[FEA] Enable HDBSCAN to build knn graph using NN Descent

cpp/include/cuml/cluster/hdbscan.hpp

@@ -18,6 +18,7 @@
 
 #include <raft/core/handle.hpp>
 #include <raft/distance/distance_types.hpp>
+#include <raft/neighbors/nn_descent_types.hpp>
 
 #include <rmm/device_uvector.hpp>
 
@@ -27,6 +28,8 @@ namespace ML {
 namespace HDBSCAN {
 namespace Common {
 
+using nn_index_params = raft::neighbors::experimental::nn_descent::index_params;
+
 /**
  * The Condensed hierarchicy is represented by an edge list with
  * parents as the source vertices, children as the destination,
@@ -134,6 +137,7 @@ class CondensedHierarchy {
 };
 
 enum CLUSTER_SELECTION_METHOD { EOM = 0, LEAF = 1 };
+enum GRAPH_BUILD_ALGO { BRUTE_FORCE_KNN = 0, NN_DESCENT = 1 };
 
 class RobustSingleLinkageParams {
  public:
@@ -151,6 +155,8 @@ class RobustSingleLinkageParams {
 class HDBSCANParams : public RobustSingleLinkageParams {
  public:
   CLUSTER_SELECTION_METHOD cluster_selection_method = CLUSTER_SELECTION_METHOD::EOM;
+  GRAPH_BUILD_ALGO build_algo                       = GRAPH_BUILD_ALGO::BRUTE_FORCE_KNN;
+  nn_index_params nn_descent_params                 = {};
 };
 
 /**
@@ -495,14 +501,19 @@ namespace HDBSCAN::HELPER {
  * @param n number of columns in X
  * @param metric distance metric to use
  * @param min_samples minimum number of samples to use for computing core distances
+ * @param build_algo build algo for building the knn graph (default: brute_force_knn)
+ * @param build_params build parameters for build_algo
  */
-void compute_core_dists(const raft::handle_t& handle,
-                        const float* X,
-                        float* core_dists,
-                        size_t m,
-                        size_t n,
-                        raft::distance::DistanceType metric,
-                        int min_samples);
+void compute_core_dists(
+  const raft::handle_t& handle,
+  const float* X,
+  float* core_dists,
+  size_t m,
+  size_t n,
+  raft::distance::DistanceType metric,
+  int min_samples,
+  HDBSCAN::Common::GRAPH_BUILD_ALGO build_algo = HDBSCAN::Common::GRAPH_BUILD_ALGO::BRUTE_FORCE_KNN,
+  HDBSCAN::Common::nn_index_params build_params = Common::nn_index_params{});
 
 /**
  * @brief Compute the map from final, normalize labels to the labels in the CondensedHierarchy