dynamic_modules_utils.py

# coding=utf-8
# Copyright 2025 The HuggingFace Inc. team.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
"""Utilities to dynamically load objects from the Hub."""

import importlib
import inspect
import json
import os
import re
import shutil
import signal
import sys
import threading
from pathlib import Path
from types import ModuleType
from typing import Dict, Optional, Union
from urllib import request

from huggingface_hub import hf_hub_download, model_info
from huggingface_hub.utils import RevisionNotFoundError, validate_hf_hub_args
from packaging import version

from .. import __version__
from . import DIFFUSERS_DYNAMIC_MODULE_NAME, HF_MODULES_CACHE, logging


logger = logging.get_logger(__name__)  # pylint: disable=invalid-name

# See https://huggingface.co/datasets/diffusers/community-pipelines-mirror
COMMUNITY_PIPELINES_MIRROR_ID = "diffusers/community-pipelines-mirror"
TIME_OUT_REMOTE_CODE = int(os.getenv("DIFFUSERS_TIMEOUT_REMOTE_CODE", 15))
_HF_REMOTE_CODE_LOCK = threading.Lock()


def get_diffusers_versions():
    url = "https://pypi.org/pypi/diffusers/json"
    releases = json.loads(request.urlopen(url).read())["releases"].keys()
    return sorted(releases, key=lambda x: version.Version(x))


def init_hf_modules():
    """
    Creates the cache directory for modules with an init, and adds it to the Python path.
    """
    # This function has already been executed if HF_MODULES_CACHE already is in the Python path.
    if HF_MODULES_CACHE in sys.path:
        return

    sys.path.append(HF_MODULES_CACHE)
    os.makedirs(HF_MODULES_CACHE, exist_ok=True)
    init_path = Path(HF_MODULES_CACHE) / "__init__.py"
    if not init_path.exists():
        init_path.touch()


def create_dynamic_module(name: Union[str, os.PathLike]):
    """
    Creates a dynamic module in the cache directory for modules.
    """
    init_hf_modules()
    dynamic_module_path = Path(HF_MODULES_CACHE) / name
    # If the parent module does not exist yet, recursively create it.
    if not dynamic_module_path.parent.exists():
        create_dynamic_module(dynamic_module_path.parent)
    os.makedirs(dynamic_module_path, exist_ok=True)
    init_path = dynamic_module_path / "__init__.py"
    if not init_path.exists():
        init_path.touch()


def get_relative_imports(module_file):
    """
    Get the list of modules that are relatively imported in a module file.

    Args:
        module_file (`str` or `os.PathLike`): The module file to inspect.
    """
    with open(module_file, "r", encoding="utf-8") as f:
        content = f.read()

    # Imports of the form `import .xxx`
    relative_imports = re.findall(r"^\s*import\s+\.(\S+)\s*$", content, flags=re.MULTILINE)
    # Imports of the form `from .xxx import yyy`
    relative_imports += re.findall(r"^\s*from\s+\.(\S+)\s+import", content, flags=re.MULTILINE)
    # Unique-ify
    return list(set(relative_imports))


def get_relative_import_files(module_file):
    """
    Get the list of all files that are needed for a given module. Note that this function recurses through the relative
    imports (if a imports b and b imports c, it will return module files for b and c).

    Args:
        module_file (`str` or `os.PathLike`): The module file to inspect.
    """
    no_change = False
    files_to_check = [module_file]
    all_relative_imports = []

    # Let's recurse through all relative imports
    while not no_change:
        new_imports = []
        for f in files_to_check:
            new_imports.extend(get_relative_imports(f))

        module_path = Path(module_file).parent
        new_import_files = [str(module_path / m) for m in new_imports]
        new_import_files = [f for f in new_import_files if f not in all_relative_imports]
        files_to_check = [f"{f}.py" for f in new_import_files]

        no_change = len(new_import_files) == 0
        all_relative_imports.extend(files_to_check)

    return all_relative_imports


def check_imports(filename):
    """
    Check if the current Python environment contains all the libraries that are imported in a file.
    """
    with open(filename, "r", encoding="utf-8") as f:
        content = f.read()

    # Imports of the form `import xxx`
    imports = re.findall(r"^\s*import\s+(\S+)\s*$", content, flags=re.MULTILINE)
    # Imports of the form `from xxx import yyy`
    imports += re.findall(r"^\s*from\s+(\S+)\s+import", content, flags=re.MULTILINE)
    # Only keep the top-level module
    imports = [imp.split(".")[0] for imp in imports if not imp.startswith(".")]

