def METHOD_NAME(self) -> List[CacheStat]:
    """Return the manager's CacheStats.
    Safe to call from any thread.
    """
    # Flatten all files into a single list
    all_files: List[UploadedFileRec] = []
    # Make copy of self.file_storage for thread safety, to be sure
    # that main storage won't be changed form other thread
    file_storage_copy = self.file_storage.copy()
    for session_storage in file_storage_copy.values():
        all_files.extend(session_storage.values())
    return [
        CacheStat(
            category_name="UploadedFileManager",
            cache_name="",
            byte_length=len(file.data),
        )
        for file in all_files
    ]