aligned_resource_adaptor.hpp

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/*
 * Copyright (c) 2021-2025, 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
 *
 * https://apache.ac.cn/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/aligned.hpp>
#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 <rmm/mr/device/per_device_resource.hpp>
#include <rmm/resource_ref.hpp>

#include <cstddef>
#include <mutex>
#include <unordered_map>

namespace RMM_NAMESPACE {
namespace mr {
template <typename Upstream>
class aligned_resource_adaptor final : public device_memory_resource {
 public
 // 使用上游资源构造一个对齐资源适配器来满足分配请求。
 explicit aligned_resource_adaptor(device_async_resource_ref upstream,
 std::size_t alignment = rmm::CUDA_ALLOCATION_ALIGNMENT,
 std::size_t alignment_threshold = default_alignment_threshold)
 : upstream_{upstream}, alignment_{alignment}, alignment_threshold_{alignment_threshold}
 {
 RMM_EXPECTS(rmm::is_supported_alignment(alignment),
 "Allocation alignment is not a power of 2.");
 }
 // 使用上游资源构造对齐资源适配器以满足分配请求。
 explicit aligned_resource_adaptor(Upstream* upstream,
 std::size_t alignment = rmm::CUDA_ALLOCATION_ALIGNMENT,
 std::size_t alignment_threshold = default_alignment_threshold)
 : upstream_{to_device_async_resource_ref_checked(upstream)},
 alignment_{alignment},
 alignment_threshold_{alignment_threshold}
 {
 RMM_EXPECTS(rmm::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;
 // 返回上游资源的 rmm::device_async_resource_ref 引用
 [[nodiscard]] rmm::device_async_resource_ref get_upstream_resource() const noexcept
 {
 return upstream_;
 }
 static constexpr std::size_t default_alignment_threshold = 0;

 private
 using lock_guard = std::lock_guard<std::mutex>

 // 实现 `do_allocate`
 void* do_allocate(std::size_t bytes, cuda_stream_view stream) override
 {
 if (alignment_ == rmm::CUDA_ALLOCATION_ALIGNMENT || bytes < alignment_threshold_) {
 return get_upstream_resource().allocate_async(bytes, 1, stream);
 }
 auto const size = upstream_allocation_size(bytes);
 void* pointer = get_upstream_resource().allocate_async(size, 1, stream);
 // NOLINTNEXTLINE(cppcoreguidelines-pro-type-reinterpret-cast)
 auto const address = reinterpret_cast<std::size_t>(pointer);
 auto const aligned_address = rmm::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;
 }
 // 实现 `do_deallocate`
 void do_deallocate(void* ptr, std::size_t bytes, cuda_stream_view stream) override
 {
 if (alignment_ == rmm::CUDA_ALLOCATION_ALIGNMENT || bytes < alignment_threshold_) {
 get_upstream_resource().deallocate_async(ptr, bytes, 1, stream);
 } else {
 {
 lock_guard lock(mtx_);
 auto const iter = pointers_.find(ptr);
 if (iter != pointers_.end()) {
 ptr = iter->second;
 pointers_.erase(iter);
 }
 }
 get_upstream_resource().deallocate_async(ptr, upstream_allocation_size(bytes), 1, stream);
 }
 }
 // 比较是否相等
 [[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);
 if (cast == nullptr) { return false; }
 return get_upstream_resource() == cast->get_upstream_resource() &&
 alignment_ == cast->alignment_ && alignment_threshold_ == cast->alignment_threshold_;
 }
 // 计算上游资源所需的分配大小
 std::size_t upstream_allocation_size(std::size_t bytes) const
 {
 auto const aligned_size = rmm::align_up(bytes, alignment_);
 return aligned_size + alignment_ - rmm::CUDA_ALLOCATION_ALIGNMENT;
 }
 device_async_resource_ref upstream_;
 std::unordered_map<void*, void*> pointers_;
 std::size_t alignment_;
 std::size_t alignment_threshold_;
 mutable std::mutex mtx_;
};
 // 组结束
} // namespace mr
} // namespace RMM_NAMESPACE