src/transformers/dynamic_module_utils.py/get_cached_module_file
def get_cached_module_file(
    pretrained_model_name_or_path: Union[str, os.PathLike],
    module_file: str,
    cache_dir: Optional[Union[str, os.PathLike]] = None,
    force_download: bool = False,
    resume_download: bool = False,
    proxies: Optional[Dict[str, str]] = None,
    use_auth_token: Optional[Union[bool, str]] = None,
    revision: Optional[str] = None,
    local_files_only: bool = False,
):
    """
    Prepares Downloads a module from a local folder or a distant repo and returns its path inside the cached
    Transformers module.

    Args:
        pretrained_model_name_or_path (`str` or `os.PathLike`):
            This can be either:

            - a string, the *model id* of a pretrained model configuration hosted inside a model repo on
              huggingface.co. Valid model ids can be located at the root-level, like `bert-base-uncased`, or namespaced
              under a user or organization name, like `dbmdz/bert-base-german-cased`.
            - a path to a *directory* containing a configuration file saved using the
              [`~PreTrainedTokenizer.save_pretrained`] method, e.g., `./my_model_directory/`.

        module_file (`str`):
            The name of the module file containing the class to look for.
        cache_dir (`str` or `os.PathLike`, *optional*):
            Path to a directory in which a downloaded pretrained model configuration should be cached if the standard
            cache should not be used.
        force_download (`bool`, *optional*, defaults to `False`):
            Whether or not to force to (re-)download the configuration files and override the cached versions if they
            exist.
        resume_download (`bool`, *optional*, defaults to `False`):
            Whether or not to delete incompletely received file. Attempts to resume the download if such a file exists.
        proxies (`Dict[str, str]`, *optional*):
            A dictionary of proxy servers to use by protocol or endpoint, e.g., `{'http': 'foo.bar:3128',
            'http://hostname': 'foo.bar:4012'}.` The proxies are used on each request.
        use_auth_token (`str` or *bool*, *optional*):
            The token to use as HTTP bearer authorization for remote files. If `True`, will use the token generated
            when running `huggingface-cli login` (stored in `~/.huggingface`).
        revision (`str`, *optional*, defaults to `"main"`):
            The specific model version to use. It can be a branch name, a tag name, or a commit id, since we use a
            git-based system for storing models and other artifacts on huggingface.co, so `revision` can be any
            identifier allowed by git.
        local_files_only (`bool`, *optional*, defaults to `False`):
            If `True`, will only try to load the tokenizer configuration from local files.

    <Tip>

    Passing `use_auth_token=True` is required when you want to use a private model.

    </Tip>

    Returns:
        `str`: The path to the module inside the cache.
    """
    if is_offline_mode() and not local_files_only:
        logger.info("Offline mode: forcing local_files_only=True")
        local_files_only = True

    # Download and cache module_file from the repo `pretrained_model_name_or_path` of grab it if it's a local file.
    pretrained_model_name_or_path = str(pretrained_model_name_or_path)
    if os.path.isdir(pretrained_model_name_or_path):
        submodule = pretrained_model_name_or_path.split(os.path.sep)[-1]
    else:
        submodule = pretrained_model_name_or_path.replace("/", os.path.sep)

    try:
        # Load from URL or cache if already cached
        resolved_module_file = cached_file(
            pretrained_model_name_or_path,
            module_file,
            cache_dir=cache_dir,
            force_download=force_download,
            proxies=proxies,
            resume_download=resume_download,
            local_files_only=local_files_only,
            use_auth_token=use_auth_token,
            revision=revision,
        )

    except EnvironmentError:
        logger.error(f"Could not locate the {module_file} inside {pretrained_model_name_or_path}.")
        raise

    # Check we have all the requirements in our environment
    modules_needed = check_imports(resolved_module_file)

    # Now we move the module inside our cached dynamic modules.
    full_submodule = TRANSFORMERS_DYNAMIC_MODULE_NAME + os.path.sep + submodule
    create_dynamic_module(full_submodule)
    submodule_path = Path(HF_MODULES_CACHE) / full_submodule
    if submodule == pretrained_model_name_or_path.split(os.path.sep)[-1]:
        # We always copy local files (we could hash the file to see if there was a change, and give them the name of
        # that hash, to only copy when there is a modification but it seems overkill for now).
        # The only reason we do the copy is to avoid putting too many folders in sys.path.
        shutil.copy(resolved_module_file, submodule_path / module_file)
        for module_needed in modules_needed:
            module_needed = f"{module_needed}.py"
            shutil.copy(os.path.join(pretrained_model_name_or_path, module_needed), submodule_path / module_needed)
    else:
        # Get the commit hash
        # TODO: we will get this info in the etag soon, so retrieve it from there and not here.
        commit_hash = model_info(pretrained_model_name_or_path, revision=revision, token=use_auth_token).sha

        # The module file will end up being placed in a subfolder with the git hash of the repo. This way we get the
        # benefit of versioning.
        submodule_path = submodule_path / commit_hash
        full_submodule = full_submodule + os.path.sep + commit_hash
        create_dynamic_module(full_submodule)

        if not (submodule_path / module_file).exists():
            shutil.copy(resolved_module_file, submodule_path / module_file)
        # Make sure we also have every file with relative
        for module_needed in modules_needed:
            if not (submodule_path / module_needed).exists():
                get_cached_module_file(
                    pretrained_model_name_or_path,
                    f"{module_needed}.py",
                    cache_dir=cache_dir,
                    force_download=force_download,
                    resume_download=resume_download,
                    proxies=proxies,
                    use_auth_token=use_auth_token,
                    revision=revision,
                    local_files_only=local_files_only,
                )
    return os.path.join(full_submodule, module_file)