wenet/transformer/attention.py

# Copyright (c) 2019 Shigeki Karita
#               2020 Mobvoi Inc (Binbin Zhang)
#               2022 Xingchen Song ([email protected])
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#   http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
"""Multi-Head Attention layer definition."""

import math
from typing import Optional, Tuple

import torch
from torch import nn

from wenet.utils.rope_utils import WENET_APPLY_ROTARY_EMB

T_CACHE = Tuple[torch.Tensor, torch.Tensor]


class MultiHeadedAttention(nn.Module):
    """Multi-Head Attention layer.
    if n_kv_head != None and n_kv_head != n_head
    see: https://arxiv.org/pdf/1911.02150.pdf
         https://arxiv.org/pdf/2305.13245.pdf

    Example:
        case 1: n_kv_head == None, head_dim == None, MultiHead attention (MHSA)
        case 2: n_kv_head=1, n_head = 16, MultiQuery attention (MQA)
        case 3: nv_kv_head=2, n_head = 16, GroupedQuery attention (GQA)

    Args:
        n_head (int): The number of heads.
        n_feat (int): The number of features.
        dropout_rate (float): Dropout rate.

    """

    def __init__(self,
                 n_head: int,
                 n_feat: int,
                 dropout_rate: float,
                 query_bias: bool = True,
                 key_bias: bool = True,
                 value_bias: bool = True,
                 use_sdpa: bool = False,
                 n_kv_head: Optional[int] = None,
                 head_dim: Optional[int] = None):
        """Construct an MultiHeadedAttention object."""
        super().__init__()

        self.inner_dim = n_feat if head_dim is None else head_dim * n_head
        if n_kv_head is not None:
            assert head_dim is not None
            self.inner_kv_dim = head_dim * n_kv_head
            n_kv_head = n_kv_head
        else:
            self.inner_kv_dim = self.inner_dim
            n_kv_head = n_head
        # We assume d_v always equals d_k
        self.d_k = self.inner_dim // n_head
        assert self.d_k == self.inner_kv_dim // n_kv_head
        self.h = n_head
        self.h_kv = n_kv_head

        self.linear_q = nn.Linear(n_feat, self.inner_dim, bias=query_bias)
        self.linear_k = nn.Linear(n_feat, self.inner_kv_dim, bias=key_bias)
        self.linear_v = nn.Linear(n_feat, self.inner_kv_dim, bias=value_bias)
        self.linear_out = nn.Linear(self.inner_dim, n_feat, bias=query_bias)
        self.dropout = nn.Dropout(p=dropout_rate)

        self.use_sdpa = use_sdpa
        self.dropout_rate = dropout_rate

    def _forward_linearx(self,
                         name: str,
                         x: torch.Tensor,
                         head_first: bool = True) -> torch.Tensor:
        assert x.ndim >= 3
        if name == 'query':
            x = self.linear_q(x)
            x_shape = x.size()
            x_shape = x_shape[:-1] + torch.Size([self.h, self.d_k])
        elif name == 'key':
            x = self.linear_k(x)
            x_shape = x.size()
            x_shape = x_shape[:-1] + torch.Size([self.h_kv, self.d_k])
        else:
            assert name == 'value'
            x = self.linear_v(x)
            x_shape = x.size()
            x_shape = x_shape[:-1] + torch.Size([self.h_kv, self.d_k])

        # split last dim
        x = x.view(x_shape)
        if head_first:
            x = x.transpose(-3,
                            -2)  # (batch, ...,  head or head_kv, time, d_k)
        return x

    def forward_qkv(
        self, query: torch.Tensor, key: torch.Tensor, value: torch.Tensor
    ) -> Tuple[torch.Tensor, torch.Tensor, torch.Tensor]:
        """Transform query, key and value.

        Args:
            query (torch.Tensor): Query tensor (#batch, ..., time1, size).
            key (torch.Tensor): Key tensor (#batch, ..., time2, size).
            value (torch.Tensor): Value tensor (#batch, ..., time2, size).

