Spaces:
Sleeping
Sleeping
File size: 8,529 Bytes
85ab89d |
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 |
# Copyright (c) Meta Platforms, Inc. and affiliates.
#
# This source code is licensed under the MIT license found in the
# LICENSE file in the root directory of this source tree.
import math
import torch
import torch.nn as nn
class RowSelfAttention(nn.Module):
"""Compute self-attention over rows of a 2D input."""
def __init__(
self,
embed_dim,
num_heads,
dropout=0.0,
max_tokens_per_msa: int = 2 ** 16,
):
super().__init__()
self.num_heads = num_heads
self.dropout = dropout
self.head_dim = embed_dim // num_heads
self.scaling = self.head_dim ** -0.5
self.max_tokens_per_msa = max_tokens_per_msa
self.attn_shape = "hnij"
self.k_proj = nn.Linear(embed_dim, embed_dim)
self.v_proj = nn.Linear(embed_dim, embed_dim)
self.q_proj = nn.Linear(embed_dim, embed_dim)
self.out_proj = nn.Linear(embed_dim, embed_dim)
self.dropout_module = nn.Dropout(dropout)
def align_scaling(self, q):
num_rows = q.size(0)
return self.scaling / math.sqrt(num_rows)
def _batched_forward(
self,
x,
self_attn_mask=None,
self_attn_padding_mask=None,
):
num_rows, num_cols, batch_size, embed_dim = x.size()
max_rows = max(1, self.max_tokens_per_msa // num_cols)
attns = 0
scaling = self.align_scaling(x)
for start in range(0, num_rows, max_rows):
attn_weights = self.compute_attention_weights(
x[start : start + max_rows],
scaling,
self_attn_mask=self_attn_mask,
self_attn_padding_mask=self_attn_padding_mask[:, start : start + max_rows]
if self_attn_padding_mask is not None
else None,
)
attns += attn_weights
attn_probs = attns.softmax(-1)
attn_probs = self.dropout_module(attn_probs)
outputs = []
for start in range(0, num_rows, max_rows):
output = self.compute_attention_update(x[start : start + max_rows], attn_probs)
outputs.append(output)
output = torch.cat(outputs, 0)
return output, attn_probs
def compute_attention_weights(
self,
x,
scaling: float,
self_attn_mask=None,
self_attn_padding_mask=None,
):
num_rows, num_cols, batch_size, embed_dim = x.size()
q = self.q_proj(x).view(num_rows, num_cols, batch_size, self.num_heads, self.head_dim)
k = self.k_proj(x).view(num_rows, num_cols, batch_size, self.num_heads, self.head_dim)
q *= scaling
if self_attn_padding_mask is not None:
# Zero out any padded aligned positions - this is important since
# we take a sum across the alignment axis.
q *= 1 - self_attn_padding_mask.permute(1, 2, 0).unsqueeze(3).unsqueeze(4).to(q)
attn_weights = torch.einsum(f"rinhd,rjnhd->{self.attn_shape}", q, k)
if self_attn_mask is not None:
raise NotImplementedError
# Mask Size: [B x R x C], Weights Size: [H x B x C x C]
if self_attn_padding_mask is not None:
attn_weights = attn_weights.masked_fill(
self_attn_padding_mask[:, 0].unsqueeze(0).unsqueeze(2),
-10000,
)
return attn_weights
def compute_attention_update(
self,
x,
attn_probs,
):
num_rows, num_cols, batch_size, embed_dim = x.size()
v = self.v_proj(x).view(num_rows, num_cols, batch_size, self.num_heads, self.head_dim)
context = torch.einsum(f"{self.attn_shape},rjnhd->rinhd", attn_probs, v)
context = context.contiguous().view(num_rows, num_cols, batch_size, embed_dim)
output = self.out_proj(context)
return output
def forward(
self,
x,
self_attn_mask=None,
self_attn_padding_mask=None,
):
num_rows, num_cols, batch_size, embed_dim = x.size()
if (num_rows * num_cols > self.max_tokens_per_msa) and not torch.is_grad_enabled():
return self._batched_forward(x, self_attn_mask, self_attn_padding_mask)
else:
scaling = self.align_scaling(x)
attn_weights = self.compute_attention_weights(
x, scaling, self_attn_mask, self_attn_padding_mask
)
attn_probs = attn_weights.softmax(-1)
attn_probs = self.dropout_module(attn_probs)
output = self.compute_attention_update(x, attn_probs)
return output, attn_probs
class ColumnSelfAttention(nn.Module):
"""Compute self-attention over columns of a 2D input."""
