Rundiz/Profiler/Profiler.php
public function getMicrotime($at_start = false)
    {
        if ($at_start === true && is_array($_SERVER) && array_key_exists('REQUEST_TIME_FLOAT', $_SERVER)) {
            return floatval($_SERVER['REQUEST_TIME_FLOAT']);
        }

        return floatval(microtime(true));
    }
public function getMicrotime($at_start = false)
    {
        if ($at_start === true && is_array($_SERVER) && array_key_exists('REQUEST_TIME_FLOAT', $_SERVER)) {
            return floatval($_SERVER['REQUEST_TIME_FLOAT']);
        }

        return floatval(microtime(true));
    }
get microtime.

@param boolean $at_start set to true if this microtime is get at the very beginning of the app. this can allow newer php version to use $_SERVER['REQUEST_TIME_FLOAT'];
@return float microtime in float.