Adding 6 methods on 'exported', 'logger' and 'entry':
- IsDebugEnabled() bool
- IsInfoEnabled() bool
- IsWarnEnabled() bool
- IsErrorEnabled() bool
- IsFatalEnabled() bool
- IsPanicEnabled() bool
Replace duplicated 'if logger.level() >= XxxxLevel' by a call to the new methods in 'logger' and 'entry'
Closes#761
Locking is enabled by default. When file is opened with appending mode,
it's safe to write concurrently to a file. In this case user can
choose to disable the lock.
While GO offers the ability to recover from panic there is no way to intercept an os.Exit event. To allow graceful shutdown and clean-up or programs which use Logrus to Fatal out I've borrowed ideas from the `atexit` package and enhanced Logrus.
Usage:
* When setting up the logger one call `RegisterExitHandler( func() {...} )` to add a handler that will be invoked for any `Fatal` call to the logger.