esp-protocols/components/asio/examples/asio_chat/main/client.hpp

//
// client.hpp
// ~~~~~~~~~~~~~~~
//
// Copyright (c) 2003-2018 Christopher M. Kohlhoff (chris at kohlhoff dot com)
//
// Distributed under the Boost Software License, Version 1.0. (See accompanying
// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
//

#ifndef CHAT_CLIENT_HPP
#define CHAT_CLIENT_HPP

#include <deque>
#include "asio.hpp"
#include "chat_message.hpp"

typedef std::deque<chat_message> chat_message_queue;

class chat_client {
public:
    chat_client(asio::io_context &io_context,
                const asio::ip::tcp::resolver::results_type &endpoints)
        : io_context_(io_context),
          socket_(io_context)
    {
        do_connect(endpoints);
    }

    void write(const chat_message &msg)
    {
        asio::post(io_context_,
        [this, msg]() {
            bool write_in_progress = !write_msgs_.empty();
            write_msgs_.push_back(msg);
            if (!write_in_progress) {
                do_write();
            }
        });
    }

    void close()
    {
        asio::post(io_context_, [this]() {
            socket_.close();
        });
    }

private:
    void do_connect(const asio::ip::tcp::resolver::results_type &endpoints)
    {
        asio::async_connect(socket_, endpoints,
        [this](std::error_code ec, asio::ip::tcp::endpoint) {
            if (!ec) {
                do_read_header();
            }
        });
    }

    void do_read_header()
    {
        asio::async_read(socket_,
                         asio::buffer(read_msg_.data(), chat_message::header_length),
        [this](std::error_code ec, std::size_t /*length*/) {
            if (!ec && read_msg_.decode_header()) {
                do_read_body();
            } else {
                socket_.close();
            }
        });
    }

    void do_read_body()
    {
        asio::async_read(socket_,
                         asio::buffer(read_msg_.body(), read_msg_.body_length()),
        [this](std::error_code ec, std::size_t /*length*/) {
            if (!ec) {
                do_read_header();
            } else {
                socket_.close();
            }
        });
    }

    void do_write()
    {
        asio::async_write(socket_,
                          asio::buffer(write_msgs_.front().data(),
                                       write_msgs_.front().length()),
        [this](std::error_code ec, std::size_t /*length*/) {
            if (!ec) {
                write_msgs_.pop_front();
                if (!write_msgs_.empty()) {
                    do_write();
                }
            } else {
                socket_.close();
            }
        });
    }

private:
    asio::io_context &io_context_;
    asio::ip::tcp::socket socket_;
    chat_message read_msg_;
    chat_message_queue write_msgs_;
};

#endif // CHAT_CLIENT_HPP