pool_memory_resource_impl.hpp

/*
 * VecMem project, part of the ACTS project (R&D line)
 *
 * (c) 2023 CERN for the benefit of the ACTS project
 *
 * Mozilla Public License Version 2.0
 */
#pragma once
 
// Local include(s).
#include "vecmem/memory/memory_resource.hpp"
#include "vecmem/memory/pool_memory_resource.hpp"
 
// System include(s).
#include <functional>
#include <vector>
 
namespace vecmem::details {

class pool_memory_resource_impl {
 
public:
    pool_memory_resource_impl(memory_resource& upstream,
                              const pool_memory_resource::options& opts);

    ~pool_memory_resource_impl();

    void* allocate(std::size_t bytes, std::size_t alignment);

    void deallocate(void* ptr, std::size_t bytes, std::size_t alignment);
 
private:
    std::reference_wrapper<memory_resource> m_upstream;
    pool_memory_resource::options m_options;

    struct chunk_descriptor {
        std::size_t size = 0u;
        void* pointer = nullptr;
    };

    struct oversized_block_descriptor {
        std::size_t size = 0u;
        std::size_t alignment = 0u;
        void* pointer = nullptr;

        bool operator<(const oversized_block_descriptor& other) const;
    };

    struct pool {
        std::vector<void*> free_blocks;
        std::size_t previous_allocated_count = 0u;
    };

    const std::size_t m_smallest_block_log2;

    std::vector<pool> m_pools;
    std::vector<chunk_descriptor> m_allocated;
    std::vector<oversized_block_descriptor> m_cached_oversized;
    std::vector<oversized_block_descriptor> m_oversized;
 
};  // class pool_memory_resource_impl
 
}  // namespace vecmem::details