min-dalle-test/min_dalle/models/dalle_bart_decoder.py
2022-07-04 08:05:55 -04:00

222 lines
8.0 KiB
Python

from typing import Tuple, List
import torch
from torch import LongTensor, nn, FloatTensor, BoolTensor
torch.set_grad_enabled(False)
from .dalle_bart_encoder import GLU, AttentionBase
class DecoderCrossAttention(AttentionBase):
def forward(
self,
decoder_state: FloatTensor,
encoder_state: FloatTensor,
attention_mask: BoolTensor
) -> FloatTensor:
keys = self.k_proj.forward(encoder_state)
values = self.v_proj.forward(encoder_state)
queries = self.q_proj.forward(decoder_state)
return super().forward(keys, values, queries, attention_mask)
class DecoderSelfAttention(AttentionBase):
def __init__(self, head_count: int, embed_count: int):
super().__init__(head_count, embed_count)
token_indices = torch.arange(256)
if torch.cuda.is_available(): token_indices = token_indices.cuda()
self.token_indices = token_indices
def forward(
self,
decoder_state: FloatTensor,
attention_state: FloatTensor,
token_index: LongTensor
) -> Tuple[FloatTensor, FloatTensor]:
keys = self.k_proj.forward(decoder_state)
values = self.v_proj.forward(decoder_state)
queries = self.q_proj.forward(decoder_state)
attn_mask = self.token_indices < token_index + 1
attn_mask = attn_mask[None][[0] * decoder_state.shape[0]]
attention_state[:, token_index] = torch.cat([keys, values])
batch_count = decoder_state.shape[0]
keys = attention_state[:batch_count]
values = attention_state[batch_count:]
decoder_state = super().forward(keys, values, queries, attn_mask)
return decoder_state, attention_state
class DecoderLayer(nn.Module):
def __init__(
self,
image_token_count: int,
head_count: int,
embed_count: int,
glu_embed_count: int
):
super().__init__()
self.image_token_count = image_token_count
self.pre_self_attn_layer_norm = nn.LayerNorm(embed_count)
self.self_attn = DecoderSelfAttention(head_count, embed_count)
self.self_attn_layer_norm = nn.LayerNorm(embed_count)
self.pre_encoder_attn_layer_norm = nn.LayerNorm(embed_count)
self.encoder_attn = DecoderCrossAttention(head_count, embed_count)
self.encoder_attn_layer_norm = nn.LayerNorm(embed_count)
self.glu = GLU(embed_count, glu_embed_count)
def forward(
self,
decoder_state: FloatTensor,
encoder_state: FloatTensor,
attention_state: FloatTensor,
attention_mask: BoolTensor,
token_index: LongTensor
) -> Tuple[FloatTensor, FloatTensor]:
# Self Attention
residual = decoder_state
decoder_state = self.pre_self_attn_layer_norm.forward(decoder_state)
decoder_state, attention_state = self.self_attn.forward(
decoder_state,
attention_state,
token_index
)
decoder_state = self.self_attn_layer_norm.forward(decoder_state)
decoder_state = residual + decoder_state
# Cross Attention
residual = decoder_state
decoder_state = self.pre_encoder_attn_layer_norm.forward(decoder_state)
decoder_state = self.encoder_attn.forward(
decoder_state,
encoder_state,
attention_mask
)
decoder_state = self.encoder_attn_layer_norm.forward(decoder_state)
decoder_state = residual + decoder_state
# Feed forward
residual = decoder_state
decoder_state = self.glu.forward(decoder_state)
decoder_state = residual + decoder_state
return decoder_state, attention_state
class DalleBartDecoder(nn.Module):
def __init__(
self,
image_vocab_count: int,
image_token_count: int,
sample_token_count: int,
embed_count: int,
attention_head_count: int,
glu_embed_count: int,
layer_count: int,
start_token: int
):
super().__init__()
self.layer_count = layer_count
self.embed_count = embed_count
self.sample_token_count = sample_token_count
self.condition_factor = 10.0
self.image_token_count = image_token_count
self.embed_tokens = nn.Embedding(image_vocab_count + 1, embed_count)
self.embed_positions = nn.Embedding(image_token_count, embed_count)
self.layers: List[DecoderLayer] = nn.ModuleList([
DecoderLayer(
image_token_count,
attention_head_count,
embed_count,
glu_embed_count
)
for _ in range(layer_count)
])
self.layernorm_embedding = nn.LayerNorm(embed_count)
self.final_ln = nn.LayerNorm(embed_count)
self.lm_head = nn.Linear(embed_count, image_vocab_count + 1, bias=False)
self.zero_prob = torch.zeros([1])
self.token_indices = torch.arange(self.sample_token_count)
self.start_token = torch.tensor([start_token]).to(torch.long)
if torch.cuda.is_available():
self.zero_prob = self.zero_prob.cuda()
self.token_indices = self.token_indices.cuda()
self.start_token = self.start_token.cuda()
def decode_step(
self,
attention_mask: BoolTensor,
encoder_state: FloatTensor,
attention_state: FloatTensor,
prev_tokens: LongTensor,
token_index: LongTensor
) -> Tuple[LongTensor, FloatTensor]:
image_count = encoder_state.shape[0] // 2
token_index_batched = token_index[[0] * image_count * 2]
prev_tokens = prev_tokens[list(range(image_count)) * 2]
decoder_state = self.embed_tokens.forward(prev_tokens)
decoder_state += self.embed_positions.forward(token_index_batched)
decoder_state = self.layernorm_embedding.forward(decoder_state)
decoder_state = decoder_state[:, None]
attention_states_new = []
for i in range(self.layer_count):
decoder_state, attention_state_layer = self.layers[i].forward(
decoder_state,
encoder_state,
attention_state[i],
attention_mask,
token_index
)
attention_states_new.append(attention_state_layer)
decoder_state = self.final_ln(decoder_state)
logits = self.lm_head(decoder_state)
a = self.condition_factor
logits: FloatTensor = (
logits[:image_count, -1] * (1 - a) +
logits[image_count:, -1] * a
)
top_logits, _ = logits.topk(50, dim=-1)
probs = torch.where(
logits < top_logits[:, [-1]],
self.zero_prob,
torch.exp(logits - top_logits[:, [0]])
)
return probs, torch.stack(attention_states_new)
def forward(
self,
image_count: int,
text_tokens: LongTensor,
encoder_state: FloatTensor
) -> LongTensor:
expanded_indices = [0] * image_count + [1] * image_count
text_tokens = text_tokens[expanded_indices]
encoder_state = encoder_state[expanded_indices]
attention_mask = text_tokens.not_equal(1)
attention_state_shape = (
self.layer_count,
image_count * 4,
self.image_token_count,
self.embed_count
)
attention_state = torch.zeros(attention_state_shape)
if torch.cuda.is_available(): attention_state = attention_state.cuda()
image_tokens = self.start_token[[0] * image_count]
image_tokens_sequence: List[LongTensor] = []
for i in range(self.sample_token_count):
probs, attention_state = self.decode_step(
attention_mask = attention_mask,
encoder_state = encoder_state,
attention_state = attention_state,
prev_tokens = image_tokens,
token_index = self.token_indices[[i]]
)
image_tokens = torch.multinomial(probs, 1)[:, 0]
image_tokens_sequence += [image_tokens]
return torch.stack(image_tokens_sequence).T