#!/usr/bin/env perl
# ex: set tabstop=4 et syn=perl:

use strict;
use warnings;
use 5.010.001;

use Benchmark qw(timethis);
use Fcntl;

my $count = shift || 1_000_000;
my $file = '/dev/shm/outfile';

my $bufsize = 256;
my $data1 = chr(1) x $bufsize;
my $data2 = chr(2) x $bufsize;


say "Double syswrite: ";
my $out;
sysopen($out, $file, O_WRONLY|O_CREAT) 
    or die "unable to write on $file";
timethis($count, sub {
    syswrite ($out, $data1, $bufsize) == $bufsize 
        or die "unable to write whole data1 buffer";
    syswrite ($out, $data2, $bufsize) == $bufsize 
        or die "unable to write whole data2 buffer";
});
close $out;

say "Data concat:";
sysopen($out, $file, O_WRONLY|O_CREAT) 
    or die "unable to write on $file";
my $doublebuf = 2 * $bufsize;
timethis($count, sub {
    syswrite ($out, $data1.$data2, $doublebuf) == $doublebuf 
        or die "unable to write all data";
});
close $out;

say "Data join:";
sysopen($out, $file, O_WRONLY|O_CREAT) 
    or die "unable to write on $file";
timethis($count, sub {
    syswrite ($out, join('', $data1, $data2), $doublebuf) == $doublebuf 
        or die "unable to write all data";
});
close $out;

unlink $file;