TCP Echo Server 深度解析：从单进程到线程池的演进之路（中）

TCP Echo Server 深度解析：从单进程到线程池的演进之路（上）-CSDN博客

把tcpserver的实现逻辑梳理一下：

---

1. Init() 函数深度剖析

void Init()
    {
        // signal(SIGCHLD,SIG_IGN); //忽略

        // 1.创建套接字
        _listensockfd = socket(AF_INET, SOCK_STREAM, 0);
        if (_listensockfd < 0)
        {
            LOG(LogLevel::DEBUG) << "socket error";
            exit(SOCKET_ERR);
        }
        LOG(LogLevel::INFO) << "socket success: " << _listensockfd; // 3

        // 2.bind总所周知的端口号
        InetAddr local(_port);
        int n = bind(_listensockfd, local.NetAddrPtr(), local.NetAddrLen());
        if (n < 0)
        {
            LOG(LogLevel::FATAL) << "bind error";
            exit(BIND_ERR);
        }
        LOG(LogLevel::INFO) << "bind success: " << _listensockfd; // 3

        // 3.设置socket状态为listen
        n = listen(_listensockfd, backlog);
        if (n < 0)
        {
            LOG(LogLevel::FATAL) << "listen error";
            exit(LISTEN_ERR);
        }
        LOG(LogLevel::INFO) << "listen success: " << _listensockfd;
    }

1.1 socket() ------ 创建通信端点

_listensockfd = socket(AF_INET, SOCK_STREAM, 0);

参数	值	含义
domain	AF_INET	Address Family Internet ------ IPv4 协议族
type	SOCK_STREAM	面向连接的、可靠的字节流服务 ------ TCP
protocol	0	自动选择协议（TCP 对应 IPPROTO_TCP）

1.1.1返回值

文件描述符 (file descriptor)

返回的 fd 是文件描述符表中的索引，指向这个socket的结构体

1.2 bind() ------ 绑定地址

InetAddr local(_port);
int n = bind(_listensockfd, local.NetAddrPtr(), local.NetAddrLen());

为什么要 bind？

端口号范围问题：

1.3 listen() ------ 设置监听状态

n = listen(_listensockfd, backlog);

为什么要 listen？

backlog 参数 ：

---

2. Run() 与 Accept 的本质

2.1 accept() 函数解析

int sockfd = accept(_listensockfd, CONV(peer), &len);

核心问题：accept 返回的 fd 和 _listensockfd 有什么区别？

accept 的参数 ：

参数	作用
sockfd	监听套接字
addr	输出参数，填充客户端地址信息
addrlen	输入输出参数，地址结构体长度

2.2 telnet ------ 简易 TCP 客户端工具

$ telnet www.baidu.com 80

2.3 netstat 查看连接状态

$ netstat -tnlp

参数含义：

• -t: TCP 协议

• -n: 数字形式显示地址和端口

• -l: 仅显示监听状态的套接字

• -p: 显示进程信息

这里我们看到有两条， 因为

1 ） TCP是全双工的

2 ）主要原因：因为我们的客户端和服务端在一台主机上！！！

3. 基础代码 -- 方便后续我们三个版本的EchoServer的实现

3.1 Cond.hpp

#pragma once

#include <iostream>
#include <pthread.h>
#include "Mutex.hpp"

using namespace MutexModule;

namespace CondModule
{
    class Cond
    {
    public:
        Cond()
        {
            pthread_cond_init(&_cond, nullptr);
        }
        void Wait(Mutex &mutex)
        {
            int n = pthread_cond_wait(&_cond, mutex.Get());
            (void)n;
        }
        void Signal()
        {
            // 唤醒在条件变量下等待的一个线程
            int n = pthread_cond_signal(&_cond);
            (void)n;
        }
        void Broadcast()
        {
            // 唤醒所有在条件变量下等待的线程
            int n = pthread_cond_broadcast(&_cond);
            (void)n;
        }
        ~Cond()
        {
            pthread_cond_destroy(&_cond);
        }
    private:
        pthread_cond_t _cond;
    };
};

3.2 InetAddr.hpp

#pragma once
#include <iostream>
#include <string>
#include <cstring>
#include <sys/socket.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include "Common.hpp"

