系列文章目录：C++ asio网络编程-CSDN博客 

1、服务器架构设计

2、单例模板类

        我们的LogicSystem类为单例类，可以只把这个类写为单例，也可以写一个单例模板类，让其它类继承它就可以形成单例。这里选择第二种，因为后面可能还会实现其他的单例类。

#pragma once
#include <memory>
#include <mutex>
#include <iostream>

template <typename T>
class Singleton
{
public:
	~Singleton() {
		std::cout << "singleton destruct" << std::endl;
	}

	static std::shared_ptr<T> getInstance() {
		static std::once_flag s_flag;
		std::call_once(s_flag, [&]() {
			_instance = std::shared_ptr<T>(new T);
		});
		return _instance;
	}

	void printAddress() {
		std::cout << _instance->get() << std::endl;
	}


protected:
	Singleton() = default;
	Singleton(const Singleton<T>&) = delete;
	Singleton& operator = (const Singleton<T>& st) = delete;

	static std::shared_ptr<T> _instance;
};

template <typename T>
std::shared_ptr<T> Singleton<T>::_instance = nullptr;

        C++基础好的同学应该很容易看明白，有不明白的地方可以利用一些ai工具解读一下，也很简单。

3、LogicSystem类

#pragma once
#include "Singleton.h"
#include <queue>
#include <thread>
#include "const.h"
#include "Session.h"
#include <map>
#include <functional>
#include <json/json.h>
#include <json/value.h>
#include <json/reader.h>

class LogicNode;
class Session;

typedef std::function<void(std::shared_ptr<Session>, const short& msg_id, const std::string& msg_data)> FunCallBack;

class LogicSystem : public Singleton<LogicSystem>
{
	friend class Singleton<LogicSystem>;

public:
	~LogicSystem();

	void postMsgToQue(std::shared_ptr<LogicNode> msg);

private:
	LogicSystem();
	void registerCallBacks();
	void helloWordCallBack(std::shared_ptr<Session>, const short& msg_id, const std::string& msg_data);
	void dealMsg();

	std::queue<std::shared_ptr<LogicNode>> _msg_que;  // 逻辑队列
	std::mutex _mutex;
	std::condition_variable _consume; // 条件变量，控制当逻辑队列为空时保证线程暂时挂起等待，不要干扰其他线程
	std::thread _worker_thread;
	bool _b_stop;  // 停止信号，控制逻辑类中止工作线程
	std::map<short, FunCallBack> _fun_callback; // 回调函数的map，根据id查找对应的逻辑处理函数
};

#include "LogicSystem.h"

LogicSystem::~LogicSystem()
{
	_b_stop = true;
	_consume.notify_one();
	_worker_thread.join();
}

void LogicSystem::postMsgToQue(std::shared_ptr<LogicNode> msg)
{
	std::unique_lock<std::mutex> ulock(_mutex);
	_msg_que.push(msg);

	if (_msg_que.size() == 1) {
		_consume.notify_one();
	}
}

LogicSystem::LogicSystem() : _b_stop(false)
{
	registerCallBacks();
	_worker_thread = std::thread(&LogicSystem::dealMsg, this);
}

void LogicSystem::registerCallBacks()
{
	_fun_callback[MSG_HELLO_WORD] = std::bind(&LogicSystem::helloWordCallBack, this,
		std::placeholders::_1, std::placeholders::_2, std::placeholders::_3);
}

void LogicSystem::helloWordCallBack(std::shared_ptr<Session> session, const short& msg_id, const std::string& msg_data)
{
	Json::Reader reader;
	Json::Value root;
	reader.parse(msg_data, root);
	std::cout << "receive msg id is " << root["id"].asInt() << "msg data is " 
		<< root["data"].asString() << std::endl;
	root["data"] = "server has receive msg: " + root["data"].asString();

	std::string return_str = root.toStyledString();
	session->send(return_str, root["id"].asInt());
}

void LogicSystem::dealMsg()
{
	for (;;) {
		std::unique_lock<std::mutex> ulock(_mutex);
		// 队列为空并且正在处理消息则用条件变量等待
		while (_msg_que.empty() && !_b_stop) {
			_consume.wait(ulock);  // 先释放资源再解锁
		}
		// 关闭状态时，取出逻辑队列所有数据及时处理，并且退出循环
		if (_b_stop) {
			while (!_msg_que.empty()) {
				auto msg_node = _msg_que.front();
				std::cout << "receive msg id: " << msg_node->_recvNode->_msg_id << std::endl;
				auto call_back_iter = _fun_callback.find(msg_node->_recvNode->_msg_id);
				if (call_back_iter == _fun_callback.end()) {
					_msg_que.pop();
					continue;
				}
				call_back_iter->second(msg_node->_session, 
					msg_node->_recvNode->_msg_id, 
					std::string(msg_node->_recvNode->_data, msg_node->_recvNode->_cur_len));
				_msg_que.pop();
			}
			break;
		}
		// 没有停服，并且队列有数据
		auto msg_node = _msg_que.front();
		std::cout << "receive msg id: " << msg_node->_recvNode->_msg_id << std::endl;
		auto call_back_iter = _fun_callback.find(msg_node->_recvNode->_msg_id);
		if (call_back_iter == _fun_callback.end()) {
			_msg_que.pop();
			continue;
		}
		call_back_iter->second(msg_node->_session,
			msg_node->_recvNode->_msg_id,
			std::string(msg_node->_recvNode->_data, msg_node->_recvNode->_cur_len));
		_msg_que.pop();
	}
}

        MSG_HELLO_WORD定义在const.h中，表示消息id

enum MSG_IDS {
	MSG_HELLO_WORD = 1001
};

4、逻辑节点

        在Session.h中，我们可以添加一个逻辑节点类

class LogicNode
{
	friend class LogicSystem;
public:
    // 第二个参数是为了防止session被提前释放
	LogicNode(std::shared_ptr<Session>, std::shared_ptr<RecvNode>); 
private:
	std::shared_ptr<Session> _session;
	std::shared_ptr<RecvNode> _recvNode;
};

LogicNode::LogicNode(std::shared_ptr<Session> session, std::shared_ptr<RecvNode> recvNode)
	: _session(session), _recvNode(recvNode)
{
}