[log4perl-devel] New composite appender: Limit

[Mike S. <msc...@ao...>]

Hi all,

if you'd like to limit the number of messages sent out via an appender, 
there's a new appender in town you might like: Use 
Log::Log4perl::Appender::Limit in conjunction with a real appender like 
Log::Dispatch::Email, and it won't send out messages more often than 
once per configurable time frame (like, one hour). Here's the docs:

NAME
   Log::Log4perl::Appender::Limit - Limit message delivery via block period

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");


DESCRIPTION
   "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
    "Log::Log4perl::Appender::Limit".

   "block_period"
    Period in seconds between delivery of messages. If messages arrive
    in between, they will be either saved (if "accumulate" is set to a
    true value) or discarded (if "accumulate" isn't set).

   "persistent"
    File name in which "Log::Log4perl::Appender::Limit" persistently
    stores delivery times. If omitted, the appender will have no
    recollection of what happened when the program restarts.

If the appender attached to "Limit" uses "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!).

-- 
-- Mike
Mike Schilli
m...@pe...