Temporary buffer to view host or device memory in device

cpp/include/raft/core/temporary_device_buffer.hpp

@@ -0,0 +1,268 @@
+/*
+ * 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 "device_mdarray.hpp"
+#include "device_mdspan.hpp"
+
+#include <raft/util/cudart_utils.hpp>
+
+#include <variant>
+
+namespace raft {
+
+/**
+ * \defgroup TemporaryDeviceBuffer `raft::temporary_device_buffer` and associated factories
+ * @{
+ */
+
+/**
+ * @brief An object which provides temporary access on-device to memory from either a host or device
+ * pointer. This object provides a `view()` method that will provide a `raft::device_mdspan` that
+ * may be read-only depending on const-qualified nature of the input pointer.
+ *
+ * @tparam ElementType type of the input
+ * @tparam Extents raft::extents
+ * @tparam LayoutPolicy layout of the input
+ * @tparam ContainerPolicy container to be used to own device memory if needed
+ */
+template <typename ElementType,
+          typename Extents,
+          typename LayoutPolicy                        = layout_c_contiguous,
+          template <typename> typename ContainerPolicy = detail::device_uvector_policy>
+class temporary_device_buffer {
+  using view_type        = device_mdspan<ElementType, Extents, LayoutPolicy>;
+  using index_type       = typename Extents::index_type;
+  using element_type     = std::remove_cv_t<ElementType>;
+  using container_policy = ContainerPolicy<element_type>;
+  using owning_device_buffer =
+    device_mdarray<element_type, Extents, LayoutPolicy, container_policy>;
+  using data_store                        = std::variant<ElementType*, owning_device_buffer>;
+  static constexpr bool is_const_pointer_ = std::is_const_v<ElementType>;
+
+ public:
+  temporary_device_buffer(temporary_device_buffer const&) = delete;
+  temporary_device_buffer& operator=(temporary_device_buffer const&) = delete;
+
+  constexpr temporary_device_buffer(temporary_device_buffer&&) = default;
+  constexpr temporary_device_buffer& operator=(temporary_device_buffer&&) = default;
+
+  /**
+   * @brief Construct a new temporary device buffer object
+   *
+   * @param handle raft::device_resources
+   * @param data input pointer
+   * @param extents dimensions of input array
+   * @param write_back if true, any writes to the `view()` of this object will be copid
+   *                   back if the original pointer was in host memory
+   */
+  temporary_device_buffer(device_resources const& handle,
+                          ElementType* data,
+                          Extents extents,
+                          bool write_back = false)
+    : stream_(handle.get_stream()),
+      original_data_(data),
+      extents_{extents},
+      write_back_(write_back),
+      length_([this]() {
+        std::size_t length = 1;
+        for (std::size_t i = 0; i < extents_.rank(); ++i) {
+          length *= extents_.extent(i);
+        }
+        return length;
+      }()),
+      device_id_{get_device_for_address(data)}
+  {
+    if (device_id_ == -1) {
+      typename owning_device_buffer::mapping_type layout{extents_};
+      typename owning_device_buffer::container_policy_type policy{handle.get_stream()};
+
+      owning_device_buffer device_data{layout, policy};
+      raft::copy(device_data.data_handle(), data, length_, handle.get_stream());
+      data_ = data_store{std::in_place_index<1>, std::move(device_data)};
+    } else {
+      data_ = data_store{std::in_place_index<0>, data};
+    }
+  }
+
+  ~temporary_device_buffer() noexcept(is_const_pointer_)
+  {
+    // only need to write data back for non const pointers
+    // when write_back=true and original pointer is in
+    // host memory
+    if constexpr (not is_const_pointer_) {
+      if (write_back_ && device_id_ == -1) {
+        raft::copy(original_data_, std::get<1>(data_).data_handle(), length_, stream_);
+      }
+    }
+  }
+
+  /**
+   * @brief Returns a `raft::device_mdspan`
+   *
+   * @return raft::device_mdspan
+   */
+  auto view() -> view_type
+  {
+    if (device_id_ == -1) {
+      return std::get<1>(data_).view();
+    } else {
+      return make_mdspan<ElementType, index_type, LayoutPolicy, false, true>(original_data_,
+                                                                             extents_);
+    }
+  }
+
+ private:
+  rmm::cuda_stream_view stream_;
+  ElementType* original_data_;
+  data_store data_;
+  Extents extents_;
+  bool write_back_;
+  std::size_t length_;
+  int device_id_;
+};
+
+/**
+ * @brief Factory to create a `raft::temporary_device_buffer`
+ *
+ * @code{.cpp}
+ * #include <raft/core/device_resources.hpp>
+ *
+ * raft::device_resources handle;
+ *
+ * // Initialize raft::device_mdarray and raft::extents
+ * // Can be either raft::device_mdarray or raft::host_mdarray
+ * auto exts  = raft::make_extents<int>(5);
+ * auto array = raft::make_device_mdarray<int, int>(handle, exts);
+ *
+ * auto d_buf = raft::make_temporary_device_buffer(handle, array.data_handle(), exts);
+ * @endcode
+ *
+ * @tparam ElementType type of the input
