log4perl-devel

[log4perl-devel] more_logging() and less_threshold()

[Mike S. <m...@pe...>]

Hi all,

just got a new request for L4p and wanted to solicit your opinions:

Given is the following L4p setup, which logs messages >= WARN to
a file and messages >= ERROR to both a file and the screen:

    use Log::Log4perl qw(get_logger);

    my $conf = q(
      log4perl.category.Bar.Twix          = WARN, Logfile, Screen

        # Appender for >= WARN
      log4perl.appender.Logfile           = Log::Log4perl::Appender::File
      log4perl.appender.Logfile.Threshold = WARN
      log4perl.appender.Logfile.filename  = test.log
      log4perl.appender.Logfile.layout    = SimpleLayout

        # Appender for >= ERROR
      log4perl.appender.Screen            = Log::Log4perl::Appender::Screen
      log4perl.appender.Screen.Threshold  = ERROR
      log4perl.appender.Screen.layout     = SimpleLayout
    );

    Log::Log4perl::init(\$conf);

    my $logger = get_logger("Bar::Twix");

        # Goes to Screen and File
    $logger->error("Error Message");
        # Goes to File
    $logger->warn("Warning Message");

Now, if the script calls $logger->more_logging() (e.g. because there's been
a -v command line switch or similar), nothing will really change, because
the appender's thresholds will block the new INFO messages.

To have both appenders adjust their thresholds to a lower level, the
application has to find out which appenders there are, what their thresholds
are, and adjust them accordingly.

If we wanted to make this kind of adjustment really easy (just like
more_logging()), what's the best way? I'm envisioning something like

    $logger->more_logging();
    $logger->lower_appender_thresholds();

or even

    $logger->more_logging({lower_appender_thresholds => 1});

to have the logger hunt down all appenders connected to it and lower
or bump up their thresholds.

What do you think, is this a case common enough to provide a convenience
function for it?

-- Mike

Mike Schilli
m...@pe...

Re: [log4perl-devel] more_logging() and less_threshold()

[Kevin G. <ke...@go...>]

Mike Schilli wrote:
> Now, if the script calls $logger->more_logging() ...the
> application has to find out which appenders there are, what their thresholds
> are, and adjust them accordingly.
> 
> If we wanted to make this kind of adjustment really easy (just like
> more_logging()), what's the best way? I'm envisioning something like
> 
>     $logger->more_logging();
>     $logger->lower_appender_thresholds();
 >
 > or even
 >
 >     $logger->more_logging({lower_appender_thresholds => 1});

You're right that it shouldn't be automatic, appenders shouldn't have 
their thresholds lowered implicitly, if I set Threshold=ERROR on my 
performance-intensive database appender I don't want it flooded with 
debug messages.

So in terms of making it explicit, I have an attraction to the first method.

> to have the logger hunt down all appenders connected to it and lower
> or bump up their thresholds.
> 
> What do you think, is this a case common enough to provide a convenience
> function for it?

It sounds pretty far out to me, if I was paying you to work on it I'd 
say it sounds like a lot of work for a pretty small feature.  But if you 
have a request and the motivation, go for it.


-- 
Happy Trails . . .

Kevin M. Goess
(and Anne and Frank)
904 Carmel Ave.
Albany, CA  94706
(510) 525-5217

Re: [log4perl-devel] more_logging() and less_threshold()

[Mike S. <m...@pe...>]

On Tue, 30 Nov 2004, Kevin Goess wrote:

> You're right that it shouldn't be automatic, appenders shouldn't have
> their thresholds lowered implicitly, if I set Threshold=ERROR on my
> performance-intensive database appender I don't want it flooded with
> debug messages.

Makes sense ... I've chosen a slightly less-intrusive approach,
here's the new docs:

=head2 Modify appender thresholds

To conveniently adjust appender thresholds (e.g. because a script
uses more_logging()), use

       # decrease thresholds of all appenders
    Log::Log4perl->appender_thresholds_adjust(-1);

This will decrease the thresholds of all appenders in the system by
one level, i.e. WARN becomes INFO, INFO becomes DEBUG, etc. To only modify
selected ones, use

       # decrease thresholds of all appenders
    Log::Log4perl->appender_thresholds_adjust(-1, ['AppName1', ...]);

and pass the names of affected appenders in a ref to an array.

-- Mike

Mike Schilli
m...@pe...