[jbosscache-dev] Caching log.isTraceEnabled() as instance variable

[Galder Zamarreno]

Hi all,

Yesterday while looking at the JBC code, I spotted that 
CommandInterceptor caches log.isTraceEnabled() as instance variable and 
that pretty much all classes extending this use it.

In a standalone world, where JBC runs on its own this is fine. However, 
when running within AS, log4j settings could change at runtime 
(conf/jboss-log4j.xml is hot deployable) and therefore, someone could 
enable TRACE logging for org.jboss.cache at runtime which wouldn't have 
any effect with the current JBC code.

As far as I can remember, it's generally recommended not to cache things 
like this in code running within AS. Then again, I can see how 
convenient caching such value is rather than calling 
log.isTraceEnabled() all the time. I doubt using an instance variable or 
calling log.isTraceEnabled() would have a real impact performance wise 
when TRACE is not enabled.

Thinking about this, I wonder whether any callback(s) could be 
implemented when the log4j settings are updated after a hot deployment 
and within this callback, update interceptors' trace settings...

Thoughts?
-- 
Galder Zamarreño
Sr. Software Maintenance Engineer
JBoss, a division of Red Hat