use strict;
use Benchmark qw(cmpthese);
use lib '/home/mason/devel/lib';
use IO::All;
use File::ReadBackwards;
my $f = "/usr/local/apache/logs/error_log";
cmpthese(
    -3,
    {
        'OP\'s' => sub {
            my $lineno = 100;
            open( FILE, "$f" ) or die "Can't find $f\n";
            my @lines = <FILE>;
            my $num = @lines;
            my @last;
            for ( ; $lineno > 0 ; $lineno-- ) {
               push(@last,$lines[ $num - $lineno ]);
            }
            close(FILE);
        },
        'IO::All->backwards' => sub {
            my $f = io($f)->backwards;
            my @lines = reverse map { $f->getline } 1 .. 100;
        },
        'File::ReadBackwards' => sub {
            my $f = File::ReadBackwards->new($f);
            my @lines = reverse map { $f->readline } 1 .. 100;
        },
        'TedYoung' => sub {
            my @lines;
            my $lines = 100;
            open F, $f or die $!;
            my @lines;
            while (<F>) {
                push @lines, $_;
                shift @lines if @lines > $lines;
            }
            close F;
        },
        '`tail -100`' => sub {
            my @lines = `tail -100 $f`;
        },
        'RandomWalk' => sub {
            my ($file, $lines) = ($f,100);
            open F, $file or die $!;
            my @lines;
            $#lines=($lines-1);
            my $i;
            while (<F>) {
            $lines[$i++] = $_;
            $i = 0 if $i == $lines;
            }
            close F;
            return @lines[$i--..$#lines, 0..$i]
        }
    }
);