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# Copyright 2024 The HuggingFace Team. All rights reserved. | |
# | |
# 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. | |
import functools | |
from typing import Any, Dict, Optional, Tuple | |
import torch | |
from ..utils.logging import get_logger | |
logger = get_logger(__name__) # pylint: disable=invalid-name | |
class ModelHook: | |
r""" | |
A hook that contains callbacks to be executed just before and after the forward method of a model. | |
""" | |
_is_stateful = False | |
def __init__(self): | |
self.fn_ref: "HookFunctionReference" = None | |
def initialize_hook(self, module: torch.nn.Module) -> torch.nn.Module: | |
r""" | |
Hook that is executed when a model is initialized. | |
Args: | |
module (`torch.nn.Module`): | |
The module attached to this hook. | |
""" | |
return module | |
def deinitalize_hook(self, module: torch.nn.Module) -> torch.nn.Module: | |
r""" | |
Hook that is executed when a model is deinitialized. | |
Args: | |
module (`torch.nn.Module`): | |
The module attached to this hook. | |
""" | |
return module | |
def pre_forward(self, module: torch.nn.Module, *args, **kwargs) -> Tuple[Tuple[Any], Dict[str, Any]]: | |
r""" | |
Hook that is executed just before the forward method of the model. | |
Args: | |
module (`torch.nn.Module`): | |
The module whose forward pass will be executed just after this event. | |
args (`Tuple[Any]`): | |
The positional arguments passed to the module. | |
kwargs (`Dict[Str, Any]`): | |
The keyword arguments passed to the module. | |
Returns: | |
`Tuple[Tuple[Any], Dict[Str, Any]]`: | |
A tuple with the treated `args` and `kwargs`. | |
""" | |
return args, kwargs | |
def post_forward(self, module: torch.nn.Module, output: Any) -> Any: | |
r""" | |
Hook that is executed just after the forward method of the model. | |
Args: | |
module (`torch.nn.Module`): | |
The module whose forward pass been executed just before this event. | |
output (`Any`): | |
The output of the module. | |
Returns: | |
`Any`: The processed `output`. | |
""" | |
return output | |
def detach_hook(self, module: torch.nn.Module) -> torch.nn.Module: | |
r""" | |
Hook that is executed when the hook is detached from a module. | |
Args: | |
module (`torch.nn.Module`): | |
The module detached from this hook. | |
""" | |
return module | |
def reset_state(self, module: torch.nn.Module): | |
if self._is_stateful: | |
raise NotImplementedError("This hook is stateful and needs to implement the `reset_state` method.") | |
return module | |
class HookFunctionReference: | |
def __init__(self) -> None: | |
"""A container class that maintains mutable references to forward pass functions in a hook chain. | |
Its mutable nature allows the hook system to modify the execution chain dynamically without rebuilding the | |
entire forward pass structure. | |
Attributes: | |
pre_forward: A callable that processes inputs before the main forward pass. | |
post_forward: A callable that processes outputs after the main forward pass. | |
forward: The current forward function in the hook chain. | |
original_forward: The original forward function, stored when a hook provides a custom new_forward. | |
The class enables hook removal by allowing updates to the forward chain through reference modification rather | |
than requiring reconstruction of the entire chain. When a hook is removed, only the relevant references need to | |
be updated, preserving the execution order of the remaining hooks. | |
""" | |
self.pre_forward = None | |
self.post_forward = None | |
self.forward = None | |
self.original_forward = None | |
class HookRegistry: | |
def __init__(self, module_ref: torch.nn.Module) -> None: | |
super().__init__() | |
self.hooks: Dict[str, ModelHook] = {} | |
self._module_ref = module_ref | |
self._hook_order = [] | |
self._fn_refs = [] | |
def register_hook(self, hook: ModelHook, name: str) -> None: | |
if name in self.hooks.keys(): | |
raise ValueError( | |
f"Hook with name {name} already exists in the registry. Please use a different name or " | |
f"first remove the existing hook and then add a new one." | |
) | |
self._module_ref = hook.initialize_hook(self._module_ref) | |
def create_new_forward(function_reference: HookFunctionReference): | |
def new_forward(module, *args, **kwargs): | |
args, kwargs = function_reference.pre_forward(module, *args, **kwargs) | |
output = function_reference.forward(*args, **kwargs) | |
return function_reference.post_forward(module, output) | |
return new_forward | |
forward = self._module_ref.forward | |
fn_ref = HookFunctionReference() | |
fn_ref.pre_forward = hook.pre_forward | |
fn_ref.post_forward = hook.post_forward | |
fn_ref.forward = forward | |
if hasattr(hook, "new_forward"): | |
fn_ref.original_forward = forward | |
fn_ref.forward = functools.update_wrapper( | |
functools.partial(hook.new_forward, self._module_ref), hook.new_forward | |
) | |
rewritten_forward = create_new_forward(fn_ref) | |
self._module_ref.forward = functools.update_wrapper( | |
functools.partial(rewritten_forward, self._module_ref), rewritten_forward | |
) | |
hook.fn_ref = fn_ref | |
self.hooks[name] = hook | |
self._hook_order.append(name) | |
self._fn_refs.append(fn_ref) | |
def get_hook(self, name: str) -> Optional[ModelHook]: | |
return self.hooks.get(name, None) | |
def remove_hook(self, name: str, recurse: bool = True) -> None: | |
if name in self.hooks.keys(): | |
num_hooks = len(self._hook_order) | |
hook = self.hooks[name] | |
index = self._hook_order.index(name) | |
fn_ref = self._fn_refs[index] | |
old_forward = fn_ref.forward | |
if fn_ref.original_forward is not None: | |
old_forward = fn_ref.original_forward | |
if index == num_hooks - 1: | |
self._module_ref.forward = old_forward | |
else: | |
self._fn_refs[index + 1].forward = old_forward | |
self._module_ref = hook.deinitalize_hook(self._module_ref) | |
del self.hooks[name] | |
self._hook_order.pop(index) | |
self._fn_refs.pop(index) | |
if recurse: | |
for module_name, module in self._module_ref.named_modules(): | |
if module_name == "": | |
continue | |
if hasattr(module, "_diffusers_hook"): | |
module._diffusers_hook.remove_hook(name, recurse=False) | |
def reset_stateful_hooks(self, recurse: bool = True) -> None: | |
for hook_name in reversed(self._hook_order): | |
hook = self.hooks[hook_name] | |
if hook._is_stateful: | |
hook.reset_state(self._module_ref) | |
if recurse: | |
for module_name, module in self._module_ref.named_modules(): | |
if module_name == "": | |
continue | |
if hasattr(module, "_diffusers_hook"): | |
module._diffusers_hook.reset_stateful_hooks(recurse=False) | |
def check_if_exists_or_initialize(cls, module: torch.nn.Module) -> "HookRegistry": | |
if not hasattr(module, "_diffusers_hook"): | |
module._diffusers_hook = cls(module) | |
return module._diffusers_hook | |
def __repr__(self) -> str: | |
registry_repr = "" | |
for i, hook_name in enumerate(self._hook_order): | |
if self.hooks[hook_name].__class__.__repr__ is not object.__repr__: | |
hook_repr = self.hooks[hook_name].__repr__() | |
else: | |
hook_repr = self.hooks[hook_name].__class__.__name__ | |
registry_repr += f" ({i}) {hook_name} - {hook_repr}" | |
if i < len(self._hook_order) - 1: | |
registry_repr += "\n" | |
return f"HookRegistry(\n{registry_repr}\n)" | |