waitUntilPortIsListening.php

<?php

function waitUntilPortIsListening($host, $port, $options = array('usleep' => 300000, 'limit' => 20)) {
	$limit = array_key_exists('limit',$options)?$options['limit']:20;
	$retries = 0;
	while (true) {
		$connection = @fsockopen($host, $port);

		if (is_resource($connection)) {
			echo "is listening\n";
			fclose($connection);
			break;
		} else {
			echo "is not responding\n";
		}
		
		usleep(array_key_exists('usleep',$options)?$options['usleep']:300000); //default 300 ms
		
		if ($retries >= $limit) {
			throw new Exception("Number of retries exceeded limit, port still not responding");
		}
		$retries++;
	}
}

This method waits until a port on an host is listening. The usleep options is the microseconds to wait before retry. The limit is the number of retries to guess until throwing an exception because the port is still not responding.