        Returns:
            torch.Tensor: Transformed query tensor, size
                (#batch, ..., n_head, time1, d_k).
            torch.Tensor: Transformed key tensor, size
                (#batch, ..., n_head_kv, time2, d_k).
            torch.Tensor: Transformed value tensor, size
                (#batch, ..., n_head_kv, time2, d_k).

        """
        q = self._forward_linearx('query', query)
        k = self._forward_linearx('key', key)
        v = self._forward_linearx('value', value)
        return q, k, v

    def forward_attention(
        self,
        value: torch.Tensor,
        scores: torch.Tensor,
        mask: torch.Tensor = torch.ones((0, 0, 0), dtype=torch.bool)
    ) -> torch.Tensor:
        """Compute attention context vector.

        Args:
            value (torch.Tensor): Transformed value, size
                (#batch, ..., n_head, time2, d_k).
            scores (torch.Tensor): Attention score, size
                (#batch, ..., n_head, time1, time2).
            mask (torch.Tensor): Mask, size (#batch, 1, time2) or
                (#batch, ..., time1, time2), (0, ..., 0, 0) means fake mask.

        Returns:
            torch.Tensor: Transformed value (#batch, time1, d_model)
                weighted by the attention score (#batch, time1, time2).

        """
        # NOTE(xcsong): When will `if mask.size(2) > 0` be True?
        #   1. onnx(16/4) [WHY? Because we feed real cache & real mask for the
        #           1st chunk to ease the onnx export.]
        #   2. pytorch training
        if mask.size(-1) > 0:  # time2 > 0
            mask = mask.unsqueeze(-3).eq(0)  # (batch, .., 1, *, time2)
            # For last chunk, time2 might be larger than scores.size(-1)
            mask = mask[..., :scores.size(-1)]  # (batch, 1, *, time2)
            scores = scores.masked_fill(mask, -float('inf'))
            attn = torch.softmax(scores.float(),
                                 dim=-1).type_as(value).masked_fill(
                                     mask, 0.0)  # (batch, head, time1, time2)
        # NOTE(xcsong): When will `if mask.size(2) > 0` be False?
        #   1. onnx(16/-1, -1/-1, 16/0)
        #   2. jit (16/-1, -1/-1, 16/0, 16/4)
        else:
            attn = torch.softmax(scores.float(), dim=-1).type_as(
                value)  # (batch, ..., head, time1, time2)

        p_attn = self.dropout(attn)
        x = torch.matmul(p_attn, value)  # (batch, ...,  head, time1, d_k)
        x = x.transpose(-3, -2).contiguous()  # [batch, ..., time1, head, d_k]
        x_shape = x.size()[:-2] + torch.Size([self.h * self.d_k])
        x = x.view(x_shape)  # (batch, ..., time1, d_model)
        return self.linear_out(x)  # (batch, ...,  time1, d_model)

