Implement maybe-owning multi-dimensional container (mdbuffer)

cpp/include/raft/core/detail/fail_container_policy.hpp

@@ -0,0 +1,146 @@
+/*
+ * Copyright (c) 2023, 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 <raft/core/error.hpp>
+#include <raft/core/logger-macros.hpp>
+#include <raft/core/resources.hpp>
+#include <raft/thirdparty/mdspan/include/experimental/mdspan>
+#include <stddef.h>
+
+namespace raft {
+namespace detail {
+
+template <typename T>
+struct fail_reference {
+  using value_type    = typename std::remove_cv_t<T>;
+  using pointer       = T*;
+  using const_pointer = T const*;
+
+  fail_reference() = default;
+  template <typename StreamViewType>
+  fail_reference(T* ptr, StreamViewType stream)
+  {
+    throw non_cuda_build_error{"Attempted to construct reference to device data in non-CUDA build"};
+  }
+
+  operator value_type() const  // NOLINT
+  {
+    throw non_cuda_build_error{"Attempted to dereference device data in non-CUDA build"};
+    return value_type{};
+  }
+  auto operator=(T const& other) -> fail_reference&
+  {
+    throw non_cuda_build_error{"Attempted to assign to device data in non-CUDA build"};
+    return *this;
+  }
+};
+
+/** A placeholder container which throws an exception on use
+ *
+ * This placeholder is used in non-CUDA builds for container types that would
+ * otherwise be provided with CUDA code. Attempting to construct a non-empty
+ * container of this type throws an exception indicating that there was an
+ * attempt to use the device from a non-CUDA build. An example of when this
+ * might happen is if a downstream application attempts to allocate a device
+ * mdarray using a library built with non-CUDA RAFT.
+ */
+template <typename T>
+struct fail_container {
+  using value_type = T;
+  using size_type  = std::size_t;
+
+  using reference       = fail_reference<T>;
+  using const_reference = fail_reference<T const>;
+
+  using pointer       = value_type*;
+  using const_pointer = value_type const*;
+
+  using iterator       = pointer;
+  using const_iterator = const_pointer;
+
+  explicit fail_container(size_t n = size_t{})
+  {
+    if (n != size_t{}) {
+      throw non_cuda_build_error{"Attempted to allocate device container in non-CUDA build"};
+    }
+  }
+
+  template <typename Index>
+  auto operator[](Index i) noexcept -> reference
+  {
+    RAFT_LOG_ERROR("Attempted to access device data in non-CUDA build");
+    return reference{};
+  }
+
+  template <typename Index>
+  auto operator[](Index i) const noexcept -> const_reference
+  {
+    RAFT_LOG_ERROR("Attempted to access device data in non-CUDA build");
+    return const_reference{};
+  }
+  void resize(size_t n)
+  {
+    if (n != size_t{}) {
+      throw non_cuda_build_error{"Attempted to allocate device container in non-CUDA build"};
+    }
+  }
+
+  [[nodiscard]] auto data() noexcept -> pointer { return nullptr; }
+  [[nodiscard]] auto data() const noexcept -> const_pointer { return nullptr; }
+};
+
+/** A placeholder container policy which throws an exception on use
+ *
+ * This placeholder is used in non-CUDA builds for container types that would
+ * otherwise be provided with CUDA code. Attempting to construct a non-empty
+ * container of this type throws an exception indicating that there was an
+ * attempt to use the device from a non-CUDA build. An example of when this
+ * might happen is if a downstream application attempts to allocate a device
+ * mdarray using a library built with non-CUDA RAFT.
+ */
+template <typename ElementType>
+struct fail_container_policy {
+  using element_type    = ElementType;
+  using container_type  = fail_container<element_type>;
+  using pointer         = typename container_type::pointer;
+  using const_pointer   = typename container_type::const_pointer;
+  using reference       = typename container_type::reference;
+  using const_reference = typename container_type::const_reference;
+
+  using accessor_policy       = std::experimental::default_accessor<element_type>;
+  using const_accessor_policy = std::experimental::default_accessor<element_type const>;
+
+  auto create(raft::resources const& res, size_t n) -> container_type { return container_type(n); }
+
+  fail_container_policy() = default;
+
+  [[nodiscard]] constexpr auto access(container_type& c, size_t n) const noexcept -> reference
+  {
+    return c[n];
+  }
+  [[nodiscard]] constexpr auto access(container_type const& c, size_t n) const noexcept
+    -> const_reference
+  {
+    return c[n];
+  }
+
+  [[nodiscard]] auto make_accessor_policy() noexcept { return accessor_policy{}; }
+  [[nodiscard]] auto make_accessor_policy() const noexcept { return const_accessor_policy{}; }
+};
+
+}  // namespace detail
+}  // namespace raft

cpp/include/raft/core/device_container_policy.hpp

@@ -21,6 +21,7 @@
  * limitations under the License.
  */
 #pragma once
+#ifndef RAFT_DISABLE_CUDA
 #include <raft/core/device_mdspan.hpp>
 #include <raft/util/cudart_utils.hpp>
 
@@ -196,3 +197,22 @@ class device_uvector_policy {
 };
 
