package Queue::Q::NaiveFIFO;
use strict;
use warnings;

use Carp qw(croak);

# enqueue_item($single_data_structure)
sub enqueue_item { croak("Unimplemented") }
# enqueue_items(@list_of_data_structures)
sub enqueue_items { croak("Unimplemented") }
# my $item_or_undef = claim_item()
sub claim_item { croak("Unimplemented") }
# my (@items_or_undefs) = claim_items($n)
sub claim_items { croak("Unimplemented") }

sub flush_queue { croak("Unimplemented") }

# my $nitems = queue_length()
sub queue_length { croak("Unimplemented") }

1;
__END__

=head1 NAME

Queue::Q::NaiveFIFO - Very primitive FIFO queue

=head1 SYNOPSIS

  use Queue::Q::NaiveFIFO::Redis; # or ::Perl

=head1 DESCRIPTION

Abstract interface class for a naive FIFO queue without
resilience against crashing workers. Implementations are
required to provide strict ordering and adhere to
the run-time complexities listed below (or better).

=head1 METHODS

=head2 enqueue_item

Given a data structure, that data structure is added to
the queue. Items enqueued with C<enqueue_item> in order
must be returned by C<claim_item> in the same order.

Complexity: O(1)

=head2 enqueue_items

Given a number data structures, enqueues them in order.
This is conceptually the same as calling C<enqueue_item> multiple
times, but may help save on network round-trips.

Complexity: O(n) where n is the number of items to enqueue.

=head2 claim_item

Returns the oldest item in the queue. Returns C<undef>
if there is none left.

Complexity: O(1)

=head2 claim_items

As C<enqueue_items> is to C<enqueue_item>, C<claim_items> is to
C<claim_item>. Takes one optional parameter (defaults to 1):
The number of items to fetch and return:

  my @items = $q->claim_items(20); # returns a batch of 20 items

If there are less than the desired number of items to be claimed,
returns a correspondingly shorter list.

Complexity: O(n) where n is the number of items claimed.

=head2 queue_length

Returns the number of items available in the queue.

Complexity: O(1)

=head2 flush_queue

Removes all content in the queue.

Complexity: O(n) where n is the number of items in the queue.

=head1 AUTHOR

Steffen Mueller, E<lt>smueller@cpan.orgE<gt>

=head1 COPYRIGHT AND LICENSE

Copyright (C) 2012 by Steffen Mueller

This library is free software; you can redistribute it and/or modify
it under the same terms as Perl itself, either Perl version 5.8.1 or,
at your option, any later version of Perl 5 you may have available.

=cut