gabime/spdlog

来源：https://github.com/gabime/spdlog

CI (https://github.com/gabime/spdlog/actions/workflows/linux.yml) CI (https://github.com/gabime/spdlog/actions/workflows/windows.yml) CI (https://github.com/gabime/spdlog/actions/workflows/macos.yml) 构建状态 (https://ci.appveyor.com/project/gabime/spdlog) 发布 (https://github.com/gabime/spdlog/releases/latest)

快速的 C++ 日志库

安装

仅头文件版本

将 include 文件夹 复制到你的构建目录中，并使用 C++11 编译器。

编译版本（推荐——编译时间快得多）

$ git clone https://github.com/gabime/spdlog.git
$ cd spdlog && mkdir build && cd build
$ cmake .. && cmake --build .

关于如何使用，请参阅示例 CMakeLists.txt。

支持平台

• Linux, FreeBSD, OpenBSD, Solaris, AIX
• Windows (msvc 2013+, cygwin)
• macOS (clang 3.5+)
• Android

包管理器：

• Debian: sudo apt install libspdlog-dev
• Homebrew: brew install spdlog
• MacPorts: sudo port install spdlog
• FreeBSD: pkg install spdlog
• Fedora: dnf install spdlog
• Gentoo: emerge dev-libs/spdlog
• Arch Linux: pacman -S spdlog
• openSUSE: sudo zypper in spdlog-devel
• ALT Linux: apt-get install libspdlog-devel
• vcpkg: vcpkg install spdlog
• conan: conan install --requires=spdlog/[*]
• conda: conda install -c conda-forge spdlog
• build2: depends: spdlog ^1.8.2

特性

• 非常快（参见下面的基准测试）。
• 仅头文件或编译版本
• 功能丰富的格式化，使用了优秀的 fmt (https://github.com/fmtlib/fmt) 库。
• 异步模式（可选）
• 自定义 (https://github.com/gabime/spdlog/wiki/Custom-formatting) 格式化。
• 多线程/单线程日志器。
• 多种日志目标：
  • 轮转日志文件。
  • 每日日志文件。
  • 控制台日志（支持颜色）。
  • syslog。
  • Windows 事件日志。
  • Windows 调试器（OutputDebugString(..)）。
  • 记录到 Qt 窗口部件（示例）。
• 可通过自定义日志目标轻松扩展 (https://github.com/gabime/spdlog/wiki/Sinks#implementing-your-own-sink)。
• 日志过滤 - 日志级别可以在运行时和编译时修改。
• 支持从 argv 或环境变量加载日志级别。
• 回溯支持 - 将调试消息存储在环形缓冲区中，并在需要时稍后显示。

使用示例

基本用法

#include "spdlog/spdlog.h"

int main()
{
    spdlog::info("Welcome to spdlog!");
    spdlog::error("Some error message with arg: {}", 1);

    spdlog::warn("Easy padding in numbers like {:08d}", 12);
    spdlog::critical("Support for int: {0:d};  hex: {0:x};  oct: {0:o}; bin: {0:b}", 42);
    spdlog::info("Support for floats {:03.2f}", 1.23456);
    spdlog::info("Positional args are {1} {0}..", "too", "supported");
    spdlog::info("{:<30}", "left aligned");

    spdlog::set_level(spdlog::level::debug); // Set *global* log level to debug
    spdlog::debug("This message should be displayed..");

    // change log pattern
    spdlog::set_pattern("[%H:%M:%S %z] [%n] [%^---%L---%$] [thread %t] %v");

    // Compile time log levels
    // Note that this does not change the current log level, it will only
    // remove (depending on SPDLOG_ACTIVE_LEVEL) the call on the release code.
    SPDLOG_TRACE("Some trace message with param {}", 42);
    SPDLOG_DEBUG("Some debug message");
}

创建 stdout/stderr 日志器对象

#include "spdlog/spdlog.h"
#include "spdlog/sinks/stdout_color_sinks.h"

void stdout_example()
{
    // create a color multi-threaded logger
    auto console = spdlog::stdout_color_mt("console");
    auto err_logger = spdlog::stderr_color_mt("stderr");
    spdlog::get("console")->info("loggers can be retrieved from a global registry using the spdlog::get(logger_name)");
}

基本文件日志器

#include "spdlog/sinks/basic_file_sink.h"

void basic_logfile_example()
{
    try
    {
        auto logger = spdlog::basic_logger_mt("basic_logger", "logs/basic-log.txt");
    }
    catch (const spdlog::spdlog_ex &ex)
    {
        std::cout << "Log init failed: " << ex.what() << std::endl;
    }
}

轮转文件

#include "spdlog/sinks/rotating_file_sink.h"

void rotating_example()
{
    // Create a file rotating logger with 5 MB size max and 3 rotated files
    auto max_size = 1048576 * 5;
    auto max_files = 3;
    auto logger = spdlog::rotating_logger_mt("some_logger_name", "logs/rotating.txt", max_size, max_files);
}

每日文件

#include "spdlog/sinks/daily_file_sink.h"

void daily_example()
{
    // Create a daily logger - a new file is created every day at 2:30 am
    auto logger = spdlog::daily_logger_mt("daily_logger", "logs/daily.txt", 2, 30);
}

回溯支持

// Debug messages can be stored in a ring buffer instead of being logged immediately.
// This is useful to display debug logs only when needed (e.g. when an error happens).
// When needed, call dump_backtrace() to dump them to your log.

spdlog::enable_backtrace(32); // Store the latest 32 messages in a buffer. 
// or my_logger->enable_backtrace(32)..
for (int i = 0; i < 100; i++)
{
    spdlog::debug("Backtrace message {}", i); // not logged yet..
}

// e.g. if some error happened:
spdlog::dump_backtrace(); // log them now! show the last 32 messages
// or my_logger->dump_backtrace(32)..