// 网络地址和主机地址之间进行转化的类

class InetAddr
{
public:
    InetAddr() {}
    InetAddr(struct sockaddr_in &addr) : _addr(addr)
    {
        // 网络转主机
        _port = ntohs(_addr.sin_port); // 这个端口号是从网络中来的！网络序列
        //_ip = inet_ntoa(_addr.sin_addr); // 4字节 -》 点分十进制的字符串
        char ipbuffer[64];
        inet_ntop(AF_INET, &_addr.sin_addr, ipbuffer, sizeof(_addr));
        _ip = ipbuffer;
    }
    InetAddr(const std::string &ip, uint16_t port) : _ip(ip), _port(port)
    {
        // 主机转网络
        memset(&_addr, 0, sizeof(_addr));
        _addr.sin_family = AF_INET;
        inet_pton(AF_INET, _ip.c_str(), &_addr.sin_addr);
        _addr.sin_port = htons(port);
    }
    InetAddr(uint16_t port) : _port(port), _ip()
    {
        // 主机转网络
        memset(&_addr, 0, sizeof(_addr));
        _addr.sin_family = AF_INET;
        _addr.sin_addr.s_addr = INADDR_ANY;
        _addr.sin_port = htons(port);
    }

    uint16_t Port() { return _port; }
    std::string Ip() { return _ip; }
    const struct sockaddr_in &NetAddr() { return _addr; }
    const struct sockaddr *NetAddrPtr()
    {
        return CONV(_addr);
    }
    socklen_t NetAddrLen()
    {
        return sizeof(_addr);
    }
    bool operator==(const InetAddr &addr)
    {
        return addr._ip == _ip && addr._port == _port;
    }
    std::string StringAddr()
    {
        return _ip + ":" + std::to_string(_port);
    }

    ~InetAddr()
    {
    }

private:
    struct sockaddr_in _addr;
    std::string _ip;
    uint16_t _port;
};

3.3 Log.hpp

#ifndef __LOG_HPP__
#define __LOG_HPP__

#include <iostream>
#include <filesystem> //c++17
#include <fstream>
#include <string>
#include <cstdio>
#include <memory>
#include <unistd.h>
#include <ctime>
#include <sstream>
#include "Mutex.hpp"

using namespace MutexModule;

namespace LogModule
{
    const std::string gsep = "\r\n";
    // 策略模式 -- C++多态特性
    //  2.刷新策略 a:显示器打印 b:向指定的文件写入
    //  刷新策略基类
    class LogStrategy
    {
    public:
        ~LogStrategy() = default;
        virtual void SyncLog(const std::string &message) = 0;

    private:
    };

    // 显示器打印日志的策略:子类
    class ConsoleLogStrategy : public LogStrategy
    {
    public:
        ConsoleLogStrategy()
        {
        }
        void SyncLog(const std::string &message) override
        {
            LockGuard lockguard(_mutex);
            std::cout << message << gsep;
        }
        ~ConsoleLogStrategy()
        {
        }

    private:
        Mutex _mutex; // 显示器也是临界资源，保证输出线程安全
    };

    // 文件打印日志的策略 : 子类
    const std::string defaultPath = "./log";
    const std::string defaultfile = "log.log";
    class FileLogStrategy : public LogStrategy
    {
    public:
        FileLogStrategy(const std::string &path = defaultPath, const std::string &file = defaultfile)
            : _path(path),
              _file(file)
        {
            LockGuard lockguard(_mutex);
            if (std::filesystem::exists(_path))
            {
                return;
            }
            try
            {
                std::filesystem::create_directories(_path);
            }
            catch (const std::filesystem::filesystem_error &e)
            {
                std::cerr << e.what() << "\n";
            }
        }
        void SyncLog(const std::string &message) override
        {
            LockGuard lockguard(_mutex);
            std::string filename = _path + (_path.back() == '/' ? "" : "/") + _file;
            //"./log/" + "my.log"
            std::ofstream out(filename, std::ios::app); // 以追加写入的方式打开
            if (!out.is_open())
            {
                return;
            }
            out << message << gsep;
            out.close();
        }

        ~FileLogStrategy()
        {
        }

    private:
        std::string _path; // 日志文件所在的路径
        std::string _file; // 日志文件本身

        Mutex _mutex;
    };

    // 形成一条完整的日志&&根据上面的策略，选择不同的刷新方式

    // 1.形成日志等级
    enum class LogLevel
    {
        DEBUG,
        INFO,
        WARNING,
        ERROR,
        FATAL
    };
    std::string Level2Str(LogLevel level)
    {
        switch (level)
        {
        case LogLevel::DEBUG:
            return "DEBUG";
        case LogLevel::INFO:
            return "INFO";
        case LogLevel::WARNING:
            return "WARNING";
        case LogLevel::ERROR:
            return "ERROR";
        case LogLevel::FATAL:
            return "FATAL";
        default:
            return "UNKNOWN";
        }
    }
    std::string GetTimeStamp()
    {
        time_t curr = time(nullptr);
        struct tm curr_tm;
        localtime_r(&curr, &curr_tm);
        char timebuffer[128];
        snprintf(timebuffer, sizeof(timebuffer), "%4d-%02d-%02d %02d:%02d:%02d",
                 curr_tm.tm_year+1900,
                 curr_tm.tm_mon+1,
                 curr_tm.tm_mday,
                 curr_tm.tm_hour,
                 curr_tm.tm_min,
                 curr_tm.tm_sec);
        return timebuffer;
    }

