train.py

# Copyright (c) 2018 PaddlePaddle Authors. All Rights Reserved.
#
# 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.

from __future__ import print_function
import argparse
import ast
import paddle.fluid as fluid
from paddle.fluid.dygraph import Embedding, LayerNorm, FC, to_variable, Layer, guard
import numpy as np
import paddle
import paddle.dataset.wmt16 as wmt16


def parse_args():
    parser = argparse.ArgumentParser("Training for Mnist.")
    parser.add_argument(
        "--use_data_parallel",
        type=ast.literal_eval,
        default=False,
        help="The flag indicating whether to use data parallel mode to train the model."
    )
    args = parser.parse_args()
    return args


args = parse_args()


# Copy from models
class TrainTaskConfig(object):
    """
    TrainTaskConfig
    """
    # support both CPU and GPU now.
    use_gpu = True
    # the epoch number to train.
    pass_num = 30
    # the number of sequences contained in a mini-batch.
    # deprecated, set batch_size in args.
    batch_size = 32
    # the hyper parameters for Adam optimizer.
    # This static learning_rate will be multiplied to the LearningRateScheduler
    # derived learning rate the to get the final learning rate.
    learning_rate = 2.0
    beta1 = 0.9
    beta2 = 0.997
    eps = 1e-9
    # the parameters for learning rate scheduling.
    warmup_steps = 8000
    # the weight used to mix up the ground-truth distribution and the fixed
    # uniform distribution in label smoothing when training.
    # Set this as zero if label smoothing is not wanted.
    label_smooth_eps = 0.1


class ModelHyperParams(object):
    """
    ModelHyperParams
    """
    # These following five vocabularies related configurations will be set
    # automatically according to the passed vocabulary path and special tokens.
    # size of source word dictionary.
    src_vocab_size = 10000
    # size of target word dictionay
    trg_vocab_size = 10000
    # # index for <bos> token
    # bos_idx = 0
    # # index for <eos> token
    # eos_idx = 1
    # # index for <unk> token
    # unk_idx = 2

    src_pad_idx = 0

    # index for <pad> token in target language.
    trg_pad_idx = 1

    # max length of sequences deciding the size of position encoding table.
    max_length = 50
    # the dimension for word embeddings, which is also the last dimension of
    # the input and output of multi-head attention, position-wise feed-forward
    # networks, encoder and decoder.
    d_model = 512
    # size of the hidden layer in position-wise feed-forward networks.
    d_inner_hid = 2048
    # the dimension that keys are projected to for dot-product attention.
    d_key = 64
    # the dimension that values are projected to for dot-product attention.
    d_value = 64
    # number of head used in multi-head attention.
    n_head = 8
    # number of sub-layers to be stacked in the encoder and decoder.
    n_layer = 6
    # dropout rates of different modules.
    prepostprocess_dropout = 0.1
    attention_dropout = 0.1
    relu_dropout = 0.1
    # to process before each sub-layer
    preprocess_cmd = "n"  # layer normalization
    # to process after each sub-layer
    postprocess_cmd = "da"  # dropout + residual connection
    # random seed used in dropout for CE.
    dropout_seed = 0
    # the flag indicating whether to share embedding and softmax weights.
    # vocabularies in source and target should be same for weight sharing.
    weight_sharing = False


