package SWISH::Prog::Queue;
use strict;
use warnings;
use base qw( SWISH::Prog::Class );
use Carp;
our $VERSION = '0.74';
=pod
=head1 NAME
SWISH::Prog::Queue - simple in-memory FIFO queue class
=head1 SYNOPSIS
use SWISH::Prog::Queue;
my $queue = SWISH::Prog::Queue->new;
$queue->put( 'foo' );
$queue->size; # returns number of items in queue (1)
$queue->peek; # returns 'foo' (next value for get())
$queue->get; # returns 'foo' locks it in queue (no one else can get it)
$queue->remove('foo'); # returns 'foo' and removes it from queue
$queue->clean; # removes all completed items from queue
=head1 DESCRIPTION
SWISH::Prog::Queue is basically a Perl array, but it defines an API
that can be implemented using any kind of storage and logic you want.
One example would be a database that tracks items to be evaluated, or a flat
file list.
=head1 METHODS
See SWISH::Prog::Class.
=cut
=head2 init
Overrides base method.
=cut
sub init {
my $self = shift;
$self->SUPER::init(@_);
$self->{q} ||= [];
}
=head2 put( I<item> )
Add I<item> to the queue. Default is to push() it to end of queue.
=cut
sub put {
my $self = shift;
push( @{ $self->{q} }, @_ );
}
=head2 get
Returns the next item. Default is to shift() it from the front of the queue.
=cut
sub get {
my $self = shift;
$self->{locks} ||= {};
my $v = shift( @{ $self->{q} } );
if ( $self->{locks}->{$v}++ ) {
return undef;
}
return $v;
}
=head2 remove( I<item> )
Removes I<item> from the queue (unlocks it).
=cut
sub remove {
my $self = shift;
my $v = shift;
return delete $self->{locks}->{$v};
}
=head2 clean
Removes all locked items from the queue.
=cut
sub clean {
my $self = shift;
delete $self->{locks};
}
=head2 peek
Returns the next item value, but leaves it on the stack.
=cut
sub peek {
return $_[0]->{q}->[0];
}
=head2 size
Returns the number of items currently in the queue.
=cut
sub size {
return scalar( @{ $_[0]->{q} } );
}
1;
__END__
=head1 AUTHOR
Peter Karman, E<lt>perl@peknet.comE<gt>
=head1 BUGS
Please report any bugs or feature requests to C<bug-swish-prog at rt.cpan.org>, or through
the web interface at L<http://rt.cpan.org/NoAuth/ReportBug.html?Queue=SWISH-Prog>.
I will be notified, and then you'll
automatically be notified of progress on your bug as I make changes.
=head1 SUPPORT
You can find documentation for this module with the perldoc command.
perldoc SWISH::Prog
You can also look for information at:
=over 4
=item * Mailing list
L<http://lists.swish-e.org/listinfo/users>
=item * RT: CPAN's request tracker
L<http://rt.cpan.org/NoAuth/Bugs.html?Dist=SWISH-Prog>
=item * AnnoCPAN: Annotated CPAN documentation
L<http://annocpan.org/dist/SWISH-Prog>
=item * CPAN Ratings
L<http://cpanratings.perl.org/d/SWISH-Prog>
=item * Search CPAN
L<http://search.cpan.org/dist/SWISH-Prog/>
=back
=head1 COPYRIGHT AND LICENSE
Copyright 2008-2009 by Peter Karman
This library is free software; you can redistribute it and/or modify
it under the same terms as Perl itself.
=head1 SEE ALSO
L<http://swish-e.org/>