 }  // namespace raft
+#else
+#include <raft/core/detail/fail_container_policy.hpp>
+namespace raft {
+
+// Provide placeholders that will allow CPU-GPU interoperable codebases to
+// compile in non-CUDA mode but which will throw exceptions at runtime on any
+// attempt to touch device data
+
+template <typename T>
+using device_reference = detail::fail_reference<T>;
+
+template <typename T>
+using device_uvector = detail::fail_container<T>;
+
+template <typename ElementType>
+using device_uvector_policy = detail::fail_container_policy<ElementType>;
+
+}  // namespace raft
+#endif

cpp/include/raft/core/device_mdspan.hpp

@@ -26,9 +26,6 @@ namespace raft {
 template <typename AccessorPolicy>
 using device_accessor = host_device_accessor<AccessorPolicy, memory_type::device>;
 
-template <typename AccessorPolicy>
-using managed_accessor = host_device_accessor<AccessorPolicy, memory_type::managed>;
-
 /**
  * @brief std::experimental::mdspan with device tag to avoid accessing incorrect memory location.
  */
@@ -38,12 +35,6 @@ template <typename ElementType,
           typename AccessorPolicy = std::experimental::default_accessor<ElementType>>
 using device_mdspan = mdspan<ElementType, Extents, LayoutPolicy, device_accessor<AccessorPolicy>>;
 
-template <typename ElementType,
-          typename Extents,
-          typename LayoutPolicy   = layout_c_contiguous,
-          typename AccessorPolicy = std::experimental::default_accessor<ElementType>>
-using managed_mdspan = mdspan<ElementType, Extents, LayoutPolicy, managed_accessor<AccessorPolicy>>;
-
 template <typename T, bool B>
 struct is_device_mdspan : std::false_type {};
 template <typename T>
@@ -61,23 +52,6 @@ using is_input_device_mdspan_t = is_device_mdspan<T, is_input_mdspan_v<T>>;
 template <typename T>
 using is_output_device_mdspan_t = is_device_mdspan<T, is_output_mdspan_v<T>>;
 
-template <typename T, bool B>
-struct is_managed_mdspan : std::false_type {};
-template <typename T>
-struct is_managed_mdspan<T, true> : std::bool_constant<T::accessor_type::is_managed_accessible> {};
-
-/**
- * @\brief Boolean to determine if template type T is either raft::managed_mdspan or a derived type
- */
-template <typename T>
-using is_managed_mdspan_t = is_managed_mdspan<T, is_mdspan_v<T>>;
-
-template <typename T>
-using is_input_managed_mdspan_t = is_managed_mdspan<T, is_input_mdspan_v<T>>;
-
-template <typename T>
-using is_output_managed_mdspan_t = is_managed_mdspan<T, is_output_mdspan_v<T>>;
-
 /**
  * @\brief Boolean to determine if variadic template types Tn are either raft::device_mdspan or a
  * derived type
@@ -102,30 +76,6 @@ using enable_if_input_device_mdspan = std::enable_if_t<is_input_device_mdspan_v<
 template <typename... Tn>
 using enable_if_output_device_mdspan = std::enable_if_t<is_output_device_mdspan_v<Tn...>>;
 
-/**
- * @\brief Boolean to determine if variadic template types Tn are either raft::managed_mdspan or a
- * derived type
- */
-template <typename... Tn>
-inline constexpr bool is_managed_mdspan_v = std::conjunction_v<is_managed_mdspan_t<Tn>...>;
-
-template <typename... Tn>
-inline constexpr bool is_input_managed_mdspan_v =
-  std::conjunction_v<is_input_managed_mdspan_t<Tn>...>;
-
-template <typename... Tn>
-inline constexpr bool is_output_managed_mdspan_v =
-  std::conjunction_v<is_output_managed_mdspan_t<Tn>...>;
-
-template <typename... Tn>
-using enable_if_managed_mdspan = std::enable_if_t<is_managed_mdspan_v<Tn...>>;
-
-template <typename... Tn>
-using enable_if_input_managed_mdspan = std::enable_if_t<is_input_managed_mdspan_v<Tn...>>;
-
-template <typename... Tn>
-using enable_if_output_managed_mdspan = std::enable_if_t<is_output_managed_mdspan_v<Tn...>>;
-
 /**
  * @brief Shorthand for 0-dim host mdspan (scalar).
  * @tparam ElementType the data type of the scalar element
@@ -186,7 +136,7 @@ using device_aligned_matrix_view =
 template <typename ElementType,
           typename IndexType    = std::uint32_t,
           typename LayoutPolicy = layout_right_padded<ElementType>>
-auto make_device_aligned_matrix_view(ElementType* ptr, IndexType n_rows, IndexType n_cols)
+auto constexpr make_device_aligned_matrix_view(ElementType* ptr, IndexType n_rows, IndexType n_cols)
 {
   using data_handle_type =
     typename std::experimental::aligned_accessor<ElementType,
@@ -203,24 +153,6 @@ auto make_device_aligned_matrix_view(ElementType* ptr, IndexType n_rows, IndexTy
   return device_aligned_matrix_view<ElementType, IndexType, LayoutPolicy>{aligned_pointer, extents};
 }
 
