I saw some code yesterday that reminded me of the usage for isDebugEnabled().

The code is:

    private void debugMessage(String msg) {
        if (log.isDebugEnabled()) {
            log.debug(msg);
        }
    }

Then a bunch of calls to that:  debugMessage("some message here");

This sort of defeats the purpose of wrapping the log.debug(). While I've always
been a fan of ALWAYS wrapping log.debug(), I've gone with the wrap them
if the strings are being concatenated.

See the discussion on spacewalk list:
http://www.mail-archive.com/spacewalk-devel@redhat.com/msg01204.html

So for candlepin, let's go with just doing log.debug("simple string")
when needed
and wrap the ones where you are dealing with concatenation i.e.
   log.debug("Found token in curator " + subToken + "  " + token);

Some would argue this is premature optimization, but having had to go through
this with 3 projects now, I'd like to go ahead and just head off this now before
we have 100k of code.

Thanks
jesus

PS sloccount shows

Totals grouped by language (dominant language first):
java:         10370 (90.61%)
python:         711 (6.21%)
sh:             249 (2.18%)
ruby:           115 (1.00%)
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public boolean isDebugEnabled()

This function is intended to lessen the computational cost of disabled log debug statements.

For some cat Category object, when you write,

      cat.debug("This is entry number: " + i );
  

You incur the cost constructing the message, concatenatiion in this case, regardless of whether the message is logged or not.

If you are worried about speed, then you should write

         if(cat.isDebugEnabled()) {
           cat.debug("This is entry number: " + i );
         }
  

This way you will not incur the cost of parameter construction if debugging is disabled for cat. On the other hand, if the cat is debug enabled, you will incur the cost of evaluating whether the category is debug enabled twice. Once in isDebugEnabled and once in the debug. This is an insignificant overhead since evaluating a category takes about 1%% of the time it takes to actually log.