code: protected synchronized void checkRollOver ()
      {
          // check to see if we should roll over the log
          String newDayStamp = _dayFormat.format(new Date());
  
          // hey! we need to roll it over!
          if (!newDayStamp.equals(_dayStamp)) {
              log("log_closed");
              _logWriter.close();
              _logWriter = null;
  
              // rename the old file
              String npath = _logPath.getPath() + "." + _dayStamp;
              if (!_logPath.renameTo(new File(npath))) {
                  log.warning("Failed to rename audit log file", "path", _logPath, "npath", npath);
              }
  
              // open our new log file
              openLog(false);
  
              // and set the next day stamp
              _dayStamp = newDayStamp;
          }
  
          scheduleNextRolloverCheck();
      }
docs: Check to see if it's time to roll over the log file.