// SPDX-License-Identifier: BSD-2-Clause

/* Copyright (C) 2018 - 2020 Intel Corporation. */

#pragma once

#include <memory>

#include <string>

#include <exception>

#include <type_traits>

#include <atomic>

#include <cstddef>

#include <stdexcept>

#include "memkind.h"

/*

 * Header file for the C++ allocator compatible with the C++ standard library allocator concepts.

 * More details in pmemallocator(3) man page.

 * Note: memory heap management is based on memkind_malloc, refer to the memkind(3) man page for more

 * information.

 *

 * Functionality defined in this header is considered as stable API (STANDARD API).

 * API standards are described in memkind(3) man page.

 */

namespace libmemkind

{

    enum class allocation_policy {

        DEFAULT = MEMKIND_MEM_USAGE_POLICY_DEFAULT,

        CONSERVATIVE = MEMKIND_MEM_USAGE_POLICY_CONSERVATIVE,

        MAX

    };

    namespace pmem

    {

        namespace internal

        {

            class kind_wrapper_t

            {

            public:

                kind_wrapper_t(const char *dir, std::size_t max_size,

                               libmemkind::allocation_policy alloc_policy=

                                   libmemkind::allocation_policy::DEFAULT)

                {

                    cfg = memkind_config_new();

                    if (!cfg) {

                        throw std::runtime_error(

                            std::string("An error occurred while creating pmem config"));

                    }

                    memkind_config_set_path(cfg, dir);

                    memkind_config_set_size(cfg, max_size);

                    memkind_config_set_memory_usage_policy(cfg,

                                                           static_cast<memkind_mem_usage_policy>(alloc_policy));

                    int err_c  = memkind_create_pmem_with_config(cfg, &kind);

                    memkind_config_delete(cfg);

                    if (err_c) {

                        throw std::runtime_error(

                            std::string("An error occurred while creating pmem kind; error code: ") +

                            std::to_string(err_c));

                    }

                }

                kind_wrapper_t(const kind_wrapper_t &) = delete;

                void operator=(const kind_wrapper_t &) = delete;

                ~kind_wrapper_t()

                {

                    memkind_destroy_kind(kind);

                }

                memkind_t get() const

                {

                    return kind;

                }

            private:

                memkind_t kind;

                struct memkind_config *cfg;

            };

        }

        template<typename T>

        class allocator

        {

            using kind_wrapper_t = internal::kind_wrapper_t;

            std::shared_ptr<kind_wrapper_t> kind_wrapper_ptr;

        public:

            using value_type = T;

            using pointer = value_type*;

            using const_pointer = const value_type*;

            using reference = value_type&;

            using const_reference = const value_type&;

            using size_type = size_t;

            using difference_type = ptrdiff_t;

            template<class U>

            struct rebind {

                using other = allocator<U>;

            };

            template<typename U>

            friend class allocator;

#if !_GLIBCXX_USE_CXX11_ABI

            /* This is a workaround for compilers (e.g GCC 4.8) that uses C++11 standard,

             * but use old - non C++11 ABI */

            template<typename V = void>

            explicit allocator()

            {

                static_assert(std::is_same<V, void>::value,

                              "libmemkind::pmem::allocator cannot be compiled without CXX11 ABI");

            }

#endif

            explicit allocator(const char *dir, size_t max_size) :

                kind_wrapper_ptr(std::make_shared<kind_wrapper_t>(dir, max_size))

            {

            }

            explicit allocator(const std::string &dir, size_t max_size) :

                allocator(dir.c_str(), max_size)

            {

            }

            explicit allocator(const char *dir, size_t max_size,

                               libmemkind::allocation_policy alloc_policy) :

                kind_wrapper_ptr(std::make_shared<kind_wrapper_t>(dir, max_size, alloc_policy))

            {

            }

            explicit allocator(const std::string &dir, size_t max_size,

                               libmemkind::allocation_policy alloc_policy) :

                allocator(dir.c_str(), max_size, alloc_policy)

            {

            }

            allocator(const allocator &other) = default;

            template <typename U>

            allocator(const allocator<U> &other) noexcept : kind_wrapper_ptr(

                    other.kind_wrapper_ptr)

            {

            }

            allocator(allocator &&other) = default;

            template <typename U>

            allocator(allocator<U> &&other) noexcept :

                kind_wrapper_ptr(std::move(other.kind_wrapper_ptr))

            {

            }

            allocator<T> &operator = (const allocator &other) = default;

            template <typename U>

            allocator<T> &operator = (const allocator<U> &other) noexcept

            {

                kind_wrapper_ptr = other.kind_wrapper_ptr;

                return *this;

            }

            allocator<T> &operator = (allocator &&other) = default;

            template <typename U>

            allocator<T> &operator = (allocator<U> &&other) noexcept

            {

                kind_wrapper_ptr = std::move(other.kind_wrapper_ptr);

                return *this;

            }

            pointer allocate(size_type n) const

            {

                pointer result = static_cast<pointer>(memkind_malloc(kind_wrapper_ptr->get(),

                                                                     n*sizeof(T)));

                if (!result) {

                    throw std::bad_alloc();

                }

                return result;

            }

            void deallocate(pointer p, size_type n) const

            {

                memkind_free(kind_wrapper_ptr->get(), static_cast<void *>(p));

            }

            template <class U, class... Args>

            void construct(U *p, Args &&... args) const

            {

                ::new((void *)p) U(std::forward<Args>(args)...);

            }

            void destroy(pointer p) const

            {

                p->~value_type();

            }

            template <typename U, typename V>

            friend bool operator ==(const allocator<U> &lhs, const allocator<V> &rhs;;

            template <typename U, typename V>

            friend bool operator !=(const allocator<U> &lhs, const allocator<V> &rhs;;

        };

        template <typename U, typename V>

        bool operator ==(const allocator<U> &lhs, const allocator<V> &rhs)

        {

            return lhs.kind_wrapper_ptr->get() == rhs.kind_wrapper_ptr->get();

        }

        template <typename U, typename V>

        bool operator !=(const allocator<U> &lhs, const allocator<V> &rhs)

        {

            return !(lhs == rhs);

        }

    }  // namespace pmem

}  // namespace libmemkind