From 0e498a85c32ec275875a973b2b6d579c7bc302b8 Mon Sep 17 00:00:00 2001
From: Tarang Jain <tarangj@nvidia.com>
Date: Tue, 23 Apr 2024 16:41:26 -0700
Subject: [PATCH] change helper to constructor

---
 cpp/include/raft/neighbors/cagra.cuh                    | 3 +--
 cpp/include/raft/neighbors/detail/cagra/cagra_build.cuh | 5 +----
 cpp/include/raft/neighbors/ivf_pq_types.hpp             | 8 +++-----
 cpp/test/neighbors/ann_cagra.cuh                        | 3 +--
 4 files changed, 6 insertions(+), 13 deletions(-)

diff --git a/cpp/include/raft/neighbors/cagra.cuh b/cpp/include/raft/neighbors/cagra.cuh
index 8fbd8e6ee6..7c1a1f6582 100644
--- a/cpp/include/raft/neighbors/cagra.cuh
+++ b/cpp/include/raft/neighbors/cagra.cuh
@@ -55,8 +55,7 @@ namespace raft::neighbors::cagra {
  * @code{.cpp}
  *   using namespace raft::neighbors;
  *   // use default index parameters
- *   ivf_pq::index_params build_params;
- *   build_params.initialize_from_dataset(dataset);
+ *   ivf_pq::index_params build_params(dataset);
  *   ivf_pq::search_params search_params;
  *   auto knn_graph      = raft::make_host_matrix<IdxT, IdxT>(dataset.extent(0), 128);
  *   // create knn graph
diff --git a/cpp/include/raft/neighbors/detail/cagra/cagra_build.cuh b/cpp/include/raft/neighbors/detail/cagra/cagra_build.cuh
index fad720a03b..fcecd4fa3c 100644
--- a/cpp/include/raft/neighbors/detail/cagra/cagra_build.cuh
+++ b/cpp/include/raft/neighbors/detail/cagra/cagra_build.cuh
@@ -59,10 +59,7 @@ void build_knn_graph(raft::resources const& res,
                                                             size_t(dataset.extent(1)),
                                                             node_degree);
 
-  if (!build_params) {
-    build_params = ivf_pq::index_params{};
-    build_params.value().initialize_from_dataset(dataset);
-  }
+  if (!build_params) { build_params = ivf_pq::index_params(dataset); }
 
   // Make model name
   const std::string model_name = [&]() {
diff --git a/cpp/include/raft/neighbors/ivf_pq_types.hpp b/cpp/include/raft/neighbors/ivf_pq_types.hpp
index 5a3e6caa24..4effc373f2 100644
--- a/cpp/include/raft/neighbors/ivf_pq_types.hpp
+++ b/cpp/include/raft/neighbors/ivf_pq_types.hpp
@@ -106,12 +106,11 @@ struct index_params : ann::index_params {
   bool conservative_memory_allocation = false;
 
   /**
-   * Helper that sets values according to the extents of the dataset mdspan.
+   * Constructor that sets values according to the extents of the dataset mdspan.
    */
   template <typename DataT, typename Accessor>
-  void initialize_from_dataset(
-    mdspan<const DataT, matrix_extent<int64_t>, row_major, Accessor> dataset,
-    raft::distance::DistanceType metric = raft::distance::L2Expanded)
+  explicit index_params(mdspan<const DataT, matrix_extent<int64_t>, row_major, Accessor> dataset,
+                        raft::distance::DistanceType metric = raft::distance::L2Expanded)
   {
     n_lists =
       dataset.extent(0) < 4 * 2500 ? 4 : static_cast<uint32_t>(std::sqrt(dataset.extent(0)));
@@ -161,7 +160,6 @@ struct search_params : ann::search_params {
   double preferred_shmem_carveout = 1.0;
 };
 
-static_assert(std::is_aggregate_v<index_params>);
 static_assert(std::is_aggregate_v<search_params>);
 
 /** Size of the interleaved group. */
diff --git a/cpp/test/neighbors/ann_cagra.cuh b/cpp/test/neighbors/ann_cagra.cuh
index 499abd7e26..313a88553b 100644
--- a/cpp/test/neighbors/ann_cagra.cuh
+++ b/cpp/test/neighbors/ann_cagra.cuh
@@ -417,8 +417,7 @@ class AnnCagraSortTest : public ::testing::TestWithParam<AnnCagraInputs> {
         raft::make_host_matrix<IdxT, int64_t>(ps.n_rows, index_params.intermediate_graph_degree);
 
       if (ps.build_algo == graph_build_algo::IVF_PQ) {
-        auto build_params = ivf_pq::index_params{};
-        build_params.initialize_from_dataset(database_view, ps.metric);
+        auto build_params = ivf_pq::index_params(database_view, ps.metric);
         if (ps.host_dataset) {
           cagra::build_knn_graph<DataT, IdxT>(
             handle_, database_host_view, knn_graph.view(), 2, build_params);