定期刷新

// periodically flush all *registered* loggers every 3 seconds:
// warning: only use if all your loggers are thread-safe ("_mt" loggers)
spdlog::flush_every(std::chrono::seconds(3));

秒表

// Stopwatch support for spdlog
#include "spdlog/stopwatch.h"

void stopwatch_example()
{
    spdlog::stopwatch sw;
    spdlog::debug("Elapsed {}", sw);
    spdlog::debug("Elapsed {:.3}", sw);
}

以十六进制记录二进制数据

// many types of std::container types can be used.
// ranges are supported too.
// format flags:
// {:X} - print in uppercase.
// {:s} - don't separate each byte with space.
// {:p} - don't print the position on each line start.
// {:n} - don't split the output into lines.
// {:a} - show ASCII if :n is not set.

#include "spdlog/fmt/bin_to_hex.h"

void binary_example()
{
    auto console = spdlog::get("console");
    std::array<char, 80> buf;
    console->info("Binary example: {}", spdlog::to_hex(buf));
    console->info("Another binary example:{:n}", spdlog::to_hex(std::begin(buf), std::begin(buf) + 10));
    // more examples:
    // logger->info("uppercase: {:X}", spdlog::to_hex(buf));
    // logger->info("uppercase, no delimiters: {:Xs}", spdlog::to_hex(buf));
    // logger->info("uppercase, no delimiters, no position info: {:Xsp}", spdlog::to_hex(buf));
}

具有多个 sink 的日志器 - 每个 sink 具有不同的格式和日志级别

// create a logger with 2 targets, with different log levels and formats.
// The console will show only warnings or errors, while the file will log all.
void multi_sink_example()
{
    auto console_sink = std::make_shared<spdlog::sinks::stdout_color_sink_mt>();
    console_sink->set_level(spdlog::level::warn);
    console_sink->set_pattern("[multi_sink_example] [%^%l%$] %v");

    auto file_sink = std::make_shared<spdlog::sinks::basic_file_sink_mt>("logs/multisink.txt", true);
    file_sink->set_level(spdlog::level::trace);

    spdlog::logger logger("multi_sink", {console_sink, file_sink});
    logger.set_level(spdlog::level::debug);
    logger.warn("this should appear in both console and file");
    logger.info("this message should not appear in the console, only in the file");
}

注册多个日志器 - 更改全局级别

// Creation of loggers. Set levels to all registered loggers.
void set_level_example()
{
    auto logger1 = spdlog::basic_logger_mt("logger1", "logs/logger1.txt");
    auto logger2 = spdlog::basic_logger_mt("logger2", "logs/logger2.txt");

    spdlog::set_default_logger(logger2);
    spdlog::default_logger()->set_level(spdlog::level::trace); // set level for the default logger (logger2) to trace
    spdlog::trace("trace message to the logger2 (specified as default)");

    spdlog::set_level(spdlog::level::off) // (sic!) set level for *all* registered loggers to off (disable)

    logger1.warn("warn message will not appear because the level set to off");
    logger2.warn("warn message will not appear because the level set to off");
    spdlog::warn("warn message will not appear because the level set to off");
}

关于日志事件的用户自定义回调

// create a logger with a lambda function callback, the callback will be called
// each time something is logged to the logger
void callback_example()
{
    auto callback_sink = std::make_shared<spdlog::sinks::callback_sink_mt>([](const spdlog::details::log_msg &msg) {
        // for example you can be notified by sending an email to yourself
    });
    callback_sink->set_level(spdlog::level::err);

    auto console_sink = std::make_shared<spdlog::sinks::stdout_color_sink_mt>();
    spdlog::logger logger("custom_callback_logger", {console_sink, callback_sink});

    logger.info("some info log");
    logger.error("critical issue"); // will notify you
}

异步日志

#include "spdlog/async.h"
#include "spdlog/sinks/basic_file_sink.h"

void async_example()
{
    // default thread pool settings can be modified *before* creating the async logger:
    // spdlog::init_thread_pool(8192, 1); // queue with 8k items and 1 backing thread.
    auto async_file = spdlog::basic_logger_mt<spdlog::async_factory>("async_file_logger", "logs/async_log.txt");
    // alternatively:
    // auto async_file = spdlog::create_async<spdlog::sinks::basic_file_sink_mt>("async_file_logger", "logs/async_log.txt");
}

