I/O não bloqueante

completo.php

<?php

$streams = [
	stream_socket_client('tcp://example.org:80'),
	fopen('composer.json', 'r'),
	fopen('package.json', 'r'),
];

foreach ($streams as $stream) {
	stream_set_blocking($stream, false);
}

fwrite($streams[0], "GET / HTTP/1.1\r\nHost: example.org\r\n\r\n");

$respostas = [];
$contentLength = [];
do {
	$streamsParaLerNoLoop = $streams;
	stream_select($streamsParaLerNoLoop, $write, $except, 1);

	foreach ($streamsParaLerNoLoop as $indice => $stream) {
		if (in_array($indice, [0], true)) { // se for HTTP
			$conteudo = stream_get_contents($stream);
			$fimHeaders = strpos($conteudo, "\r\n\r\n");

			$headers = substr($conteudo, 0, $fimHeaders);
			$corpo = $fimHeaders ? substr($conteudo, $fimHeaders + 4) : $conteudo;

			if (!isset($respostas[$indice])) {
				$respostas[$indice] = '';
			}
			$respostas[$indice] .= $corpo;

			preg_match('/Content-Length: (\d+)/', $headers, $matches);
			if (isset($matches[1])) {
				$contentLength[$indice] = (int) $matches[1];
			}

			echo $respostas[$indice] . PHP_EOL;

			if (strlen($respostas[$indice]) === $contentLength[$indice]) {
				fclose($stream);
				unset($streams[$indice]);
			}

			continue;
		}
		echo 'Arquivo: ' . strlen(stream_get_contents($stream)) . PHP_EOL;

		if (feof($stream)) {
			fclose($stream);
			unset($streams[$indice]);
		}
	}
} while (!empty($streams));

simples.php

<?php

$streams = [
	stream_socket_client('tcp://example.org:80'),
	fopen('composer.json', 'r'),
	fopen('package.json', 'r'),
];

foreach ($streams as $stream) {
	stream_set_blocking($stream, false);
}

fwrite($streams[0], "GET / HTTP/1.1\r\nHost: example.org\r\n\r\n");

do {
	$streamsParaLer = $streams;
	stream_select($streamsParaLer, $write, $except, 1);

	foreach ($streamsParaLer as $indice => $stream) {
		if ($indice > 0) { // arquivo
			echo strlen(stream_get_contents($stream)) . PHP_EOL;

			fclose($stream);
			unset($streams[$indice]);
			continue;
		}

		$conteudo = stream_get_contents($stream);
		echo $conteudo . PHP_EOL;
		echo strlen($conteudo);
		fclose($stream);
		unset($streams[$indice]);
	}
} while(!empty($streams));