package Log::Log4perl::Appender::Limit;
use strict;
use warnings;
use Storable;
our @ISA = qw(Log::Log4perl::Appender);
our $CVSVERSION = '$Revision: 1.6 $';
our ($VERSION) = ($CVSVERSION =~ /(\d+\.\d+)/);
sub new {
my($class, %options) = @_;
my $self = {
max_until_flushed => undef,
max_until_discarded => undef,
appender => undef,
accumulate => 1,
persistent => undef,
block_period => 3600,
buffer => [],
%options,
};
push @{$options{l4p_depends_on}}, $self->{appender};
push @{$options{l4p_post_config_subs}}, sub { $self->post_init() };
bless $self, $class;
if(defined $self->{persistent}) {
$self->restore();
}
return $self;
}
sub log {
my($self, %params) = @_;
my $discard = 0;
if(defined $self->{max_until_discarded} and
scalar @{$self->{buffer}} >= $self->{max_until_discarded} - 1) {
$discard = 1;
}
my $flush = 0;
if(defined $self->{max_until_flushed} and
scalar @{$self->{buffer}} >= $self->{max_until_flushed} - 1) {
$flush = 1;
}
if(!$flush and
(exists $self->{sent_last} and
$self->{sent_last} + $self->{block_period} > time()
)
) {
return if $discard;
$params{log4p_logtime} =
$self->{app}->{layout}->{time_function}->() if exists
$self->{app}->{layout}->{time_function};
push @{$self->{buffer}}, \%params if $self->{accumulate};
$self->save() if $self->{persistent};
return;
}
$Log::Log4perl::caller_depth += 2;
$self->flush();
$self->{app}->SUPER::log(\%params,
$params{log4p_category},
$params{log4p_level});
$Log::Log4perl::caller_depth -= 2;
$self->{sent_last} = time();
$self->save() if $self->{persistent};
}
sub post_init {
my($self) = @_;
if(! exists $self->{appender}) {
die "No appender defined for " . __PACKAGE__;
}
my $appenders = Log::Log4perl->appenders();
my $appender = Log::Log4perl->appenders()->{$self->{appender}};
if(! defined $appender) {
die "Appender $self->{appender} not defined (yet) when " .
__PACKAGE__ . " needed it";
}
$self->{app} = $appender;
}
sub save {
my($self) = @_;
my $pdata = [$self->{buffer}, $self->{sent_last}];
store $pdata, $self->{persistent} or
die "Cannot save messages in $self->{persistent} ($!)";
}
sub restore {
my($self) = @_;
if(-f $self->{persistent}) {
my $pdata = retrieve $self->{persistent} or
die "Cannot retrieve messages from $self->{persistent} ($!)";
($self->{buffer}, $self->{sent_last}) = @$pdata;
}
}
sub flush {
my($self) = @_;
for(@{$self->{buffer}}) {
local $self->{app}->{layout}->{time_function};
$self->{app}->{layout}->{time_function} =
sub { $_->{log4p_logtime} };
$self->{app}->SUPER::log($_,
$_->{log4p_category},
$_->{log4p_level});
}
$self->{buffer} = [];
}
sub DESTROY {
my($self) = @_;
}
1;
__END__
=head1 NAME
Log::Log4perl::Appender::Limit - Limit message delivery via block period
=head1 SYNOPSIS
use Log::Log4perl qw(:easy);
my $conf = qq(
log4perl.category = WARN, Limiter
# Email appender
log4perl.appender.Mailer = Log::Dispatch::Email::MailSend
log4perl.appender.Mailer.to = drone\@pageme.com
log4perl.appender.Mailer.subject = Something's broken!
log4perl.appender.Mailer.buffered = 0
log4perl.appender.Mailer.layout = PatternLayout
log4perl.appender.Mailer.layout.ConversionPattern=%d %m %n
# Limiting appender, using the email appender above
log4perl.appender.Limiter = Log::Log4perl::Appender::Limit
log4perl.appender.Limiter.appender = Mailer
log4perl.appender.Limiter.block_period = 3600
);
Log::Log4perl->init(\$conf);
WARN("This message will be sent immediately");
WARN("This message will be delayed by one hour.");
sleep(3601);
WARN("This message plus the last one will be sent now");
=head1 DESCRIPTION
=over 4
=item C<appender>
Specifies the name of the appender used by the limiter. The
appender specified must be defined somewhere in the configuration file,
not necessarily before the definition of
C<Log::Log4perl::Appender::Limit>.
=item C<block_period>
Period in seconds between delivery of messages. If messages arrive in between,
they will be either saved (if C<accumulate> is set to a true value) or
discarded (if C<accumulate> isn't set).
=item C<persistent>
File name in which C<Log::Log4perl::Appender::Limit> persistently stores
delivery times. If omitted, the appender will have no recollection of what
happened when the program restarts.
=item C<max_until_flushed>
Maximum number of accumulated messages. If exceeded, the appender flushes
all messages, regardless if the interval set in C<block_period>
has passed or not. Don't mix with C<max_until_discarded>.
=item C<max_until_discarded>
Maximum number of accumulated messages. If exceeded, the appender will
simply discard additional messages, waiting for C<block_period> to expire
to flush all accumulated messages. Don't mix with C<max_until_flushed>.
=back
If the appender attached to C<Limit> uses C<PatternLayout> with a timestamp
specifier, you will notice that the message timestamps are reflecting the
original log event, not the time of the message rendering in the
attached appender. Major trickery has applied to accomplish this (Cough!).
=head1 DEVELOPMENT NOTES
C<Log::Log4perl::Appender::Limit> is a I<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 I<not> applied to the sub-appender. Same applies to appender
thresholds. This behaviour might change in the future.
=head1 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.
=head1 AUTHOR
2004, Mike Schilli <m@perlmeister.com>