C++ spdlog日志管理

【1】spdlog簡介

spdlog是一個開源的、快速的、僅有頭文件的基於C++11實現的一款C++專用日志管理庫。

【2】源碼下載

下載地址：https://github.com/gabime/spdlog

【3】工程配置

（1）解壓縮源碼包

解壓后，找到include文件夾。類比本地：

注意：include文件夾里是所需的頭文件及源碼。

（2）工程配置

2.1 新建一個C++控制台應用程序空項目spdlog

2.2 在項目屬性頁：VC++目錄->包含目錄 中添加上述include路徑，如下圖：

2.3 在項目中添加頭文件即可，如下：

#include "spdlog/spdlog.h"
using namespace spdlog;

OK 請盡情享用。是的，沒錯，就是這么簡單，你不用懷疑你自己。。。。

【4】應用示例

為了更權威、更有說服力，遂決定把源碼包中的example示例貼出來（加了若干自己理解的信息）

應用示例如下：

//
// Copyright(c) 2015 Gabi Melman.
// Distributed under the MIT License (http://opensource.org/licenses/MIT)

// spdlog usage example

#include <cstdio>

// 標准輸出類型
void stdout_logger_example();
// 基本類型：日志文件會一直被寫入，不斷變大。
void basic_example();
// 滾動類型：日志文件會先寫入一個文件，當超出規定大小時，會備份(或刪除)當前日志內容，重建文件開始寫入。
/* 說明：從函數聲明可以看出，參數max_file_size規定了文件數量的最大值，當文件數量超過此值就會把最早的先清空。
參數max_file_size規定了滾動文件的個數。當logger_name存滿時，將其名稱更改為logger_name.1，再新建一個logger_name文件來存儲新的日志。
再次存滿時，把logger_name.1改名為logger_name.2，logger_name改名為logger_name.1，再新建一個logger_name來存放新的日志。
以此類推，max_files 數量為幾，就可以有幾個logger_name文件用來滾動。
*/
void rotating_example();
// 每日類型：每天新建一個日志，新建日志文件時間可以自定義。
void daily_example();
// 異步模式類型
void async_example();
// 二進制類型
void binary_example();
// 追蹤類型
void trace_example();
// 多匯入類型
/* 帶多接收器的記錄器 - 每個接收器都有不同的格式和日志級別
譬如，創建具有 2 個不同日志級別和格式的目標的記錄器。
控制台將僅顯示警告或錯誤，而文件將記錄所有。
*/
void multi_sink_example();
// 自定義類型
void user_defined_example();
// 錯誤處理類型
/*
自定義錯誤處理程序。將在日志失敗時觸發。
可以全局設置或針對性設置
*/
void err_handler_example();
// 系統類型 (linux/osx/freebsd)
void syslog_example();

// 重點備注:
// 日志實時寫入接口：logger->flush();
/*
上述各種日志文件，僅在程序退出時才保存日志。
如果要想在程序運行時也能夠實時保存日志，可以在程序中添加如上語句。
具體參見譬如166行的應用示例
*/

#include "spdlog/spdlog.h"

int main(int, char* [])
{
    spdlog::info("Welcome to spdlog version {}.{}.{}  !", SPDLOG_VER_MAJOR, SPDLOG_VER_MINOR, SPDLOG_VER_PATCH);
    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("{:>8} aligned, {:<8} aligned", "right", "left");

    // Runtime log levels
    // 支持設置日志級別：低於設置級別的日志將不會被輸出。各level排序詳見源碼，數值越大級別越高：
    /*
    enum level_enum
    {
        trace = SPDLOG_LEVEL_TRACE,
        debug = SPDLOG_LEVEL_DEBUG,
        info = SPDLOG_LEVEL_INFO,
        warn = SPDLOG_LEVEL_WARN,
        err = SPDLOG_LEVEL_ERROR,
        critical = SPDLOG_LEVEL_CRITICAL,
        off = SPDLOG_LEVEL_OFF,
    };
    */
    spdlog::set_level(spdlog::level::info); // Set global log level to info
    spdlog::debug("This message should not be displayed!");
    spdlog::set_level(spdlog::level::trace); // Set specific logger's log level
    spdlog::debug("This message should be displayed..");

    // Customize msg format for all loggers
    // 支持自定義日志格式
    spdlog::set_pattern("[%H:%M:%S %z] [%^%L%$] [thread %t] %v");
    spdlog::info("This an info message with custom format");
    spdlog::set_pattern("%+"); // back to default format
    spdlog::set_level(spdlog::level::info);

