【Linux系统】日志与策略模式

[可读性很好的时间] [⽇志等级] [进程pid] [打印对应⽇志的⽂件名][⾏号] - 消息内容，⽀持可变参数
[2024-08-04 12:27:03] [DEBUG] [202938] [main.cc] [16] - hello world
[2024-08-04 12:27:03] [DEBUG] [202938] [main.cc] [17] - hello world
[2024-08-04 12:27:03] [DEBUG] [202938] [main.cc] [18] - hello world
[2024-08-04 12:27:03] [DEBUG] [202938] [main.cc] [20] - hello world
[2024-08-04 12:27:03] [DEBUG] [202938] [main.cc] [21] - hello world
[2024-08-04 12:27:03] [WARNING] [202938] [main.cc] [23] - hello world

#ifndef __LOG_HPP__
#define __LOG_HPP__

#include <iostream>
#include <filesystem> // C++17
#include <fstream>
#include <cstdio>
#include <string>
#include "Mutex.hpp"

namespace LogModule
{
    using namespace MutexModule;
    
    const std::string gsep = "\r\n";
    // 策略模式
    // 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——抽象类
    class LogStrategy
    {
    public:
        ~LogStrategy() = default; // 本质也是虚函数，多态行为，防止资源泄漏
        virtual void SyncLog(const std::string& message) = 0; // 纯虚函数
    };

    // 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 << std::endl;
        }

        ~ConsoleLogStrategy() {}
    private:
        Mutex _mutex;
    };

    const std::string defaultpath = "./log";
    const std::string defaultfile = "my.log";
    // 文件打印日志的策略 : 子类
    class FileLogStrategy : public LogStrategy
    {
    public:
        FileLogStrategy(const std::string& path = defaultpath, const std::string& file = defaultfile)
            :_path(path), _file(file)
            {
                LockGuard lockguard(_mutex);
                // 判断文件路径存不存在
                if(std::filesystem::exists(_path))
                {
                    return;
                }
                try
                {
                    std::filesystem::create_directories(_path); // 不存在则创建路径
                }
                catch(const std::filesystem::filesystem_error &e)
                {
                    std::cerr << e.what() << '\n'; // 失败就抛异常，并捕获
                }
            }

        void SyncLog(const std::string& message) override
        {
            LockGuard lockguard(_mutex);
            std::string filename = _path + (_path.back() == '/' ? "" : "/") + _file;
            std::ofstream out(filename, std::ios::app); // 以追加的方式打开文件
            if(!out.is_open())
            {
                return; // 打开失败就返回
            }
            out << message << gsep;
            out.close();
        } 

        ~FileLogStrategy() {}

    private:
        std::string _path; // 日志文件所在路径
        std::string _file; // 日志文件
        Mutex _mutex;
    };

}


#endif

class LogStrategy {
public:
    ~LogStrategy() = default; // 关键：虚析构函数确保派生类正确释放
    virtual void SyncLog(const std::string& message) = 0; // 纯虚函数，定义策略契约
};

class ConsoleLogStrategy : public LogStrategy {
public:
    ConsoleLogStrategy() {} // 构造函数通常不需要特殊操作
    void SyncLog(const std::string& message) override {
        LockGuard lockguard(_mutex); // 线程安全关键！
        std::cout << message << std::endl; // 核心操作：输出到控制台
    }
    ~ConsoleLogStrategy() {}
private:
    Mutex _mutex; // 互斥锁，保证多线程下输出不混乱
};

class FileLogStrategy : public LogStrategy {
public:
    FileLogStrategy(const std::string& path = defaultpath, const std::string& file = defaultfile)
        :_path(path), _file(file) {
        LockGuard lockguard(_mutex);
        // 构造时检查并创建日志目录
        if(!std::filesystem::exists(_path)) {
            try {
                std::filesystem::create_directories(_path);
            } catch(const std::filesystem::filesystem_error &e) {
                std::cerr << e.what() << '\n'; // 异常处理：目录创建失败
            }
        }
    }

    void SyncLog(const std::string& message) override {
        LockGuard lockguard(_mutex); // 线程安全
        std::string filename = _path + (_path.back() == '/' ? "" : "/") + _file;
        std::ofstream out(filename, std::ios::app); // 核心：以追加模式打开文件
        if(!out.is_open()) {
            return; // 处理文件打开失败
        }
        out << message << gsep; // 写入文件并换行 
        out.close(); // 显式关闭文件（也可依赖析构函数自动关闭）
    }
private:
    std::string _path;
    std::string _file;
    Mutex _mutex; // 保证多线程写文件安全
};

#include "Log.hpp"

using namespace LogModule;

int main()
{
    std::unique_ptr<LogStrategy> strategy = std::make_unique<ConsoleLogStrategy>(); 
    //std::unique_ptr<LogStrategy> strategy = std::make_unique<FileLogStrategy>(); 
    strategy->SyncLog("hello log!");
    return 0;
}

ltx@iv-ye1i2elts0wh2yp1ahah:~/gitLinux/Linux_system/lesson_thread/ThreadPool$ ./test
hello log!

