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# Copyright (c) Facebook, Inc. and its affiliates.
#
# This source code is licensed under the MIT license found in the
# LICENSE file in the root directory of this source tree.
import torch
import torch.nn as nn
import torch.nn.functional as F
from fairseq import utils
from fairseq.incremental_decoding_utils import with_incremental_state
from fairseq.modules.fairseq_dropout import FairseqDropout
from .unfold import unfold1d
def DynamicConv(
input_size,
kernel_size=1,
padding_l=None,
num_heads=1,
weight_dropout=0.0,
weight_softmax=False,
renorm_padding=False,
bias=False,
conv_bias=False,
query_size=None,
in_proj=False,
):
if torch.cuda.is_available():
try:
from fairseq.modules.dynamicconv_layer import DynamicconvLayer
return DynamicconvLayer(
input_size,
kernel_size=kernel_size,
padding_l=padding_l,
num_heads=num_heads,
weight_dropout=weight_dropout,
weight_softmax=weight_softmax,
renorm_padding=renorm_padding,
bias=bias,
conv_bias=conv_bias,
query_size=query_size,
)
except ImportError as e:
print(e)
return DynamicConv1dTBC(
input_size,
kernel_size=kernel_size,
padding_l=padding_l,
num_heads=num_heads,
weight_dropout=weight_dropout,
weight_softmax=weight_softmax,
renorm_padding=renorm_padding,
bias=bias,
conv_bias=conv_bias,
query_size=query_size,
)
def Linear(in_features, out_features, bias=True):
m = nn.Linear(in_features, out_features, bias)
nn.init.xavier_uniform_(m.weight)
if bias:
nn.init.constant_(m.bias, 0.0)
return m
@with_incremental_state
class DynamicConv1dTBC(nn.Module):
"""Dynamic lightweight convolution taking T x B x C inputs
Args:
input_size: # of channels of the input
kernel_size: convolution channels
padding_l: padding to the left when using "same" padding
num_heads: number of heads used. The weight is of shape (num_heads, 1, kernel_size)
weight_dropout: the drop rate of the DropConnect to drop the weight
weight_softmax: normalize the weight with softmax before the convolution
renorm_padding: re-normalize the filters to ignore the padded part (only the non-padding parts sum up to 1)
bias: use bias
conv_bias: bias of the convolution
query_size: specified when feeding a different input as the query
in_proj: project the input and generate the filter together
Shape:
Input: TxBxC, i.e. (timesteps, batch_size, input_size)
Output: TxBxC, i.e. (timesteps, batch_size, input_size)
Attributes:
weight: the learnable weights of the module of shape
`(num_heads, 1, kernel_size)`
bias: the learnable bias of the module of shape `(input_size)`
"""
def __init__(
self,
input_size,
kernel_size=1,
padding_l=None,
num_heads=1,
weight_dropout=0.0,
weight_softmax=False,
renorm_padding=False,
bias=False,
conv_bias=False,
query_size=None,
in_proj=False,
):
super().__init__()
self.input_size = input_size
self.query_size = input_size if query_size is None else query_size
self.kernel_size = kernel_size
self.padding_l = padding_l
self.num_heads = num_heads
self.weight_dropout_module = FairseqDropout(
weight_dropout, module_name=self.__class__.__name__
)
self.weight_softmax = weight_softmax
self.renorm_padding = renorm_padding
if in_proj:
self.weight_linear = Linear(
self.input_size, self.input_size + num_heads * kernel_size * 1
)
else:
self.weight_linear = Linear(
self.query_size, num_heads * kernel_size * 1, bias=bias
)
if conv_bias:
self.conv_bias = nn.Parameter(torch.Tensor(input_size))
else:
self.conv_bias = None
self.reset_parameters()
@property
def in_proj(self):
return (
self.weight_linear.out_features
== self.input_size + self.num_heads * self.kernel_size
)
def reset_parameters(self):
self.weight_linear.reset_parameters()
if self.conv_bias is not None:
nn.init.constant_(self.conv_bias, 0.0)
def forward(self, x, incremental_state=None, query=None, unfold=None):
"""Assuming the input, x, of the shape T x B x C and producing an output in the shape T x B x C
args:
x: Input of shape T x B x C, i.e. (timesteps, batch_size, input_size)
incremental_state: A dict to keep the state
unfold: unfold the input or not. If not, we use the matrix trick instead
query: use the specified query to predict the conv filters
"""
unfold = (
x.size(0) > 512 if unfold is None else unfold
) # use unfold mode as default for long sequence to save memory
unfold = unfold or (incremental_state is not None)
assert query is None or not self.in_proj
if query is None:
query = x
if unfold:
output = self._forward_unfolded(x, incremental_state, query)
else:
output = self._forward_expanded(x, incremental_state, query)
if self.conv_bias is not None:
output = output + self.conv_bias.view(1, 1, -1)
return output
def _forward_unfolded(self, x, incremental_state, query):
"""The conventional implementation of convolutions.
Unfolding the input by having a window shifting to the right."""