    // 支持回溯分析
    // Backtrace support
    // Loggers can store in a ring buffer all messages (including debug/trace) for later inspection.
    // When needed, call dump_backtrace() to see what happened:
    spdlog::enable_backtrace(10); // create ring buffer with capacity of 10  messages
    for (int i = 0; i < 100; i++)
    {
        spdlog::debug("Backtrace message {}", i); // not logged.
    }
    // e.g. if some error happened:
    spdlog::dump_backtrace(); // log them now!

    try
    {
        stdout_logger_example();
        basic_example();
        rotating_example();
        daily_example();
        async_example();
        binary_example();
        multi_sink_example();
        user_defined_example();
        err_handler_example();
        trace_example();

        // Flush all *registered* loggers using a worker thread every 3 seconds.
        // note: registered loggers *must* be thread safe for this to work correctly!
        spdlog::flush_every(std::chrono::seconds(3));

        // Apply some function on all registered loggers
        spdlog::apply_all([&](std::shared_ptr<spdlog::logger> l) { l->info("End of example."); });

        // Release all spdlog resources, and drop all loggers in the registry.
        // This is optional (only mandatory if using windows + async log).
        spdlog::shutdown();
    }

    // Exceptions will only be thrown upon failed logger or sink construction (not during logging).
    catch (const spdlog::spdlog_ex & ex)
    {
        std::printf("Log initialization failed: %s\n", ex.what());
        return 1;
    }
}

#include "spdlog/sinks/stdout_color_sinks.h"
// or #include "spdlog/sinks/stdout_sinks.h" if no colors needed.
void stdout_logger_example()
{
    // Create color multi threaded logger.
    auto console = spdlog::stdout_color_mt("console");
    // or for stderr:
    // auto console = spdlog::stderr_color_mt("error-logger");
}

#include "spdlog/sinks/basic_file_sink.h"
void basic_example()
{
    // Create basic file logger (not rotated).
    auto my_logger = spdlog::basic_logger_mt("file_logger", "logs/basic-log.txt");
}

#include "spdlog/sinks/rotating_file_sink.h"
void rotating_example()
{
    // Create a file rotating logger with 5mb size max and 3 rotated files.
    auto rotating_logger = spdlog::rotating_logger_mt("some_logger_name", "logs/rotating.txt", 1048576 * 5, 3);
    int a = 100, b = 200;
    rotating_logger->error("error!");
    rotating_logger->info("a = {}, b = {}, a/b = {}, a%b = {}", a, b, a / b, a % b);
    rotating_logger->flush();
}

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

#include "spdlog/async.h"
void async_example()
{
    // Default thread pool settings can be modified *before* creating the async logger:
    // spdlog::init_thread_pool(32768, 1); // queue with max 32k items 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");

    for (int i = 1; i < 101; ++i)
    {
        async_file->info("Async message #{}", i);
    }
}

// Log binary data as hex.
// Many types of std::container<char> types can be used.
// Iterator 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 to lines.

#include "spdlog/fmt/bin_to_hex.h"
void binary_example()
{
    std::vector<char> buf;
    for (int i = 0; i < 80; i++)
    {
        buf.push_back(static_cast<char>(i & 0xff));
    }
    spdlog::info("Binary example: {}", spdlog::to_hex(buf));
    spdlog::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));
}

// Compile time log levels.
// define SPDLOG_ACTIVE_LEVEL to required level (e.g. SPDLOG_LEVEL_TRACE)
void trace_example()
{
    // trace from default logger
    SPDLOG_TRACE("Some trace message.. {} ,{}", 1, 3.23);
    // debug from default logger
    SPDLOG_DEBUG("Some debug message.. {} ,{}", 1, 3.23);

    // trace from logger object
    auto logger = spdlog::get("file_logger");
    SPDLOG_LOGGER_TRACE(logger, "another trace message");
}

// A logger with multiple sinks (stdout and file) - each with a different format and log level.
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");
}

// User defined types logging by implementing operator<<
#include "spdlog/fmt/ostr.h" // must be included
struct my_type
{
    int i;
    template<typename OStream>
    friend OStream& operator<<(OStream& os, const my_type& c)
    {
        return os << "[my_type i=" << c.i << "]";
    }
};

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

// Custom error handler. Will be triggered on log failure.
void err_handler_example()
{
    // can be set globally or per logger(logger->set_error_handler(..))
    spdlog::set_error_handler([](const std::string& msg) { printf("*** Custom log error handler: %s ***\n", msg.c_str()); });
}

// syslog example (linux/osx/freebsd)
#ifndef _WIN32
#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.");
}
#endif

// Android example.
#if defined(__ANDROID__)
#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.");
}

#endif

 

good good study, day day up.

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