-/**
- * @brief Create a raft::managed_mdspan
- * @tparam ElementType the data type of the matrix elements
- * @tparam IndexType the index type of the extents
- * @tparam LayoutPolicy policy for strides and layout ordering
- * @param ptr Pointer to the data
- * @param exts dimensionality of the array (series of integers)
- * @return raft::managed_mdspan
- */
-template <typename ElementType,
-          typename IndexType    = std::uint32_t,
-          typename LayoutPolicy = layout_c_contiguous,
-          size_t... Extents>
-auto make_managed_mdspan(ElementType* ptr, extents<IndexType, Extents...> exts)
-{
-  return make_mdspan<ElementType, IndexType, LayoutPolicy, true, true>(ptr, exts);
-}
-
 /**
  * @brief Create a 0-dim (scalar) mdspan instance for device value.
  *
@@ -229,7 +161,7 @@ auto make_managed_mdspan(ElementType* ptr, extents<IndexType, Extents...> exts)
  * @param[in] ptr on device to wrap
  */
 template <typename ElementType, typename IndexType = std::uint32_t>
-auto make_device_scalar_view(ElementType* ptr)
+auto constexpr make_device_scalar_view(ElementType* ptr)
 {
   scalar_extent<IndexType> extents;
   return device_scalar_view<ElementType, IndexType>{ptr, extents};
@@ -249,7 +181,7 @@ auto make_device_scalar_view(ElementType* ptr)
 template <typename ElementType,
           typename IndexType    = std::uint32_t,
           typename LayoutPolicy = layout_c_contiguous>
-auto make_device_matrix_view(ElementType* ptr, IndexType n_rows, IndexType n_cols)
+auto constexpr make_device_matrix_view(ElementType* ptr, IndexType n_rows, IndexType n_cols)
 {
   matrix_extent<IndexType> extents{n_rows, n_cols};
   return device_matrix_view<ElementType, IndexType, LayoutPolicy>{ptr, extents};
@@ -269,10 +201,10 @@ auto make_device_matrix_view(ElementType* ptr, IndexType n_rows, IndexType n_col
  * @param[in] stride leading dimension / stride of data
  */
 template <typename ElementType, typename IndexType, typename LayoutPolicy = layout_c_contiguous>
-auto make_device_strided_matrix_view(ElementType* ptr,
-                                     IndexType n_rows,
-                                     IndexType n_cols,
-                                     IndexType stride)
+auto constexpr make_device_strided_matrix_view(ElementType* ptr,
+                                               IndexType n_rows,
+                                               IndexType n_cols,
+                                               IndexType stride)
 {
   constexpr auto is_row_major = std::is_same_v<LayoutPolicy, layout_c_contiguous>;
   IndexType stride0           = is_row_major ? (stride > 0 ? stride : n_cols) : 1;
@@ -295,7 +227,7 @@ auto make_device_strided_matrix_view(ElementType* ptr,
  * @return raft::device_vector_view
  */
 template <typename ElementType, typename IndexType, typename LayoutPolicy = layout_c_contiguous>
-auto make_device_vector_view(ElementType* ptr, IndexType n)
+auto constexpr make_device_vector_view(ElementType* ptr, IndexType n)
 {
   return device_vector_view<ElementType, IndexType, LayoutPolicy>{ptr, n};
 }
@@ -310,7 +242,7 @@ auto make_device_vector_view(ElementType* ptr, IndexType n)
  * @return raft::device_vector_view
  */
 template <typename ElementType, typename IndexType, typename LayoutPolicy = layout_c_contiguous>
-auto make_device_vector_view(
+auto constexpr make_device_vector_view(
   ElementType* ptr,
   const typename LayoutPolicy::template mapping<vector_extent<IndexType>>& mapping)
 {

cpp/include/raft/core/host_container_policy.hpp

@@ -62,4 +62,5 @@ class host_vector_policy {
   [[nodiscard]] auto make_accessor_policy() noexcept { return accessor_policy{}; }
   [[nodiscard]] auto make_accessor_policy() const noexcept { return const_accessor_policy{}; }
 };
+
 }  // namespace raft

cpp/include/raft/core/host_device_accessor.hpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2022, NVIDIA CORPORATION.
+ * Copyright (c) 2022-2023, NVIDIA CORPORATION.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -42,6 +42,16 @@ struct host_device_accessor : public AccessorPolicy {
   using AccessorPolicy::AccessorPolicy;
   using offset_policy = host_device_accessor;
   host_device_accessor(AccessorPolicy const& that) : AccessorPolicy{that} {}  // NOLINT
+
+  // Prevent implicit conversion from incompatible host_device_accessor types
+  template <memory_type OtherMemType>
+  host_device_accessor(host_device_accessor<AccessorPolicy, OtherMemType> const& that) = delete;
+
+  template <memory_type OtherMemType, typename = std::enable_if_t<mem_type == OtherMemType>>
+  host_device_accessor(host_device_accessor<AccessorPolicy, OtherMemType> const& that)
+    : AccessorPolicy{that}
+  {
+  }
 };
 
 }  // namespace raft