public static int structureSize(Object o, Class baseClass) {
    return structureSize(o, baseClass, new IdentityHashMap());
  }
  
  static int structureSize(Object o, Class baseClass,
    IdentityHashMap seen) {
    if (o == null || seen.containsKey(o)) return 0;
    seen.put(o, Boolean.TRUE);
    int size = 1;
    Class c = o.getClass();
    if (c.isArray()) {
      int n = Array.getLength(o);
      for (int i = 0; i < n; i++)
        size += structureSize(Array.get(o, i), baseClass, seen);
    } else
      while (c != Object.class && c != baseClass) {
        Field[] fields = c.getDeclaredFields();
        for (Field field : fields) {
          if ((field.getModifiers() & Modifier.STATIC) != 0)
            continue;
          if (field.getType().isPrimitive())
            ++size;
          else {
            Object value = null;
            try {
              value = field.get(o);
            } catch (IllegalAccessException e) {
              throw new RuntimeException(e);
            }
            size += structureSize(value, baseClass, seen);
          }
        }
        c = c.getSuperclass();
      }
    return size;
  }