    # Unique-ify and test we got them all
    imports = list(set(imports))
    missing_packages = []
    for imp in imports:
        try:
            importlib.import_module(imp)
        except ImportError:
            missing_packages.append(imp)

    if len(missing_packages) > 0:
        raise ImportError(
            "This modeling file requires the following packages that were not found in your environment: "
            f"{', '.join(missing_packages)}. Run `pip install {' '.join(missing_packages)}`"
        )

    return get_relative_imports(filename)


def _raise_timeout_error(signum, frame):
    raise ValueError(
        "Loading this model requires you to execute custom code contained in the model repository on your local "
        "machine. Please set the option `trust_remote_code=True` to permit loading of this model."
    )


def resolve_trust_remote_code(trust_remote_code, model_name, has_remote_code):
    if trust_remote_code is None:
        if has_remote_code and TIME_OUT_REMOTE_CODE > 0:
            prev_sig_handler = None
            try:
                prev_sig_handler = signal.signal(signal.SIGALRM, _raise_timeout_error)
                signal.alarm(TIME_OUT_REMOTE_CODE)
                while trust_remote_code is None:
                    answer = input(
                        f"The repository for {model_name} contains custom code which must be executed to correctly "
                        f"load the model. You can inspect the repository content at https://hf.co/{model_name}.\n"
                        f"You can avoid this prompt in future by passing the argument `trust_remote_code=True`.\n\n"
                        f"Do you wish to run the custom code? [y/N] "
                    )
                    if answer.lower() in ["yes", "y", "1"]:
                        trust_remote_code = True
                    elif answer.lower() in ["no", "n", "0", ""]:
                        trust_remote_code = False
                signal.alarm(0)
            except Exception:
                # OS which does not support signal.SIGALRM
                raise ValueError(
                    f"The repository for {model_name} contains custom code which must be executed to correctly "
                    f"load the model. You can inspect the repository content at https://hf.co/{model_name}.\n"
                    f"Please pass the argument `trust_remote_code=True` to allow custom code to be run."
                )
            finally:
                if prev_sig_handler is not None:
                    signal.signal(signal.SIGALRM, prev_sig_handler)
                    signal.alarm(0)
        elif has_remote_code:
            # For the CI which puts the timeout at 0
            _raise_timeout_error(None, None)

    if has_remote_code and not trust_remote_code:
        raise ValueError(
            f"Loading {model_name} requires you to execute the configuration file in that"
            " repo on your local machine. Make sure you have read the code there to avoid malicious use, then"
            " set the option `trust_remote_code=True` to remove this error."
        )

    return trust_remote_code


def get_class_in_module(class_name, module_path, force_reload=False):
    """
    Import a module on the cache directory for modules and extract a class from it.
    """
    name = os.path.normpath(module_path)
    if name.endswith(".py"):
        name = name[:-3]
    name = name.replace(os.path.sep, ".")
    module_file: Path = Path(HF_MODULES_CACHE) / module_path

    with _HF_REMOTE_CODE_LOCK:
        if force_reload:
            sys.modules.pop(name, None)
            importlib.invalidate_caches()
        cached_module: Optional[ModuleType] = sys.modules.get(name)
        module_spec = importlib.util.spec_from_file_location(name, location=module_file)

        module: ModuleType
        if cached_module is None:
            module = importlib.util.module_from_spec(module_spec)
            # insert it into sys.modules before any loading begins
            sys.modules[name] = module
        else:
            module = cached_module

        module_spec.loader.exec_module(module)

    if class_name is None:
        return find_pipeline_class(module)

    return getattr(module, class_name)


def find_pipeline_class(loaded_module):
    """
    Retrieve pipeline class that inherits from `DiffusionPipeline`. Note that there has to be exactly one class
    inheriting from `DiffusionPipeline`.
    """
    from ..pipelines import DiffusionPipeline

    cls_members = dict(inspect.getmembers(loaded_module, inspect.isclass))

    pipeline_class = None
    for cls_name, cls in cls_members.items():
        if (
            cls_name != DiffusionPipeline.__name__
            and issubclass(cls, DiffusionPipeline)
            and cls.__module__.split(".")[0] != "diffusers"
        ):
            if pipeline_class is not None:
                raise ValueError(
                    f"Multiple classes that inherit from {DiffusionPipeline.__name__} have been found:"
                    f" {pipeline_class.__name__}, and {cls_name}. Please make sure to define only one in"
                    f" {loaded_module}."
                )
            pipeline_class = cls

    return pipeline_class


@validate_hf_hub_args
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,
    proxies: Optional[Dict[str, str]] = None,
    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.
        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.
        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 `transformers-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>

    You may pass a token in `token` if you are not logged in (`hf auth login`) and want to use private or [gated
    models](https://huggingface.co/docs/hub/models-gated#gated-models).

