'''
* Copyright (c) 2022, salesforce.com, inc.
* All rights reserved.
* SPDX-License-Identifier: BSD-3-Clause
* For full license text, see LICENSE.txt file in the repo root or https://opensource.org/licenses/BSD-3-Clause
* By Junnan Li
'''
from models.med import BertConfig, BertModel, BertLMHeadModel
from transformers import BertTokenizer
import transformers
transformers.logging.set_verbosity_error()
import torch
from torch import nn
import torch.nn.functional as F
from models.blip import create_vit, init_tokenizer, load_checkpoint
class BLIP_Pretrain(nn.Module):
def __init__(self,
med_config = 'configs/bert_config.json',
image_size = 224,
vit = 'base',
vit_grad_ckpt = False,
vit_ckpt_layer = 0,
embed_dim = 256,
queue_size = 57600,
momentum = 0.995,
):
"""
Args:
med_config (str): path for the mixture of encoder-decoder model's configuration file
image_size (int): input image size
vit (str): model size of vision transformer
"""
super().__init__()
self.visual_encoder, vision_width = create_vit(vit,image_size, vit_grad_ckpt, vit_ckpt_layer, 0)
if vit=='base':
checkpoint = torch.hub.load_state_dict_from_url(
url="https://dl.fbaipublicfiles.com/deit/deit_base_patch16_224-b5f2ef4d.pth",
map_location="cpu", check_hash=True)
state_dict = checkpoint["model"]
msg = self.visual_encoder.load_state_dict(state_dict,strict=False)
elif vit=='large':
from timm.models.helpers import load_custom_pretrained
from timm.models.vision_transformer import default_cfgs
load_custom_pretrained(self.visual_encoder,default_cfgs['vit_large_patch16_224_in21k'])
self.tokenizer = init_tokenizer()
encoder_config = BertConfig.from_json_file(med_config)
encoder_config.encoder_width = vision_width
self.text_encoder = BertModel.from_pretrained('bert-base-uncased',config=encoder_config, add_pooling_layer=False)
self.text_encoder.resize_token_embeddings(len(self.tokenizer))
text_width = self.text_encoder.config.hidden_size
self.vision_proj = nn.Linear(vision_width, embed_dim)
self.text_proj = nn.Linear(text_width, embed_dim)
self.itm_head = nn.Linear(text_width, 2)
# create momentum encoders
self.visual_encoder_m, vision_width = create_vit(vit,image_size)
self.vision_proj_m = nn.Linear(vision_width, embed_dim)
self.text_encoder_m = BertModel(config=encoder_config, add_pooling_layer=False)
self.text_proj_m = nn.Linear(text_width, embed_dim)
self.model_pairs = [[self.visual_encoder,self.visual_encoder_m],
[self.vision_proj,self.vision_proj_m],
[self.text_encoder,self.text_encoder_m],
[self.text_proj,self.text_proj_m],
]
self.copy_params()
# create the queue
self.register_buffer("image_queue", torch.randn(embed_dim, queue_size))
self.register_buffer("text_queue", torch.randn(embed_dim, queue_size))
self.register_buffer("queue_ptr", torch.zeros(1, dtype=torch.long))
self.image_queue = nn.functional.normalize(self.image_queue, dim=0)
self.text_queue = nn.functional.normalize(self.text_queue, dim=0)
self.queue_size = queue_size
self.momentum = momentum
self.temp = nn.Parameter(0.07*torch.ones([]))
# create the decoder
decoder_config = BertConfig.from_json_file(med_config)
decoder_config.encoder_width = vision_width
self.text_decoder = BertLMHeadModel.from_pretrained('bert-base-uncased',config=decoder_config)
self.text_decoder.resize_token_embeddings(len(self.tokenizer))
tie_encoder_decoder_weights(self.text_decoder.bert,self.text_encoder,'','/attention')
def forward(self, image, caption, alpha):
with torch.no_grad():
self.temp.clamp_(0.001,0.5)
image_embeds = self.visual_encoder(image)
image_atts = torch.ones(image_embeds.size()[:-1],dtype=torch.long).to(image.device)
image_feat = F.normalize(self.vision_proj(image_embeds[:,0,:]),dim=-1)
text = self.tokenizer(caption, padding='max_length', truncation=True, max_length=30,
return_tensors="pt").to(image.device)
text_output = self.text_encoder(text.input_ids, attention_mask = text.attention_mask,
return_dict = True, mode = 'text')
text_feat = F.normalize(self.text_proj(text_output.last_hidden_state[:,0,:]),dim=-1)