    // 1.形成日志 && 2.根据不同的策略，完成刷新
    class Logger
    {
    public:
        Logger()
        {
            EnableConsoleLogStrategy();
        }
        void EnableFileLogStrategy()
        {
            _fflush_strategy = std::make_unique<FileLogStrategy>();
        }
        void EnableConsoleLogStrategy()
        {
            _fflush_strategy = std::make_unique<ConsoleLogStrategy>();
        }

        // 内部类  表示的是未来的一条日志
        class LogMessage
        {
        public:
            LogMessage(LogLevel &level, std::string &src_name, int line_number, Logger &logger)
                : _curr_time(GetTimeStamp()),
                  _level(level),
                  _pid(getpid()),
                  _src_name(src_name),
                  _line_number(line_number),
                  _logger(logger)
            {
                // 日志左边部分，合并起来
                std::stringstream ss;
                ss << "[" << _curr_time << "]"
                   << "[" << Level2Str(_level) << "]"
                   << "[" << _pid << "]"
                   << "[" << _src_name << "]"
                   << "[" << _line_number << "]"
                   << "- ";
                _loginfo = ss.str();
            };

            // LogMessage() << "hello world" << "xxxx" << 3.14 << 1234;
            // 需要支持重载
            template <typename T>
            LogMessage &operator<<(const T &info)
            {
                // 日志右边部分，可变的
                std::stringstream ss;
                ss << info;
                _loginfo += ss.str();
                return *this;
            }

            ~LogMessage()
            {
                if (_logger._fflush_strategy)
                {
                    _logger._fflush_strategy->SyncLog(_loginfo);
                }
            };

        private:
            std::string _curr_time;
            LogLevel _level;
            pid_t _pid;
            std::string _src_name;
            int _line_number;
            std::string _loginfo; // 合并完成之后，一条完整的信息
            Logger &_logger;
        };
        // 这里故意写成返回临时对象
        LogMessage operator()(LogLevel level, std::string name, int line)
        {
            return LogMessage(level, name, line, *this);
        }
        ~Logger() {}

    private:
        std::unique_ptr<LogStrategy> _fflush_strategy;
    };

    // 全局日志对象
    Logger logger;

// 使用宏，简化用户操作，获取文件名和行号
#define LOG(level) logger(level, __FILE__, __LINE__)
#define Enable_Console_Log_Stratege() logger.EnableConsoleLogStrategy();
#define Enable_File_Log_Stratege() logger.EnableFileLogStrategy();
}

#endif

3.4 Mutex.hpp

#pragma once

#include <iostream>
#include <pthread.h>

namespace MutexModule
{
    class Mutex
    {
    public:
        Mutex()
        {
            pthread_mutex_init(&_mutex, nullptr);
        }
        void Lock()
        {
            int n = pthread_mutex_lock(&_mutex);
            (void)n;
        }
        void Unlock()
        {
            int n = pthread_mutex_unlock(&_mutex);
            (void)n;
        }
        ~Mutex()
        {
            pthread_mutex_destroy(&_mutex);
        }
        pthread_mutex_t *Get()
        {
            return &_mutex;
        }
    private:
        pthread_mutex_t _mutex;
    };

    class LockGuard
    {
    public:
        LockGuard(Mutex &mutex) : _mutex(mutex)
        {
            _mutex.Lock();
        };
        ~LockGuard()
        {
            _mutex.Unlock();
        };

    private:
        Mutex &_mutex;
    };
}

3.5 Thread.hpp

#ifndef _THREAD_H_
#define _THREAD_H_

#include <iostream>
#include <string>
#include <pthread.h>
#include <cstdio>
#include <cstring>
#include <functional>

namespace ThreadModlue
{
    static uint32_t number = 1; // bug

    class Thread
    {
        using func_t = std::function<void()>; // 暂时这样写，完全够了
    private:
        void EnableDetach()
        {
            _isdetach = true;
        }
        void EnableRunning()
        {
            _isrunning = true;
        }
        static void *Routine(void *args) // 属于类内的成员函数，默认包含this指针！
        {
            Thread *self = static_cast<Thread *>(args);
            self->EnableRunning();
            if (self->_isdetach)
                self->Detach();
            pthread_setname_np(self->_tid, self->_name.c_str());
            self->_func(); // 回调处理

            return nullptr;
        }
        // bug
    public:
        Thread(func_t func)
            : _tid(0),
              _isdetach(false),
              _isrunning(false),
              res(nullptr),
              _func(func)
        {
            _name = "thread-" + std::to_string(number++);
        }
        void Detach()
        {
            if (_isdetach)
                return;
            if (_isrunning)
                pthread_detach(_tid);
            EnableDetach();
        }

