Xiaoyan Lin b2651cc351 Make all InternalLoggerFactory implementations be singletons
Motivation:

It's better to make all InternalLoggerFactory implementations be singletons according to the discussions in #5047

Modifications:

Make all InternalLoggerFactory implementations be singletons and hide the construtors.

Result:

All InternalLoggerFactory implementations be singletons.
2016-04-08 09:39:47 +02:00
..