基于C++ spdlog日志库的完善封装

spdlog是一个C++编写的极速日志打印库，支持异步写日志以及多种模式和格式化选项。以下基于spdlog库封装了一个简单易用的功能类，采用的是header-only方式，便于项目集成。

代码

#pragma once
#include <iostream>
#include <string>
#include <memory>
#include <time.h>
#include <chrono>
#include "spdlog/spdlog.h"
#include "spdlog/async.h"
#include "spdlog/sinks/stdout_color_sinks.h" // or "../stdout_sinks.h" if no color needed
#include "spdlog/sinks/basic_file_sink.h"
#include "spdlog/sinks/rotating_file_sink.h"

static inline int NowDateToInt()
{
	time_t now;
	time(&now);

	// choose thread save version in each platform
	tm p;
#ifdef _WIN32
	localtime_s(&p, &now);
#else
	localtime_r(&now, &p);
#endif // _WIN32
	int now_date = (1900 + p.tm_year) * 10000 + (p.tm_mon + 1) * 100 + p.tm_mday;
	return now_date;
}

static inline int NowTimeToInt()
{
	time_t now;
	time(&now);
	// choose thread save version in each platform
	tm p;
#ifdef _WIN32
	localtime_s(&p, &now);
#else
	localtime_r(&now, &p);
#endif // _WIN32

	int now_int = p.tm_hour * 10000 + p.tm_min * 100 + p.tm_sec;
	return now_int;
}

class XLogger
{
public:
	static XLogger* getInstance()
	{
		static XLogger xlogger;
		return &xlogger;
	}

	std::shared_ptr<spdlog::logger> getLogger()
	{
		return m_logger;
	}

private:
	// make constructor private to avoid outside instance
	XLogger()
	{
		// hardcode log path
		const std::string log_dir = "./log"; // should create the folder if not exist
		const std::string logger_name_prefix = "test_";

		// decide print to console or log file
		bool console = false;

		// decide the log level
		std::string level = "debug";

		try
		{
			// logger name with timestamp
			int date = NowDateToInt();
			int time = NowTimeToInt();
			const std::string logger_name = logger_name_prefix + std::to_string(date) + "_" + std::to_string(time);

			if (console)
				m_logger = spdlog::stdout_color_st(logger_name); // single thread console output faster
			else
				//m_logger = spdlog::create_async<spdlog::sinks::basic_file_sink_mt>(logger_name, log_dir + "/" + logger_name + ".log"); // only one log file
				m_logger = spdlog::create_async<spdlog::sinks::rotating_file_sink_mt>(logger_name, log_dir + "/" + logger_name + ".log", 500 * 1024 * 1024, 1000); // multi part log files, with every part 500M, max 1000 files

			// custom format
			m_logger->set_pattern("%Y-%m-%d %H:%M:%S.%f <thread %t> [%l] [%@] %v"); // with timestamp, thread_id, filename and line number

            if (level == "trace")
			{
				m_logger->set_level(spdlog::level::trace);
				m_logger->flush_on(spdlog::level::trace);
			}
			else if (level == "debug")
			{
				m_logger->set_level(spdlog::level::debug);
				m_logger->flush_on(spdlog::level::debug);
			}
			else if (level == "info")
			{
				m_logger->set_level(spdlog::level::info);
				m_logger->flush_on(spdlog::level::info);
			}
			else if (level == "warn")
			{
				m_logger->set_level(spdlog::level::warn);
				m_logger->flush_on(spdlog::level::warn);
			}
			else if (level == "error")
			{
				m_logger->set_level(spdlog::level::err);
				m_logger->flush_on(spdlog::level::err);
			}
		}
		catch (const spdlog::spdlog_ex& ex)
		{
			std::cout << "Log initialization failed: " << ex.what() << std::endl;
		}
	}

	~XLogger()
	{
		spdlog::drop_all(); // must do this
	}

	void* operator new(size_t size)
	{}

	XLogger(const XLogger&) = delete;
	XLogger& operator=(const XLogger&) = delete;

private:
	std::shared_ptr<spdlog::logger> m_logger;
};

// use embedded macro to support file and line number
#define XLOG_TRACE(...) SPDLOG_LOGGER_CALL(XLogger::getInstance()->getLogger().get(), spdlog::level::trace, __VA_ARGS__)
#define XLOG_DEBUG(...) SPDLOG_LOGGER_CALL(XLogger::getInstance()->getLogger().get(), spdlog::level::debug, __VA_ARGS__)
#define XLOG_INFO(...) SPDLOG_LOGGER_CALL(XLogger::getInstance()->getLogger().get(), spdlog::level::info, __VA_ARGS__)
#define XLOG_WARN(...) SPDLOG_LOGGER_CALL(XLogger::getInstance()->getLogger().get(), spdlog::level::warn, __VA_ARGS__)
#define XLOG_ERROR(...) SPDLOG_LOGGER_CALL(XLogger::getInstance()->getLogger().get(), spdlog::level::err, __VA_ARGS__)

int main()
{
	// print log test, you can transfer any param to do format
	int param = 1;

	XLOG_TRACE("this is trace log record, param: {}", ++param); // int type param is ok
	XLOG_DEBUG("this is debug log record, param: {}", ++param);
	XLOG_INFO("this is info log record, param: {}", ++param);
	XLOG_WARN("this is warn log record, param: {}", double(++param)); // double type param is ok
	XLOG_ERROR("this is error log record, param: {}", std::to_string(++param)); // string type param is ok

	return 0;
}

• 支持打印到控制台和文件两种方式
• 采用单例模式，多种日志级别的宏调用封装
• 格式化打印，尽可能的打印调试所需信息
• 可以选择将每一行都立即刷新到文件，但要注意级别，尽量不要在info或者debug级别上开启，这个选项会导致日志刷新时间戳延迟

输出

例如，日志文件：test_20201230_154656.log

2020-12-30 15:46:56.681969 <thread 91920> [debug] [main.cpp:135] this is debug log record, param: 2
2020-12-30 15:46:56.681969 <thread 91920> [info] [main.cpp:136] this is info log record, param: 3
2020-12-30 15:46:56.682457 <thread 91920> [warning] [main.cpp:137] this is warn log record, param: 4
2020-12-30 15:46:56.682457 <thread 91920> [error] [main.cpp:138] this is error log record, param: 5