managed_memory_resource.hpp

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/*
 * SPDX-FileCopyrightText: Copyright (c) 2019-2025, NVIDIA CORPORATION.
 * SPDX-License-Identifier: Apache-2.0
 */
#pragma once
 
#include <rmm/cuda_stream_view.hpp>
#include <rmm/detail/error.hpp>
#include <rmm/detail/export.hpp>
#include <rmm/mr/device/device_memory_resource.hpp>
 
#include <cstddef>
 
namespace RMM_NAMESPACE {
namespace mr {
class managed_memory_resource final : public device_memory_resource {
 public:
  managed_memory_resource()                               = default;
  ~managed_memory_resource() override                     = default;
  managed_memory_resource(managed_memory_resource const&) = default;  
  managed_memory_resource(managed_memory_resource&&)      = default;  
  managed_memory_resource& operator=(managed_memory_resource const&) =
    default;  
  managed_memory_resource& operator=(managed_memory_resource&&) =
    default;  
 
 private:
  void* do_allocate(std::size_t bytes, [[maybe_unused]] cuda_stream_view stream) override
  {
    // FIXME: Unlike cudaMalloc, cudaMallocManaged will throw an error for 0
    // size allocations.
    if (bytes == 0) { return nullptr; }
 
    void* ptr{nullptr};
    RMM_CUDA_TRY_ALLOC(cudaMallocManaged(&ptr, bytes), bytes);
    return ptr;
  }
 
  void do_deallocate(void* ptr,
                     [[maybe_unused]] std::size_t bytes,
                     [[maybe_unused]] cuda_stream_view stream) noexcept override
  {
    RMM_ASSERT_CUDA_SUCCESS(cudaFree(ptr));
  }
 
  [[nodiscard]] bool do_is_equal(device_memory_resource const& other) const noexcept override
  {
    return dynamic_cast<managed_memory_resource const*>(&other) != nullptr;
  }
};
  // end of group
}  // namespace mr
}  // namespace RMM_NAMESPACE