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| 1 | +# Copyright 2024 The HuggingFace Team. All rights reserved. |
| 2 | +# |
| 3 | +# Licensed under the Apache License, Version 2.0 (the "License"); |
| 4 | +# you may not use this file except in compliance with the License. |
| 5 | +# You may obtain a copy of the License at |
| 6 | +# |
| 7 | +# http://www.apache.org/licenses/LICENSE-2.0 |
| 8 | +# |
| 9 | +# Unless required by applicable law or agreed to in writing, software |
| 10 | +# distributed under the License is distributed on an "AS IS" BASIS, |
| 11 | +# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 12 | +# See the License for the specific language governing permissions and |
| 13 | +# limitations under the License. |
| 14 | + |
| 15 | +import functools |
| 16 | +from typing import Any, Dict, Tuple |
| 17 | + |
| 18 | +import torch |
| 19 | + |
| 20 | + |
| 21 | +# Reference: https://github.com/huggingface/accelerate/blob/ba7ab93f5e688466ea56908ea3b056fae2f9a023/src/accelerate/hooks.py |
| 22 | +class ModelHook: |
| 23 | + r""" |
| 24 | + A hook that contains callbacks to be executed just before and after the forward method of a model. |
| 25 | + """ |
| 26 | + |
| 27 | + _is_stateful = False |
| 28 | + |
| 29 | + def init_hook(self, module: torch.nn.Module) -> torch.nn.Module: |
| 30 | + r""" |
| 31 | + Hook that is executed when a model is initialized. |
| 32 | + Args: |
| 33 | + module (`torch.nn.Module`): |
| 34 | + The module attached to this hook. |
| 35 | + """ |
| 36 | + return module |
| 37 | + |
| 38 | + def pre_forward(self, module: torch.nn.Module, *args, **kwargs) -> Tuple[Tuple[Any], Dict[str, Any]]: |
| 39 | + r""" |
| 40 | + Hook that is executed just before the forward method of the model. |
| 41 | + Args: |
| 42 | + module (`torch.nn.Module`): |
| 43 | + The module whose forward pass will be executed just after this event. |
| 44 | + args (`Tuple[Any]`): |
| 45 | + The positional arguments passed to the module. |
| 46 | + kwargs (`Dict[Str, Any]`): |
| 47 | + The keyword arguments passed to the module. |
| 48 | + Returns: |
| 49 | + `Tuple[Tuple[Any], Dict[Str, Any]]`: |
| 50 | + A tuple with the treated `args` and `kwargs`. |
| 51 | + """ |
| 52 | + return args, kwargs |
| 53 | + |
| 54 | + def post_forward(self, module: torch.nn.Module, output: Any) -> Any: |
| 55 | + r""" |
| 56 | + Hook that is executed just after the forward method of the model. |
| 57 | + Args: |
| 58 | + module (`torch.nn.Module`): |
| 59 | + The module whose forward pass been executed just before this event. |
| 60 | + output (`Any`): |
| 61 | + The output of the module. |
| 62 | + Returns: |
| 63 | + `Any`: The processed `output`. |
| 64 | + """ |
| 65 | + return output |
| 66 | + |
| 67 | + def detach_hook(self, module: torch.nn.Module) -> torch.nn.Module: |
| 68 | + r""" |
| 69 | + Hook that is executed when the hook is detached from a module. |
| 70 | + Args: |
| 71 | + module (`torch.nn.Module`): |
| 72 | + The module detached from this hook. |
| 73 | + """ |
| 74 | + return module |
| 75 | + |
| 76 | + def reset_state(self, module: torch.nn.Module): |
| 77 | + if self._is_stateful: |
| 78 | + raise NotImplementedError("This hook is stateful and needs to implement the `reset_state` method.") |
| 79 | + |
| 80 | + |
| 81 | +class SequentialHook(ModelHook): |
| 82 | + r"""A hook that can contain several hooks and iterates through them at each event.""" |
| 83 | + |
| 84 | + def __init__(self, *hooks): |
| 85 | + self.hooks = hooks |
| 86 | + |
| 87 | + def init_hook(self, module): |
| 88 | + for hook in self.hooks: |
| 89 | + module = hook.init_hook(module) |
| 90 | + return module |
| 91 | + |
| 92 | + def pre_forward(self, module, *args, **kwargs): |
| 93 | + for hook in self.hooks: |
| 94 | + args, kwargs = hook.pre_forward(module, *args, **kwargs) |
| 95 | + return args, kwargs |
| 96 | + |
| 97 | + def post_forward(self, module, output): |
| 98 | + for hook in self.hooks: |
| 99 | + output = hook.post_forward(module, output) |
| 100 | + return output |
| 101 | + |
| 102 | + def detach_hook(self, module): |
| 103 | + for hook in self.hooks: |
| 104 | + module = hook.detach_hook(module) |
| 105 | + return module |
| 106 | + |
| 107 | + def reset_state(self, module): |
| 108 | + for hook in self.hooks: |
| 109 | + if hook._is_stateful: |
| 110 | + hook.reset_state(module) |
| 111 | + |
| 112 | + |
| 113 | +def add_hook_to_module(module: torch.nn.Module, hook: ModelHook, append: bool = False) -> torch.nn.Module: |
| 114 | + r""" |
| 115 | + Adds a hook to a given module. This will rewrite the `forward` method of the module to include the hook, to remove |
| 116 | + this behavior and restore the original `forward` method, use `remove_hook_from_module`. |
