基于FIFO的c++多进程log封装

#ifndef PROCESS_LOG_H
#define PROCESS_LOG_H

#include <string>
#include <sstream>
#include <cstring>

#include <fcntl.h>
#include <sys/stat.h>
#include <sys/types.h>
#include<sys/time.h>
#include<unistd.h>

using std::string;

#define LOG_KIND_FILE_NAME 1
#define LOG_KIND_FIFO_NAME 2

#define LOG_ERROR_OPEN_FILE 1
#define LOG_ERROR_MKFIFO 2
#define LOG_ERROR_OPEN_FIFO 3
#define LOG_ERROR_FORK 4
#define LOG_ERROR_WRITE 5

class Log
{
private:
    string _log_file_name;
    string _log_fifo_name;
    int _log_file_fd;
    int _log_fifo_fd;
public:
    Log();
    Log & bind(int kind, string s);
    void start();
    void stop();
    void add(int pid, string s);
    ~Log();
};

 inline string getTime(void);

#endif

log.cpp:

#include "log.h"

//TODO  Log构造函数
Log::Log(/* args */) : _log_fifo_name(""),
    _log_file_fd(-1),
    _log_file_name("")
{
}

//TODO Log析构函数
Log::~Log()
{
    //释放文件
    if(_log_file_fd>0){
        close(_log_file_fd);
    }
    if(_log_fifo_fd > 0){
        close(_log_fifo_fd);
    }
}

//TODO 设置Log的属性（log文件名、FIFO文件名）
Log & Log::bind(int kind, string s)
{
    switch (kind)
    {
    case LOG_KIND_FILE_NAME:
        this->_log_file_name = s;
        break;
    case LOG_KIND_FIFO_NAME:
        this->_log_fifo_name = s;
        break;
    default:
        throw -1;
        break;
    }
    return *this;
}

//TODO 添加日志
void Log::add(int pid, string s)
{
    //构造日志格式[pid time] info
    std::stringstream ss;
    ss << "[" << pid << " " << getTime() << "]" << s;
    s = ss.str();
    //写入fifo
    write(this->_log_fifo_fd, s.c_str(), s.length());
}

//TODO 停止Log
void Log::stop()
{
    if(write(this->_log_fifo_fd, "STOP",  4) < 0){
        throw LOG_ERROR_WRITE;
    }
}

//TODO 启动Log进程
void Log::start()
{
    if(mkfifo(this->_log_fifo_name.c_str(), 0777) != 0){
        throw LOG_ERROR_MKFIFO;
    }

    //打开log文件
    this->_log_file_fd = open(this->_log_file_name.c_str(), O_WRONLY);
    if(_log_file_fd < 0){
        throw LOG_ERROR_OPEN_FILE;
    }
    
    //创建进程
    int fid = fork();
    //原进程
    if(fid > 0 ){
        //只写方式打开fifo
        this->_log_fifo_fd = open(this->_log_fifo_name.c_str(), O_WRONLY);
        if(this->_log_fifo_fd <= 0){
            throw LOG_ERROR_OPEN_FIFO;
        }
        return ;
    } 
    //log进程
    else if( fid == 0){
        //只读方式打开fifo
        this->_log_fifo_fd = open(this->_log_fifo_name.c_str(), O_RDONLY);
        if(this->_log_fifo_fd <= 0){
            throw LOG_ERROR_OPEN_FIFO;
        }

        //Loop
        bool stop_flag = false;
        while (!stop_flag)
        {
            //读取fifo
            char buf[1024];
            int len = read(this->_log_fifo_fd, buf, 1023);
            if(len <= 0){
                continue;
            }
            buf[len] = '\0';

            //停止
            if(strcasecmp("STOP",  buf) == 0){
                stop_flag = true;
            }
            //写入log
            if(write(this->_log_file_fd, buf, len) < 0){
                throw LOG_ERROR_WRITE;
            }

            //刷新文件
            sync();
        }
        //退出进程
        exit(0);
        
    } else {
        throw LOG_ERROR_FORK;
    }
}

    // TODO: 获取时间
 inline string getTime(void)
{
    timeval tv;
    tm * time;
   std::stringstream ss;

    if(gettimeofday(&tv, nullptr) == -1){
      throw errno;
    }
     time = localtime(&(tv.tv_sec));
    char systime[40];
    strftime(systime, 40, "%Y-%m-%d %H:%M:%S.",  time);
        
    ss << systime << (int64_t)(tv.tv_usec / 1000);
        
    return ss.str();
}