code: protected int getBufferSize(Dsn dsn) {
          return Util.parseInteger(Lookup.lookup(BUFFER_SIZE_OPTION, dsn), BUFFER_SIZE_DEFAULT);
      }
docs: Get the maximum number of events to cache offline when network is down.
  
  @param dsn Dsn passed in by the user.
  @return the maximum number of events to cache offline when network is down.