NAME

MooseX::Workers - Simple sub-process management for asynchronous tasks

SYNOPSIS

package Manager;
use Moose;
with qw(MooseX::Workers);

sub run {
    $_[0]->spawn( sub { sleep 3; print "Hello World\n" } );
    warn "Running now ... ";
    POE::Kernel->run();
}

# Implement our Interface
sub worker_manager_start { warn 'started worker manager' }
sub worker_manager_stop  { warn 'stopped worker manager' }
sub max_workers_reached  { warn 'maximum worker count reached' }

sub worker_stdout  { shift; warn join ' ', @_;  }
sub worker_stderr  { shift; warn join ' ', @_;  }
sub worker_error   { shift; warn join ' ', @_;  }
sub worker_done    { shift; warn join ' ', @_;  }
sub worker_started { shift; warn join ' ', @_;  }
sub sig_child      { shift; warn join ' ', @_;  }
sub sig_TERM       { shift; warn 'Handled TERM' }
no Moose;

Manager->new->run();

DESCRIPTION

MooseX::Workers is a Role that provides easy delegation of long-running tasks into a managed child process. Process managment is taken care of via POE and it's POE::Wheel::Run module.

METHODS

spawn ($command)

fork ($command)

run_command ($command)

These three methods are the whole point of this module. They pass $command through to the MooseX::Worker::Engine which will take care of running $command for you.

spawn() and fork() both envoke POE::Kernel call(), which is synchronous.

run_command() envokes POE::Kernel yield(), which is asynchronous.

If max_workers() has been reached, run_command() warns and does nothing. It is up to you to re-submit $command. See enqueue() if you want us to run $command as soon as another worker is free.

enqueue($command)

Just like run_command(), only that if max_workers() has been set and that number of workers has been reached, then we add $command to a FIFO command queue. As soon as any running worker exits, the first $command in queue (if any) will be run.

check_worker_threshold

This will check to see how many workers you have compared to the max_workers limit. It returns true if the $num_workers is >= $max_workers;

max_workers($count)

An accessor for the maxium number of workers. This is delegated to the MooseX::Workers::Engine object.

has_workers

Check to see if we have *any* workers currently. This is delegated to the MooseX::Workers::Engine object.

num_workers

Return the current number of workers. This is delegated to the MooseX::Workers::Engine object.

meta

The Metaclass for MooseX::Workers::Engine see Moose's documentation.

INTERFACE

MooseX::Worker::Engine supports the following callbacks:

worker_manager_start

Called when the managing session is started

worker_manager_stop

Called when the managing session stops

max_workers_reached

Called when we reach the maximum number of workers

worker_stdout

Called when a child prints to STDOUT

worker_stderr

Called when a child prints to STDERR

worker_error

Called when there is an error condition detected with the child.

worker_done

Called when a worker completes $command

worker_started

Called when a worker starts $command

sig_child

Called when the mangaging session recieves a SIG CHDL event

sig_*

Called when the underlying POE Kernel receives a signal; this is not limited to OS signals (ie. what you'd usually handle in Perl's %SIG) so will also accept arbitrary POE signals (sent via POE::Kernel->signal), but does exclude SIGCHLD/SIGCHILD, which is instead handled by sig_child above.

These interface methods are automatically inserted when MooseX::Worker::Engine detects that your manager class contains any methods beginning with sig_. Signals are case-sensitive, so if you wish to handle a TERM signal, you must define a sig_TERM() method. Note also that this action is performed upon MooseX::Worker::Engine startup, so any run-time modification of your class which 'does' MooseX::Workers is not likely to be detected.

See the sig_TERM handler in the SYNOPSIS for an example.

See MooseX::Workers::Engine for more details. Also see MooseX::Workers::Job if you'd like to give your tasks names, or set timeouts on them.

CONFIGURATION AND ENVIRONMENT

MooseX::Workers requires no configuration files or environment variables.

DEPENDENCIES

Moose, POE, POE::Wheel::Run

INCOMPATIBILITIES

None reported.

BUGS AND LIMITATIONS

No bugs have been reported.

Please report any bugs or feature requests to bug-moosex-workers@rt.cpan.org, or through the web interface at http://rt.cpan.org.

AUTHORS

Chris Prather <perigrin@cpan.org>

Tom Lanyon <dec@cpan.org>

Jay Hannah <jay@jays.net>

Justin Hunter <justin.d.hunter@gmail.com>

LICENCE AND COPYRIGHT

Copyright (c) 2007-2010, Chris Prather <perigrin@cpan.org>. Some 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.

cpanm MooseX::Workers

perl -MCPAN -e shell
install MooseX::Workers