Appender::BuffeUser)Contributed Perl DocumentAppender::Buffer(3p)


NAME
           Log::Log4perl::Appender::Buffer - Buffering Appender

SYNOPSIS
           use Log::Log4perl qw(:easy);

           my $conf = qq(
           log4perl.category                  = DEBUG, Buffer

               # Regular Screen Appender
           log4perl.appender.Screen           = Log::Log4perl::Appender::Screen
           log4perl.appender.Screen.stdout    = 1
           log4perl.appender.Screen.layout    = PatternLayout
           log4perl.appender.Screen.layout.ConversionPattern = %d %p %c %m %n

               # Buffering appender, using the appender above as outlet
           log4perl.appender.Buffer               = Log::Log4perl::Appender::Buffer
           log4perl.appender.Buffer.appender      = Screen
           log4perl.appender.Buffer.trigger_level = ERROR
           );

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

           DEBUG("This message gets buffered.");
           INFO("This message gets buffered also.");

           # Time passes. Nothing happens. But then ...

           print "It's GO time!!!\n";

           ERROR("This message triggers a buffer flush.");

DESCRIPTION
       "Log::Log4perl::Appender::Buffer" takes these arguments:

       "appender"
           Specifies the name of the appender it buffers messages for. The
           appender specified must be defined somewhere in the configuration
           file, not necessarily before the definition of
           "Log::Log4perl::Appender::Buffer".

       "max_messages"
           Specifies the maximum number of messages the appender will hold in
           its ring buffer. "max_messages" is optional. By default,
           "Log::Log4perl::Appender::Buffer" will not limit the number of
           messages buffered. This might be undesirable in long-running
           processes accumulating lots of messages before a flush happens. If
           "max_messages" is set to a numeric value,
           "Log::Log4perl::Appender::Buffer" will displace old messages in its
           buffer to make room if the buffer is full.

       "trigger_level"
           If trigger_level is set to one of Log4perl's levels (see
           Log::Log4perl::Level), a "trigger" function will be defined



perl v5.12.2                2009-05-02                          1





Appender::BuffeUser)Contributed Perl DocumentAppender::Buffer(3p)


           internally to flush the buffer if a message with a priority of
           $level or higher comes along. This is just a convenience function.
           Defining

               log4perl.appender.Buffer.trigger_level = ERROR

           is equivalent to creating a trigger function like

               log4perl.appender.Buffer.trigger = sub {   \
                   my($self, $params) = @_;               \
                   return $params->{log4p_level} >=       \
                          $Log::Log4perl::Level::ERROR; }

           See the next section for defining generic trigger functions.

       "trigger"
           "trigger" holds a reference to a subroutine, which
           "Log::Log4perl::Appender::Buffer" will call on every incoming
           message with the same parameters as the appender's "log()" method:

                   my($self, $params) = @_;

           $params references a hash containing the message priority (key
           "l4p_level"), the message category (key "l4p_category") and the
           content of the message (key "message").

           If the subroutine returns 1, it will trigger a flush of buffered
           messages.

           Shortcut

DEVELOPMENT NOTES
       "Log::Log4perl::Appender::Buffer" is a composite appender.  Unlike
       other appenders, it doesn't log any messages, it just passes them on to
       its attached sub-appender.  For this reason, it doesn't need a layout
       (contrary to regular appenders).  If it defines none, messages are
       passed on unaltered.

       Custom filters are also applied to the composite appender only.  They
       are not applied to the sub-appender. Same applies to appender
       thresholds. This behaviour might change in the future.

LEGALESE
       Copyright 2004 by Mike Schilli, all rights reserved.  This program is
       free software, you can redistribute it and/or modify it under the same
       terms as Perl itself.

AUTHOR
       2004, Mike Schilli <mATperlmeister.com>








perl v5.12.2                2009-05-02                          2