/**
  * Add session id in front of log line
  *
  * @param  array    $event    event data
  * @return string             formatted line to write to the log
  */
 public function format($event)
 {
     $output = parent::format($event);
     $output = str_replace($this->_search, $this->_replace, $output);
     $timelog = '';
     if (self::$_logdifftime || self::$_logruntime) {
         $currenttime = microtime(true);
         if (self::$_logruntime) {
             $timelog = Tinebase_Helper::formatMicrotimeDiff($currenttime - self::$_starttime) . ' ';
         }
         if (self::$_logdifftime) {
             $timelog .= Tinebase_Helper::formatMicrotimeDiff($currenttime - (self::$_lastlogtime ? self::$_lastlogtime : $currenttime)) . ' ';
             self::$_lastlogtime = $currenttime;
         }
     }
     return self::getPrefix() . ' ' . self::getUsername() . ' ' . $timelog . '- ' . $output;
 }