def __init__(
self,
embed_dim,
num_heads,
dropout=0.0,
max_tokens_per_msa: int = 2 ** 16,
):
super().__init__()
self.num_heads = num_heads
self.dropout = dropout
self.head_dim = embed_dim // num_heads
self.scaling = self.head_dim ** -0.5
self.max_tokens_per_msa = max_tokens_per_msa
self.k_proj = nn.Linear(embed_dim, embed_dim)
self.v_proj = nn.Linear(embed_dim, embed_dim)
self.q_proj = nn.Linear(embed_dim, embed_dim)
self.out_proj = nn.Linear(embed_dim, embed_dim)
self.dropout_module = nn.Dropout(dropout)
def _batched_forward(
self,
x,
self_attn_mask=None,
self_attn_padding_mask=None,
):
num_rows, num_cols, batch_size, embed_dim = x.size()
max_cols = max(1, self.max_tokens_per_msa // num_rows)
outputs = []
attns = []
for start in range(0, num_cols, max_cols):
output, attn = self(
x[:, start : start + max_cols],
self_attn_mask=self_attn_mask,
self_attn_padding_mask=self_attn_padding_mask[:, :, start : start + max_cols]
if self_attn_padding_mask is not None
else None,
)
outputs.append(output)
attns.append(attn)
output = torch.cat(outputs, 1)
attns = torch.cat(attns, 1)
return output, attns
def compute_attention_update(
self,
x,
self_attn_mask=None,
self_attn_padding_mask=None,
):
num_rows, num_cols, batch_size, embed_dim = x.size()
if num_rows == 1:
# if there is only 1 position, this is equivalent and doesn't break with padding
attn_probs = torch.ones(
self.num_heads,
num_cols,
batch_size,
num_rows,
num_rows,
device=x.device,
dtype=x.dtype,
)
output = self.out_proj(self.v_proj(x))
else:
q = self.q_proj(x).view(num_rows, num_cols, batch_size, self.num_heads, self.head_dim)
k = self.k_proj(x).view(num_rows, num_cols, batch_size, self.num_heads, self.head_dim)
v = self.v_proj(x).view(num_rows, num_cols, batch_size, self.num_heads, self.head_dim)
q *= self.scaling
attn_weights = torch.einsum("icnhd,jcnhd->hcnij", q, k)
if self_attn_mask is not None:
raise NotImplementedError
if self_attn_padding_mask is not None:
attn_weights = attn_weights.masked_fill(
self_attn_padding_mask.permute(2, 0, 1).unsqueeze(0).unsqueeze(3),
-10000,
)
attn_probs = attn_weights.softmax(-1)
attn_probs = self.dropout_module(attn_probs)
context = torch.einsum("hcnij,jcnhd->icnhd", attn_probs, v)
context = context.contiguous().view(num_rows, num_cols, batch_size, embed_dim)
output = self.out_proj(context)
return output, attn_probs
def forward(
self,
x,
self_attn_mask=None,
self_attn_padding_mask=None,
):
num_rows, num_cols, batch_size, embed_dim = x.size()
# if False and num_rows * num_cols > 2 ** 14 and not torch.is_grad_enabled():
if (num_rows * num_cols) > self.max_tokens_per_msa and not torch.is_grad_enabled():
return self._batched_forward(
x,
self_attn_mask,
self_attn_padding_mask,
)
else:
return self.compute_attention_update(x, self_attn_mask, self_attn_padding_mask)
|