    def _update_kv_and_cache(
            self,
            k: torch.Tensor,
            v: torch.Tensor,
            cache: T_CACHE,
            head_first: bool = True
    ) -> Tuple[torch.Tensor, torch.Tensor, T_CACHE]:
        new_cache = cache
        seq_axis = -2 if head_first else -3
        head_axis = -3 if head_first else -2
        if not self.training:
            # NOTE(xcsong):
            #   when export onnx model, for 1st chunk, we feed
            #       cache(1, head, 0, d_k * 2) (16/-1, -1/-1, 16/0 mode)
            #       or cache(1, head, real_cache_t, d_k * 2) (16/4 mode).
            #       In all modes, `if cache.size(0) > 0` will alwayse be `True`
            #       and we will always do splitting and
            #       concatnation(this will simplify onnx export). Note that
            #       it's OK to concat & split zero-shaped tensors(see code below).
            #   when export jit  model, for 1st chunk, we always feed
            #       cache(0, 0, 0, 0) since jit supports dynamic if-branch.
            # >>> a = torch.ones((1, 2, 0, 4))
            # >>> b = torch.ones((1, 2, 3, 4))
            # >>> c = torch.cat((a, b), dim=2)
            # >>> torch.equal(b, c)        # True
            # >>> d = torch.split(a, 2, dim=-1)
            # >>> torch.equal(d[0], d[1])  # True
            key_cache, value_cache = cache
            if key_cache.size(0) > 0:
                k = torch.cat([key_cache, k], dim=seq_axis)
            if value_cache.size(0) > 0:
                v = torch.cat([value_cache, v], dim=seq_axis)
            # NOTE(xcsong): We do cache slicing in encoder.forward_chunk, since it's
            #   non-trivial to calculate `next_cache_start` here.
            # new_cache = torch.cat((k, v), dim=-1) if not self.training else cache
            new_cache = (k, v)
        # for multi query or multi group attention
        if self.h_kv != self.h and self.h_kv != 1:
            # NOTE: onnxruntime issues:
            #     https://github.com/wenet-e2e/wenet/issues/2517
            # k = torch.repeat_interleave(
            #     k,
            #     self.h // self.h_kv,
            #     dim=-3,
            # )
            # v = torch.repeat_interleave(
            #     v,
            #     self.h // self.h_kv,
            #     dim=-3,
            # )
            n_repeat = self.h // self.h_kv
            k_shape = k.size()
            repeat_axis = head_axis + 1
            k = k.unsqueeze(head_axis).expand(
                k_shape[:repeat_axis] + torch.Size([n_repeat]) +
                k_shape[repeat_axis:]).reshape(
                    k_shape[:head_axis] + torch.Size([self.h_kv * n_repeat]) +
                    k_shape[repeat_axis:])
            v_shape = v.size()
            v = v.unsqueeze(head_axis).expand(
                v_shape[:repeat_axis] + torch.Size([n_repeat]) +
                v_shape[(repeat_axis):]).reshape(
                    v_shape[:head_axis] + torch.Size([self.h_kv * n_repeat]) +
                    v_shape[repeat_axis:])

        return k, v, new_cache

    def forward(
        self,
        query: torch.Tensor,
        key: torch.Tensor,
        value: torch.Tensor,
        mask: torch.Tensor = torch.ones((0, 0, 0), dtype=torch.bool),
        pos_emb: torch.Tensor = torch.empty(0),
        cache: T_CACHE = (torch.zeros(0, 0, 0, 0), torch.zeros(0, 0, 0, 0)),
    ) -> Tuple[torch.Tensor, T_CACHE]:
        """Compute scaled dot product attention.

        Args:
            query (torch.Tensor): Query tensor (#batch, time1, size).
            key (torch.Tensor): Key tensor (#batch, time2, size).
            value (torch.Tensor): Value tensor (#batch, time2, size).
            mask (torch.Tensor): Mask tensor (#batch, 1, time2) or
                (#batch, time1, time2).
                1.When applying cross attention between decoder and encoder,
                the batch padding mask for input is in (#batch, 1, T) shape.
                2.When applying self attention of encoder,
                the mask is in (#batch, T, T)  shape.
                3.When applying self attention of decoder,
                the mask is in (#batch, L, L)  shape.
                4.If the different position in decoder see different block
                of the encoder, such as Mocha, the passed in mask could be
                in (#batch, L, T) shape. But there is no such case in current
                Wenet.
            cache (torch.Tensor): Cache tensor (1, head, cache_t, d_k * 2),
                where `cache_t == chunk_size * num_decoding_left_chunks`
                and `head * d_k == size`


        Returns:
            torch.Tensor: Output tensor (#batch, time1, d_model).
            torch.Tensor: Cache tensor (1, head, cache_t + time1, d_k * 2)
                where `cache_t == chunk_size * num_decoding_left_chunks`
                and `head * d_k == size`