    </Tip>

    Returns:
        `str`: The path to the module inside the cache.
    """
    # 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)

    module_file_or_url = os.path.join(pretrained_model_name_or_path, module_file)

    if os.path.isfile(module_file_or_url):
        resolved_module_file = module_file_or_url
        submodule = "local"
    elif pretrained_model_name_or_path.count("/") == 0:
        available_versions = get_diffusers_versions()
        # cut ".dev0"
        latest_version = "v" + ".".join(__version__.split(".")[:3])

        # retrieve github version that matches
        if revision is None:
            revision = latest_version if latest_version[1:] in available_versions else "main"
            logger.info(f"Defaulting to latest_version: {revision}.")
        elif revision in available_versions:
            revision = f"v{revision}"
        elif revision == "main":
            revision = revision
        else:
            raise ValueError(
                f"`custom_revision`: {revision} does not exist. Please make sure to choose one of"
                f" {', '.join(available_versions + ['main'])}."
            )

        try:
            resolved_module_file = hf_hub_download(
                repo_id=COMMUNITY_PIPELINES_MIRROR_ID,
                repo_type="dataset",
                filename=f"{revision}/{pretrained_model_name_or_path}.py",
                cache_dir=cache_dir,
                force_download=force_download,
                proxies=proxies,
                local_files_only=local_files_only,
            )
            submodule = "git"
            module_file = pretrained_model_name_or_path + ".py"
        except RevisionNotFoundError as e:
            raise EnvironmentError(
                f"Revision '{revision}' not found in the community pipelines mirror. Check available revisions on"
                " https://huggingface.co/datasets/diffusers/community-pipelines-mirror/tree/main."
                " If you don't find the revision you are looking for, please open an issue on https://github.com/huggingface/diffusers/issues."
            ) from e
        except EnvironmentError:
            logger.error(f"Could not locate the {module_file} inside {pretrained_model_name_or_path}.")
            raise
    else:
        try:
            # Load from URL or cache if already cached
            resolved_module_file = hf_hub_download(
                pretrained_model_name_or_path,
                module_file,
                cache_dir=cache_dir,
                force_download=force_download,
                proxies=proxies,
                local_files_only=local_files_only,
                token=token,
            )
            submodule = os.path.join("local", "--".join(pretrained_model_name_or_path.split("/")))
        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 = DIFFUSERS_DYNAMIC_MODULE_NAME + os.path.sep + submodule
    create_dynamic_module(full_submodule)
    submodule_path = Path(HF_MODULES_CACHE) / full_submodule
    if submodule == "local" or submodule == "git":
        # 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.copyfile(resolved_module_file, submodule_path / module_file)
        for module_needed in modules_needed:
            if len(module_needed.split(".")) == 2:
                module_needed = "/".join(module_needed.split("."))
                module_folder = module_needed.split("/")[0]
                if not os.path.exists(submodule_path / module_folder):
                    os.makedirs(submodule_path / module_folder)
            module_needed = f"{module_needed}.py"
            shutil.copyfile(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=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():
            if len(module_file.split("/")) == 2:
                module_folder = module_file.split("/")[0]
                if not os.path.exists(submodule_path / module_folder):
                    os.makedirs(submodule_path / module_folder)
            shutil.copyfile(resolved_module_file, submodule_path / module_file)

        # Make sure we also have every file with relative
        for module_needed in modules_needed:
            if len(module_needed.split(".")) == 2:
                module_needed = "/".join(module_needed.split("."))
            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,
                    proxies=proxies,
                    token=token,
                    revision=revision,
                    local_files_only=local_files_only,
                )
    return os.path.join(full_submodule, module_file)


@validate_hf_hub_args
def get_class_from_dynamic_module(
    pretrained_model_name_or_path: Union[str, os.PathLike],
    module_file: str,
    class_name: Optional[str] = None,
    cache_dir: Optional[Union[str, os.PathLike]] = None,
    force_download: bool = False,
    proxies: Optional[Dict[str, str]] = None,
    token: Optional[Union[bool, str]] = None,
    revision: Optional[str] = None,
    local_files_only: bool = False,
    **kwargs,
):
    """
    Extracts a class from a module file, present in the local folder or repository of a model.

    <Tip warning={true}>

    Calling this function will execute the code in the module file found locally or downloaded from the Hub. It should
    therefore only be called on trusted repos.

    </Tip>

    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.
        class_name (`str`):
            The name of the class to import in the module.
        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.
        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.
        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 `transformers-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>

    You may pass a token in `token` if you are not logged in (`hf auth login`) and want to use private or [gated
    models](https://huggingface.co/docs/hub/models-gated#gated-models).

    </Tip>

    Returns:
        `type`: The class, dynamically imported from the module.

    Examples:

    ```python
    # Download module `modeling.py` from huggingface.co and cache then extract the class `MyBertModel` from this
    # module.
    cls = get_class_from_dynamic_module("sgugger/my-bert-model", "modeling.py", "MyBertModel")
    ```"""
    # And lastly we get the class inside our newly created module
    final_module = get_cached_module_file(
        pretrained_model_name_or_path,
        module_file,
        cache_dir=cache_dir,
        force_download=force_download,
        proxies=proxies,
        token=token,
        revision=revision,
        local_files_only=local_files_only,
    )
    return get_class_in_module(class_name, final_module)