C++多线程异步日志实现

使用C++11标准，构建了一个方便使用的、轻量化的日志系统。封装线程安全的lockQueue，实现对每条日志添加信息、push到lockQueue中的LogTmp类，实现一个多线程异步的日志系统Logger。

lockqueue.h

#pragma once
#include <queue>
#include <string>
#include <thread>
#include <mutex> // pthread_mutex_t
#include <condition_variable> // pthread_condition_t

// 异步写日志的日志队列
class LockQueue
{
public:
    // 多个worker线程都会写日志queue 
    void Push(const std::string &data)
    {
        std::lock_guard<std::mutex> lock(m_mutex);
        m_queue.push(data);
        m_condvariable.notify_one();
    }

    // 一个线程读日志queue，写日志文件
    std::string Pop()
    {
        std::unique_lock<std::mutex> lock(m_mutex);
        while (m_queue.empty())
        {
            // 日志队列为空，线程进入wait状态
            m_condvariable.wait(lock);
        }

        std::string data = m_queue.front();
        m_queue.pop();
        return data;
    }
private:
    std::queue<std::string> m_queue;
    std::mutex m_mutex;
    std::condition_variable m_condvariable;
};

 logger.h

#pragma once
#include "lockqueue.h"
#include "timestamp.h"
#include <sstream>
#include <string>
#include <mutex>
#include <fstream>
#include <atomic>

// 定义日志级别 INFO  ERROR  FATAL  DEBUG
enum LogLevel
{
    DEBUG = 0, // 调试信息
    INFO,  // 普通信息
    ERROR, // 错误信息
    FATAL, // core信息
};

class LogTmp;
class Logger;

// 直接使用左移运算法<<进行输出，末尾不需要加换行
#define LOG_INFO \
    if(Logger::getInstance()->isEnable() && LogLevel::INFO >= Logger::getInstance()->getLogLevel()) \
        LogTmp::ptr(new LogTmp(Logger::getInstance(), INFO, __FILE__, __LINE__, __FUNCTION__))->getStringStream()
// 直接使用左移运算法<<进行输出，末尾不需要加换行
#define LOG_ERROR \
    if(Logger::getInstance()->isEnable() && LogLevel::ERROR >= Logger::getInstance()->getLogLevel()) \
        LogTmp::ptr(new LogTmp(Logger::getInstance(), ERROR, __FILE__, __LINE__, __FUNCTION__))->getStringStream()
// 直接使用左移运算法<<进行输出，末尾不需要加换行
#define LOG_FATAL \
    if(Logger::getInstance()->isEnable() && LogLevel::FATAL >= Logger::getInstance()->getLogLevel()) \
        LogTmp::ptr(new LogTmp(Logger::getInstance(), FATAL, __FILE__, __LINE__, __FUNCTION__))->getStringStream()


#define LOG_DEBUG \
    if(Logger::getInstance()->isEnable() && LogLevel::DEBUG >= Logger::getInstance()->getLogLevel()) \
        LogTmp::ptr(new LogTmp(Logger::getInstance(), DEBUG, __FILE__, __LINE__, __FUNCTION__))->getStringStream()



class LogTmp{
public:
    using ptr = std::unique_ptr<LogTmp>; // 使用指针，防止对象提前被析构
    LogTmp(Logger* logger, const int logLevel, const char *file, const int line, const char* func);
    ~LogTmp();
    std::stringstream& getStringStream();
private:
    Logger* logger_;
    std::stringstream ss_; // 通过<<接收用户的多种数据的log信息
};


// 可以设置是否启用日志（默认为启用）和日志等级（默认为最低级）
class Logger
{
public:
    // static std::stringstream& getStringStream(const int logLevel,
    //             const char* file = __FILE__,   
    //             const int line = __LINE__,
    //             const char* func = __FUNCTION__);

    static Logger* getInstance();

    void setEnableLogger(bool flag);

    void setLogLevel(LogLevel level);
    int getLogLevel(){ return logLevel_; }

    bool isEnable(){ return enableLogger_; }

    void pushLog(const std::string& log);

private:
    Logger();
    ~Logger();
    std::atomic_bool enableLogger_; // 设置是否启用日志功能，默认为true
    
    std::atomic_int logLevel_;

