@Override
  public int getInheritorCount(@NotNull CompilerRef.CompilerClassHierarchyElementDef baseClass) throws ReferenceIndexUnavailableException {
    try {
      if (!myReadDataLock.tryLock()) return -1;
      try {
        if (myReader == null) {
          throw new ReferenceIndexUnavailableException();
        }
        CompilerRef.NamedCompilerRef[] hierarchy = myReader.getHierarchy(baseClass, false, true, -1);
        return hierarchy == null ? -1 : hierarchy.length;
      }
      finally {
        myReadDataLock.unlock();
      }
    }
    catch (Exception e) {
      onException(e, "inheritor count");
      throw new ReferenceIndexUnavailableException();
    }
  }
@Override
  public int getInheritorCount(@NotNull CompilerRef.CompilerClassHierarchyElementDef baseClass)