# get momentum features
with torch.no_grad():
self._momentum_update()
image_embeds_m = self.visual_encoder_m(image)
image_feat_m = F.normalize(self.vision_proj_m(image_embeds_m[:,0,:]),dim=-1)
image_feat_all = torch.cat([image_feat_m.t(),self.image_queue.clone().detach()],dim=1)
text_output_m = self.text_encoder_m(text.input_ids, attention_mask = text.attention_mask,
return_dict = True, mode = 'text')
text_feat_m = F.normalize(self.text_proj_m(text_output_m.last_hidden_state[:,0,:]),dim=-1)
text_feat_all = torch.cat([text_feat_m.t(),self.text_queue.clone().detach()],dim=1)
sim_i2t_m = image_feat_m @ text_feat_all / self.temp
sim_t2i_m = text_feat_m @ image_feat_all / self.temp
sim_targets = torch.zeros(sim_i2t_m.size()).to(image.device)
sim_targets.fill_diagonal_(1)
sim_i2t_targets = alpha * F.softmax(sim_i2t_m, dim=1) + (1 - alpha) * sim_targets
sim_t2i_targets = alpha * F.softmax(sim_t2i_m, dim=1) + (1 - alpha) * sim_targets
sim_i2t = image_feat @ text_feat_all / self.temp
sim_t2i = text_feat @ image_feat_all / self.temp
loss_i2t = -torch.sum(F.log_softmax(sim_i2t, dim=1)*sim_i2t_targets,dim=1).mean()
loss_t2i = -torch.sum(F.log_softmax(sim_t2i, dim=1)*sim_t2i_targets,dim=1).mean()
loss_ita = (loss_i2t+loss_t2i)/2
self._dequeue_and_enqueue(image_feat_m, text_feat_m)
###============== Image-text Matching ===================###
encoder_input_ids = text.input_ids.clone()
encoder_input_ids[:,0] = self.tokenizer.enc_token_id
# forward the positve image-text pair
bs = image.size(0)
output_pos = self.text_encoder(encoder_input_ids,
attention_mask = text.attention_mask,
encoder_hidden_states = image_embeds,
encoder_attention_mask = image_atts,
return_dict = True,
)
with torch.no_grad():
weights_t2i = F.softmax(sim_t2i[:,:bs],dim=1)+1e-4
weights_t2i.fill_diagonal_(0)
weights_i2t = F.softmax(sim_i2t[:,:bs],dim=1)+1e-4
weights_i2t.fill_diagonal_(0)
# select a negative image for each text
image_embeds_neg = []
for b in range(bs):
neg_idx = torch.multinomial(weights_t2i[b], 1).item()
image_embeds_neg.append(image_embeds[neg_idx])
image_embeds_neg = torch.stack(image_embeds_neg,dim=0)
# select a negative text for each image
text_ids_neg = []
text_atts_neg = []
for b in range(bs):
neg_idx = torch.multinomial(weights_i2t[b], 1).item()
text_ids_neg.append(encoder_input_ids[neg_idx])
text_atts_neg.append(text.attention_mask[neg_idx])
text_ids_neg = torch.stack(text_ids_neg,dim=0)
text_atts_neg = torch.stack(text_atts_neg,dim=0)
text_ids_all = torch.cat([encoder_input_ids, text_ids_neg],dim=0)
text_atts_all = torch.cat([text.attention_mask, text_atts_neg],dim=0)
image_embeds_all = torch.cat([image_embeds_neg,image_embeds],dim=0)
image_atts_all = torch.cat([image_atts,image_atts],dim=0)
output_neg = self.text_encoder(text_ids_all,
attention_mask = text_atts_all,
encoder_hidden_states = image_embeds_all,
encoder_attention_mask = image_atts_all,
return_dict = True,
)
vl_embeddings = torch.cat([output_pos.last_hidden_state[:,0,:], output_neg.last_hidden_state[:,0,:]],dim=0)
vl_output = self.itm_head(vl_embeddings)
itm_labels = torch.cat([torch.ones(bs,dtype=torch.long),torch.zeros(2*bs,dtype=torch.long)],
dim=0).to(image.device)
loss_itm = F.cross_entropy(vl_output, itm_labels)
##================= LM ========================##
decoder_input_ids = text.input_ids.clone()
decoder_input_ids[:,0] = self.tokenizer.bos_token_id
decoder_targets = decoder_input_ids.masked_fill(decoder_input_ids == self.tokenizer.pad_token_id, -100)
decoder_output = self.text_decoder(decoder_input_ids,
attention_mask = text.attention_mask,
encoder_hidden_states = image_embeds,
encoder_attention_mask = image_atts,
labels = decoder_targets,
return_dict = True,
)
loss_lm = decoder_output.loss
return loss_ita, loss_itm, loss_lm
@torch.no_grad()
def copy_params(self):
for model_pair in self.model_pairs:
for param, param_m in zip(model_pair[0].parameters(), model_pair[1].parameters()):
param_m.data.copy_(param.data) # initialize
