Catalyst::Plugin::Scheduler(3pm)			User Contributed Perl Documentation			  Catalyst::Plugin::Scheduler(3pm)

NAME

       Catalyst::Plugin::Scheduler - Schedule events to run in a cron-like fashion

SYNOPSIS

	   use Catalyst qw/Scheduler/;

	   # run remove_sessions in the Cron controller every hour
	   __PACKAGE__->schedule(
	       at    => '0 * * * *',
	       event => '/cron/remove_sessions'
	   );

	   # Run a subroutine at 4:05am every Sunday
	   __PACKAGE__->schedule(
	       at    => '5 4 * * sun',
	       event => &do_stuff,
	   );

	   # A long-running scheduled event that must be triggered
	   # manually by an authorized user
	   __PACKAGE__->schedule(
	       trigger => 'rebuild_search_index',
	       event   => '/cron/rebuild_search_index',
	   );
	   $ wget -q http://www.myapp.com/?schedule_trigger=rebuild_search_index

DESCRIPTION

       This plugin allows you to schedule events to run at recurring intervals.  Events will run during the first request which meets or exceeds
       the specified time.  Depending on the level of traffic to the application, events may or may not run at exactly the correct time, but it
       should be enough to satisfy many basic scheduling needs.

CONFIGURATION

       Configuration is optional and is specified in MyApp->config->{scheduler}.

   logging
       Set to 1 to enable logging of events as they are executed.  This option is enabled by default when running under -Debug mode.  Errors are
       always logged regardless of the value of this option.

   time_zone
       The time zone of your system.  This will be autodetected where possible, or will default to UTC (GMT).  You can override the detection by
       providing a valid DateTime time zone string, such as 'America/New_York'.

   state_file
       The current state of every event is stored in a file.  By default this is $APP_HOME/scheduler.state.  This file is created on the first
       request if it does not already exist.

   yaml_file
       The location of the optional YAML event configuration file.  By default this is $APP_HOME/scheduler.yml.

   hosts_allow
       This option specifies IP addresses for trusted users.  This option defaults to 127.0.0.1.  Multiple addresses can be specified by using an
       array reference.  This option is used for both events where auto_run is set to 0 and for manually-triggered events.

	   __PACKAGE__->config->{scheduler}->{hosts_allow} = '192.168.1.1';
	   __PACKAGE__->config->{scheduler}->{hosts_allow} = [
	       '127.0.0.1',
	       '192.168.1.1'
	   ];

SCHEDULING

   AUTOMATED EVENTS
       Events are scheduled by calling the class method "schedule".

	   MyApp->schedule(
	       at	=> '0 * * * *',
	       event	=> '/cron/remove_sessions',
	   );

	   package MyApp::Controller::Cron;

	   sub remove_sessions : Private {
	       my ( $self, $c ) = @_;

	       $c->delete_expired_sessions;
	   }

       at

       The time to run an event is specified using crontab(5)-style syntax.

	   5 0 * * *	  # 5 minutes after midnight, every day
	   15 14 1 * *	  # run at 2:15pm on the first of every month
	   0 22 * * 1-5   # run at 10 pm on weekdays
	   5 4 * * sun	  # run at 4:05am every Sunday

       From crontab(5):

	   field	  allowed values
	   -----	  --------------
	   minute	  0-59
	   hour 	  0-23
	   day of month   1-31
	   month	  0-12 (or names, see below)
	   day of week	  0-7 (0 or 7 is Sun, or use names)

       Instead of the first five fields, one of seven special strings may appear:

	   string	  meaning
	   ------	  -------
	   @yearly	  Run once a year, "0 0 1 1 *".
	   @annually	  (same as @yearly)
	   @monthly	  Run once a month, "0 0 1 * *".
	   @weekly	  Run once a week, "0 0 * * 0".
	   @daily	  Run once a day, "0 0 * * *".
	   @midnight	  (same as @daily)
	   @hourly	  Run once an hour, "0 * * * *".

       event

       The event to run at the specified time can be either a Catalyst private action path or a coderef.  Both types of event methods will receive
       the $c object from the current request, but you must not rely on any request-specific information present in $c as it will be from a random
       user request at or near the event's specified run time.

       Important: Methods used for events should be marked "Private" so that they can not be executed via the browser.

       auto_run

       The auto_run parameter specifies when the event is allowed to be executed.  By default this option is set to 1, so the event will be
       executed during the first request that matches the specified time in "at".

       If set to 0, the event will only run when a request is made by a user from an authorized address.  The purpose of this option is to allow
       long-running tasks to execute only for certain users.