    // 日志等级
    enum class LogLevel
    {
        DEBUG,
        INFO,
        WARNING,
        ERROR,
        FATAL
    };

    std::string LevelToStr(const 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 cur = time(nullptr);
        struct tm curr_tm;
        localtime_r(&cur, &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;
    }

    class Logger
    {
    public:
        Logger()
        {
            // 默认使用控制台策略
            EnableConsoleLogStrategy();
        }

        void EnableFileLogStrategy()
        {
            _flush_strategy = std::make_unique<FileLogStrategy>();
        }

        void EnableConsoleLogStrategy()
        {
            _flush_strategy = std::make_unique<ConsoleLogStrategy>();
        }

        // 一条日志信息
        class LogMessage
        {
        public:
            LogMessage(LogLevel& level, const std::string& src_name, int line, Logger& logger)
                :_cur_time(GetTimeStamp())
                ,_level(level)
                ,_pid(getpid())
                ,_src_name(src_name)
                ,_line(line)
                ,_logger(logger)
                {
                    // 日志的左边信息，合并起来
                    std::stringstream ss;
                    ss << "[" << _cur_time << "] "
                        << "[" << LevelToStr(_level) << "] "
                        << "[" << _pid << "] "
                        << "[" << _src_name << "] "
                        << "[" << _line << "] "
                        << "- ";
                    _loginfo = ss.str();
                }

            // 日志的右边信息，合并起来
            template<class T>
            LogMessage& operator<<(const T& info) // 注意使用引用返回，可以持续输入
            {
                std::stringstream ss;
                ss << info;
                _loginfo += ss.str();
                return *this;
            }
            
            ~LogMessage() 
            {
                // 如果刷新策略的指针不为空，就将日志刷新到选择的策略中
                if(_logger._flush_strategy)
                {
                    _logger._flush_strategy->SyncLog(_loginfo);
                }
            }

        private:
            std::string _cur_time; // 当前时间
            LogLevel _level; // 日志等级
            pid_t _pid; // 进程pid
            std::string _src_name; // 源文件名
            int _line; // 行号
            std::string _loginfo; // 一条完整日志信息
            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> _flush_strategy;
    };

    // 定义全局对象
    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_Strategy() logger.EnableConsoleLogStrategy()
    #define Enable_File_Log_Strategy() logger.EnableFileLogStrategy()

std::string GetTimeStamp()
{
    time_t cur = time(nullptr);           // 1. 获取当前时间戳
    struct tm curr_tm;
    localtime_r(&cur, &curr_tm);          // 2. 转换为本地时间结构
    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); // 3. 格式化时间
    
    return timebuffer;
}

// 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);
}

#include "Log.hpp"

using namespace LogModule;

void fun()
{
    int a = 10;
    LOG(LogLevel::FATAL) << "hello world" << 1234 << ", 3.14" << 'c' << a;
}
int main()
{
    LOG(LogLevel::DEBUG) << "hello world";
    LOG(LogLevel::DEBUG) << "hello world";
    LOG(LogLevel::DEBUG) << "hello world";

    LOG(LogLevel::DEBUG) << "hello world";
    LOG(LogLevel::DEBUG) << "hello world";
    LOG(LogLevel::WARNING) << "hello world";
    fun();
    return 0;
}

ltx@iv-ye1i2elts0wh2yp1ahah:~/gitLinux/Linux_system/lesson_thread/ThreadPool$ ./test
[2025-09-09 23:15:59] [DEBUG] [3580018] [Main.cc] [12] - hello world
[2025-09-09 23:15:59] [DEBUG] [3580018] [Main.cc] [13] - hello world
[2025-09-09 23:15:59] [DEBUG] [3580018] [Main.cc] [14] - hello world
[2025-09-09 23:15:59] [DEBUG] [3580018] [Main.cc] [16] - hello world
[2025-09-09 23:15:59] [DEBUG] [3580018] [Main.cc] [17] - hello world
[2025-09-09 23:15:59] [WARNING] [3580018] [Main.cc] [18] - hello world
[2025-09-09 23:15:59] [FATAL] [3580018] [Main.cc] [8] - hello world1234, 3.14c10