log4cplus is a simple to use C++11 logging API providing thread--safe,
flexible, and arbitrarily granular control over log management and
configuration. It is modeled after the Java log4j API.

wiki: https://sourceforge.net/p/log4cplus/wiki/Home/
github: https://github.com/log4cplus/log4cplus

Signed-off-by: BangLang Huang <banglang.huang@foxmail.com>