# The placeholder for batch_size in compile time. Must be -1 currently to be
# consistent with some ops' infer-shape output in compile time, such as the
# sequence_expand op used in beamsearch decoder.
batch_size = -1
# The placeholder for squence length in compile time.
seq_len = ModelHyperParams.max_length
# Here list the data shapes and data types of all inputs.
# The shapes here act as placeholder and are set to pass the infer-shape in
# compile time.
input_descs = {
    # The actual data shape of src_word is:
    # [batch_size, max_src_len_in_batch, 1]
    "src_word": [(batch_size, seq_len, 1), "int64", 2],
    # The actual data shape of src_pos is:
    # [batch_size, max_src_len_in_batch, 1]
    "src_pos": [(batch_size, seq_len, 1), "int64"],
    # This input is used to remove attention weights on paddings in the
    # encoder.
    # The actual data shape of src_slf_attn_bias is:
    # [batch_size, n_head, max_src_len_in_batch, max_src_len_in_batch]
    "src_slf_attn_bias": [(batch_size, ModelHyperParams.n_head, seq_len,
                           seq_len), "float32"],
    # The actual data shape of trg_word is:
    # [batch_size, max_trg_len_in_batch, 1]
    "trg_word": [(batch_size, seq_len, 1), "int64",
                 2],  # lod_level is only used in fast decoder.
    # The actual data shape of trg_pos is:
    # [batch_size, max_trg_len_in_batch, 1]
    "trg_pos": [(batch_size, seq_len, 1), "int64"],
    # This input is used to remove attention weights on paddings and
    # subsequent words in the decoder.
    # The actual data shape of trg_slf_attn_bias is:
    # [batch_size, n_head, max_trg_len_in_batch, max_trg_len_in_batch]
    "trg_slf_attn_bias": [(batch_size, ModelHyperParams.n_head, seq_len,
                           seq_len), "float32"],
    # This input is used to remove attention weights on paddings of the source
    # input in the encoder-decoder attention.
    # The actual data shape of trg_src_attn_bias is:
    # [batch_size, n_head, max_trg_len_in_batch, max_src_len_in_batch]
    "trg_src_attn_bias": [(batch_size, ModelHyperParams.n_head, seq_len,
                           seq_len), "float32"],
    # This input is used in independent decoder program for inference.
    # The actual data shape of enc_output is:
    # [batch_size, max_src_len_in_batch, d_model]
    "enc_output": [(batch_size, seq_len, ModelHyperParams.d_model), "float32"],
    # The actual data shape of label_word is:
    # [batch_size * max_trg_len_in_batch, 1]
    "lbl_word": [(batch_size * seq_len, 1), "int64"],
    # This input is used to mask out the loss of paddding tokens.
    # The actual data shape of label_weight is:
    # [batch_size * max_trg_len_in_batch, 1]
    "lbl_weight": [(batch_size * seq_len, 1), "float32"],
    # This input is used in beam-search decoder.
    "init_score": [(batch_size, 1), "float32", 2],
    # This input is used in beam-search decoder for the first gather
    # (cell states updation)
    "init_idx": [(batch_size, ), "int32"],
}

# Names of word embedding table which might be reused for weight sharing.
word_emb_param_names = (
    "src_word_emb_table",
    "trg_word_emb_table", )
# Names of position encoding table which will be initialized externally.
pos_enc_param_names = (
    "src_pos_enc_table",
    "trg_pos_enc_table", )
# separated inputs for different usages.
encoder_data_input_fields = (
    "src_word",
    "src_pos",
    "src_slf_attn_bias", )
decoder_data_input_fields = (
    "trg_word",
    "trg_pos",
    "trg_slf_attn_bias",
    "trg_src_attn_bias",
    "enc_output", )
label_data_input_fields = (
    "lbl_word",
    "lbl_weight", )
# In fast decoder, trg_pos (only containing the current time step) is generated
# by ops and trg_slf_attn_bias is not needed.
fast_decoder_data_input_fields = (
    "trg_word",
    "init_score",
    "init_idx",
    "trg_src_attn_bias", )


def merge_cfg_from_list(cfg_list, g_cfgs):
    """
    Set the above global configurations using the cfg_list.
    """
    assert len(cfg_list) % 2 == 0
    for key, value in zip(cfg_list[0::2], cfg_list[1::2]):
        for g_cfg in g_cfgs:
            if hasattr(g_cfg, key):
                try:
                    value = eval(value)
                except Exception:  # for file path
                    pass
                setattr(g_cfg, key, value)
                break


def position_encoding_init(n_position, d_pos_vec):
    """
    Generate the initial values for the sinusoid position encoding table.
    """
    channels = d_pos_vec
    position = np.arange(n_position)
    num_timescales = channels // 2
    log_timescale_increment = (np.log(float(1e4) / float(1)) /
                               (num_timescales - 1))
    inv_timescales = np.exp(np.arange(
        num_timescales)) * -log_timescale_increment
    scaled_time = np.expand_dims(position, 1) * np.expand_dims(inv_timescales,
                                                               0)
    signal = np.concatenate([np.sin(scaled_time), np.cos(scaled_time)], axis=1)
    signal = np.pad(signal, [[0, 0], [0, np.mod(channels, 2)]], 'constant')
    position_enc = signal
    return position_enc.astype("float32")


def create_data(np_values, is_static=False):
    """
    create_data
    :param np_values:
    :param is_static:
    :return:
    """
    # pdb.set_trace()
    [
        src_word_np, src_pos_np, trg_word_np, trg_pos_np, src_slf_attn_bias_np,
        trg_slf_attn_bias_np, trg_src_attn_bias_np, lbl_word_np, lbl_weight_np
    ] = np_values