param_m.requires_grad = False # not update by gradient
@torch.no_grad()
def _momentum_update(self):
for model_pair in self.model_pairs:
for param, param_m in zip(model_pair[0].parameters(), model_pair[1].parameters()):
param_m.data = param_m.data * self.momentum + param.data * (1. - self.momentum)
@torch.no_grad()
def _dequeue_and_enqueue(self, image_feat, text_feat):
# gather keys before updating queue
image_feats = concat_all_gather(image_feat)
text_feats = concat_all_gather(text_feat)
batch_size = image_feats.shape[0]
ptr = int(self.queue_ptr)
assert self.queue_size % batch_size == 0 # for simplicity
# replace the keys at ptr (dequeue and enqueue)
self.image_queue[:, ptr:ptr + batch_size] = image_feats.T
self.text_queue[:, ptr:ptr + batch_size] = text_feats.T
ptr = (ptr + batch_size) % self.queue_size # move pointer
self.queue_ptr[0] = ptr
def blip_pretrain(**kwargs):
model = BLIP_Pretrain(**kwargs)
return model
@torch.no_grad()
def concat_all_gather(tensor):
"""
Performs all_gather operation on the provided tensors.
*** Warning ***: torch.distributed.all_gather has no gradient.
"""
tensors_gather = [torch.ones_like(tensor)
for _ in range(torch.distributed.get_world_size())]
torch.distributed.all_gather(tensors_gather, tensor, async_op=False)
output = torch.cat(tensors_gather, dim=0)
return output
from typing import List
def tie_encoder_decoder_weights(encoder: nn.Module, decoder: nn.Module, base_model_prefix: str, skip_key:str):
uninitialized_encoder_weights: List[str] = []
if decoder.__class__ != encoder.__class__:
logger.info(
f"{decoder.__class__} and {encoder.__class__} are not equal. In this case make sure that all encoder weights are correctly initialized."
)
def tie_encoder_to_decoder_recursively(
decoder_pointer: nn.Module,
encoder_pointer: nn.Module,
module_name: str,
uninitialized_encoder_weights: List[str],
skip_key: str,
depth=0,
):
assert isinstance(decoder_pointer, nn.Module) and isinstance(
encoder_pointer, nn.Module
), f"{decoder_pointer} and {encoder_pointer} have to be of type torch.nn.Module"
if hasattr(decoder_pointer, "weight") and skip_key not in module_name:
assert hasattr(encoder_pointer, "weight")
encoder_pointer.weight = decoder_pointer.weight
if hasattr(decoder_pointer, "bias"):
assert hasattr(encoder_pointer, "bias")
encoder_pointer.bias = decoder_pointer.bias
print(module_name+' is tied')
return
encoder_modules = encoder_pointer._modules
decoder_modules = decoder_pointer._modules
if len(decoder_modules) > 0:
assert (
len(encoder_modules) > 0
), f"Encoder module {encoder_pointer} does not match decoder module {decoder_pointer}"
all_encoder_weights = set([module_name + "/" + sub_name for sub_name in encoder_modules.keys()])
encoder_layer_pos = 0
for name, module in decoder_modules.items():
if name.isdigit():
encoder_name = str(int(name) + encoder_layer_pos)
decoder_name = name
if not isinstance(decoder_modules[decoder_name], type(encoder_modules[encoder_name])) and len(
encoder_modules
) != len(decoder_modules):
# this can happen if the name corresponds to the position in a list module list of layers
# in this case the decoder has added a cross-attention that the encoder does not have
# thus skip this step and subtract one layer pos from encoder
encoder_layer_pos -= 1
continue
elif name not in encoder_modules:
continue
elif depth > 500:
raise ValueError(
"Max depth of recursive function `tie_encoder_to_decoder` reached. It seems that there is a circular dependency between two or more `nn.Modules` of your model."
)
else:
decoder_name = encoder_name = name
tie_encoder_to_decoder_recursively(
decoder_modules[decoder_name],
encoder_modules[encoder_name],
module_name + "/" + name,
uninitialized_encoder_weights,
skip_key,
depth=depth + 1,
)
all_encoder_weights.remove(module_name + "/" + encoder_name)
uninitialized_encoder_weights += list(all_encoder_weights)
# tie weights recursively
tie_encoder_to_decoder_recursively(decoder, encoder, base_model_prefix, uninitialized_encoder_weights, skip_key)