| 117 | + <Tip warning={true}> |
| 118 | + If the module already contains a hook, this will replace it with the new hook passed by default. To chain two hooks |
| 119 | + together, pass `append=True`, so it chains the current and new hook into an instance of the `SequentialHook` class. |
| 120 | + </Tip> |
| 121 | + Args: |
| 122 | + module (`torch.nn.Module`): |
| 123 | + The module to attach a hook to. |
| 124 | + hook (`ModelHook`): |
| 125 | + The hook to attach. |
| 126 | + append (`bool`, *optional*, defaults to `False`): |
| 127 | + Whether the hook should be chained with an existing one (if module already contains a hook) or not. |
| 128 | + Returns: |
| 129 | + `torch.nn.Module`: |
| 130 | + The same module, with the hook attached (the module is modified in place, so the result can be discarded). |
| 131 | + """ |
| 132 | + original_hook = hook |
| 133 | + |
| 134 | + if append and getattr(module, "_diffusers_hook", None) is not None: |
| 135 | + old_hook = module._diffusers_hook |
| 136 | + remove_hook_from_module(module) |
| 137 | + hook = SequentialHook(old_hook, hook) |
| 138 | + |
| 139 | + if hasattr(module, "_diffusers_hook") and hasattr(module, "_old_forward"): |
| 140 | + # If we already put some hook on this module, we replace it with the new one. |
| 141 | + old_forward = module._old_forward |
| 142 | + else: |
| 143 | + old_forward = module.forward |
| 144 | + module._old_forward = old_forward |
| 145 | + |
| 146 | + module = hook.init_hook(module) |
| 147 | + module._diffusers_hook = hook |
| 148 | + |
| 149 | + if hasattr(original_hook, "new_forward"): |
| 150 | + new_forward = original_hook.new_forward |
| 151 | + else: |
| 152 | + |
| 153 | + def new_forward(module, *args, **kwargs): |
| 154 | + args, kwargs = module._diffusers_hook.pre_forward(module, *args, **kwargs) |
| 155 | + output = module._old_forward(*args, **kwargs) |
| 156 | + return module._diffusers_hook.post_forward(module, output) |
| 157 | + |
| 158 | + # Overriding a GraphModuleImpl forward freezes the forward call and later modifications on the graph will fail. |
| 159 | + # Reference: https://pytorch.slack.com/archives/C3PDTEV8E/p1705929610405409 |
| 160 | + if "GraphModuleImpl" in str(type(module)): |
| 161 | + module.__class__.forward = functools.update_wrapper(functools.partial(new_forward, module), old_forward) |
| 162 | + else: |
| 163 | + module.forward = functools.update_wrapper(functools.partial(new_forward, module), old_forward) |
| 164 | + |
| 165 | + return module |
| 166 | + |
| 167 | + |
| 168 | +def remove_hook_from_module(module: torch.nn.Module, recurse: bool = False) -> torch.nn.Module: |
| 169 | + """ |
| 170 | + Removes any hook attached to a module via `add_hook_to_module`. |
| 171 | + Args: |
| 172 | + module (`torch.nn.Module`): |
| 173 | + The module to attach a hook to. |
| 174 | + recurse (`bool`, defaults to `False`): |
| 175 | + Whether to remove the hooks recursively |
| 176 | + Returns: |
| 177 | + `torch.nn.Module`: |
| 178 | + The same module, with the hook detached (the module is modified in place, so the result can be discarded). |
| 179 | + """ |
| 180 | + |
| 181 | + if hasattr(module, "_diffusers_hook"): |
| 182 | + module._diffusers_hook.detach_hook(module) |
| 183 | + delattr(module, "_diffusers_hook") |
| 184 | + |
| 185 | + if hasattr(module, "_old_forward"): |
| 186 | + # Overriding a GraphModuleImpl forward freezes the forward call and later modifications on the graph will fail. |
| 187 | + # Reference: https://pytorch.slack.com/archives/C3PDTEV8E/p1705929610405409 |
| 188 | + if "GraphModuleImpl" in str(type(module)): |
| 189 | + module.__class__.forward = module._old_forward |
| 190 | + else: |
| 191 | + module.forward = module._old_forward |
| 192 | + delattr(module, "_old_forward") |
| 193 | + |
| 194 | + if recurse: |
| 195 | + for child in module.children(): |
| 196 | + remove_hook_from_module(child, recurse) |
| 197 | + |
| 198 | + return module |
| 199 | + |
| 200 | + |
| 201 | +def reset_stateful_hooks(module: torch.nn.Module, recurse: bool = False): |
| 202 | + """ |
| 203 | + Resets the state of all stateful hooks attached to a module. |
| 204 | + Args: |
| 205 | + module (`torch.nn.Module`): |
| 206 | + The module to reset the stateful hooks from. |
| 207 | + """ |
| 208 | + if hasattr(module, "_diffusers_hook") and ( |
| 209 | + module._diffusers_hook._is_stateful or isinstance(module._diffusers_hook, SequentialHook) |
| 210 | + ): |
| 211 | + module._diffusers_hook.reset_state(module) |
| 212 | + |
| 213 | + if recurse: |
| 214 | + for child in module.children(): |
| 215 | + reset_stateful_hooks(child, recurse) |
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