use strict;
use warnings;

use MCE;
use MCE::Candy;
use Time::HiRes 'time';

# usage: script_gather2.pl [ N ]

open my $fh_out, ">:utf8", "output.txt";

my $mce = MCE->new(
    gather      => MCE::Candy::out_iter_fh($fh_out),
    max_workers => 3,
    chunk_size  => 5,
    user_func   => \&user_func,
)->spawn;

my $start = time;
$mce->process( make_iterator( shift || 1000 ) );
my $duration = time - $start;

$mce->shutdown;
close $fh_out;

printf "duration: %0.3f\n", $duration;

sub make_iterator {
    my $max_id = shift;
    my $nxt_id = 0;

    # closure block receives chunk_size value

    return sub {
        my ( $chunk_size, @data ) = @_;
        return if $nxt_id >= $max_id;

        for ( 1 .. $chunk_size ) {
            push @data, ++$nxt_id;
            last if $nxt_id >= $max_id;
        }

        return @data;
    };
}

sub user_func {
    my ( $mce, $chunk_ref, $chunk_id ) = @_;
    my $output = '';

    # chunking requires looping inside user_func

    for ( 0 .. $#{ $chunk_ref } ) {
        $output .= $chunk_ref->[$_]."\n";
    }

    # gather with chunk_id must be called one time only

    MCE->gather($chunk_id, $output);
}


##</code><code>##

use strict;
use warnings;

use MCE;
use Time::HiRes 'time';

# usage: script_relay2.pl [ N ]

open my $fh_out, ">:utf8", "output.txt";
$fh_out->autoflush(1);

my $mce = MCE->new(
    init_relay  => 0,
    max_workers => 3,
    chunk_size  => 5,
    user_func   => \&user_func,
)->spawn;

my $start = time;
$mce->process( make_iterator( shift || 1000 ) );
my $duration = time - $start;

$mce->shutdown;
close $fh_out;

printf "duration: %0.3f\n", $duration;

sub make_iterator {
    my $max_id = shift;
    my $nxt_id = 0;

    # closure block receives chunk_size value

    return sub {
        my ( $chunk_size, @data ) = @_;
        return if $nxt_id >= $max_id;

        for ( 1 .. $chunk_size ) {
            push @data, ++$nxt_id;
            last if $nxt_id >= $max_id;
        }

        return @data;
    };
}

sub user_func {
    my ( $mce, $chunk_ref, $chunk_id ) = @_;
    my $output = '';

    # chunking requires looping inside user_func

    for ( 0 .. $#{ $chunk_ref } ) {
        $output .= $chunk_ref->[$_]."\n";
    }

    # relay must be called one time only

    MCE::relay { print {$fh_out} $output };
}