aligned_resource_adaptor.hpp

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/*
 * Copyright (c) 2021, 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 <rmm/cuda_stream_view.hpp>
#include <rmm/detail/aligned.hpp>
#include <rmm/detail/error.hpp>
#include <rmm/mr/device/device_memory_resource.hpp>
 
#include <cstddef>
#include <mutex>
#include <optional>
#include <unordered_map>
 
namespace rmm::mr {
template <typename Upstream>
class aligned_resource_adaptor final : public device_memory_resource {
 public:
  explicit aligned_resource_adaptor(Upstream* upstream,
                                    std::size_t alignment = rmm::detail::CUDA_ALLOCATION_ALIGNMENT,
                                    std::size_t alignment_threshold = default_alignment_threshold)
    : upstream_{upstream}, alignment_{alignment}, alignment_threshold_{alignment_threshold}
  {
    RMM_EXPECTS(nullptr != upstream, "Unexpected null upstream resource pointer.");
    RMM_EXPECTS(rmm::detail::is_supported_alignment(alignment),
                "Allocation alignment is not a power of 2.");
  }
 
  aligned_resource_adaptor()                                           = delete;
  ~aligned_resource_adaptor() override                                 = default;
  aligned_resource_adaptor(aligned_resource_adaptor const&)            = delete;
  aligned_resource_adaptor(aligned_resource_adaptor&&)                 = delete;
  aligned_resource_adaptor& operator=(aligned_resource_adaptor const&) = delete;
  aligned_resource_adaptor& operator=(aligned_resource_adaptor&&)      = delete;
 
  Upstream* get_upstream() const noexcept { return upstream_; }
 
  [[nodiscard]] bool supports_streams() const noexcept override
  {
    return upstream_->supports_streams();
  }
 
  [[nodiscard]] bool supports_get_mem_info() const noexcept override
  {
    return upstream_->supports_get_mem_info();
  }
 
  static constexpr std::size_t default_alignment_threshold = 0;
 
 private:
  using lock_guard = std::lock_guard<std::mutex>;
 
  void* do_allocate(std::size_t bytes, cuda_stream_view stream) override
  {
    if (alignment_ == rmm::detail::CUDA_ALLOCATION_ALIGNMENT || bytes < alignment_threshold_) {
      return upstream_->allocate(bytes, stream);
    }
    auto const size = upstream_allocation_size(bytes);
    void* pointer   = upstream_->allocate(size, stream);
    // NOLINTNEXTLINE(cppcoreguidelines-pro-type-reinterpret-cast)
    auto const address         = reinterpret_cast<std::size_t>(pointer);
    auto const aligned_address = rmm::detail::align_up(address, alignment_);
    // NOLINTNEXTLINE(cppcoreguidelines-pro-type-reinterpret-cast,performance-no-int-to-ptr)
    void* aligned_pointer = reinterpret_cast<void*>(aligned_address);
    if (pointer != aligned_pointer) {
      lock_guard lock(mtx_);
      pointers_.emplace(aligned_pointer, pointer);
    }
    return aligned_pointer;
  }
 
  void do_deallocate(void* ptr, std::size_t bytes, cuda_stream_view stream) override
  {
    if (alignment_ == rmm::detail::CUDA_ALLOCATION_ALIGNMENT || bytes < alignment_threshold_) {
      upstream_->deallocate(ptr, bytes, stream);
    } else {
      {
        lock_guard lock(mtx_);
        auto const iter = pointers_.find(ptr);
        if (iter != pointers_.end()) {
          ptr = iter->second;
          pointers_.erase(iter);
        }
      }
      upstream_->deallocate(ptr, upstream_allocation_size(bytes), stream);
    }
  }
 
  [[nodiscard]] bool do_is_equal(device_memory_resource const& other) const noexcept override
  {
    if (this == &other) { return true; }
    auto cast = dynamic_cast<aligned_resource_adaptor<Upstream> const*>(&other);
    return cast != nullptr && upstream_->is_equal(*cast->get_upstream()) &&
           alignment_ == cast->alignment_ && alignment_threshold_ == cast->alignment_threshold_;
  }
 
  [[nodiscard]] std::pair<std::size_t, std::size_t> do_get_mem_info(
    cuda_stream_view stream) const override
  {
    return upstream_->get_mem_info(stream);
  }
 
  std::size_t upstream_allocation_size(std::size_t bytes) const
  {
    auto const aligned_size = rmm::detail::align_up(bytes, alignment_);
    return aligned_size + alignment_ - rmm::detail::CUDA_ALLOCATION_ALIGNMENT;
  }
 
  Upstream* upstream_;  
  std::unordered_map<void*, void*> pointers_;  
  std::size_t alignment_;                      
  std::size_t alignment_threshold_;  
  mutable std::mutex mtx_;           
};
  // end of group
}  // namespace rmm::mr