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cPanel-TaskQueue-0.503_04
River stage zero No dependents
3 ++
/ cPanel::TaskQueue::Processor

NAME

cPanel::TaskQueue::Processor - Processes an individual task from the cPanel::TaskQueue.

VERSION

This document describes cPanel::TaskQueue::Processor version 0.503_04.

SYNOPSIS

    package NewTask;

    use base 'cPanel::TaskQueue::Processor';

    sub process_task {
        my ($self, $task) = @_;
        
        # do something exciting.

        return;
    }

    sub is_valid_args {
        my ($self, $task) = @_;
        # all args must be numeric
        return !grep { /[^-\d]/ } $task->args();
    }

DESCRIPTION

This module provides an abstraction for commands to be executed from/by the TaskQueue. It is used as a base class to provide default behavior for every method except process_task that is used by the cPanel::TaskQueue.

PUBLIC METHODS

cPanel::TaskQueue::Processor->new

Create a new cPanel::TaskQueue::Processor object.

$proc->is_dupe( $task_a, $task_b )

Return true if the two supplied cPanel::TaskQueue::Task objects are equivalent. The parameters are guaranteed not to be undef.

The method should return a true value if the parameters are duplicates and a false value if they are not. If the method fails for some reason, throw an exception.

A subclass might want to override this to give more specific processing. The default definition is to check if the arguments for the two supplied task descriptors is the same. If so, return true, else return undef.

$proc->overrides( $new_task, $old_task )

Return true if the new_task cPanel::TaskQueue::Task object should override the old_task object. The parameters are guaranteed not to be undef.

The method should return a true value if there is no need to execute the old_task since the new_task results will override whatever old_task was going to do. For example, if the old task changes a user's password, and the new task deletes that user, there is no need to run the first task. Otherwise the method should return a false value. If the method fails for some reason, throw an exception.

A subclass might want to override this to give more specific processing. The default definition is aways return undef.

$proc->is_valid_args( $task )

Return true if the arguments in the supplied cPanel::TaskQueue::Task are valid for this task. The parameter is guaranteed not to be undef.

The method should return a true value if the supplied task has valid arguments for the command, otherwise it should return false. If the method fails for some reason, the method should throw an exception.

A subclass will probably want to override this method for more specific processing. The default definition is to return true regardless of the state of the supplied task descriptor.

$proc->process_task( $task, $logger )

Perform the task that is described by the supplied cPanel::TaskQueue::Task. The parameter is guaranteed not to be undef. The $logger parameter is an object providing logging facilities for the system. See "#LOGGER OBJECT" in cPanel::TaskQueue for the interface of this object.

This method should return a 0 if the code processing is complete. If the processing spawns a child to handle the work, the method should return the pid of the child. If the processing fails, it should throw an exception.

A subclass must override this method to get any processing. The default throws an exception if called.

$proc->get_timeout()

Return the number of seconds before the task should be considered timed out. The default method returns undef. Any false value uses whatever the default value for the TaskQueue defines. A subclass may override this method to provide a longer time out value for cases where the processing is known to take some time.

$proc->deferral_tags( $task )

Return a list of tags that that the supplied $task defers.

$proc->is_task_deferred( $task, $defer_hash )

Check the supplied $task against the $defer_hash to decide if the task should be deferred. Return a true value if the task should be deferred, false otherwise.

UTILITY METHODS

This section describes convenience methods that may be useful to classes derived from the Processor class.

$proc->checked_system( $hashref )

In many cases, the task to be processed depends on running another program. Since handling the return code from system is annoying, it often gets ignored. This method calls the core system routine, and checks the return code. It logs an appropriate message for error conditions and is quiet on success. checked_system returns the same return code as system.

The method expects a hash ref describing the request. The parameters in the hash ref are:

logger

This required parameter should provide an object following the logging interface described in "#LOGGER OBJECT" in cPanel::TaskQueue. If this parameter is missing, the method throws an exception.

name

This required parameter provides a name used in any error messages. If this parameter is missing, the method throws an exception.

cmd

This required parameter provides the command that system is to execute. If this parameter is missing, the method throws an exception.

args

This optional parameter is an array reference containing the parameters to pass with the command to the system call. If this parameter is missing, an empty list is assumed.

DIAGNOSTICS

No processing has been specified for this task.

Either this base class has been used directly as a processor for a command or the process_task method was not overridden in a derived class.

In either case, the default behavior for process_task is to throw an exception.

CONFIGURATION AND ENVIRONMENT

cPanel::TaskQueue::Processor requires no configuration files or environment variables.

DEPENDENCIES

None.

SEE ALSO

cPanel::TaskQueue, cPanel::TaskQueue::Task

INCOMPATIBILITIES

None reported.

BUGS AND LIMITATIONS

No bugs have been reported.

AUTHOR

G. Wade Johnson wade@cpanel.net

LICENCE AND COPYRIGHT

Copyright (c) 2011, cPanel, Inc. All rights reserved.

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

DISCLAIMER OF WARRANTY

BECAUSE THIS SOFTWARE IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY FOR THE SOFTWARE, TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES PROVIDE THE SOFTWARE "AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE SOFTWARE IS WITH YOU. SHOULD THE SOFTWARE PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING, REPAIR, OR CORRECTION.

IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR REDISTRIBUTE THE SOFTWARE AS PERMITTED BY THE ABOVE LICENCE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR INABILITY TO USE THE SOFTWARE (INCLUDING BUT NOT LIMITED TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD PARTIES OR A FAILURE OF THE SOFTWARE TO OPERATE WITH ANY OTHER SOFTWARE), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.