protected function setFile($file)
    {
        if ($file == $this->file) {
            // no change
            return;
        }
        if ($this->fileHandle) {
            // close existing file
            \fclose($this->fileHandle);
            $this->fileHandle = null;
        }
        $this->file = $file;
        if (empty($file)) {
            return;
        }
        $fileExists = \file_exists($file);
        $this->fileHandle = \fopen($file, 'a');
        if ($this->fileHandle) {
            \fwrite($this->fileHandle, '***** '.\date('Y-m-d H:i:s').' *****'."\n");
            if (!$fileExists) {
                // we just created file
                \chmod($file, 0660);
            }
        }
    }