[Hawkular-dev] [Metrics] HWKMETRICS-125 Use JBoss Logging as in all other Hawkular components

[Thomas Segismont]

Hi,

I created a pull request for $subject.
https://github.com/hawkular/hawkular-metrics/pull/352

I'm writing to share some implementation details.

I followed some Hawkular wide conventions (which I gathered from mailing 
list threads, so tell me if it's wrong):
- put logging stuff into a 'log' package
- in the message logger interface, method names should start with the 
log level [1]
- logger instances should be named 'log' [2]
- only put messages which need an id (level INFO and above) in logger 
interfaces [3]

I tried to draw up some Metrics specific conventions (some may not be 
specific, I just found no mention of them in the threads):
- group all messages in one class for maintainability [4]
- instead of creating a logger instance in the message logger interface, 
use XXXLogging helper class to get a logger instance with proper 
category (inspired by what Hibernate does) [5]
- use existing message logger instance to log trace/debug messages 
instead of creating a separate logger instance [6]

The logging 'projectCode' is 'HAWKMETRICS'. Does that fit everyone?

Note that until we no longer need to support EAP 6.4, we must not use 
primitive arguments in logging interfaces. [7]

Also, logback is now the logging backend for tests. It allows to set log 
level with a system property while still having a default value. [8][9] 
No Maven filtering/replace dance involved.

If there's no issue with all of the above, then maybe we should not wait 
too long before merging, because a bunch of files are impacted.

Thanks,
Thomas

[1] 
https://github.com/hawkular/hawkular-metrics/pull/352/files#diff-75a8549533d503e0f032038ff7442e06R63
[2] 
https://github.com/hawkular/hawkular-metrics/pull/352/files#diff-26d97c7615667d28c50de926537fd343R35
[3] 
https://github.com/hawkular/hawkular-metrics/pull/352/files#diff-1354be094ca909a30eedafc9fdf8fc1fR70

[4] 
https://github.com/hawkular/hawkular-metrics/pull/352/files#diff-75a8549533d503e0f032038ff7442e06R39
[5] 
https://github.com/hawkular/hawkular-metrics/pull/352/files#diff-fb0691f5bb1e1793a11ed3f20a3fb6d2R28
[6] 
https://github.com/hawkular/hawkular-metrics/pull/352/files#diff-04e1ad2ad2cadc473893730a61b3e271R607 


[7] http://lists.jboss.org/pipermail/hawkular-dev/2015-March/000378.html

[8] 
https://github.com/hawkular/hawkular-metrics/pull/352/files#diff-e0d878a774dafba50428080c38a192b8R24
[9] 
https://github.com/hawkular/hawkular-metrics/pull/352/files#diff-e0d878a774dafba50428080c38a192b8R33