NetworkThread.hpp

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/***************************************************
 *       _   _            _                        *
 *      | | | |          (_)                       *
 *      | |_| | ___  _ __ _ _______  _ __          *
 *      |  _  |/ _ \| '__| |_  / _ \| '_  \        *
 *      | | | | (_) | |  | |/ / (_) | | | |        *
 *      \_| |_/\___/|_|  |_/___\___/|_| |_|        *
 ***************************************************
 * This file is part of Horizon (c).
 *
 * Copyright (c) 2019 Sagun K. (sagunxp@gmail.com).
 * Copyright (c) 2019 Horizon Dev Team.
 *
 * Base Author - Sagun K. (sagunxp@gmail.com)
 *
 * This library is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 *  (at your option) any later version.
 * 
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this library.  If not, see <http://www.gnu.org/licenses/>.
 **************************************************/
 
#ifndef HORIZON_NETWORKING_NETWORKTHREAD_HPP
#define HORIZON_NETWORKING_NETWORKTHREAD_HPP
 
#include "Core/Logging/Logger.hpp"
 
#include <thread>
#include <atomic>
#include <mutex>
#include <cassert>
#include <boost/asio/ip/tcp.hpp>
#include <boost/asio/deadline_timer.hpp>
 
using boost::asio::ip::tcp;
 
namespace Horizon
{
namespace Networking
{
template <class SocketType>
class NetworkThread
{
    typedef std::vector<std::shared_ptr<SocketType>> SocketContainer;
public:
    NetworkThread()
    : _connections(0), _finalizing(false), _update_timer(_io_context)
    {
        // Constructor
    }
 
    virtual ~NetworkThread()
    {
        finalize();
    }
 
    virtual void finalize()
    {
        _finalizing.exchange(true);
    }
 
    void join()
    {
        try {
            _thread->join();
        } catch (std::system_error &error) {
            HLog(error) << "Error joining network thread2: " << error.what();
        }
    }
 
    virtual bool start(int segment_number = 1)
    {
        if (_thread != nullptr)
            return false;
 
        _segment_number = segment_number;
        _thread.reset(new std::thread(&NetworkThread::run, this));
        return true;
    }
 
    virtual void add_socket(std::shared_ptr<SocketType> sock)
    {
        std::lock_guard<std::mutex> lock(_new_socket_queue_lock);
 
        _new_socket_queue.push_back(sock);  // Add socket to queue.
    }
 
    std::shared_ptr<tcp::socket> get_new_socket() { return std::make_shared<tcp::socket>(_io_context); }
 
    int32_t connection_count() const { return _connections; }
 
    bool is_finalizing() { return _finalizing; }
protected:
    virtual void run()
    {
        _update_timer.expires_from_now(boost::posix_time::microseconds(500));
        _update_timer.async_wait(std::bind(&NetworkThread<SocketType>::update, this));
 
        _io_context.run();
 
        _new_socket_queue.clear();
        _active_sockets.clear();
    }
 
    virtual void on_socket_removed(std::shared_ptr<SocketType> sock) = 0;
    virtual void on_socket_added(std::shared_ptr<SocketType> sock) = 0;
 
    virtual void update()
    {
        _update_timer.expires_from_now(boost::posix_time::microseconds(500));
        _update_timer.async_wait(std::bind(&NetworkThread<SocketType>::update, this));
 
        add_new_sockets();
        
        // The following code removes all non-active from the active sockets list by shifting all 
        // active sockets to the left and then erasing the extra
        _active_sockets.erase(std::remove_if(_active_sockets.begin(), _active_sockets.end(),
            [this] (std::shared_ptr<SocketType> sock)
            {
                if (!sock->update() || is_finalizing()) {
 
                    if (sock->is_open())
                        sock->close_socket();
 
                    on_socket_removed(sock);
 
                    --_connections;
 
                    HLog(info) << "Socket closed in networking thread " << (void *) (_thread.get()) << " (Connections: " << _connections << ")";
 
                    return true;
                }
 
                return false;
            }), _active_sockets.end());
 
        if (is_finalizing()) {
            _io_context.stop();
            _finalizing.exchange(false);
            HLog(info) << "Network thread " << (void *) (_thread.get()) << " has been finalized.";
        }
    }
 
    virtual void add_new_sockets()
    {
        if (is_finalizing())
            return;
 
        std::lock_guard<std::mutex> lock(_new_socket_queue_lock);
 
        if (_new_socket_queue.empty())
            return;
 
        for (std::shared_ptr<SocketType> sock : _new_socket_queue) {
            if (sock->is_open()) {
                _active_sockets.push_back(sock);
                // Start receiving from the socket.
                sock->start();
 
                on_socket_added(sock);
 
                ++_connections; // Increment network connections.
 
                HLog(trace) << "A new socket has been added to network thread " << (void *) (_thread.get()) << " (Connections: " << _connections << ")";
            }
        }
 
        _new_socket_queue.clear();
    }
 
protected:
    SocketContainer _active_sockets;
private:
    int _segment_number{1};
    std::atomic<int32_t> _connections;
    std::atomic<bool> _finalizing;
 
    std::unique_ptr<std::thread> _thread;
 
    SocketContainer _new_socket_queue;
 
    std::mutex _new_socket_queue_lock;
 
    boost::asio::io_context _io_context;
    boost::asio::deadline_timer _update_timer;
};
}
}
 
#endif // HORIZON_NETWORKING_NETWORKTHREAD_HPP