muduo网络库学习：日志类封装

 

示例代码

	LOG_TRACE<<"trace ...";
	LOG_DEBUG<<"debug ...";
	LOG_INFO<<"info ...";
	LOG_WARN<<"warn ...";
	LOG_ERROR<<"error ...";
	//LOG_FATAL<<"fatal ...";
	errno = 13;
	LOG_SYSERR<<"syserr ...";
	LOG_SYSFATAL<<"sysfatal ...";

输出示例

宏定义

#define LOG_TRACE if (muduo::Logger::logLevel() <= muduo::Logger::TRACE) \
  muduo::Logger(__FILE__, __LINE__, muduo::Logger::TRACE, __func__).stream()
#define LOG_DEBUG if (muduo::Logger::logLevel() <= muduo::Logger::DEBUG) \
  muduo::Logger(__FILE__, __LINE__, muduo::Logger::DEBUG, __func__).stream()
#define LOG_INFO if (muduo::Logger::logLevel() <= muduo::Logger::INFO) \
  muduo::Logger(__FILE__, __LINE__).stream()
#define LOG_WARN muduo::Logger(__FILE__, __LINE__, muduo::Logger::WARN).stream()
#define LOG_ERROR muduo::Logger(__FILE__, __LINE__, muduo::Logger::ERROR).stream()
#define LOG_FATAL muduo::Logger(__FILE__, __LINE__, muduo::Logger::FATAL).stream()
#define LOG_SYSERR muduo::Logger(__FILE__, __LINE__, false).stream()
#define LOG_SYSFATAL muduo::Logger(__FILE__, __LINE__, true).stream()

Logger UML类图

对象析构时输出日志信息

Logger::~Logger()
{
  impl_.finish();
  const LogStream::Buffer& buf(stream().buffer());
  g_output(buf.data(), buf.length());
  if (impl_.level_ == FATAL)
  {
    g_flush();
    abort();
  }
}

        g_output ，g_flush 默认输出到标准输出，可自定义输出到文件

FILE* g_file;
g_file = ::fopen("/tmp/muduo_log", "ae");

void dummyOutput(const char* msg, int len)
{
	if (g_file)
	{
		fwrite(msg, 1, len, g_file);
	}
}

void dummyFlush()
{
	fflush(g_file);
}

Logger::setOutput(dummyOutput);
Logger::setFlush(dummyFlush);

调用关系

　　Logger => Impl => LogStream => operator<< FixedBuffer
     => g_output => g_flush