messaging_session.h

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// BSD 3-Clause License
// Copyright (c) 2024, 🍀☀🌕🌥 🌊
// See the LICENSE file in the project root for full license information.
 
#pragma once
 
#include <atomic>
#include <deque>
#include <functional>
#include <memory>
#include <mutex>
#include <span>
#include <string>
#include <string_view>
#include <vector>
 
#include <asio.hpp>
 
#include "kcenon/network/interfaces/i_session.h"
 
namespace kcenon::network::internal
{
    class tcp_socket;
}
 
// Use nested namespace definition in C++17
namespace kcenon::network::session
{
 
    class messaging_session
        : public interfaces::i_session
        , public std::enable_shared_from_this<messaging_session>
    {
    public:
        // Using string_view in constructor for efficiency (C++17)
    messaging_session(asio::ip::tcp::socket socket,
                          std::string_view server_id);
 
        ~messaging_session() noexcept override;
 
        // ========================================================================
        // i_session interface implementation
        // ========================================================================
 
        [[nodiscard]] auto id() const -> std::string_view override {
            return server_id_;
        }
 
        [[nodiscard]] auto is_connected() const -> bool override {
            return !is_stopped_.load(std::memory_order_acquire);
        }
 
        [[nodiscard]] auto send(std::vector<uint8_t>&& data) -> VoidResult override;
 
        auto close() -> void override { stop_session(); }
 
        // ========================================================================
        // Legacy API (maintained for backward compatibility)
        // ========================================================================
 
        auto start_session() -> void;
 
        auto stop_session() -> void;
 
        [[nodiscard]] auto is_stopped() const noexcept -> bool {
            return is_stopped_.load(std::memory_order_relaxed);
        }
 
        auto send_packet(std::vector<uint8_t>&& data) -> void;
 
        auto set_receive_callback(
            std::function<void(const std::vector<uint8_t>&)> callback) -> void;
 
        auto set_disconnection_callback(
            std::function<void(const std::string&)> callback) -> void;
 
        auto set_error_callback(
            std::function<void(std::error_code)> callback) -> void;
 
        [[nodiscard]] auto server_id() const -> const std::string& {
            return server_id_;
        }
 
    private:
        auto on_receive(std::span<const uint8_t> data) -> void;
 
        auto on_error(std::error_code ec) -> void;
 
        auto process_next_message() -> void;
 
    private:
        std::string server_id_; 
        std::shared_ptr<internal::tcp_socket>
            socket_;            
        std::atomic<bool> is_stopped_{
            false
        }; 
        std::deque<std::vector<uint8_t>> pending_messages_;
 
        mutable std::mutex queue_mutex_;
 
        static constexpr size_t max_pending_messages_ = 1000;
 
        std::function<void(const std::vector<uint8_t>&)> receive_callback_;
        std::function<void(const std::string&)> disconnection_callback_;
        std::function<void(std::error_code)> error_callback_;
 
        mutable std::mutex callback_mutex_;
    };
 
} // namespace kcenon::network::session