RingBuffer.hpp

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/*
    MIT License
 
    DiscordCoreAPI, A bot library for Discord, written in C++, and featuring explicit multithreading through the usage of custom, asynchronous C++ CoRoutines.
 
    Copyright 2022, 2023 Chris M. (RealTimeChris)
 
    Permission is hereby granted, free of charge, to any person obtaining a copy
    of this software and associated documentation files (the "Software"), to deal
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/// RingBuffer.hpp - Header file for the ring_buffer class.
/// Jun 28, 2022
/// https://discordcoreapi.com
/// \file RingBuffer.hpp
#pragma once
 
#include <jsonifier/Index.hpp>
 
#include <string_view>
#include <cstring>
#include <cstdint>
#include <vector>
#include <array>
 
namespace discord_core_api {
 
    namespace discord_core_internal {
 
        /**
        * \addtogroup discord_core_internal
        * @{
        */
 
        /// @brief Enum representing different access types for a ring buffer.
        enum class ring_buffer_access_type { read = 0, write = 1 };
 
        /// @brief A template interface for a ring buffer.
        /// @tparam value_type the type of data stored in the buffer.
        /// @tparam size the size of the buffer.
        template<typename value_type_new, uint64_t size> class ring_buffer_interface {
          public:
            using value_type = value_type_new;
            using pointer    = value_type*;
            using size_type  = uint64_t;
 
            /// @brief Constructor. initializes the buffer size.
            ring_buffer_interface() {
                arrayValue.resize(size);
            }
 
            ring_buffer_interface& operator=(ring_buffer_interface&&) noexcept      = default;
            ring_buffer_interface(ring_buffer_interface&&) noexcept                 = default;
            ring_buffer_interface& operator=(const ring_buffer_interface&) noexcept = default;
            ring_buffer_interface(const ring_buffer_interface&) noexcept            = default;
 
            // forward declaration to grant friendship to the ring_buffer class.
            template<typename value_type2, size_type slice_count> friend class ring_buffer;
 
            /// @brief Modify the read or write position of the buffer.
            /// @param type the access type (read or write).
            /// @param sizeNew the size by which to modify the position.
            void modifyReadOrWritePosition(ring_buffer_access_type type, size_type sizeNew) {
                if (type == ring_buffer_access_type::read) {
                    tail += sizeNew;
                } else {
                    head += sizeNew;
                }
            }
 
            /// @brief Get the used space in the buffer.
            /// @return the used space in the buffer.
            size_type getUsedSpace() {
                return head - tail;
            }
 
            /// @brief Get a pointer to the current tail position.
            /// @return a pointer to the current tail position.
            pointer getCurrentTail() {
                return arrayValue.data() + (tail % size);
            }
 
            /// @brief Get a pointer to the current head position.
            /// @return a pointer to the current head position.
            pointer getCurrentHead() {
                return arrayValue.data() + (head % size);
            }
 
            /// @brief Check if the buffer is empty.
            /// @return true if the buffer is empty, otherwise false.
            bool isItEmpty() {
                return tail == head;
            }
 
            /// @brief Check if the buffer is full.
            /// @return true if the buffer is full, otherwise false.
            bool isItFull() {
                return getUsedSpace() == size;
            }
 
            /// @brief Clear the buffer by resetting positions.
            void clear() {
                tail = 0;
                head = 0;
            }
 
          protected:
            jsonifier::vector<std::unwrap_ref_decay_t<value_type>> arrayValue{};///< The underlying data array.
            size_type tail{};///< The tail position in the buffer.
            size_type head{};///< The head position in the buffer.
        };
 
        /// @brief A template implementation of a ring buffer using ring_buffer_interface.
        /// @tparam value_type the type of data stored in the buffer.
        /// @tparam slice_count the number of slices.
        template<typename value_type_new, uint64_t slice_count> class ring_buffer
            : public ring_buffer_interface<ring_buffer_interface<std::unwrap_ref_decay_t<value_type_new>, 1024 * 16>, slice_count> {
          public:
            using base_type     = ring_buffer_interface<ring_buffer_interface<std::unwrap_ref_decay_t<value_type_new>, 1024 * 16>, slice_count>;
            using value_type    = typename ring_buffer_interface<std::unwrap_ref_decay_t<value_type_new>, 1024 * 16>::value_type;
            using const_pointer = const value_type*;
            using pointer       = value_type*;
            using size_type     = uint64_t;
 
            /// @brief Default constructor. initializes the buffer size.
            ring_buffer() noexcept                              = default;
            ring_buffer& operator=(ring_buffer&&) noexcept      = default;
            ring_buffer(ring_buffer&&) noexcept                 = default;
            ring_buffer& operator=(const ring_buffer&) noexcept = default;
            ring_buffer(const ring_buffer&) noexcept            = default;
 
            /// @brief Write data into the buffer.
            /// @tparam value_type_new the type of data to be written.
            /// @param data pointer to the data.
            /// @param sizeNew size of the data.
            template<typename value_type_newer> void writeData(value_type_newer* data, size_type sizeNew) {
                if (base_type::isItFull() || base_type::getCurrentHead()->getUsedSpace() + sizeNew >= 16384) {
                    base_type::getCurrentTail()->clear();
                    base_type::modifyReadOrWritePosition(ring_buffer_access_type::read, 1);
                }
                size_type writeSize{ sizeNew };
                std::memcpy(base_type::getCurrentHead()->getCurrentHead(), data, sizeNew);
                base_type::getCurrentHead()->modifyReadOrWritePosition(ring_buffer_access_type::write, writeSize);
                base_type::modifyReadOrWritePosition(ring_buffer_access_type::write, 1);
            }
 
            /// @brief Read data from the buffer.
            /// @return a string view containing the read data.
            jsonifier::string_view_base<std::unwrap_ref_decay_t<value_type>> readData() {
                jsonifier::string_view_base<std::unwrap_ref_decay_t<value_type>> returnData{};
                if (base_type::getCurrentTail()->getUsedSpace() > 0) {
                    returnData = jsonifier::string_view_base<std::unwrap_ref_decay_t<value_type>>{ base_type::getCurrentTail()->getCurrentTail(),
                        base_type::getCurrentTail()->getUsedSpace() };
                    base_type::getCurrentTail()->clear();
                    base_type::modifyReadOrWritePosition(ring_buffer_access_type::read, 1);
                }
                return returnData;
            }
        };
 
        /**@}*/
    }
}