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/error.hpp>
#include <rmm/detail/export.hpp>
 
#include <cuda/memory_resource>
#include <cuda/stream_ref>
#include <cuda_runtime_api.h>
 
#include <cstddef>
 
namespace RMM_NAMESPACE {
namespace mr {
 
class pinned_host_memory_resource final {
 public:
  pinned_host_memory_resource()  = default;
  ~pinned_host_memory_resource() = 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;  
 
  void* allocate([[maybe_unused]] cuda::stream_ref stream,
                 std::size_t bytes,
                 [[maybe_unused]] std::size_t alignment = rmm::CUDA_ALLOCATION_ALIGNMENT)
  {
    // don't allocate anything if the user requested zero bytes
    if (0 == bytes) { return nullptr; }
 
    std::size_t constexpr alloc_alignment = rmm::CUDA_ALLOCATION_ALIGNMENT;
    return rmm::detail::aligned_host_allocate(bytes, alloc_alignment, [](std::size_t size) {
      void* ptr{nullptr};
      RMM_CUDA_TRY_ALLOC(cudaHostAlloc(&ptr, size, cudaHostAllocDefault), size);
      return ptr;
    });
  }
 
  void deallocate([[maybe_unused]] cuda::stream_ref stream,
                  void* ptr,
                  std::size_t bytes,
                  [[maybe_unused]] std::size_t alignment = rmm::CUDA_ALLOCATION_ALIGNMENT) noexcept
  {
    std::size_t constexpr alloc_alignment = rmm::CUDA_ALLOCATION_ALIGNMENT;
    rmm::detail::aligned_host_deallocate(ptr, bytes, alloc_alignment, [](void* ptr) {
      RMM_ASSERT_CUDA_SUCCESS_SAFE_SHUTDOWN(cudaFreeHost(ptr));
    });
  }
 
  void* allocate_sync(std::size_t bytes, std::size_t alignment = rmm::CUDA_ALLOCATION_ALIGNMENT)
  {
    auto* ptr = allocate(cuda::stream_ref{cudaStream_t{nullptr}}, bytes, alignment);
    RMM_CUDA_TRY(cudaStreamSynchronize(cudaStream_t{nullptr}));
    return ptr;
  }
 
  void deallocate_sync(void* ptr,
                       std::size_t bytes,
                       std::size_t alignment = rmm::CUDA_ALLOCATION_ALIGNMENT) noexcept
  {
    deallocate(cuda::stream_ref{cudaStream_t{nullptr}}, ptr, bytes, alignment);
  }
 
  RMM_CONSTEXPR_FRIEND void get_property(pinned_host_memory_resource const&,
                                         cuda::mr::device_accessible) noexcept
  {
  }
 
  RMM_CONSTEXPR_FRIEND void get_property(pinned_host_memory_resource const&,
                                         cuda::mr::host_accessible) noexcept
  {
  }
 
  [[nodiscard]] bool operator==(pinned_host_memory_resource const&) const noexcept { return true; }
 
  [[nodiscard]] bool operator!=(pinned_host_memory_resource const&) const noexcept { return false; }
};
 
// static property checks
static_assert(cuda::mr::synchronous_resource<pinned_host_memory_resource>);
static_assert(cuda::mr::resource<pinned_host_memory_resource>);
static_assert(
  cuda::mr::synchronous_resource_with<pinned_host_memory_resource, cuda::mr::device_accessible>);
static_assert(
  cuda::mr::synchronous_resource_with<pinned_host_memory_resource, cuda::mr::host_accessible>);
static_assert(cuda::mr::resource_with<pinned_host_memory_resource, cuda::mr::device_accessible>);
static_assert(cuda::mr::resource_with<pinned_host_memory_resource, cuda::mr::host_accessible>);
  // end of group
}  // namespace mr
}  // namespace RMM_NAMESPACE