How can I change a log4perl appender's filters at run time? - perl

Question

I'v been trying to figure out if I can change an appender's filter at run-time that I've defined via a configuration file.
log4perl.filter.M1 = Log::Log4perl::Filter::LevelMatch
log4perl.filter.M2 = Log::Log4perl::Filter::LevelMatch
log4perl.filter.M1.LevelToMatch = INFO
log4perl.filter.M1.AcceptOnMatch = true
log4perl.filter.M2.LevelToMatch = WARN
log4perl.filter.M2.AcceptOnMatch = true
log4perl.filter.MyBoolean0 = Log::Log4perl::Filter::Boolean
log4perl.filter.MyBoolean0.logic = M1
log4perl.filter.MyBoolean1 = Log::Log4perl::Filter::Boolean
log4perl.filter.MyBoolean1.logic = M1 || M2
log4perl.appender.SCREEN.Filter = MyBoolean0
I'd like to change this filter from MyBoolean0 for the SCREEN to MyBoolean1, but do it after my program has started running.
Poking at the APPENDER_BY_NAME hash for SCREEN using Data::Dumper shows the following:
$VAR1 = bless( {
'appender' => bless( {
'Filter' => 'MyBoolean0',
'color' => {
...
...
'filter' => bless( {·
'params' => {·
'M3' => bless( {·
'LevelToMatch' => 'ERROR',
'name' => 'M3',
'AcceptOnMatch' => 1
}, 'Log::Log4perl::Filter::LevelMatch' ),
'M1' => bless( {·
'LevelToMatch' => 'INFO',
'name' => 'M1',
'AcceptOnMatch' => 1
}, 'Log::Log4perl::Filter::LevelMatch' ),
'M2' => bless( {·
'LevelToMatch' => 'WARN',
'name' => 'M2',
'AcceptOnMatch' => 1
}, 'Log::Log4perl::Filter::LevelMatch' )
},
'name' => 'MyBoolean0',
'eval_func' => sub { "DUMMY" },
'logic' => 'M1 || M2 || M3'
}, 'Log::Log4perl::Filter::Boolean' ),
'warp_message' => undef,
'name' => 'SCREEN'
}, 'Log::Log4perl::Appender' );
But mucking with this HASH seems hackish to me. Is there a better way to change an appender's filters?

Answer 1

You may use undocumented appender's property filter:
$Log::Log4perl::Logger::APPENDER_BY_NAME{'SCREEN'}->filter(
Log::Log4perl::Filter::by_name('MyBoolean1')
);
Also you may use two appenders:
log4perl.appender.SCREEN0.Filter = MyBoolean0
log4perl.appender.SCREEN1.Filter = MyBoolean1
And change it in runtime:
$logger->remove_appender('SCREEN0', 1);
$logger->add_appender(
Log::Log4perl::Config::create_appender_instance(
$Log::Log4perl::Config::OLD_CONFIG,
'SCREEN1',
\%Log::Log4perl::Logger::APPENDER_BY_NAME
)
);