# to run
perl demo.pl haukex
perl demo.pl karlary
perl demo.pl karlseq


##</code><code>##

#!/usr/bin/env perl

# Re^2: search for particular elements of hash with multiple values
# http://www.perlmonks.org/?node_id=1188488

use strict;
use warnings;
use feature qw ( say );

use MCE::Loop;

use constant {
    _FOWPRIM => 0, _REVPRIM => 1, _BC_PAIR => 2, _BC_PNUM => 3
};

# Note: The karlhash function requires MCE 1.828 to be released soon.

sub usage {
    warn "usage: $0 ( haukex | karlary | karlhash | karlseq )\n\n";
    exit 1;
}

my $func_name = shift || usage();

usage() unless __PACKAGE__->can($func_name);

my $max = 1000000;

my $data =
  [ 'AGCTCGTTGTTCGATCCA', 'GAGAGATAGATGATAGTG', 'TTTT_CCCC', 0 ];

our %barcode_hash = map { $_ => $data } 1 .. $max - 2;

$barcode_hash{ ($max - 1) } =
  [ 'AGCTCGTTGTTCGATCCA', 'GAGAGATAGATGATAGTG', 'TTTT_AAAA', 0 ];

$barcode_hash{ ($max) } =
  [ 'AGCTCGTTGTTCGATCCA', 'GAGAGATAGATGATAGTG', 'TTTT_AAAA', 0 ];

our $barcode_pair_35 = 'TTTT_AAAA';

$| = 1;

{
    no strict qw ( refs );
    my @found = $func_name->();

    # increment the bc_pair_num field
    $barcode_hash{$_}[_BC_PNUM]++ for @found;

    # display summary and found keys
    printf "Found %d keys\n", scalar @found;
    say join ', ', sort { $a <=> $b } @found;
}

exit(0);

sub haukex {
    # Serial code.
    my @found;

    for my $key (1 .. $max) {
        if ($barcode_hash{$key}[_BC_PAIR] eq $barcode_pair_35) {
            say "Found at $key";
            push @found, $key;
        }
    }

    return @found;
}

sub karlary {
    # Workers receive next array chunk.

    MCE::Loop::init {
        max_workers => 4
    };

    my @found = mce_loop {
        my ($mce, $chunk_ref, $chunk_id) = @_;
        for my $key ( @$chunk_ref ) {
            if ($barcode_hash{$key}[_BC_PAIR] eq $barcode_pair_35) {
                MCE->say("Found at $key, chunk_id: $chunk_id");
                MCE->gather($key);
            }
        }
    }
    1 .. $max;

    MCE::Loop::finish();

    return @found;
}

sub karlhash {
    # Workers receive next array chunk.

    MCE::Loop::init {
        max_workers => 4
    };

    # Must have MCE 1.828 or later to run this demonstration.
    # See http://www.perlmonks.org/?node_id=1188593 for a faster
    # solution using hashref as input by spawning workers early.
    # That will run better on the Windows platform.

    my @found = mce_loop {
        my ($mce, $chunk_ref, $chunk_id) = @_;
        for my $key ( keys %{ $chunk_ref } ) {
            if ($chunk_ref->{$key}[_BC_PAIR] eq $barcode_pair_35) {
                MCE->say("Found at $key, chunk_id: $chunk_id");
                MCE->gather($key);
            }
        }
    }
    \%barcode_hash;

    MCE::Loop::finish();

    return @found;
}

sub karlseq {
    # Workers receive next sequence 'begin' and 'end' boundaries.

    MCE::Loop::init {
        max_workers => 4, bounds_only => 1
    };

    # The bounds_only option applies to sequence which means for
    # workers to compute the begin and end boundaries only and
    # not the items in between. The result is lesser overhead.

    my @found = mce_loop_s {
        my ($mce, $chunk_ref, $chunk_id) = @_;
        for my $key ($chunk_ref->[0] .. $chunk_ref->[1]) {
            if ($barcode_hash{$key}[_BC_PAIR] eq $barcode_pair_35) {
                MCE->say("Found at $key, chunk_id: $chunk_id");
                MCE->gather($key);
            }
        }
    }
    1, $max;

    MCE::Loop::finish();

    return @found;
}