add 1ms delay after write to pipe

[anktx]

A small delay, needed on fast configurations, allow R-command to be executed.

Just a small test:

<?php

use Okvpn\R\Process\RProcess;
use Okvpn\R\UnixPipes;

require DIR . '/vendor/autoload.php';

$process = new RProcess(new UnixPipes(), '/usr/bin/R');
$process->start();

print_r($process->write('head(cars)')->getAllOutput());

Without delay we have:

Array
(
[0] => options(error=expression(NULL))
)

With this delay we have expected result:

Array
(
[0] => options(error=expression(NULL))
head(cars)
speed dist
1 4 2
2 4 10
3 7 4
4 7 22
5 8 16
6 9 10
)

[anktx]

Also, a delay can be in pipe read cycle (/src/UnixPipes.php):

$data = fread($pipe, self::CHUNK_SIZE);
usleep(1000);
$read[$type] .= $data;

kachkaev/php-r have such delay: link.