	   MyApp->schedule(
	       at	=> '0 0 * * *',
	       event	=> '/cron/rebuild_search_index',
	       auto_run => 0,
	   );

	   package MyApp::Controller::Cron;

	   sub rebuild_search_index : Private {
	       my ( $self, $c ) = @_;

	       # rebuild the search index, this may take a long time
	   }

       Now, the search index will only be rebuilt when a request is made from a user whose IP address matches the list in the "hosts_allow" config
       option.	To run this event, you probably want to ping the app from a cron job.

	   0 0 * * * wget -q http://www.myapp.com/

   MANUAL EVENTS
       To create an event that does not run on a set schedule and must be manually triggered, you can specify the "trigger" option instead of
       "at".

	   __PACKAGE__->schedule(
	       trigger => 'send_email',
	       event   => '/events/send_email',
	   );

       The event may then be triggered by a standard web request from an authorized user.  The trigger to run is specified by using a special GET
       parameter, 'schedule_trigger'; the path requested does not matter.

	   http://www.myapp.com/?schedule_trigger=send_email

       By default, manual events may only be triggered by requests made from localhost (127.0.0.1).  To allow other addresses to run events, use
       the configuration option "hosts_allow".

SCHEDULING USING A YAML FILE

       As an alternative to using the schedule() method, you may define scheduled events in an external YAML file.  By default, the plugin looks
       for the existence of a file called "scheduler.yml" in your application's home directory.  You can change the filename using the
       configuration option "yaml_file".

       Modifications to this file will be re-read once per minute during the normal event checking process.

       Here's an example YAML configuration file with 4 events.  Each event is denoted with a '-' character, followed by the same parameters used
       by the "schedule" method.  Note that coderef events are not supported by the YAML file.

	   ---
	   - at: '* * * * *'
	     event: /cron/delete_sessions
	   - event: /cron/send_email
	     trigger: send_email
	   - at: '@hourly'
	     event: /cron/hourly
	   - at: 0 0 * * *
	     auto_run: 0
	     event: /cron/rebuild_search_index

SECURITY

       All events are run inside of an eval container.	This protects the user from receiving any error messages or page crashes if an event fails
       to run properly.  All event errors are logged, even if logging is disabled.

PLUGIN SUPPORT

       Other plugins may register scheduled events if they need to perform periodic maintenance.  Plugin authors, be sure to inform your users if
       you do this!  Events should be registered from a plugin's "setup" method.

	   sub setup {
	       my $c = shift;
	       $c->maybe::next::method(@_);

	       if ( $c->can('schedule') ) {
		   $c->schedule(
		       at    => '0 * * * *',
		       event => &cleanup,
		   );
	       }
	   }

CAVEATS

       The time at which an event will run is determined completely by the requests made to the application.  Apps with heavy traffic may have
       events run at very close to the correct time, whereas apps with low levels of traffic may see events running much later than scheduled.	If
       this is a problem, you can use a real cron entry that simply hits your application at the desired time.

	   0 * * * * wget -q http://www.myapp.com/

       Events which consume a lot of time will slow the request processing for the user who triggers the event.  For these types of events, you
       should use auto_run => 0 or manual event triggering.

PERFORMANCE

       The plugin only checks once per minute if any events need to be run, so the overhead on each request is minimal.  On my test server, the
       difference between running with Scheduler and without was only around 0.02% (0.004 seconds).

       Of course, when a scheduled event runs, performance will depend on what's being run in the event.

METHODS

   schedule
       Schedule is a class method for adding scheduled events.	See the "SCHEDULING"" in " section for more information.

   scheduler_state
       The current state of all scheduled events is available in an easy-to-use format by calling $c->scheduler_state.	You can use this data to
       build an admin view into the scheduling engine, for example.  This same data is also displayed on the Catalyst debug screen.

       This method returns an array reference containing a hash reference for each event.

	   [
	       {
		   'last_run'	 => '2005-12-29 16:29:33 EST',
		   'auto_run'	 => 1,
		   'last_output' => 1,
		   'at' 	 => '0 0 * * *',
		   'next_run'	 => '2005-12-30 00:00:00 EST',
		   'event'	 => '/cron/session_cleanup'
	       },
	       {
		   'auto_run'	 => 1,
		   'at' 	 => '0 0 * * *',
		   'next_run'	 => '2005-12-30 00:00:00 EST',
		   'event'	 => '/cron/build_rss'
	       },
	   ]

INTERNAL METHODS

       The following methods are extended by this plugin.

       dispatch
	   The main scheduling logic takes place during the dispatch phase.

       dump_these
	   On the Catalyst debug screen, all scheduled events are displayed along with the next time they will be executed.

       setup

SEE ALSO

       crontab(5)

AUTHOR

       Andy Grundman, <andy@hybridized.org>

COPYRIGHT

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

perl v5.14.2							    2010-05-03					  Catalyst::Plugin::Scheduler(3pm)