Add refine to the Python and C api's

cpp/CMakeLists.txt

@@ -555,8 +555,13 @@ target_link_options(cuvs PRIVATE "${CMAKE_CURRENT_BINARY_DIR}/fatbin.ld")
 if(BUILD_C_LIBRARY)
   add_library(
     cuvs_c SHARED
-    src/core/c_api.cpp src/neighbors/brute_force_c.cpp src/neighbors/ivf_flat_c.cpp
-    src/neighbors/ivf_pq_c.cpp src/neighbors/cagra_c.cpp src/distance/pairwise_distance_c.cpp
+    src/core/c_api.cpp
+    src/neighbors/brute_force_c.cpp
+    src/neighbors/ivf_flat_c.cpp
+    src/neighbors/ivf_pq_c.cpp
+    src/neighbors/cagra_c.cpp
+    src/neighbors/refine/refine_c.cpp
+    src/distance/pairwise_distance_c.cpp
   )
 
   add_library(cuvs::c_api ALIAS cuvs_c)

cpp/include/cuvs/core/detail/interop.hpp

@@ -16,6 +16,8 @@
 
 #pragma once
 
+#include <cuda_fp16.h>
+
 #include <raft/core/device_mdspan.hpp>
 #include <raft/core/error.hpp>
 #include <raft/core/host_mdspan.hpp>
@@ -44,7 +46,9 @@ DLDataType data_type_to_DLDataType()
 {
   uint8_t const bits{sizeof(T) * 8};
   uint16_t const lanes{1};
-  if constexpr (std::is_floating_point_v<T>) {
+  // std::is_floating_point returns false for the half type - handle
+  // that here
+  if constexpr (std::is_floating_point_v<T> || std::is_same_v<T, half>) {
     return DLDataType{kDLFloat, bits, lanes};
   } else if constexpr (std::is_signed_v<T>) {
     return DLDataType{kDLInt, bits, lanes};
@@ -72,9 +76,13 @@ inline MdspanType from_dlpack(DLManagedTensor* managed_tensor)
 
   auto to_data_type = data_type_to_DLDataType<typename MdspanType::value_type>();
   RAFT_EXPECTS(to_data_type.code == tensor.dtype.code,
-               "code mismatch between return mdspan and DLTensor");
+               "code mismatch between return mdspan (%i) and DLTensor (%i)",
+               to_data_type.code,
+               tensor.dtype.code);
   RAFT_EXPECTS(to_data_type.bits == tensor.dtype.bits,
-               "bits mismatch between return mdspan and DLTensor");
+               "bits mismatch between return mdspan (%i) and DLTensor (%i)",
+               to_data_type.bits,
+               tensor.dtype.bits);
   RAFT_EXPECTS(to_data_type.lanes == tensor.dtype.lanes,
                "lanes mismatch between return mdspan and DLTensor");
   RAFT_EXPECTS(tensor.dtype.lanes == 1, "More than 1 DLTensor lanes not supported");

cpp/include/cuvs/neighbors/refine.h

@@ -0,0 +1,61 @@
+/*
+ * Copyright (c) 2024, NVIDIA CORPORATION.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <cuvs/core/c_api.h>
+#include <cuvs/distance/distance.h>
+#include <dlpack/dlpack.h>
+#include <stdint.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+/**
+ * @defgroup ann_refine_c Approximate Nearest Neighbors Refinement C-API
+ * @{
+ */
+/**
+ * @brief Refine nearest neighbor search.
+ *
+ * Refinement is an operation that follows an approximate NN search. The approximate search has
+ * already selected n_candidates neighbor candidates for each query. We narrow it down to k
+ * neighbors. For each query, we calculate the exact distance between the query and its
+ * n_candidates neighbor candidate, and select the k nearest ones.
+ *
+ * @param[in] res cuvsResources_t opaque C handle
+ * @param[in] dataset device matrix that stores the dataset [n_rows, dims]
+ * @param[in] queries device matrix of the queries [n_queris, dims]
+ * @param[in] candidates indices of candidate vectors [n_queries, n_candidates], where
+ *   n_candidates >= k
+ * @param[in] metric distance metric to use. Euclidean (L2) is used by default
+ * @param[out] indices device matrix that stores the refined indices [n_queries, k]
+ * @param[out] distances device matrix that stores the refined distances [n_queries, k]
+ */
+cuvsError_t cuvsRefine(cuvsResources_t res,
+                       DLManagedTensor* dataset,
+                       DLManagedTensor* queries,
+                       DLManagedTensor* candidates,
+                       cuvsDistanceType metric,
+                       DLManagedTensor* indices,
+                       DLManagedTensor* distances);
+/**
+ * @}
+ */
+
+#ifdef __cplusplus
+}
+#endif