    // 静态变量，全局只有一个，在多线程的多个实例化对象中也可保持线程安全
    static std::mutex fileMutex_;
    static std::mutex loggerMutex_;
    static LockQueue lockQue_;
    static std::unique_ptr<std::thread> writeLogThread_;

    static Logger *logger_;
};

 logger.cc

#include "logger.h"
#include <thread>
#include <iostream>
 
LockQueue Logger::lockQue_;
std::mutex Logger::fileMutex_;
std::mutex Logger::loggerMutex_;
std::unique_ptr<std::thread> Logger::writeLogThread_;
Logger* Logger::logger_ = nullptr;

LogTmp::LogTmp(Logger* logger, const int logLevel, const char *file, const int line, const char* func)
    : logger_(logger)
{
    std::string time = Timestamp::now().toString();
    ss_ << time;
    switch (logLevel)
    {
    case INFO:
        ss_ << "[INFO] ";
        break;
    case ERROR:
        ss_ << "[ERROR]";
        break;
    case FATAL:
        ss_ << "[FATAL]";
        break;
    case DEBUG:
        ss_ << "[DEBUG]";
        break;
    default:
        break;
    }
    ss_ << " FILE:" << file << " LINE:" << line << " FUNC:" << func << "::";
    // std::cout << ss_.str() << std::endl;
}

LogTmp::~LogTmp(){
    ss_ << std::endl;
    // std::cout << "LogTmp::~LogTmp()" << std::endl;
    logger_->pushLog(ss_.str());
}
std::stringstream& LogTmp::getStringStream(){
    // std::cout << "LogTmp::getStringStream()" << std::endl;
    return this->ss_;
}

Logger::Logger()
    : enableLogger_(true), logLevel_(LogLevel::DEBUG)
{
    // 启动写文件的新线程，专门从lockQue中取日志写文件
    if(writeLogThread_ == nullptr){
        writeLogThread_ = std::make_unique<std::thread>([&](){
            while(1){
                // 取出一条日志
                std::string loginfo = lockQue_.Pop();
                // std::cout << "aaa" << loginfo;
                // 获取当前日期
                std::string time = Timestamp::now().toString();
                std::string filePath = time.substr(0, 10) + "-log.txt";
                // std::cout << "aaa" << filePath << std::endl;
                std::unique_lock<std::mutex> ulock(fileMutex_);
                // C++ 文件流
                std::ofstream file(filePath, std::ios::app);
                if (file.is_open())
                {
                    file << loginfo;
                    file.close();
                }
                else
                {
                    std::cout << "error : log file not open!" << std::endl;
                    return;
                }
            }
        });
        // 设置分离线程，守护线程
        writeLogThread_->detach();
    }
}

// 在此处将ss_中所有内容写入LockQue
Logger::~Logger()
{}
void Logger::pushLog(const std::string& log){
    lockQue_.Push(log);
}

// std::stringstream& Logger::getStringStream(const int logLevel, const char *file, const int line, const char *func)
// {
//     {
//         std::unique_lock<std::mutex> ulock(loggerMutex_);
//         if(logger_ == nullptr){
//             logger_ = new Logger();
//         }
//     }

//     LogTmp logTmp(logger_, logLevel, file, line, func);
//     return logTmp.getStringStream();
// }

Logger *Logger::getInstance()
{
    std::unique_lock<std::mutex> ulock(loggerMutex_);
    if(logger_ == nullptr){
        logger_ = new Logger();
    }
    ulock.unlock();
    return logger_;
}

void Logger::setEnableLogger(bool flag)
{
    enableLogger_ = flag;
}

void Logger::setLogLevel(LogLevel level)
{
    logLevel_ = level;
}

testlog.cc

#include "logger.h"

int main(){
    Logger::getInstance()->setLogLevel(LogLevel::DEBUG);
    {
    LOG_DEBUG << "debug";
    LOG_INFO << "info";
    LOG_ERROR << "error";
    LOG_FATAL << "fatal";
    }

    Logger::getInstance()->setLogLevel(LogLevel::INFO);
    {
    LOG_DEBUG << "debug";
    LOG_INFO << "info";
    LOG_ERROR << "error";
    LOG_FATAL << "fatal";
    }

    Logger::getInstance()->setLogLevel(LogLevel::ERROR);
    {
    LOG_DEBUG << "debug";
    LOG_INFO << "info";
    LOG_ERROR << "error";
    LOG_FATAL << "fatal";
    }

    Logger::getInstance()->setLogLevel(LogLevel::FATAL);
    {
    LOG_DEBUG << "debug";
    LOG_INFO << "info";
    LOG_ERROR << "error";
    LOG_FATAL << "fatal";
    }
    
    getchar();
    return 0;
}

 日志写入测试结果

上图中空行是测试完成后手打进去的，便于查看日志分级结果。 （第一行的hello是之前的日志）