check valid nn_descent graph-degree / rename build_paramas to graph_b…

…uild_params

cpp/include/cuvs/neighbors/cagra.hpp

@@ -69,7 +69,7 @@ struct index_params : cuvs::neighbors::index_params {
 
   // struct graph_build_params build_params = ivf_pq::graph_build_params{};
   std::variant<graph_build_params::ivf_pq_params, graph_build_params::nn_descent_params>
-    build_params = graph_build_params::ivf_pq_params{};
+    graph_build_params = graph_build_params::ivf_pq_params{};
 };
 
 /**

cpp/src/neighbors/cagra_c.cpp

@@ -44,15 +44,15 @@ void* _build(cuvsResources_t res, cuvsCagraIndexParams params, DLManagedTensor*
 
   switch (params.build_algo) {
     case cuvsCagraGraphBuildAlgo::IVF_PQ:
-      index_params.build_params = cuvs::neighbors::cagra::graph_build_params::ivf_pq_params{};
+      index_params.graph_build_params = cuvs::neighbors::cagra::graph_build_params::ivf_pq_params{};
       break;
     case cuvsCagraGraphBuildAlgo::NN_DESCENT:
       cuvs::neighbors::cagra::graph_build_params::nn_descent_params nn_descent_params{};
       nn_descent_params                           = cuvs::neighbors::nn_descent::index_params{};
       nn_descent_params.max_iterations            = params.nn_descent_niter;
       nn_descent_params.graph_degree              = index_params.intermediate_graph_degree;
       nn_descent_params.intermediate_graph_degree = 1.5 * index_params.intermediate_graph_degree;
-      index_params.build_params                   = nn_descent_params;
+      index_params.graph_build_params             = nn_descent_params;
       break;
   };
 

cpp/src/neighbors/detail/cagra/cagra_build.cuh

@@ -421,9 +421,9 @@ index<T, IdxT> build(
 
   // dispatch graph_build_params
   if (std::holds_alternative<cuvs::neighbors::cagra::graph_build_params::ivf_pq_params>(
-        params.build_params)) {
-    auto ivf_pq_params =
-      std::get<cuvs::neighbors::cagra::graph_build_params::ivf_pq_params>(params.build_params);
+        params.graph_build_params)) {
+    auto ivf_pq_params = std::get<cuvs::neighbors::cagra::graph_build_params::ivf_pq_params>(
+      params.graph_build_params);
     build_knn_graph(res,
                     dataset,
                     knn_graph->view(),
@@ -435,7 +435,20 @@ index<T, IdxT> build(
       params.metric == cuvs::distance::DistanceType::L2Expanded,
       "L2Expanded is the only distance metrics supported for CAGRA build with nn_descent");
     auto nn_descent_params =
-      std::get<cuvs::neighbors::cagra::graph_build_params::nn_descent_params>(params.build_params);
+      std::get<cuvs::neighbors::cagra::graph_build_params::nn_descent_params>(
+        params.graph_build_params);
+
+    if (nn_descent_params.graph_degree != intermediate_degree) {
+      RAFT_LOG_WARN(
+        "Graph degree (%lu) for nn-descent needs to match cagra intermediate graph degree (%lu), "
+        "aligning "
+        "nn-descent graph_degree.",
+        nn_descent_params.graph_degree,
+        intermediate_degree);
+      nn_descent_params.graph_degree              = intermediate_degree;
+      nn_descent_params.intermediate_graph_degree = 1.5 * intermediate_degree;
+    }
+
     // Use nn-descent to build CAGRA knn graph
     build_knn_graph<T, IdxT>(res, dataset, knn_graph->view(), nn_descent_params);
   }

cpp/test/neighbors/ann_cagra.cuh

@@ -240,18 +240,18 @@ class AnnCagraTest : public ::testing::TestWithParam<AnnCagraInputs> {
                                           // not used for knn_graph building.
         switch (ps.build_algo) {
           case graph_build_algo::IVF_PQ:
-            index_params.build_params = graph_build_params::ivf_pq_params{};
+            index_params.graph_build_params = graph_build_params::ivf_pq_params{};
             if (ps.ivf_pq_search_refine_ratio) {
               std::get<cuvs::neighbors::cagra::graph_build_params::ivf_pq_params>(
-                index_params.build_params)
+                index_params.graph_build_params)
                 .refinement_rate = *ps.ivf_pq_search_refine_ratio;
             }
             break;
           case graph_build_algo::NN_DESCENT:
             graph_build_params::nn_descent_params build_params{};
             build_params.graph_degree              = index_params.intermediate_graph_degree;
             build_params.intermediate_graph_degree = 1.5 * index_params.intermediate_graph_degree;
-            index_params.build_params              = build_params;
+            index_params.graph_build_params        = build_params;
             break;
         };