restore HNSW example

Author: tfeher

examples/cpp/src/hnsw_openai_example.cu

@@ -1,5 +1,5 @@
 /*
- * SPDX-FileCopyrightText: Copyright (c) 2025, NVIDIA CORPORATION.
+ * SPDX-FileCopyrightText: Copyright (c) 2025-2026, NVIDIA CORPORATION.
  * SPDX-License-Identifier: Apache-2.0
  */
 
@@ -71,21 +71,7 @@ int cagra_build_search_ace(raft::resources const& res)
   params.ef_construction = 200;
   params.hierarchy       = cuvs::neighbors::hnsw::HnswHierarchy::GPU;
 
-  // hnsw::build()
-  auto index_params =
-    cagra::index_params::from_hnsw_params(dataset_host_view.extents(),
-                                          params.M,
-                                          params.ef_construction,
-                                          cagra::hnsw_heuristic_type::SAME_GRAPH_FOOTPRINT,
-                                          params.metric);
-
-  std::cout << "Building CAGRA index (search graph)" << std::endl;
-  auto cagra_index = cagra::build(res, index_params, dataset_host_view);
-
-  // Convert CAGRA index to HNSW
-  std::cout << "Converting CAGRA index to HNSW" << std::endl;
-  hnsw::index_params hnsw_params;
-  auto hnsw_index = hnsw::from_cagra(res, hnsw_params, cagra_index);
+  auto hnsw_index = hnsw::build(res, params, dataset_host_view);
 
   std::string hnsw_index_path = "hnsw_index.bin";
   cuvs::neighbors::hnsw::serialize(res, hnsw_index_path, *hnsw_index);
@@ -100,16 +86,16 @@ int main()
 {
   raft::resources res;
 
-  // Set pool memory resource with 1 GiB initial pool size. All allocations use the same pool.
-  rmm::mr::pool_memory_resource<rmm::mr::device_memory_resource> pool_mr(
-    rmm::mr::get_current_device_resource(), 1024 * 1024 * 1024ull);
-  rmm::mr::set_current_device_resource(&pool_mr);
+  // // Set pool memory resource with 1 GiB initial pool size. All allocations use the same pool.
+  // rmm::mr::pool_memory_resource<rmm::mr::device_memory_resource> pool_mr(
+  //   rmm::mr::get_current_device_resource(), 1024 * 1024 * 1024ull);
+  // rmm::mr::set_current_device_resource(&pool_mr);
 
   // Alternatively, one could define a pool allocator for temporary arrays (used within RAFT
   // algorithms). In that case only the internal arrays would use the pool, any other allocation
   // uses the default RMM memory resource. Here is how to change the workspace memory resource to
   // a pool with 2 GiB upper limit.
-  // raft::resource::set_workspace_to_pool_resource(res, 2 * 1024 * 1024 * 1024ull);
+  raft::resource::set_workspace_to_pool_resource(res, 2 * 1024 * 1024 * 1024ull);
 
   // ACE build and search example.
   cagra_build_search_ace(res);