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""" huggingface model adapter
Wraps HuggingFace transformers (https://github.com/huggingface/transformers) models for use as a text tower in CLIP model.
"""
import re
import torch
import torch.nn as nn
from torch.nn import functional as F
from torch import TensorType
try:
import transformers
from transformers import AutoModel, AutoModelForMaskedLM, AutoTokenizer, AutoConfig, PretrainedConfig
from transformers.modeling_outputs import BaseModelOutput, BaseModelOutputWithPooling, \
BaseModelOutputWithPoolingAndCrossAttentions
except ImportError as e:
transformers = None
class BaseModelOutput:
pass
class PretrainedConfig:
pass
from .hf_configs import arch_dict
# utils
def _camel2snake(s):
return re.sub(r'(?<!^)(?=[A-Z])', '_', s).lower()
# TODO: ?last - for gpt-like models
_POOLERS = {}
def register_pooler(cls):
"""Decorator registering pooler class"""
_POOLERS[_camel2snake(cls.__name__)] = cls
return cls
@register_pooler
class MeanPooler(nn.Module):
"""Mean pooling"""
def forward(self, x:BaseModelOutput, attention_mask:TensorType):
masked_output = x.last_hidden_state * attention_mask.unsqueeze(-1)
return masked_output.sum(dim=1) / attention_mask.sum(-1, keepdim=True)
@register_pooler
class MaxPooler(nn.Module):
"""Max pooling"""
def forward(self, x:BaseModelOutput, attention_mask:TensorType):
masked_output = x.last_hidden_state.masked_fill(attention_mask.unsqueeze(-1), -torch.inf)
return masked_output.max(1).values
@register_pooler
class ClsPooler(nn.Module):
"""CLS token pooling"""
def __init__(self, use_pooler_output=True):
super().__init__()
self.cls_token_position = 0
self.use_pooler_output = use_pooler_output
def forward(self, x:BaseModelOutput, attention_mask:TensorType):
if (self.use_pooler_output and
isinstance(x, (BaseModelOutputWithPooling, BaseModelOutputWithPoolingAndCrossAttentions)) and
(x.pooler_output is not None)
):
return x.pooler_output
return x.last_hidden_state[:, self.cls_token_position, :]
class HFTextEncoder(nn.Module):
"""HuggingFace model adapter"""
def __init__(
self,
model_name_or_path: str,
output_dim: int,
tokenizer_name: str = None,
config: PretrainedConfig = None,
pooler_type: str = None,
proj: str = None,
pretrained: bool = True,
masked_language_modeling: bool = False):
super().__init__()
self.output_dim = output_dim
# TODO: find better way to get this information
uses_transformer_pooler = (pooler_type == "cls_pooler")
if transformers is None:
raise RuntimeError("Please `pip install transformers` to use pre-trained HuggingFace models")
if config is None:
self.config = AutoConfig.from_pretrained(model_name_or_path)
if masked_language_modeling:
create_func, model_args = (AutoModelForMaskedLM.from_pretrained, model_name_or_path) if pretrained else (
AutoModelForMaskedLM.from_config, self.config)
else:
create_func, model_args = (AutoModel.from_pretrained, model_name_or_path) if pretrained else (
AutoModel.from_config, self.config)
# TODO: do all model configs have this attribute? PretrainedConfig does so yes??
if hasattr(self.config, "is_encoder_decoder") and self.config.is_encoder_decoder:
self.transformer = create_func(model_args)
self.transformer = self.transformer.encoder
else:
self.transformer = create_func(model_args, add_pooling_layer=uses_transformer_pooler)
else:
self.config = config
if masked_language_modeling:
self.transformer = AutoModelForMaskedLM.from_config(config)
else:
self.transformer = AutoModel.from_config(config)
if pooler_type is None: # get default arch pooler
self.pooler = _POOLERS[(arch_dict[self.config.model_type]["pooler"])]()
else:
self.pooler = _POOLERS[pooler_type]()
d_model = getattr(self.config, arch_dict[self.config.model_type]["config_names"]["width"])
if (d_model == output_dim) and (proj is None): # do we always need a proj?