        """
        q, k, v = self.forward_qkv(query, key, value)
        k, v, new_cache = self._update_kv_and_cache(k, v, cache)

        if not self.use_sdpa:
            scores = torch.matmul(q, k.transpose(-2, -1)) / math.sqrt(self.d_k)
            return self.forward_attention(v, scores, mask), new_cache
        else:
            output = torch.nn.functional.scaled_dot_product_attention(
                q,
                k,
                v,
                attn_mask=mask.unsqueeze(1),
                dropout_p=self.dropout_rate,
                scale=1 / math.sqrt(self.d_k),
            )
            output = (output.transpose(1, 2).contiguous().view(
                query.size(0), -1,
                self.h * self.d_k))  # (batch, time1, d_model)
            return self.linear_out(output), new_cache


class RelPositionMultiHeadedAttention(MultiHeadedAttention):
    """Multi-Head Attention layer with relative position encoding.
    Paper: https://arxiv.org/abs/1901.02860
    Args:
        n_head (int): The number of heads.
        n_feat (int): The number of features.
        dropout_rate (float): Dropout rate.
    """

    def __init__(self,
                 n_head: int,
                 n_feat: int,
                 dropout_rate: float,
                 query_bias: bool = True,
                 key_bias: bool = True,
                 value_bias: bool = True,
                 use_sdpa: bool = False,
                 n_kv_head: Optional[int] = None,
                 head_dim: Optional[int] = None):
        """Construct an RelPositionMultiHeadedAttention object."""
        super().__init__(n_head, n_feat, dropout_rate, query_bias, key_bias,
                         value_bias, use_sdpa, n_kv_head, head_dim)
        # linear transformation for positional encoding
        self.linear_pos = nn.Linear(n_feat, n_feat, bias=False)
        # these two learnable bias are used in matrix c and matrix d
        # as described in https://arxiv.org/abs/1901.02860 Section 3.3
        self.pos_bias_u = nn.Parameter(torch.Tensor(self.h, self.d_k))
        self.pos_bias_v = nn.Parameter(torch.Tensor(self.h, self.d_k))
        torch.nn.init.xavier_uniform_(self.pos_bias_u)
        torch.nn.init.xavier_uniform_(self.pos_bias_v)

    def rel_shift(self, x, zero_triu: bool = False):
        """Compute relative positinal encoding.
        Args:
            x (torch.Tensor): Input tensor (batch, time, size).
            zero_triu (bool): If true, return the lower triangular part of
                the matrix.
        Returns:
            torch.Tensor: Output tensor.
        """

        zero_pad = torch.zeros((x.size()[0], x.size()[1], x.size()[2], 1),
                               device=x.device,
                               dtype=x.dtype)
        x_padded = torch.cat([zero_pad, x], dim=-1)

        x_padded = x_padded.view(x.size()[0],
                                 x.size()[1],
                                 x.size(3) + 1, x.size(2))
        x = x_padded[:, :, 1:].view_as(x)

        if zero_triu:
            ones = torch.ones((x.size(2), x.size(3)))
            x = x * torch.tril(ones, x.size(3) - x.size(2))[None, None, :, :]

        return x

    def forward(
        self,
        query: torch.Tensor,
        key: torch.Tensor,
        value: torch.Tensor,
        mask: torch.Tensor = torch.ones((0, 0, 0), dtype=torch.bool),
        pos_emb: torch.Tensor = torch.empty(0),
        cache: T_CACHE = (torch.zeros((0, 0, 0, 0)), torch.zeros((0, 0, 0, 0)))
    ) -> Tuple[torch.Tensor, T_CACHE]:
        """Compute 'Scaled Dot Product Attention' with rel. positional encoding.
        Args:
            query (torch.Tensor): Query tensor (#batch, time1, size).
            key (torch.Tensor): Key tensor (#batch, time2, size).
            value (torch.Tensor): Value tensor (#batch, time2, size).
            mask (torch.Tensor): Mask tensor (#batch, 1, time2) or
                (#batch, time1, time2), (0, 0, 0) means fake mask.
            pos_emb (torch.Tensor): Positional embedding tensor
                (#batch, time2, size).
            cache (torch.Tensor): Cache tensor (1, head, cache_t, d_k * 2),
                where `cache_t == chunk_size * num_decoding_left_chunks`
                and `head * d_k == size`
        Returns:
            torch.Tensor: Output tensor (#batch, time1, d_model).
            torch.Tensor: Cache tensor (1, head, cache_t + time1, d_k * 2)
                where `cache_t == chunk_size * num_decoding_left_chunks`
                and `head * d_k == size`
        """
        q, k, v = self.forward_qkv(query, key, value)
        q = q.transpose(1, 2)  # (batch, time1, head, d_k)
        k, v, new_cache = self._update_kv_and_cache(k, v, cache)

        n_batch_pos = pos_emb.size(0)
        p = self.linear_pos(pos_emb).view(n_batch_pos, -1, self.h, self.d_k)
        p = p.transpose(1, 2)  # (batch, head, time1, d_k)

