framework/log/Target.php
protected function getTime($timestamp)
    {
        $parts = explode('.', sprintf('%F', $timestamp));

        return date('Y-m-d H:i:s', $parts[0]) . ($this->microtime ? ('.' . $parts[1]) : '');
    }
protected function getTime($timestamp)
    {
        $parts = explode('.', sprintf('%F', $timestamp));

        return date('Y-m-d H:i:s', $parts[0]) . ($this->microtime ? ('.' . $parts[1]) : '');
    }
Returns formatted ('Y-m-d H:i:s') timestamp for message.
If [[microtime]] is configured to true it will return format 'Y-m-d H:i:s.u'.
@param float $timestamp
@return string
@since 2.0.13