+ * @tparam IndexType index type of `raft::extents`
+ * @tparam LayoutPolicy layout of the input
+ * @tparam ContainerPolicy container to be used to own device memory if needed
+ * @tparam Extents variadic dimensions for `raft::extents`
+ * @param handle raft::device_resources
+ * @param data input pointer
+ * @param extents dimensions of input array
+ * @param write_back if true, any writes to the `view()` of this object will be copid
+ *                   back if the original pointer was in host memory
+ * @return raft::temporary_device_buffer
+ */
+template <typename ElementType,
+          typename IndexType                           = std::uint32_t,
+          typename LayoutPolicy                        = layout_c_contiguous,
+          template <typename> typename ContainerPolicy = detail::device_uvector_policy,
+          size_t... Extents>
+auto make_temporary_device_buffer(raft::device_resources const& handle,
+                                  ElementType* data,
+                                  raft::extents<IndexType, Extents...> extents,
+                                  bool write_back = false)
+{
+  return temporary_device_buffer<ElementType, decltype(extents), LayoutPolicy, ContainerPolicy>(
+    handle, data, extents, write_back);
+}
+
+/**
+ * @brief Factory to create a `raft::temporary_device_buffer` which produces a
+ *        read-only `raft::device_mdspan` from `view()` method with
+ *        `write_back=false`
+ *
+ * @code{.cpp}
+ * #include <raft/core/device_resources.hpp>
+ *
+ * raft::device_resources handle;
+ *
+ * // Initialize raft::device_mdarray and raft::extents
+ * // Can be either raft::device_mdarray or raft::host_mdarray
+ * auto exts  = raft::make_extents<int>(5);
+ * auto array = raft::make_device_mdarray<int, int>(handle, exts);
+ *
+ * auto d_buf = raft::make_readonly_temporary_device_buffer(handle, array.data_handle(), exts);
+ * @endcode
+ *
+ * @tparam ElementType type of the input
+ * @tparam IndexType index type of `raft::extents`
+ * @tparam LayoutPolicy layout of the input
+ * @tparam ContainerPolicy container to be used to own device memory if needed
+ * @tparam Extents variadic dimensions for `raft::extents`
+ * @param handle raft::device_resources
+ * @param data input pointer
+ * @param extents dimensions of input array
+ * @return raft::temporary_device_buffer
+ */
+template <typename ElementType,
+          typename IndexType                           = std::uint32_t,
+          typename LayoutPolicy                        = layout_c_contiguous,
+          template <typename> typename ContainerPolicy = detail::device_uvector_policy,
+          size_t... Extents>
+auto make_readonly_temporary_device_buffer(raft::device_resources const& handle,
+                                           ElementType* data,
+                                           raft::extents<IndexType, Extents...> extents)
+{
+  return temporary_device_buffer<std::add_const_t<ElementType>,
+                                 decltype(extents),
+                                 LayoutPolicy,
+                                 ContainerPolicy>(handle, data, extents, false);
+}
+
+/**
+ * @brief Factory to create a `raft::temporary_device_buffer` which produces a
+ *        writeable `raft::device_mdspan` from `view()` method with
+ *        `write_back=true`
+ *
+ * @code{.cpp}
+ * #include <raft/core/device_resources.hpp>
+ *
+ * raft::device_resources handle;
+ *
+ * // Initialize raft::host_mdarray and raft::extents
+ * // Can be either raft::device_mdarray or raft::host_mdarray
+ * auto exts  = raft::make_extents<int>(5);
+ * auto array = raft::make_host_mdarray<int, int>(handle, exts);
+ *
+ * auto d_buf = raft::make_writeback_temporary_device_buffer(handle, array.data_handle(), exts);
+ * @endcode
+ *
+ * @tparam ElementType type of the input
+ * @tparam IndexType index type of `raft::extents`
+ * @tparam LayoutPolicy layout of the input
+ * @tparam ContainerPolicy container to be used to own device memory if needed
+ * @tparam Extents variadic dimensions for `raft::extents`
+ * @param handle raft::device_resources
+ * @param data input pointer
+ * @param extents dimensions of input array
+ * @return raft::temporary_device_buffer
+ */
+template <typename ElementType,
+          typename IndexType                           = std::uint32_t,
+          typename LayoutPolicy                        = layout_c_contiguous,
+          template <typename> typename ContainerPolicy = detail::device_uvector_policy,
+          size_t... Extents,
+          typename = std::enable_if_t<not std::is_const_v<ElementType>>>
+auto make_writeback_temporary_device_buffer(raft::device_resources const& handle,
+                                            ElementType* data,
+                                            raft::extents<IndexType, Extents...> extents)
+{
+  return temporary_device_buffer<ElementType, decltype(extents), LayoutPolicy, ContainerPolicy>(
+    handle, data, extents, true);
+}
+
+/**@}*/
+
+}  // namespace raft

