# Log::Log4perl::Appender::Buffer - phpMan

## 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
        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.

## LICENSE
    Copyright 2002-2013 by Mike Schilli <<m@perlmeister.com>> and Kevin Goess
    <<cpan@goess.org>>.

    This library is free software; you can redistribute it and/or modify it
    under the same terms as Perl itself.

## AUTHOR
    Please contribute patches to the project on Github:

        <http://github.com/mschilli/log4perl>

    Send bug reports or requests for enhancements to the authors via our

    MAILING LIST (questions, bug reports, suggestions/patches):
    <log4perl-devel@lists.sourceforge.net>

    Authors (please contact them via the list above, not directly): Mike
    Schilli <<m@perlmeister.com>>, Kevin Goess <<cpan@goess.org>>

    Contributors (in alphabetical order): Ateeq Altaf, Cory Bennett, Jens
    Berthold, Jeremy Bopp, Hutton Davidson, Chris R. Donnelly, Matisse
    Enzer, Hugh Esco, Anthony Foiani, James FitzGibbon, Carl Franks, Dennis
    Gregorovic, Andy Grundman, Paul Harrington, Alexander Hartmaier David
    Hull, Robert Jacobson, Jason Kohles, Jeff Macdonald, Markus Peter, Brett
    Rann, Peter Rabbitson, Erik Selberg, Aaron Straup Cope, Lars Thegler,
    David Viner, Mac Yang.