        # (batch, head, time1, d_k)
        q_with_bias_u = (q + self.pos_bias_u).transpose(1, 2)
        # (batch, head, time1, d_k)
        q_with_bias_v = (q + self.pos_bias_v).transpose(1, 2)

        # compute matrix b and matrix d
        # (batch, head, time1, time2)
        matrix_bd = torch.matmul(q_with_bias_v, p.transpose(-2, -1))
        # Remove rel_shift since it is useless in speech recognition,
        # and it requires special attention for streaming.
        # matrix_bd = self.rel_shift(matrix_bd)
        if not self.use_sdpa:
            # compute attention score
            # first compute matrix a and matrix c
            # as described in https://arxiv.org/abs/1901.02860 Section 3.3
            # (batch, head, time1, time2)
            matrix_ac = torch.matmul(q_with_bias_u, k.transpose(-2, -1))

            scores = (matrix_ac + matrix_bd) / math.sqrt(
                self.d_k)  # (batch, head, time1, time2)

            return self.forward_attention(v, scores, mask), new_cache
        else:
            # NOTE(Mddct): we need mask bias, not boolean mask
            assert mask.dtype != torch.bool
            mask = mask.unsqueeze(1)
            # matrix_bd as a mask bias
            mask = (matrix_bd + mask) / math.sqrt(self.d_k)
            output = torch.nn.functional.scaled_dot_product_attention(
                q_with_bias_u,
                k,
                v,
                attn_mask=mask,
                dropout_p=self.dropout_rate,
                scale=1 / math.sqrt(self.d_k),
            )
            output = (output.transpose(1, 2).contiguous().view(
                query.size(0), -1,
                self.h * self.d_k))  # (batch, time1, d_model)
            return self.linear_out(output), new_cache


class MultiHeadedCrossAttention(MultiHeadedAttention):

    def __init__(self,
                 n_head: int,
                 n_feat: int,
                 dropout_rate: float,
                 query_bias: bool = True,
                 key_bias: bool = True,
                 value_bias: bool = True,
                 use_sdpa: bool = False,
                 n_kv_head: Optional[int] = None,
                 head_dim: Optional[int] = None):
        super().__init__(n_head, n_feat, dropout_rate, query_bias, key_bias,
                         value_bias, use_sdpa, n_kv_head, head_dim)

    def forward(
        self,
        query: torch.Tensor,
        key: torch.Tensor,
        value: torch.Tensor,
        mask: torch.Tensor = torch.ones((0, 0, 0), dtype=torch.bool),
        pos_emb: torch.Tensor = torch.empty(0),
        cache: T_CACHE = (torch.zeros((0, 0, 0, 0)), torch.zeros((0, 0, 0, 0)))
    ) -> Tuple[torch.Tensor, T_CACHE]:
        del pos_emb
        key_cache, value_cache = cache
        assert key_cache.size(0) == value_cache.size(0)
        if key_cache.size(0) > 0:
            assert not self.training
            q = self._forward_linearx('query', query)
            k, v = key_cache, value_cache

        else:
            q, k, v = self.forward_qkv(query, key, value)
        new_cache = (k, v) if not self.training else cache
        # for multi query or multi groups attention
        if self.h_kv != self.h and self.h_kv != 1:
            k = torch.repeat_interleave(
                k,
                self.h // self.h_kv,
                dim=-3,
            )
            v = torch.repeat_interleave(
                v,
                self.h // self.h_kv,
                dim=-3,
            )
        B = query.size(0)
        Beams = 1
        if B != k.size(0):
            assert not self.training
            Beams = B // k.size(0)
            B = k.size(0)
            q = q.view(B, Beams, q.size(-3), q.size(-2), q.size(-1))
            k = k.unsqueeze(1)
            v = v.unsqueeze(1)
            mask = mask.unsqueeze(1)