cpp/test/CMakeLists.txt

@@ -109,6 +109,7 @@ if(BUILD_TESTS)
     test/core/memory_type.cpp
     test/core/span.cpp
     test/core/span.cu
+    test/core/temporary_device_buffer.cu
     test/test.cpp
   )
 

cpp/test/core/mdarray.cu

@@ -13,6 +13,9 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
+
+#include "../test_utils.cuh"
+
 #include <gtest/gtest.h>
 #include <raft/core/device_mdarray.hpp>
 #include <raft/core/host_mdarray.hpp>

cpp/test/core/temporary_device_buffer.cu

@@ -0,0 +1,84 @@
+/*
+ * 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.
+ * 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 "../test_utils.cuh"
+
+#include <raft/core/host_mdarray.hpp>
+#include <raft/core/temporary_device_buffer.hpp>
+
+#include <rmm/device_uvector.hpp>
+
+#include <gtest/gtest.h>
+
+namespace raft {
+
+TEST(TemporaryDeviceBuffer, DevicePointer)
+{
+  {
+    raft::device_resources handle;
+    auto exts  = raft::make_extents<int>(5);
+    auto array = raft::make_device_mdarray<int, int>(handle, exts);
+
+    auto d_buf = raft::make_temporary_device_buffer(handle, array.data_handle(), exts);
+
+    ASSERT_EQ(array.data_handle(), d_buf.view().data_handle());
+    static_assert(!std::is_const_v<typename decltype(d_buf.view())::element_type>,
+                  "element_type should not be const");
+  }
+
+  {
+    raft::device_resources handle;
+    auto exts  = raft::make_extents<int>(5);
+    auto array = raft::make_device_mdarray<int, int>(handle, exts);
+
+    auto d_buf = raft::make_readonly_temporary_device_buffer(handle, array.data_handle(), exts);
+
+    ASSERT_EQ(array.data_handle(), d_buf.view().data_handle());
+    static_assert(std::is_const_v<typename decltype(d_buf.view())::element_type>,
+                  "element_type should be const");
+  }
+}
+
+TEST(TemporaryDeviceBuffer, HostPointerWithWriteBack)
+{
+  raft::device_resources handle;
+  auto exts  = raft::make_extents<int>(5);
+  auto array = raft::make_host_mdarray<int, int>(exts);
+  thrust::fill(array.data_handle(), array.data_handle() + array.extent(0), 1);
+  rmm::device_uvector<int> result(5, handle.get_stream());
+
+  {
+    auto d_buf  = raft::make_writeback_temporary_device_buffer(handle, array.data_handle(), exts);
+    auto d_view = d_buf.view();
+
+    thrust::fill(rmm::exec_policy(handle.get_stream()),
+                 d_view.data_handle(),
+                 d_view.data_handle() + d_view.extent(0),
+                 10);
+    raft::copy(result.data(), d_view.data_handle(), d_view.extent(0), handle.get_stream());
+
+    static_assert(!std::is_const_v<typename decltype(d_buf.view())::element_type>,
+                  "element_type should not be const");
+  }
+
+  ASSERT_TRUE(raft::devArrMatchHost(array.data_handle(),
+                                    result.data(),
+                                    array.extent(0),
+                                    raft::Compare<int>(),
+                                    handle.get_stream()));
+}
+
+}  // namespace raft

docs/source/cpp_api/mdspan.rst

@@ -16,3 +16,4 @@ This page provides C++ class references for the RAFT's 1d span and multi-dimensi
    mdspan_mdspan.rst
    mdspan_mdarray.rst
    mdspan_span.rst
+   mdspan_temporary_device_buffer.rst