#! perl -slw
use strict;
use List::Util qw[ shuffle ];
use Benchmark::Timer;

our $N ||= 1_000_000;

sub my_shuffle (\@) {
	my( $aref, $x ) = shift;
	for my $y ( 0 .. $#{ $aref } ) {
		$x = $y + rand( @{ $aref } - $y );
		@$aref[ $y, $x ] = @$aref[ $x, $y ];
	}
}
my $timer = new Benchmark::Timer;
my @array;

print 'Pre-allocation'; <STDIN>;

push @array, $_ for 1 .. $N;

print 'Pre-inplace shuffle'; <STDIN>;

$timer->start('Inplace');
my_shuffle @array;
$timer->stop('Inplace');

print 'Post-inplace shuffle'; <STDIN>;


$timer->start('Copied');
my @shuffled = shuffle @array;
$timer->stop('Copied');

print 'Post-XS_copy shuffle'; <STDIN>;
$timer->report;


__END__
P:\test>test -N=2000000
Pre-allocation

Pre-inplace shuffle

Post-inplace shuffle

Post-XS_copy shuffle

     1 trial  of Inplace    (41.760s total)

     1 trial  of Copied     (48.400s total)