        if not self.use_sdpa:
            scores = torch.matmul(q, k.transpose(-2, -1)) / math.sqrt(self.d_k)
            output = self.forward_attention(v, scores, mask)
        else:
            output = torch.nn.functional.scaled_dot_product_attention(
                q,
                k,
                v,
                attn_mask=mask.unsqueeze(1),
                dropout_p=self.dropout_rate,
                scale=1 / math.sqrt(self.d_k),
            )
            output = output.transpose(-2, -3).contiguous()
            output_shape = output.size()[:-2] + torch.Size([self.h * self.d_k])
            output = output.view(output_shape)  # (batch, ...,  time1, d_model)
            output = self.linear_out(output)

        if query.size(0) != B:
            assert not self.training
            output_shape = torch.Size([B * Beams]) + output.size()[2:]
            output = output.view(output_shape)
        return output, new_cache


class ShawRelPositionMultiHeadedAttention(MultiHeadedAttention):
    """ https://arxiv.org/pdf/1803.02155.pdf
    """

    def __init__(self,
                 n_head: int,
                 n_feat: int,
                 dropout_rate: float,
                 query_bias: bool = True,
                 key_bias: bool = True,
                 value_bias: bool = True,
                 use_sdpa: bool = False,
                 n_kv_head: Optional[int] = None,
                 head_dim: Optional[int] = None):
        del n_kv_head, head_dim
        super().__init__(n_head, n_feat, dropout_rate, query_bias, key_bias,
                         value_bias, use_sdpa, None, None)
        # TODO(Mddct): 64 8 1 as args
        self.max_right_rel_pos = 8
        self.max_left_rel_pos = 64
        self.rel_k_embed = torch.nn.Embedding(
            self.max_left_rel_pos + self.max_right_rel_pos + 1, self.d_k)

    def _relative_indices(self, keys: torch.Tensor) -> torch.Tensor:
        # (S, 1)
        indices = torch.arange(keys.size(2), device=keys.device).unsqueeze(0)

        # (S, S)
        rel_indices = indices - indices.transpose(0, 1)

        rel_indices = torch.clamp(rel_indices, -self.max_left_rel_pos,
                                  self.max_right_rel_pos)

        return rel_indices + self.max_left_rel_pos

    def forward(
        self,
        query: torch.Tensor,
        key: torch.Tensor,
        value: torch.Tensor,
        mask: torch.Tensor = torch.ones((0, 0, 0), dtype=torch.bool),
        pos_emb: torch.Tensor = torch.empty(0),
        cache: T_CACHE = (torch.zeros((0, 0, 0, 0)), torch.zeros(0, 0, 0, 0))
    ) -> Tuple[torch.Tensor, T_CACHE]:
        del pos_emb
        q, k, v = self.forward_qkv(query, key, value)
        k, v, new_cache = self._update_kv_and_cache(k, v, cache)

        rel_k = self.rel_k_embed(self._relative_indices(k))  # (t2, t2, d_k)
        rel_k = rel_k[-q.size(2):]
        rel_att_weights = torch.einsum("bhld,lrd->bhlr", q, rel_k)

        if not self.use_sdpa:
            scores = (torch.matmul(q, k.transpose(-2, -1)) +
                      rel_att_weights) / math.sqrt(self.d_k)
            return self.forward_attention(v, scores, mask), new_cache
        else:
            # NOTE(Mddct): we need mask bias, not boolean mask
            assert mask.dtype != torch.bool
            mask = mask.unsqueeze(1)
            # matrix_bd as a mask bias
            mask = (rel_att_weights + mask) / math.sqrt(self.d_k)
            output = torch.nn.functional.scaled_dot_product_attention(
                q,
                k,
                v,
                attn_mask=mask,
                dropout_p=self.dropout_rate,
                scale=1 / math.sqrt(self.d_k),
            )
            output = (output.transpose(1, 2).contiguous().view(
                query.size(0), -1,
                self.h * self.d_k))  # (batch, time1, d_model)
            return self.linear_out(output), new_cache


