/**
  * overwritten parent constructor to load configuration, calls parent constructor
  * 
  * supported configuration keys:
  * logruntime    => prepend time passed since request started
  * logdifftime   => prepend time passed since last log message
  *
  * @param string $format
  */
 function __construct(string $format = null)
 {
     parent::__construct($format);
     if (!self::$_prefix) {
         self::$_prefix = Tinebase_Record_Abstract::generateUID(5);
     }
     if (self::$_starttime === NULL) {
         self::$_starttime = Tinebase_Core::get(Tinebase_Core::STARTTIME);
         if (self::$_starttime === NULL) {
             self::$_starttime = microtime(true);
         }
     }
     if (self::$_logruntime === NULL || self::$_logdifftime === NULL) {
         $config = Tinebase_Core::getConfig();
         if ($config->logger->logruntime) {
             self::$_logruntime = true;
         } else {
             self::$_logruntime = false;
         }
         if ($config->logger->logdifftime) {
             self::$_logdifftime = true;
         } else {
             self::$_logdifftime = false;
         }
     }
 }