Default Appender/root?

[Mark Womack <mw...@bevocal.com>]

I know the documentation says that log4j makes no assumptions about the
logging environment, and so when it cannot find a valid log4j.configuration
property setting, it reports the error and does nothing...BUT is there a way
where you can have it set up something as a default?  For example, if I do
not specify any settings, I would like log4j to default to root using the
stock console appender with the priority set to WARN or above.

Is there a way to do this in the code?  If not, there should be, IMHO.

I would appreciate any guidance anyone can provide on this...

Thanks,
-Mark

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Forcing DailyRollingFileAppender to Rollover

[Mike Papper <mi...@bodaro.com>]

Sometimes I have appenders that dont get log messages very often - usually
cause they set their thresholds to "error" or above. The
DailyRollingFileAppender doesnt work right with these classes cause the
files dont get considered for rollover unless a log event has occured -
sometimes days after the event. The behaviour I would like to see is for a
file to rollover on the hour - if there are any items and not to rollover if
there are no items.

Note that this problem is not fixed using the Roller class - what that does
is force a rollover "every so often". What I want is to "ping" the subAppend
method "every so often" so that it will periodically check whether it needs
to rollover or not.

I have some of my own Appenders and I implemented a public method called
"timeToRollover" in them. I have setup a java.util.Timer (which runs every
minute) and a java.util.TimerTask that calls this timeToRollover method of
its Appender (but the Appender is really one of my subclasses - so I can do
this easily). This way, I have a thread that pokes and prods my Appender
every minute to "ask" it to check if it should rollover.

However I cannot do this so straightforwardly with the
DailyRollingFileAppender class. I could have duplicated what the subAppend
method does (except to not log the LoggingEvent) except that the neccessary
members are private. I am wondering if calling subAppend with a "bogus"
LoggingEvent (constructed with all null objects) will do the trick for me?
Kinda like side-effect programming.

I was also considering just calling rollOver anyway as it has some code:

    String datedFilename = fileName+sdf.format(now);
    if (scheduledFilename.equals(datedFilename))
      return;

that looks like it will almost but not quite "test" before rolling over. I
think that calling this will actually result in files that are rolled over
too soon. So a given hour may have entries scattered across 2 files. ??

Any ideas? Should we add a method named "checkTimeToRollover" to the
Appender interface!

----------------------- interlude
Concerning private members (my opinion): Using private as the default access
level for member variables and methods closes the door on many things
subclasses could do - usually these are things the original writer of the
class never envisioned at the time of writing but come to be a need later
on.

Presumably the writer of DailyRollingFileAppender never concieved of the
need for ensuring consistent rollovers. I think all Appenders seem to suffer
from this problem of not rollingover unles an event is logged. And now that
the need is there, I cannot implement via a subclass cause the superclass
(DailyRollingFileAppender) uses private members!
------------------------------------

Note: I cannot just go ahead an log "null" (or innocuous) events as some
Appenders have threshold of error - and the sign that these files are EMPTY
is used so I can see the system is running smoothly. Having these files
populated with a bunch of "null" events would be very annoying.

Mike Papper
mike@bodaro.com



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Re: Default Appender/root?

[Robert Leftwich <di...@ix.net.au>]

At 06:39 AM 24/07/2001, Mark Womack wrote:
>I know the documentation says that log4j makes no assumptions about the
>logging environment, and so when it cannot find a valid log4j.configuration
>property setting, it reports the error and does nothing...BUT is there a way
>where you can have it set up something as a default?  For example, if I do
>not specify any settings, I would like log4j to default to root using the
>stock console appender with the priority set to WARN or above.
>
>Is there a way to do this in the code?  If not, there should be, IMHO.
>
>I would appreciate any guidance anyone can provide on this...

A simple solution would be to check if log4j had already been initialized, 
if not then init it yourself using a default_log4j.properties file which 
you ship in your jar (or have in your classpath), i.e. have something like 
the following in a category class (or your main) :

         static {
                 if ( !isConfigured() ) {
                         PropertyConfigurator.configure("\myapp_default_log4j.properties");
                 }
         }

         // this code (from Ceki Gülcü) checks to see if there are any 
appenders defined for log4j
         // which is the definitive way to tell if log4j is already initialised
         private static boolean isConfigured() {
                 Enumeration enum = Category.getRoot().getAllAppenders();

                 if ( !(enum instanceof 
org.apache.log4j.helpers.NullEnumeration) ) {
                         return true;
                 } else {
                         Enumeration cats =  Category.getCurrentCategories();
                         while ( cats.hasMoreElements() ) {
                                 Category c = (Category) cats.nextElement();
                                 if ( !(c.getAllAppenders() instanceof 
org.apache.log4j.helpers.NullEnumeration) )
                                         return true;
                         }
                 }
                 return false;
         }

HTH

Robert


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