【Qt】【第三方库】spdlog日志模块的使用

版本

spdlog版本：1.5.0

采用1.5.0版本主要基于以下考虑：兼容Qt5.9.X版本和兼容C++11。

spdlog 1.5.0下载地址：https://github.com/gabime/spdlog/releases/tag/v1.5.0

摘要

在Qt应用程序开发中，良好的日志系统至关重要。本文将介绍如何使用spdlog 1.5.0创建满足以下要求的日志系统：

自定义文件名格式：yyyyMMdd_hhmmss_毫秒.log，不使用spdlog提供的日志轮转功能

spdlog::sinks::rotating_file_sink_mt，采用自定义custom_rotating_file_sink；
保留最近10个日志文件，每个日志文件大小限制为1MB。

例子

logmanager.h文件

cpp 复制代码

#ifndef LOGMANAGER_H
#define LOGMANAGER_H

#include <QObject>
#include <memory>
#include <spdlog/spdlog.h>

class LogManager : public QObject
{
    Q_OBJECT
public:
    static LogManager& instance();

    void initialize(const QString& logDir = "logs",
                    const QString& appName = "app",
                    size_t maxFileSize = 1024 * 1024, // 1MB
                    size_t maxFiles = 10);
    void shutdown();

    template<typename... Args>
    static void log(spdlog::level::level_enum level, const QString& message, Args... args)
    {
        if (instance().m_logger)
        {
            instance().m_logger->log(level, message.toStdString().c_str(), args...);
        }
    }

    // 便捷方法
    static void trace(const QString& message)
    {
        log(spdlog::level::trace, message);
    }
    static void debug(const QString& message)
    {
        log(spdlog::level::debug, message);
    }
    static void info(const QString& message)
    {
        log(spdlog::level::info, message);
    }
    static void warn(const QString& message)
    {
        log(spdlog::level::warn, message);
    }
    static void error(const QString& message)
    {
        log(spdlog::level::err, message);
    }
    static void critical(const QString& message)
    {
        log(spdlog::level::critical, message);
    }


private:
    LogManager(QObject* parent = nullptr);
    ~LogManager();

    std::shared_ptr<spdlog::logger> createCustomLogger(const std::string& base_filename,
            size_t max_size,
            size_t max_files);

    std::shared_ptr<spdlog::logger> m_logger;
    std::atomic<bool> m_shuttingDown{false};

signals:
    void aboutToShutdown();

private slots:
    void onAboutToQuit();

};

// 日志宏定义
#define LOG_TRACE(...)    LogManager::log(spdlog::level::trace, __VA_ARGS__)
#define LOG_DEBUG(...)    LogManager::log(spdlog::level::debug, __VA_ARGS__)
#define LOG_INFO(...)     LogManager::log(spdlog::level::info, __VA_ARGS__)
#define LOG_WARN(...)     LogManager::log(spdlog::level::warn, __VA_ARGS__)
#define LOG_ERROR(...)    LogManager::log(spdlog::level::err, __VA_ARGS__)
#define LOG_CRITICAL(...) LogManager::log(spdlog::level::critical, __VA_ARGS__)

#endif // LOGMANAGER_H

logmanager.cpp文件

cpp 复制代码

#include "logmanager.h"
#include <spdlog/sinks/base_sink.h>
#include <spdlog/details/file_helper.h>
#include <mutex>
#include <chrono>
#include <iomanip>
#include <sstream>
#include <vector>
#include <algorithm>
#include <QDir>
#include <QFileInfo>
#include <QDateTime>
#include <QCoreApplication>
#include <csignal>
#include <QDebug>

// 替换 std::filesystem 的 C++11 兼容实现
namespace spdlog
{
    class custom_rotating_file_sink : public spdlog::sinks::base_sink<std::mutex>
    {
    public:
        custom_rotating_file_sink(const std::string& base_filename,
                                  std::size_t max_size,
                                  std::size_t max_files)
            : base_filename_(base_filename),
              max_size_(max_size),
              max_files_(max_files)
        {
            file_helper_.open(gen_filename());
        }

    protected:
        void sink_it_(const spdlog::details::log_msg& msg) override
        {
            spdlog::memory_buf_t formatted;
            formatter_->format(msg, formatted);

            if (file_helper_.size() + formatted.size() > max_size_)
            {
                rotate_();
            }

            file_helper_.write(formatted);
        }

        void flush_() override
        {
            file_helper_.flush();
        }

    private:
        std::string gen_filename()
        {
            QDateTime now = QDateTime::currentDateTime();
            QString timeStr = now.toString("yyyyMMddhhmmss");