        bool Start()
        {
            if (_isrunning)
                return false;
            int n = pthread_create(&_tid, nullptr, Routine, this);
            if (n != 0)
            {
                return false;
            }
            else
            {
                return true;
            }
        }
        bool Stop()
        {
            if (_isrunning)
            {
                int n = pthread_cancel(_tid);
                if (n != 0)
                {
                    return false;
                }
                else
                {
                    _isrunning = false;
                    return true;
                }
            }
            return false;
        }
        void Join()
        {
            if (_isdetach)
            {
                return;
            }
            int n = pthread_join(_tid, &res);
            if (n != 0)
            {
            }
            else
            {
            }
        }
        pthread_t Id()
        {
            return _tid;
        }
        std::string Name()
        {
            return _name;
        }
        ~Thread()
        {
        }

    private:
        pthread_t _tid;
        std::string _name;
        bool _isdetach;
        bool _isrunning;
        void *res;
        func_t _func;
    };
}

#endif

3.6 ThreadPool.hpp

#pragma once
#include <iostream>
#include <string>
#include <vector>
#include <queue>
#include "Log.hpp"
#include "Thread.hpp"
#include "Cond.hpp"
#include "Mutex.hpp"

// .hpp header only

namespace ThreadPoolModule
{
    using namespace ThreadModlue;
    using namespace LogModule;
    using namespace CondModule;
    using namespace MutexModule;

    static const int gnum = 15;
    template <typename T>
    class ThreadPool
    {
    private:
        void WakeUpAllThread()
        {
            LockGuard lockguard(_mutex);
            if (_sleepernum)
                _cond.Broadcast();
            LOG(LogLevel::INFO) << "唤醒所有的休眠线程";
        }

        void WakeUpOne()
        {
            _cond.Signal();
            LOG(LogLevel::INFO) << "唤醒一个休眠线程";
        }

        ThreadPool(int num = gnum) : _num(num), _isrunning(false), _sleepernum(0)
        {
            for (int i = 0; i < num; i++)
            {
                _threads.emplace_back(
                    [this]()
                    {
                        HandlerTask();
                    });
            }
        }
        void Start()
        {
            if (_isrunning)
                return;
            _isrunning = true;
            for (auto &thread : _threads)
            {
                thread.Start();
                LOG(LogLevel::INFO) << "start new thread success: " << thread.Name();
            }
        }

        ThreadPool(const ThreadPool<T> &) = delete;
        ThreadPool<T> &operator=(const ThreadPool<T> &) = delete;

    public:
        static ThreadPool<T> *GetInstance()
        {
            if (inc == nullptr)
            {
                LockGuard lockguard(_lock);

                LOG(LogLevel::DEBUG) << "获取单例....";
                if (inc == nullptr)
                {
                    LOG(LogLevel::DEBUG) << "首次使用单例, 创建之....";
                    inc = new ThreadPool<T>();
                    inc->Start();
                }
            }

            return inc;
        }
        void Stop()
        {
            if (!_isrunning)
                return;
            _isrunning = false;

            // 唤醒所有的线层
            WakeUpAllThread();
        }
        void Join()
        {
            for (auto &thread : _threads)
            {
                thread.Join();
            }
        }
        void HandlerTask()
        {
            char name[128];
            pthread_getname_np(pthread_self(), name, sizeof(name));
            while (true)
            {
                T t;
                {
                    LockGuard lockguard(_mutex);
                    // 1. a.队列为空 b. 线程池没有退出
                    while (_taskq.empty() && _isrunning)
                    {
                        _sleepernum++;
                        _cond.Wait(_mutex);
                        _sleepernum--;
                    }
                    // 2. 内部的线程被唤醒
                    if (!_isrunning && _taskq.empty())
                    {
                        LOG(LogLevel::INFO) << name << " 退出了, 线程池退出&&任务队列为空";
                        break;
                    }

                    // 一定有任务
                    t = _taskq.front(); // 从q中获取任务，任务已经是线程私有的了！！！
                    _taskq.pop();
                }
                t(); // 处理任务，需/要在临界区内部处理吗？1 0
            }
        }
        bool Enqueue(const T &in)
        {
            if (_isrunning)
            {
                LockGuard lockguard(_mutex);
                _taskq.push(in);
                if (_threads.size() == _sleepernum)
                    WakeUpOne();
                return true;
            }
            return false;
        }
        ~ThreadPool()
        {
        }

    private:
        std::vector<Thread> _threads;
        int _num; // 线程池中，线程的个数
        std::queue<T> _taskq;
        Cond _cond;
        Mutex _mutex;

        bool _isrunning;
        int _sleepernum;

        // bug??
        static ThreadPool<T> *inc; // 单例指针
        static Mutex _lock;
    };

    template <typename T>
    ThreadPool<T> *ThreadPool<T>::inc = nullptr;

    template <typename T>
    Mutex ThreadPool<T>::_lock;

}