C++ spdlog日志管理

 #include "spdlog/spdlog.h"

 using namespace spdlog;

 //

 // Copyright(c) 2015 Gabi Melman.

 // Distributed under the MIT License (http://opensource.org/licenses/MIT)

 // spdlog usage example

 #include <cstdio>

 // 标准输出类型

 void stdout_logger_example();

 // 基本类型：日志文件会一直被写入，不断变大。

 void basic_example();

 // 滚动类型：日志文件会先写入一个文件，当超出规定大小时，会备份(或删除)当前日志内容，重建文件开始写入。

 /* 说明：从函数声明可以看出，参数max_file_size规定了文件数量的最大值，当文件数量超过此值就会把最早的先清空。

 参数max_file_size规定了滚动文件的个数。当logger_name存满时，将其名称更改为logger_name.1，再新建一个logger_name文件来存储新的日志。

 再次存满时，把logger_name.1改名为logger_name.2，logger_name改名为logger_name.1，再新建一个logger_name来存放新的日志。

 以此类推，max_files 数量为几，就可以有几个logger_name文件用来滚动。

 */

 void rotating_example();

 // 每日类型：每天新建一个日志，新建日志文件时间可以自定义。

 void daily_example();

 // 异步模式类型

 void async_example();

 // 二进制类型

 void binary_example();

 // 追踪类型

 void trace_example();

 // 多汇入类型

 /* 带多接收器的记录器 - 每个接收器都有不同的格式和日志级别

 譬如，创建具有 2 个不同日志级别和格式的目标的记录器。

 控制台将仅显示警告或错误，而文件将记录所有。

 */

 void multi_sink_example();

 // 自定义类型

 void user_defined_example();

 // 错误处理类型

 /*

 自定义错误处理程序。将在日志失败时触发。

 可以全局设置或针对性设置

 */

 void err_handler_example();

 // 系统类型 (linux/osx/freebsd)

 void syslog_example();

 // 重点备注:

 // 日志实时写入接口：logger->flush();

 /*

 上述各种日志文件，仅在程序退出时才保存日志。

 如果要想在程序运行时也能够实时保存日志，可以在程序中添加如上语句。

 具体参见譬如166行的应用示例

 */

 #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}", );

     spdlog::critical("Support for int: {0:d};  hex: {0:x};  oct: {0:o}; bin: {0:b}", );

     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

     // 支持设置日志级别：低于设置级别的日志将不会被输出。各level排序详见源码，数值越大级别越高：

     /*

     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

     // 支持自定义日志格式

     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(); // create ring buffer with capacity of 10  messages

     for (int i = ; i < ; 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());

         // 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 ;

     }

 }

 #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",  * , );

     int a = , b = ;

     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", , );

 }

 #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 = ; i < ; ++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 = ; i < ; 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) + ));

     // 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.. {} ,{}", , 3.23);

     // debug from default logger

     SPDLOG_DEBUG("Some debug message.. {} ,{}", , 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{  });

 }

 // 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