class RopeMultiHeadedAttention(MultiHeadedAttention):

    def __init__(self,
                 n_head: int,
                 n_feat: int,
                 dropout_rate: float,
                 query_bias: bool = True,
                 key_bias: bool = True,
                 value_bias: bool = True,
                 use_sdpa: bool = False,
                 n_kv_head: Optional[int] = None,
                 head_dim: Optional[int] = None,
                 style='google'):
        super().__init__(n_head, n_feat, dropout_rate, query_bias, key_bias,
                         value_bias, use_sdpa, n_kv_head, head_dim)
        self.style = style

    def forward(
        self,
        query: torch.Tensor,
        key: torch.Tensor,
        value: torch.Tensor,
        mask: torch.Tensor = torch.ones((0, 0, 0), dtype=torch.bool),
        pos_emb: torch.Tensor = torch.empty(0),
        cache: T_CACHE = (torch.zeros((0, 0, 0, 0)), torch.zeros(0, 0, 0, 0))
    ) -> Tuple[torch.Tensor, T_CACHE]:
        """Compute rope scaled dot product attention.

        Args:
            query (torch.Tensor): Query tensor (#batch, time1, size).
            key (torch.Tensor): Key tensor (#batch, time2, size).
            value (torch.Tensor): Value tensor (#batch, time2, size).
            mask (torch.Tensor): Mask tensor (#batch, 1, time2) or
                (#batch, time1, time2).
                1.When applying cross attention between decoder and encoder,
                the batch padding mask for input is in (#batch, 1, T) shape.
                2.When applying self attention of encoder,
                the mask is in (#batch, T, T)  shape.
                3.When applying self attention of decoder,
                the mask is in (#batch, L, L)  shape.
                4.If the different position in decoder see different block
                of the encoder, such as Mocha, the passed in mask could be
                in (#batch, L, T) shape. But there is no such case in current
                Wenet.
            cache (torch.Tensor): Cache tensor (1, head, cache_t, d_k * 2),
                where `cache_t == chunk_size * num_decoding_left_chunks`
                and `head * d_k == size`


        Returns:
            torch.Tensor: Output tensor (#batch, time1, d_model).
            torch.Tensor: Cache tensor (1, head, cache_t + time1, d_k * 2)
                where `cache_t == chunk_size * num_decoding_left_chunks`
                and `head * d_k == size`

        """
        q = self._forward_linearx('query', query, head_first=False)
        k = self._forward_linearx('key', key, head_first=False)
        v = self._forward_linearx('value', value, head_first=False)
        # NOTE(Mddct): In order to make the code easier to read,
        #    these two lines are not placed in MultiHeadedAttention.
        q = WENET_APPLY_ROTARY_EMB[self.style](q, pos_emb)
        k = WENET_APPLY_ROTARY_EMB[self.style](k, pos_emb)

        k, v, new_cache = self._update_kv_and_cache(k,
                                                    v,
                                                    cache,
                                                    head_first=False)

        q = q.transpose(1, 2)
        k = k.transpose(1, 2)
        v = v.transpose(1, 2)
        if not self.use_sdpa:
            scores = torch.matmul(q, k.transpose(-2, -1)) / math.sqrt(self.d_k)
            return self.forward_attention(v, scores, mask), new_cache
        else:
            output = torch.nn.functional.scaled_dot_product_attention(
                q,
                k,
                v,
                attn_mask=mask.unsqueeze(1),
                dropout_p=self.dropout_rate,
                scale=1 / math.sqrt(self.d_k),
            )
            output = (output.transpose(1, 2).contiguous().view(
                query.size(0), -1,
                self.h * self.d_k))  # (batch, time1, d_model)
            return self.linear_out(output), new_cache