    if is_static:
        return [
            src_word_np, src_pos_np, src_slf_attn_bias_np, trg_word_np,
            trg_pos_np, trg_slf_attn_bias_np, trg_src_attn_bias_np, lbl_word_np,
            lbl_weight_np
        ]
    else:
        enc_inputs = [
            to_variable(
                src_word_np, name='src_word'), to_variable(
                    src_pos_np, name='src_pos'), to_variable(
                        src_slf_attn_bias_np, name='src_slf_attn_bias')
        ]
        dec_inputs = [
            to_variable(
                trg_word_np, name='trg_word'), to_variable(
                    trg_pos_np, name='trg_pos'), to_variable(
                        trg_slf_attn_bias_np, name='trg_slf_attn_bias'),
            to_variable(
                trg_src_attn_bias_np, name='trg_src_attn_bias')
        ]
        label = to_variable(lbl_word_np, name='lbl_word')
        weight = to_variable(lbl_weight_np, name='lbl_weight')
        return enc_inputs, dec_inputs, label, weight


def create_feed_dict_list(data, init=False):
    """
    create_feed_dict_list
    :param data:
    :param init:
    :return:
    """
    if init:
        data_input_names = encoder_data_input_fields + \
                           decoder_data_input_fields[:-1] + label_data_input_fields + pos_enc_param_names
    else:
        data_input_names = encoder_data_input_fields + \
                           decoder_data_input_fields[:-1] + label_data_input_fields
    feed_dict_list = dict()
    for i in range(len(data_input_names)):
        feed_dict_list[data_input_names[i]] = data[i]
    return feed_dict_list


def make_all_inputs(input_fields):
    """
    Define the input data layers for the transformer model.
    """
    inputs = []
    for input_field in input_fields:
        input_var = fluid.layers.data(
            name=input_field,
            shape=input_descs[input_field][0],
            dtype=input_descs[input_field][1],
            lod_level=input_descs[input_field][2]
            if len(input_descs[input_field]) == 3 else 0,
            append_batch_size=False)
        inputs.append(input_var)
    return inputs


def prepare_batch_input(insts, src_pad_idx, trg_pad_idx, n_head):
    """
    Pad the instances to the max sequence length in batch, and generate the
    corresponding position data and attention bias. Then, convert the numpy
    data to tensors and return a dict mapping names to tensors.
    """

    def __pad_batch_data(insts,
                         pad_idx,
                         n_head,
                         is_target=False,
                         is_label=False,
                         return_attn_bias=True,
                         return_max_len=True,
                         return_num_token=False):
        """
        Pad the instances to the max sequence length in batch, and generate the
        corresponding position data and attention bias.
        """
        return_list = []
        max_len = max(len(inst) for inst in insts)
        # Any token included in dict can be used to pad, since the paddings' loss
        # will be masked out by weights and make no effect on parameter gradients.
        inst_data = np.array(
            [inst + [pad_idx] * (max_len - len(inst)) for inst in insts])
        return_list += [inst_data.astype("int64").reshape([-1, 1])]
        if is_label:  # label weight
            inst_weight = np.array([[1.] * len(inst) + [0.] *
                                    (max_len - len(inst)) for inst in insts])
            return_list += [inst_weight.astype("float32").reshape([-1, 1])]
        else:  # position data
            inst_pos = np.array([
                list(range(0, len(inst))) + [0] * (max_len - len(inst))
                for inst in insts
            ])
            return_list += [inst_pos.astype("int64").reshape([-1, 1])]
        if return_attn_bias:
            if is_target:
                # This is used to avoid attention on paddings and subsequent
                # words.
                slf_attn_bias_data = np.ones(
                    (inst_data.shape[0], max_len, max_len))
                slf_attn_bias_data = np.triu(
                    slf_attn_bias_data, 1).reshape([-1, 1, max_len, max_len])
                slf_attn_bias_data = np.tile(slf_attn_bias_data,
                                             [1, n_head, 1, 1]) * [-1e9]
            else:
                # This is used to avoid attention on paddings.
                slf_attn_bias_data = np.array([[0] * len(inst) + [-1e9] *
                                               (max_len - len(inst))
                                               for inst in insts])
                slf_attn_bias_data = np.tile(
                    slf_attn_bias_data.reshape([-1, 1, 1, max_len]),
                    [1, n_head, max_len, 1])
            return_list += [slf_attn_bias_data.astype("float32")]
        if return_max_len:
            return_list += [max_len]
        if return_num_token:
            num_token = 0
            for inst in insts:
                num_token += len(inst)
            return_list += [num_token]
        return return_list if len(return_list) > 1 else return_list[0]