            // 添加毫秒部分(3位)
            int ms = now.time().msec();
            timeStr += QString("_%1").arg(ms, 3, 10, QLatin1Char('0'));

            return base_filename_ + "_" + timeStr.toStdString() + ".log";
        }

        void rotate_()
        {
            file_helper_.close();
            cleanup_old_files();
            file_helper_.open(gen_filename());
        }

        void cleanup_old_files()
        {
            if (max_files_ == 0) return;

            QFileInfo base_info(QString::fromStdString(base_filename_));
            QDir dir = base_info.absoluteDir();
            QString base_name = base_info.fileName();

            QFileInfoList files = dir.entryInfoList(QStringList() << (base_name + "_*.log"),
                                                    QDir::Files, QDir::Time);

            // 删除最旧的文件
            while (files.size() >= static_cast<int>(max_files_))
            {
                QFile::remove(files.last().absoluteFilePath());
                files.removeLast();
            }
        }

        std::string base_filename_;
        std::size_t max_size_;
        std::size_t max_files_;
        spdlog::details::file_helper file_helper_;
    };

} // namespace

LogManager::LogManager(QObject* parent) : QObject(parent)
{
    // 连接Qt退出信号
    connect(qApp, &QCoreApplication::aboutToQuit, this, &LogManager::onAboutToQuit);

    // 处理异常信号
    static auto handleSignal = [](int)
    {
        LogManager::instance().shutdown();
        std::_Exit(1);
    };

    std::signal(SIGTERM, handleSignal);
    std::signal(SIGSEGV, handleSignal);
    std::signal(SIGINT, handleSignal);
    std::signal(SIGABRT, handleSignal);
}

LogManager::~LogManager()
{
    shutdown();
}

LogManager& LogManager::instance()
{
    static LogManager instance;
    return instance;
}

void LogManager::initialize(const QString& logDir, const QString& appName, size_t maxFileSize, size_t maxFiles)
{
    if (m_logger)
    {
        return;
    }

    // 确保日志目录存在
    QDir().mkpath(logDir);

    std::string base_filename = QDir(logDir).absoluteFilePath(appName).toStdString();
    m_logger = createCustomLogger(base_filename, maxFileSize, maxFiles);

    // 设置默认日志格式
    m_logger->set_pattern("[%Y-%m-%d %H:%M:%S.%e] [%l] [thread %t] %v");
    m_logger->set_level(spdlog::level::trace);

    spdlog::register_logger(m_logger);
    spdlog::set_default_logger(m_logger);
}

void LogManager::shutdown()
{
    /*
    if (m_logger)
    {
        spdlog::drop(m_logger->name());
        m_logger.reset();
    }
    spdlog::shutdown();
    */
    if (m_shuttingDown) return;
    m_shuttingDown = true;

    emit aboutToShutdown();

    try
    {
        if (m_logger)
        {
            m_logger->flush();
            spdlog::drop(m_logger->name());
        }
        spdlog::shutdown();
        m_logger.reset();
    }
    catch (const spdlog::spdlog_ex& ex)
    {
        qCritical() << "Log shutdown error:" << ex.what();
    }
}

void LogManager::onAboutToQuit()
{
    shutdown();
}

std::shared_ptr<spdlog::logger> LogManager::createCustomLogger(const std::string& base_filename,
        size_t max_size,
        size_t max_files)
{
    auto sink = std::make_shared<spdlog::custom_rotating_file_sink>(base_filename, max_size, max_files);
    auto logger = std::make_shared<spdlog::logger>("qt_logger", sink);
    return logger;
}

main.cpp文件

cpp 复制代码

#include <QCoreApplication>
#include "logmanager.h"
#include <QTimer>
#include <QDebug>

int main(int argc, char* argv[])
{
    QCoreApplication a(argc, argv);

    // 初始化日志系统
    LogManager::instance().initialize("logs", "MyAppTest");

    // 连接关闭信号进行额外清理
    QObject::connect(&LogManager::instance(), &LogManager::aboutToShutdown, []()
    {
        LOG_INFO("Performing final cleanup before shutdown...");
    });

    for (int i = 0; i < 5000; ++i)
    {
        LOG_INFO("This is a test message to fill up the log file. Iteration: {}", i);
    }

    return a.exec();
}

下载地址：https://download.csdn.net/download/sunriver2000/90602858