self.proj = nn.Identity()
elif proj == 'linear':
self.proj = nn.Linear(d_model, output_dim, bias=False)
elif proj == 'mlp':
hidden_size = (d_model + output_dim) // 2
self.proj = nn.Sequential(
nn.Linear(d_model, hidden_size, bias=False),
nn.GELU(),
nn.Linear(hidden_size, output_dim, bias=False),
)
# self.itm_proj = nn.Linear(d_model, 2, bias=False)
# self.mlm_proj = nn.Linear(d_model, self.config.vocab_size), bias=False)
self.tokenizer = AutoTokenizer.from_pretrained(tokenizer_name)
# def forward_itm(self, x:TensorType, image_embeds:TensorType) -> TensorType:
# image_atts = torch.ones(image_embeds.size()[:-1],dtype=torch.long).to(x.device)
# attn_mask = (x != self.config.pad_token_id).long()
# out = self.transformer(
# input_ids=x,
# attention_mask=attn_mask,
# encoder_hidden_states = image_embeds,
# encoder_attention_mask = image_atts,
# )
# pooled_out = self.pooler(out, attn_mask)
# return self.itm_proj(pooled_out)
def mask(self, input_ids, vocab_size, device, targets=None, masked_indices=None, probability_matrix=None):
if masked_indices is None:
masked_indices = torch.bernoulli(probability_matrix).bool()
masked_indices[input_ids == self.tokenizer.pad_token_id] = False
masked_indices[input_ids == self.tokenizer.cls_token_id] = False
if targets is not None:
targets[~masked_indices] = -100 # We only compute loss on masked tokens
# 80% of the time, we replace masked input tokens with tokenizer.mask_token ([MASK])
indices_replaced = torch.bernoulli(torch.full(input_ids.shape, 0.8)).bool() & masked_indices
input_ids[indices_replaced] = self.tokenizer.mask_token_id
# 10% of the time, we replace masked input tokens with random word
indices_random = torch.bernoulli(torch.full(input_ids.shape, 0.5)).bool() & masked_indices & ~indices_replaced
random_words = torch.randint(vocab_size, input_ids.shape, dtype=torch.long).to(device)
input_ids[indices_random] = random_words[indices_random]
# The rest of the time (10% of the time) we keep the masked input tokens unchanged
if targets is not None:
return input_ids, targets
else:
return input_ids
def forward_mlm(self, input_ids, image_embeds, mlm_probability=0.25):
labels = input_ids.clone()
attn_mask = (input_ids != self.config.pad_token_id).long()
image_atts = torch.ones(image_embeds.size()[:-1],dtype=torch.long).to(input_ids.device)
vocab_size = getattr(self.config, arch_dict[self.config.model_type]["config_names"]["vocab_size"])
probability_matrix = torch.full(labels.shape, mlm_probability)
input_ids, labels = self.mask(input_ids, vocab_size, input_ids.device, targets=labels,
probability_matrix = probability_matrix)
mlm_output = self.transformer(input_ids,
attention_mask = attn_mask,
encoder_hidden_states = image_embeds,
encoder_attention_mask = image_atts,
return_dict = True,
labels = labels,
)
return mlm_output.loss
# mlm_output = self.transformer(input_ids,
# attention_mask = attn_mask,
# encoder_hidden_states = image_embeds,
# encoder_attention_mask = image_atts,
# return_dict = True,
# ).last_hidden_state
# logits = self.mlm_proj(mlm_output)
# # logits = logits[:, :-1, :].contiguous().view(-1, vocab_size)
# logits = logits[:, 1:, :].contiguous().view(-1, vocab_size)
# labels = labels[:, 1:].contiguous().view(-1)
# mlm_loss = F.cross_entropy(
# logits,
# labels,
# # label_smoothing=0.1,
# )
# return mlm_loss
def forward(self, x:TensorType) -> TensorType:
attn_mask = (x != self.config.pad_token_id).long()
out = self.transformer(input_ids=x, attention_mask=attn_mask)
pooled_out = self.pooler(out, attn_mask)
return self.proj(pooled_out)
def lock(self, unlocked_layers:int=0, freeze_layer_norm:bool=True):
if not unlocked_layers: # full freezing
for n, p in self.transformer.named_parameters():
p.requires_grad = (not freeze_layer_norm) if "LayerNorm" in n.split(".") else False
return
encoder = self.transformer.encoder if hasattr(self.transformer, 'encoder') else self.transformer
layer_list = getattr(encoder, arch_dict[self.config.model_type]["config_names"]["layer_attr"])
print(f"Unlocking {unlocked_layers}/{len(layer_list) + 1} layers of hf model")
embeddings = getattr(
self.transformer, arch_dict[self.config.model_type]["config_names"]["token_embeddings_attr"])
modules = [embeddings, *layer_list][:-unlocked_layers]
# freeze layers
for module in modules:
for n, p in module.named_parameters():
p.requires_grad = (not freeze_layer_norm) if "LayerNorm" in n.split(".") else False
@torch.jit.ignore
def set_grad_checkpointing(self, enable=True):
self.transformer.gradient_checkpointing_enable()
def get_num_layers(self):
encoder = self.transformer.encoder if hasattr(self.transformer, 'encoder') else self.transformer
layer_list = getattr(encoder, arch_dict[self.config.model_type]["config_names"]["layer_attr"])
return len(layer_list)
def init_parameters(self):
pass
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