具有多个 sink 的异步日志器

#include "spdlog/async.h"
#include "spdlog/sinks/stdout_color_sinks.h"
#include "spdlog/sinks/rotating_file_sink.h"

void multi_sink_example2()
{
    spdlog::init_thread_pool(8192, 1);
    auto stdout_sink = std::make_shared<spdlog::sinks::stdout_color_sink_mt>();
    auto rotating_sink = std::make_shared<spdlog::sinks::rotating_file_sink_mt>("mylog.txt", 1024*1024*10, 3);
    std::vector<spdlog::sink_ptr> sinks {stdout_sink, rotating_sink};
    auto logger = std::make_shared<spdlog::async_logger>("loggername", sinks.begin(), sinks.end(), spdlog::thread_pool(), spdlog::async_overflow_policy::block);
    spdlog::register_logger(logger);
}

用户自定义类型

template<>
struct fmt::formatter<my_type> : fmt::formatter<std::string>
{
    auto format(my_type my, format_context &ctx) const -> decltype(ctx.out())
    {
        return fmt::format_to(ctx.out(), "[my_type i={}]", my.i);
    }
};

void user_defined_example()
{
    spdlog::info("user defined type: {}", my_type(14));
}

日志模式中的用户自定义标志

// Log patterns can contain custom flags.
// the following example will add new flag '%*' - which will be bound to a instance.
#include "spdlog/pattern_formatter.h"

class my_formatter_flag : public spdlog::custom_flag_formatter
{
public:
    void format(const spdlog::details::log_msg &, const std::tm &, spdlog::memory_buf_t &dest) override
    {
        std::string some_txt = "custom-flag";
        dest.append(some_txt.data(), some_txt.data() + some_txt.size());
    }

    std::unique_ptr<spdlog::custom_flag_formatter> clone() const override
    {
        return spdlog::details::make_unique<my_formatter_flag>();
    }
};

void custom_flags_example()
{
    auto formatter = std::make_unique<spdlog::pattern_formatter>();
    formatter->add_flag('*').set_pattern("[%n] [%*] [%^%l%$] %v");
    spdlog::set_formatter(std::move(formatter));
}

自定义错误处理器

void err_handler_example()
{
    // can be set globally or per logger(logger->set_error_handler(..))
    spdlog::set_error_handler([](const std::string &msg) {
        spdlog::get("console")->error("*** LOGGER ERROR ***: {}", msg);
    });
    spdlog::get("console")->info("some invalid message to trigger an error {}{}{}{}", 3);
}

syslog

#include "spdlog/sinks/syslog_sink.h"

void syslog_example()
{
    std::string ident = "spdlog-example";
    auto syslog_logger = spdlog::syslog_logger_mt("syslog", ident, LOG_PID);
    syslog_logger->warn("This is warning that will end up in syslog.");
}

Android 示例

#include "spdlog/sinks/android_sink.h"

void android_example()
{
    std::string tag = "spdlog-android";
    auto android_logger = spdlog::android_logger_mt("android", tag);
    android_logger->critical("Use \"adb shell logcat\" to view this message.");
}

从环境变量或 argv 加载日志级别

#include "spdlog/cfg/env.h"

int main (int argc, char *argv[])
{
    spdlog::cfg::load_env_levels();
    // or specify the env variable name:
    // MYAPP_LEVEL=info,mylogger=trace && ./example
    // spdlog::cfg::load_env_levels("MYAPP_LEVEL");

    // or from the command line:
    // ./example SPDLOG_LEVEL=info,mylogger=trace
    // #include "spdlog/cfg/argv.h" // for loading levels from argv
    // spdlog::cfg::load_argv_levels(argc, argv);
}

然后你可以：

$ export SPDLOG_LEVEL=info,mylogger=trace
$ ./example

日志文件打开/关闭事件处理器

// You can get callbacks from spdlog before/after a log file has been opened or closed.
// This is useful for cleanup procedures or for adding something to the start/end of the log file.
void file_events_example()
{
    // pass the spdlog::file_event_handlers to file sinks for open/close log file notifications
    spdlog::file_event_handlers handlers;
    handlers.before_open = [](spdlog::filename_t filename) {
        spdlog::info("Before opening {}", filename);
    };
    handlers.after_open = [](spdlog::filename_t filename, std::FILE *fstream) {
        fputs("After opening\n", fstream);
    };
    handlers.before_close = [](spdlog::filename_t filename, std::FILE *fstream) {
        fputs("Before closing\n", fstream);
    };
    handlers.after_close = [](spdlog::filename_t filename) {
        spdlog::info("After closing {}", filename);
    };

    auto my_logger = spdlog::basic_logger_st("some_logger", "logs/events-sample.txt", true, handlers);
}

替换默认日志器

void replace_default_logger_example()
{
    auto new_logger = spdlog::basic_logger_mt("new_default_logger", "logs/new-default-log.txt", true);
    spdlog::set_default_logger(new_logger);
    spdlog::info("new logger log message");
}

使用漂亮的颜色记录到 Qt

#include "spdlog/spdlog.h"
#include "spdlog/sinks/qt_sinks.h"

MainWindow::MainWindow(QWidget *parent) : QMainWindow(parent)
{