cpp/src/neighbors/refine/refine_c.cpp

@@ -0,0 +1,146 @@
+/*
+ * Copyright (c) 2024, NVIDIA CORPORATION.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <cstdint>
+#include <dlpack/dlpack.h>
+
+#include <raft/core/error.hpp>
+#include <raft/core/mdspan_types.hpp>
+#include <raft/core/resources.hpp>
+
+#include <cuvs/core/c_api.h>
+#include <cuvs/core/exceptions.hpp>
+#include <cuvs/core/interop.hpp>
+#include <cuvs/neighbors/refine.h>
+#include <cuvs/neighbors/refine.hpp>
+
+namespace {
+
+template <typename T>
+void _refine(bool on_device,
+             cuvsResources_t res,
+             DLManagedTensor* dataset_tensor,
+             DLManagedTensor* queries_tensor,
+             DLManagedTensor* candidates_tensor,
+             cuvsDistanceType metric,
+             DLManagedTensor* indices_tensor,
+             DLManagedTensor* distances_tensor)
+{
+  auto res_ptr = reinterpret_cast<raft::resources*>(res);
+
+  if (on_device) {
+    using queries_type    = raft::device_matrix_view<const T, int64_t, raft::row_major>;
+    using candidates_type = raft::device_matrix_view<const int64_t, int64_t, raft::row_major>;
+    using indices_type    = raft::device_matrix_view<int64_t, int64_t, raft::row_major>;
+    using distances_type  = raft::device_matrix_view<float, int64_t, raft::row_major>;
+    auto dataset          = cuvs::core::from_dlpack<queries_type>(dataset_tensor);
+    auto queries          = cuvs::core::from_dlpack<queries_type>(queries_tensor);
+    auto candidates       = cuvs::core::from_dlpack<candidates_type>(candidates_tensor);
+    auto indices          = cuvs::core::from_dlpack<indices_type>(indices_tensor);
+    auto distances        = cuvs::core::from_dlpack<distances_type>(distances_tensor);
+    cuvs::neighbors::refine(*res_ptr, dataset, queries, candidates, indices, distances, metric);
+  } else {
+    using queries_type    = raft::host_matrix_view<const T, int64_t, raft::row_major>;
+    using candidates_type = raft::host_matrix_view<const int64_t, int64_t, raft::row_major>;
+    using indices_type    = raft::host_matrix_view<int64_t, int64_t, raft::row_major>;
+    using distances_type  = raft::host_matrix_view<float, int64_t, raft::row_major>;
+    auto dataset          = cuvs::core::from_dlpack<queries_type>(dataset_tensor);
+    auto queries          = cuvs::core::from_dlpack<queries_type>(queries_tensor);
+    auto candidates       = cuvs::core::from_dlpack<candidates_type>(candidates_tensor);
+    auto indices          = cuvs::core::from_dlpack<indices_type>(indices_tensor);
+    auto distances        = cuvs::core::from_dlpack<distances_type>(distances_tensor);
+    cuvs::neighbors::refine(*res_ptr, dataset, queries, candidates, indices, distances, metric);
+  }
+}
+}  // namespace
+
+extern "C" cuvsError_t cuvsRefine(cuvsResources_t res,
+                                  DLManagedTensor* dataset_tensor,
+                                  DLManagedTensor* queries_tensor,
+                                  DLManagedTensor* candidates_tensor,
+                                  cuvsDistanceType metric,
+                                  DLManagedTensor* indices_tensor,
+                                  DLManagedTensor* distances_tensor)
+{
+  return cuvs::core::translate_exceptions([=] {
+    auto dataset    = dataset_tensor->dl_tensor;
+    auto queries    = queries_tensor->dl_tensor;
+    auto candidates = candidates_tensor->dl_tensor;
+    auto indices    = indices_tensor->dl_tensor;
+    auto distances  = distances_tensor->dl_tensor;
+
+    // all matrices must either be on host or on device, can't mix and match
+    bool on_device = cuvs::core::is_dlpack_device_compatible(dataset);
+    if (on_device != cuvs::core::is_dlpack_device_compatible(queries) ||
+        on_device != cuvs::core::is_dlpack_device_compatible(candidates) ||
+        on_device != cuvs::core::is_dlpack_device_compatible(indices) ||
+        on_device != cuvs::core::is_dlpack_device_compatible(distances)) {
+      RAFT_FAIL("Tensors must either all be on device memory, or all on host memory");
+    }
+
+    RAFT_EXPECTS(candidates.dtype.code == kDLInt && candidates.dtype.bits == 64,
+                 "candidates should be of type int64_t");
+    RAFT_EXPECTS(indices.dtype.code == kDLInt && indices.dtype.bits == 64,
+                 "indices should be of type int64_t");
+    RAFT_EXPECTS(distances.dtype.code == kDLFloat && distances.dtype.bits == 32,
+                 "distances should be of type float32");
+
+    RAFT_EXPECTS(queries.dtype.code == dataset.dtype.code,
+                 "type mismatch between dataset and queries");
+
+    if (queries.dtype.code == kDLFloat && queries.dtype.bits == 32) {
+      _refine<float>(on_device,
+                     res,
+                     dataset_tensor,
+                     queries_tensor,
+                     candidates_tensor,
+                     metric,
+                     indices_tensor,
+                     distances_tensor);
+    } else if (queries.dtype.code == kDLFloat && queries.dtype.bits == 16) {
+      _refine<half>(on_device,
+                    res,
+                    dataset_tensor,
+                    queries_tensor,
+                    candidates_tensor,
+                    metric,
+                    indices_tensor,
+                    distances_tensor);
+    } else if (queries.dtype.code == kDLInt && queries.dtype.bits == 8) {
+      _refine<int8_t>(on_device,
+                      res,
+                      dataset_tensor,
+                      queries_tensor,
+                      candidates_tensor,
+                      metric,
+                      indices_tensor,
+                      distances_tensor);
+    } else if (queries.dtype.code == kDLUInt && queries.dtype.bits == 8) {
+      _refine<uint8_t>(on_device,
+                       res,
+                       dataset_tensor,
+                       queries_tensor,
+                       candidates_tensor,
+                       metric,
+                       indices_tensor,
+                       distances_tensor);
+    } else {
+      RAFT_FAIL("Unsupported queries DLtensor dtype: %d and bits: %d",
+                queries.dtype.code,
+                queries.dtype.bits);
+    }
+  });
+}

