/ 
IPC-Concurrency-DBI-1.0.2
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/ IPC::Concurrency::DBI::Application

NAME

IPC::Concurrency::DBI::Application - Application identifier that represents the resource that will be limited.

VERSION

Version 1.0.2

SYNOPSIS

This module allows controlling how many instances of a given program are allowed to run in parallel. It does not manage forking or starting those instances.

See the documentation of IPC::Concurrency::DBI for more information.

# Configure the concurrency object.
use IPC::Concurrency::DBI;
my $concurrency_manager = IPC::Concurrency::DBI->new(
	'database_handle' => $dbh,
	'verbose'         => 1,
);

# Retrieve the application.
my $application = $concurrency_manager->get_application(
	name => 'cron_script.pl',
);

# Count how many instances are currently running.
my $instances_count = $application->get_instances_count();

# NOT IMPLEMENTED YET: Get a list of what instances are currently running.
# my $instances = $application->get_instances_list()

# Start a new instance of the application. If this returns undef, we've
# reached the limit.
my $instance = $concurrent_program->start_instance();
unless ( defined( $instance ) )
{
	print "Too many instances of $0 are already running.\n";
	exit;
}

# [...] Do some work.

# Now that the application is about to exit, flag the instance as completed.
# (note: this is implicit when $instance is destroyed).
$instance->finish();

METHODS

new()

Create a new IPC::Concurrency::DBI::Application object. This function should not be called directly and its API could change, instead use IPC::Concurrency::DBI->get_application().

# Retrieve the application by name.
my $application = IPC::Concurrency::DBI::Application->new(
	database_handle => $dbh,
	name            => 'cron_script.pl',
);
die 'Application not found'
	unless defined( $application );

# Retrieve the application by ID.
my $application = IPC::Concurrency::DBI::Application->new(
	database_handle => $dbh,
	id              => 12345,
);
die 'Application not found'
	unless defined( $application );

'database handle': mandatory, a DBI object.

'name': the name of the application to retrieve.

'id': the internal ID of the application to retrieve.

start_instance()

Start a new instance of the current application.

my $instance = $application->start_instance();
unless ( defined( $instance ) )
{
	print "Too many instances of $0 are already running.\n";
	exit;
}

GETTERS / SETTERS

get_instances_count()

Retrieve the number of instances that currently running.

my $instances_count = $application->get_instances_count();

get_maximum_instances()

Retrieve the maximum number of instances of the current application that are allowed to run in parallel.

my $maximum_instances = $application->get_maximum_instances();

set_maximum_instances()

Change the maximum number of instances of the current application that are allowed to run in parallel.

$application->set_maximum_instances( 10 );

get_name()

Returns the name of the current application.

my $name = $application->get_name();

get_id()

Returns the internal ID of the current application.

my $application_id = $self->get_id();

INTERNAL METHODS

_get_database_handle()

Returns the database handle used for this queue.

my $database_handle = $concurrency_manager->_get_database_handle();

AUTHOR

Guillaume Aubert, <aubertg at cpan.org>.

BUGS

Please report any bugs or feature requests to bug-ipc-concurrency-dbi at rt.cpan.org, or through the web interface at http://rt.cpan.org/NoAuth/ReportBug.html?Queue=IPC-Concurrency-DBI. I will be notified, and then you'll automatically be notified of progress on your bug as I make changes.

SUPPORT

You can find documentation for this module with the perldoc command.

perldoc IPC::Concurrency::DBI

You can also look for information at:

ACKNOWLEDGEMENTS

Thanks to ThinkGeek (http://www.thinkgeek.com/) and its corporate overlords at Geeknet (http://www.geek.net/), for footing the bill while I eat pizza and write code for them!

Thanks to Jacob Rose <jacob at thinkgeek.com> for suggesting the idea of this module and brainstorming with me about the features it should offer.

COPYRIGHT & LICENSE

Copyright 2011-2012 Guillaume Aubert.

This program is free software; you can redistribute it and/or modify it under the terms of the Artistic License.

See http://dev.perl.org/licenses/ for more information.