stream_select_demo.php

<?php
class Buffer
{
	public $data = '';
	public $end = FALSE;
}

class Loop
{
	public $readStreams = [];
	public $writeStreams = [];
	public $buffers = []; // streamId => buffer

	public function run()
	{
		while (count($this->readStreams) + count($this->writeStreams)) {
			$r = $this->readStreams;
			$w = $this->writeStreams;
			$e = NULL;
			if (stream_select($r, $w, $e, 0) > 0) {
				foreach ((array) $r as $stream) {
					$buffer = $this->buffers[(int) $stream];
					$buffer->data .= fread($stream, 1024);
					if (feof($stream)) {
						unset($this->readStreams[(int) $stream]);
						$buffer->end = TRUE;
					}
				}

				foreach ((array) $w as $stream) {
					$buffer = $this->buffers[(int) $stream];
					if ($buffer->data) {
						fwrite($stream, $buffer->data);
						$buffer->data = '';
						if ($buffer->end) {
							unset($this->writeStreams[(int) $stream]);
						}
					}
				}
			}
		}
	}
}

// =====================================================================================================================

function downloadAsync($files)
{
	$loop = new Loop();

	foreach ($files as $file => $url) {
		$readStream = fopen($url, 'rb');
		$writeStream = fopen($file, 'wb');
		$buffer = new Buffer();

		stream_set_blocking($readStream, 0);
		stream_set_blocking($writeStream, 0);

		$loop->readStreams[(int) $readStream] = $readStream;
		$loop->writeStreams[(int) $writeStream] = $writeStream;
		$loop->buffers[(int) $readStream] = $buffer;
		$loop->buffers[(int) $writeStream] = $buffer;
	}

	$loop->run();
}

function downloadSync($files)
{
	foreach ($files as $file => $url) {
		copy($url, $file);
	}
}

// =====================================================================================================================

$files = array(
	'node-v0.6.18.tar.gz' => 'http://nodejs.org/dist/v0.6.18/node-v0.6.18.tar.gz',
	'php-5.5.0.tar.gz' => 'http://cz1.php.net/get/php-5.5.0.tar.xz/from/this/mirror',
	'ruby-2.0.0-p195-i386-mingw32.7z' => 'http://rubyforge.org/frs/download.php/76957/ruby-2.0.0-p195-i386-mingw32.7z',
);


$start = microtime(TRUE);
downloadAsync($files);
$end = microtime(TRUE);
printf("Async download time: %.3f seconds\n", $end - $start);

$start = microtime(TRUE);
downloadSync($files);
$end = microtime(TRUE);
printf("Sync download time: %.3f seconds\n", $end - $start);