#!/usr/bin/perl
use strict;
use warnings;
use Benchmark qw(cmpthese);

my $file='test.txt';
my $file_size=60*1024*1024; # 60MB
my $iter=10;

# create file
{
  my $lines=int($file_size/81);
  print "create file $file ($file_size Byte) with $lines Lines and 81 chars per line\n";
  open(my $fh, '>', $file) or die("$file : $!\n");
  for(1..$lines)
  {
    print $fh join('',map{chr(int(rand(94))+32)}(1..80))."\n";
  }
  close($fh);
}

# open only once
open(my $fh, '<', $file) or die("$file : $!\n");

# loding file in OS-Filesystem-Cache:
{
  local $/=undef;
  <$fh>;
}

print "Run Benchmark\n";
cmpthese($iter, {
'read all' => sub{
    # goto file start

    seek($fh,0,0);
    my @l=<$fh>;
  },
'read push' => sub{
    # goto file start
    seek($fh,0,0);

    my @l;
    while(<$fh>)
    { push(@l,$_); }
  },
});

close($fh);