protected function get_changed_sockets($bucket = self::DEFAULT_BUCKET, $timeout = 0)
	{
		$write_dummy = null;
		$exception_dummy = null;

		// grab all the children sockets
		$sockets = array();
		foreach ($this->forked_children as $pid => $child)
		{
			if ($child['bucket'] == $bucket)
			{
				$sockets[$pid] = $child['socket'];
			}
		}

		if (!empty($sockets))
		{
			// find changed sockets and return the array of them
			$result = @socket_select($sockets, $write_dummy, $exception_dummy, $timeout);
			if ($result !== false && $result > 0)
			{
				return $sockets;
			}
		}

		return null;
	}