pinned_host_memory_resource.hpp

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/*
 * SPDX-FileCopyrightText: Copyright (c) 2024-2026, NVIDIA CORPORATION.
 * SPDX-License-Identifier: Apache-2.0
 */
#pragma once
 
#include <rmm/aligned.hpp>
#include <rmm/detail/aligned.hpp>
#include <rmm/detail/cccl_adaptors.hpp>
#include <rmm/detail/error.hpp>
#include <rmm/detail/export.hpp>
#include <rmm/detail/nvtx/ranges.hpp>
#include <rmm/mr/device_memory_resource.hpp>
 
#include <cuda/stream_ref>
#include <cuda_runtime_api.h>
 
#include <cstddef>
 
namespace RMM_NAMESPACE {
namespace mr {
 
class pinned_host_memory_resource final : public device_memory_resource {
 public:
  pinned_host_memory_resource()           = default;
  ~pinned_host_memory_resource() override = default;
  pinned_host_memory_resource(pinned_host_memory_resource const&) =
    default;  
  pinned_host_memory_resource(pinned_host_memory_resource&&) =
    default;  
  pinned_host_memory_resource& operator=(pinned_host_memory_resource const&) =
    default;  
  pinned_host_memory_resource& operator=(pinned_host_memory_resource&&) =
    default;  
 
 private:
  void* do_allocate(std::size_t bytes, [[maybe_unused]] cuda_stream_view stream) override
  {
    // don't allocate anything if the user requested zero bytes
    if (0 == bytes) { return nullptr; }
 
    // TODO: Use the alignment parameter as an argument to do_allocate
    std::size_t constexpr alignment = rmm::CUDA_ALLOCATION_ALIGNMENT;
    return rmm::detail::aligned_host_allocate(bytes, alignment, [](std::size_t size) {
      void* ptr{nullptr};
      RMM_CUDA_TRY_ALLOC(cudaHostAlloc(&ptr, size, cudaHostAllocDefault), size);
      return ptr;
    });
  }
 
  void do_deallocate(void* ptr,
                     std::size_t bytes,
                     [[maybe_unused]] cuda_stream_view stream) noexcept override
  {
    // TODO: Use the alignment parameter as an argument to do_deallocate
    std::size_t constexpr alignment = rmm::CUDA_ALLOCATION_ALIGNMENT;
    rmm::detail::aligned_host_deallocate(ptr, bytes, alignment, [](void* ptr) {
      RMM_ASSERT_CUDA_SUCCESS_SAFE_SHUTDOWN(cudaFreeHost(ptr));
    });
  }
 
  [[nodiscard]] bool do_is_equal(device_memory_resource const& other) const noexcept override
  {
    return dynamic_cast<pinned_host_memory_resource const*>(&other) != nullptr;
  }
 
  friend void get_property(pinned_host_memory_resource const&, cuda::mr::device_accessible) noexcept
  {
  }
 
  friend void get_property(pinned_host_memory_resource const&, cuda::mr::host_accessible) noexcept
  {
  }
};
 
static_assert(cuda::mr::resource_with<pinned_host_memory_resource,
                                      cuda::mr::device_accessible,
                                      cuda::mr::host_accessible>);
  // end of group
}  // namespace mr
}  // namespace RMM_NAMESPACE