python/cuvs/cuvs/common/cydlpack.pyx

@@ -53,6 +53,9 @@ cdef DLManagedTensor* dlpack_c(ary):
     elif ary.dtype == np.float64:
         dtype.code = DLDataTypeCode.kDLFloat
         dtype.bits = 64
+    elif ary.dtype == np.float16:
+        dtype.code = DLDataTypeCode.kDLFloat
+        dtype.bits = 16
     elif ary.dtype == np.int8:
         dtype.code = DLDataTypeCode.kDLInt
         dtype.bits = 8
@@ -74,6 +77,8 @@ cdef DLManagedTensor* dlpack_c(ary):
     elif ary.dtype == np.bool_:
         dtype.code = DLDataTypeCode.kDLFloat
         dtype.bits = 8
+    else:
+        raise ValueError(f"Unsupported dtype {ary.dtype}")
 
     dtype.lanes = 1
 

python/cuvs/cuvs/neighbors/CMakeLists.txt

@@ -16,3 +16,14 @@ add_subdirectory(brute_force)
 add_subdirectory(cagra)
 add_subdirectory(ivf_flat)
 add_subdirectory(ivf_pq)
+
+# Set the list of Cython files to build
+set(cython_sources refine.pyx)
+set(linked_libraries cuvs::cuvs cuvs::c_api)
+
+# Build all of the Cython targets
+rapids_cython_create_modules(
+  CXX
+  SOURCE_FILES "${cython_sources}"
+  LINKED_LIBRARIES "${linked_libraries}" ASSOCIATED_TARGETS cuvs MODULE_PREFIX neighbors_refine_
+)

python/cuvs/cuvs/neighbors/__init__.py

@@ -15,4 +15,6 @@
 
 from cuvs.neighbors import brute_force, cagra, ivf_flat, ivf_pq
 
-__all__ = ["brute_force", "cagra", "ivf_flat", "ivf_pq"]
+from .refine import refine
+
+__all__ = ["brute_force", "cagra", "ivf_flat", "ivf_pq", "refine"]

python/cuvs/cuvs/neighbors/refine.pxd

@@ -0,0 +1,30 @@
+#
+# Copyright (c) 2024, NVIDIA CORPORATION.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+# cython: language_level=3
+
+from cuvs.common.c_api cimport cuvsError_t, cuvsResources_t
+from cuvs.common.cydlpack cimport DLDataType, DLManagedTensor
+from cuvs.distance_type cimport cuvsDistanceType
+
+
+cdef extern from "cuvs/neighbors/refine.h" nogil:
+    cuvsError_t cuvsRefine(cuvsResources_t res,
+                           DLManagedTensor* dataset,
+                           DLManagedTensor* queries,
+                           DLManagedTensor* candidates,
+                           cuvsDistanceType metric,
+                           DLManagedTensor* indices,
+                           DLManagedTensor* distances) except +