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From "Ed Coleman" <d...@etcoleman.com>
Subject Proposal for splitting ACCUMULO-1242 into subtasks.
Date Tue, 13 May 2014 01:15:44 GMT
I am willing to take another run at the Consistent Logging ticket,
ACCUMULO-1242, but I'd like to achieve a consensus on an approach before
starting.  

The tl;dr version - I would like to split ACCUMULO-1242 into subtasks.
Target version would be 1.7.0 (or whatever it gets called, would not mind
doing it for 1.6.1 too, to ease merges of bug fixes - esp. for the "easy"
conversions.

Now the novel-length version (and sorry for the length)

I think that the ACCUMULO-1242 should be split into a number of subtasks -
at least three or maybe four. This way individual subtasks can be committed
independently to allow a thorough review of the more complex changes. The
breakdown that I am thinking of would go from easy, mostly non-functional
changes and progressively become more complex and could require rethinking
the way certain things are done for the "hardest" ones.  The breakdown would
also narrow the number of files effected as the subtasks progressed from
easy to hard.  The "easy" changes would impact most files, while the most
complex changes would impact relatively few. 

To be clear, with this approach some files may be changed multiple times by
different sub-tasks - in case that influences anyone's opinion to this
approach. 

The breakdown that I am suggesting as a starting point for discussion is:

Subtask-1: 

a) Replace package statements and Logger.getLogger to
LoggerFactory.getLogger

b) Use parameterized messages ( {} ) instead of concatenation and remove any
if level enabled tests (.isDebugEnabled(), .isInfoEnabled().)- this may
provide a very slight performance gain.

c) Add messages to all exceptions - required by slf4j and generally an
accepted practice.

d) Eliminate printStackTrace with log messages of an appropriate level
(ACCUMULO-2628 covers this and could be done at the same time.)

This is the low hanging fruit and should eliminate log4j dependencies in
most classes - maybe 80% to 90% or more. [Because (c) and (d) will slightly
change the log output, maybe they are more appropriate for subtask-2?]
[Question: any issue with changing log statement wording in (b) if it
improves clarity? - which would also slightly change log output which would
break anyone that is doing log scraping.]

Subtask-2:

a) Remove FATAL level and replace with MARKER interface supported by logback
and log4j-2 [a future effort could be to extend MARKER usage to allow finer
grained log filtering, but probably not as part of this effort.]

b) Remove dynamic manipulation of log levels in testing by using
test-specific parameter files (if desired)

Subtask-3:

a) Rework TRACING and log forwarding so they do not have a log4j dependency

Subtask-4: 

a) Rework shell debug command facility that dynamically changes the log
level. 

With the current code base it may be impractical to completely remove direct
log4j dependencies, but we should be able to isolate it to a few instances
in the server-side code and completely remove it from the client-side code.

Another thing to note is that many of the limitations of slf4j are present
in log4j-2 -neither allow dynamic log level changes programmatically or
through DOM manipulation but instead watch the property file and react when
it is modified. So, even if you really don't care about slf4j, similar
changes will be required to upgrade log4j-2.

Once there is a consensus I (or Christopher ?) could make the sub-tasks and
I'll get started.

 


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