tensor& indices,
       const torch::optional<torch::Tensor>& node_type_offset,
       const torch::optional<torch::Tensor>& type_per_edge);
 
@@ -62,7 +62,7 @@ class CSCSamplingGraph : public torch::CustomClassHolder {
    * @return CSCSamplingGraph
    */
   static c10::intrusive_ptr<CSCSamplingGraph> FromCSC(
-      torch::Tensor indptr, torch::Tensor indices,
+      const torch::Tensor indptr, const torch::Tensor indices,
       const torch::optional<torch::Tensor>& node_type_offset,
       const torch::optional<torch::Tensor>& type_per_edge);
 

graphbolt/src/csc_sampling_graph.cc

@@ -11,7 +11,7 @@ namespace graphbolt {
 namespace sampling {
 
 CSCSamplingGraph::CSCSamplingGraph(
-    torch::Tensor& indptr, torch::Tensor& indices,
+    const torch::Tensor& indptr, const torch::Tensor& indices,
     const torch::optional<torch::Tensor>& node_type_offset,
     const torch::optional<torch::Tensor>& type_per_edge)
     : indptr_(indptr),
@@ -24,7 +24,7 @@ CSCSamplingGraph::CSCSamplingGraph(
 }
 
 c10::intrusive_ptr<CSCSamplingGraph> CSCSamplingGraph::FromCSC(
-    torch::Tensor indptr, torch::Tensor indices,
+    const torch::Tensor indptr, const torch::Tensor indices,
     const torch::optional<torch::Tensor>& node_type_offset,
     const torch::optional<torch::Tensor>& type_per_edge) {
   if (node_type_offset.has_value()) {