T, B, C = x.size()
K, H = self.kernel_size, self.num_heads
R = C // H
assert R * H == C == self.input_size
if self.in_proj:
proj = self.weight_linear(x)
x = proj.narrow(2, 0, self.input_size).contiguous()
weight = (
proj.narrow(2, self.input_size, H * K).contiguous().view(T * B * H, -1)
)
else:
weight = self.weight_linear(query).view(T * B * H, -1)
# renorm_padding is only implemented in _forward_expanded
assert not self.renorm_padding or incremental_state is not None
if incremental_state is not None:
input_buffer = self._get_input_buffer(incremental_state)
if input_buffer is None:
input_buffer = x.new()
x_unfold = torch.cat([input_buffer, x.unsqueeze(3)], dim=3)
if self.kernel_size > 1:
self._set_input_buffer(
incremental_state, x_unfold[:, :, :, -self.kernel_size + 1 :]
)
x_unfold = x_unfold.view(T * B * H, R, -1)
else:
padding_l = self.padding_l
if K > T and padding_l == K - 1:
weight = weight.narrow(1, K - T, T)
K, padding_l = T, T - 1
# unfold the input: T x B x C --> T' x B x C x K
x_unfold = unfold1d(x, K, padding_l, 0)
x_unfold = x_unfold.view(T * B * H, R, K)
if self.weight_softmax and not self.renorm_padding:
weight = F.softmax(weight, dim=1)
weight = weight.narrow(1, 0, K)
if incremental_state is not None:
weight = weight[:, -x_unfold.size(2) :]
K = weight.size(1)
if self.weight_softmax and self.renorm_padding:
weight = F.softmax(weight, dim=1)
weight = self.weight_dropout_module(weight, inplace=False)
output = torch.bmm(x_unfold, weight.unsqueeze(2)) # T*B*H x R x 1
output = output.view(T, B, C)
return output
def _forward_expanded(self, x, incremental_stat, query):
"""Turn the convolution filters into band matrices and do matrix multiplication.
This is faster when the sequence is short, but less memory efficient.
This is not used in the decoder during inference.
"""
T, B, C = x.size()
K, H = self.kernel_size, self.num_heads
R = C // H
assert R * H == C == self.input_size
if self.in_proj:
proj = self.weight_linear(x)
x = proj.narrow(2, 0, self.input_size).contiguous()
weight = (
proj.narrow(2, self.input_size, H * K).contiguous().view(T * B * H, -1)
)
else:
weight = self.weight_linear(query).view(T * B * H, -1)
if not self.renorm_padding:
if self.weight_softmax:
weight = F.softmax(weight, dim=1)
weight = self.weight_dropout_module(weight, inplace=False)
weight = weight.narrow(1, 0, K).contiguous()
weight = weight.view(T, B * H, K).transpose(0, 1)
x = x.view(T, B * H, R).transpose(0, 1)
if self.weight_softmax and self.renorm_padding:
# turn the convolution filters into band matrices
weight_expanded = weight.new(B * H, T, T + K - 1).fill_(float("-inf"))
weight_expanded.as_strided(
(B * H, T, K), (T * (T + K - 1), T + K, 1)
).copy_(weight)
weight_expanded = weight_expanded.narrow(2, self.padding_l, T)
# normalize the weight over valid positions like self-attention
weight_expanded = F.softmax(weight_expanded, dim=2)
weight_expanded = self.weight_dropout_module(weight_expanded, inplace=False)
else:
P = self.padding_l
# For efficiency, we cut the kernel size and reduce the padding when the kernel is larger than the length
if K > T and P == K - 1:
weight = weight.narrow(2, K - T, T)
K, P = T, T - 1
# turn the convolution filters into band matrices
weight_expanded = weight.new_zeros(B * H, T, T + K - 1, requires_grad=False)
weight_expanded.as_strided(
(B * H, T, K), (T * (T + K - 1), T + K, 1)
).copy_(weight)
weight_expanded = weight_expanded.narrow(2, P, T) # B*H x T x T
output = torch.bmm(weight_expanded, x)
output = output.transpose(0, 1).contiguous().view(T, B, C)
return output
def reorder_incremental_state(self, incremental_state, new_order):
input_buffer = self._get_input_buffer(incremental_state)
if input_buffer is not None:
input_buffer = input_buffer.index_select(1, new_order)
self._set_input_buffer(incremental_state, input_buffer)
def _get_input_buffer(self, incremental_state):
return utils.get_incremental_state(self, incremental_state, "input_buffer")
def _set_input_buffer(self, incremental_state, new_buffer):
return utils.set_incremental_state(
self, incremental_state, "input_buffer", new_buffer
)
def extra_repr(self):
s = "{}, kernel_size={}, padding_l={}, num_heads={}, weight_softmax={}, conv_bias={}, renorm_padding={}, in_proj={}".format(
self.input_size,
self.kernel_size,
self.padding_l,
self.num_heads,
self.weight_softmax,
self.conv_bias is not None,
self.renorm_padding,
self.in_proj,
)
if self.query_size != self.input_size:
s += ", query_size={}".format(self.query_size)
if self.weight_dropout_module.p > 0.0:
s += ", weight_dropout={}".format(self.weight_dropout_module.p)
return s
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