    src_word, src_pos, src_slf_attn_bias, src_max_len = __pad_batch_data(
        [inst[0] for inst in insts], src_pad_idx, n_head, is_target=False)
    src_word = src_word.reshape(-1, src_max_len, 1)
    src_pos = src_pos.reshape(-1, src_max_len, 1)
    trg_word, trg_pos, trg_slf_attn_bias, trg_max_len = __pad_batch_data(
        [inst[1] for inst in insts], trg_pad_idx, n_head, is_target=True)
    trg_word = trg_word.reshape(-1, trg_max_len, 1)
    trg_pos = trg_pos.reshape(-1, trg_max_len, 1)

    trg_src_attn_bias = np.tile(src_slf_attn_bias[:, :, ::src_max_len, :],
                                [1, 1, trg_max_len, 1]).astype("float32")

    lbl_word, lbl_weight, num_token = __pad_batch_data(
        [inst[2] for inst in insts],
        trg_pad_idx,
        n_head,
        is_target=False,
        is_label=True,
        return_attn_bias=False,
        return_max_len=False,
        return_num_token=True)

    return [
        src_word, src_pos, trg_word, trg_pos, src_slf_attn_bias,
        trg_slf_attn_bias, trg_src_attn_bias, lbl_word, lbl_weight
    ]


pos_inp1 = position_encoding_init(ModelHyperParams.max_length + 1,
                                  ModelHyperParams.d_model)
pos_inp2 = position_encoding_init(ModelHyperParams.max_length + 1,
                                  ModelHyperParams.d_model)


class PrePostProcessLayer(Layer):
    """
    PrePostProcessLayer
    """

    def __init__(self, name_scope, process_cmd, shape_len=None):
        super(PrePostProcessLayer, self).__init__(name_scope)
        for cmd in process_cmd:
            if cmd == "n":
                self._layer_norm = LayerNorm(
                    name_scope=self.full_name(),
                    begin_norm_axis=shape_len - 1,
                    param_attr=fluid.ParamAttr(
                        initializer=fluid.initializer.Constant(1.)),
                    bias_attr=fluid.ParamAttr(
                        initializer=fluid.initializer.Constant(0.)))

    def forward(self, prev_out, out, process_cmd, dropout_rate=0.):
        """
        forward
        :param prev_out:
        :param out:
        :param process_cmd:
        :param dropout_rate:
        :return:
        """
        for cmd in process_cmd:
            if cmd == "a":  # add residual connection
                out = out + prev_out if prev_out else out
            elif cmd == "n":  # add layer normalization
                out = self._layer_norm(out)
            elif cmd == "d":  # add dropout
                if dropout_rate:
                    out = fluid.layers.dropout(
                        out,
                        dropout_prob=dropout_rate,
                        seed=ModelHyperParams.dropout_seed,
                        is_test=False)
        return out


class PositionwiseFeedForwardLayer(Layer):
    """
    PositionwiseFeedForwardLayer
    """

    def __init__(self, name_scope, d_inner_hid, d_hid, dropout_rate):
        super(PositionwiseFeedForwardLayer, self).__init__(name_scope)
        self._i2h = FC(name_scope=self.full_name(),
                       size=d_inner_hid,
                       num_flatten_dims=2,
                       act="relu")
        self._h2o = FC(name_scope=self.full_name(),
                       size=d_hid,
                       num_flatten_dims=2)
        self._dropout_rate = dropout_rate

    def forward(self, x):
        """
        forward
        :param x:
        :return:
        """
        hidden = self._i2h(x)
        if self._dropout_rate:
            hidden = fluid.layers.dropout(
                hidden,
                dropout_prob=self._dropout_rate,
                seed=ModelHyperParams.dropout_seed,
                is_test=False)
        out = self._h2o(hidden)
        return out


class MultiHeadAttentionLayer(Layer):
    """
    MultiHeadAttentionLayer
    """

    def __init__(self,
                 name_scope,
                 d_key,
                 d_value,
                 d_model,
                 n_head=1,
                 dropout_rate=0.,
                 cache=None,
                 gather_idx=None,
                 static_kv=False):
        super(MultiHeadAttentionLayer, self).__init__(name_scope)
        self._n_head = n_head
        self._d_key = d_key
        self._d_value = d_value
        self._d_model = d_model
        self._dropout_rate = dropout_rate
        self._q_fc = FC(name_scope=self.full_name(),
                        size=d_key * n_head,
                        bias_attr=False,
                        num_flatten_dims=2)
        self._k_fc = FC(name_scope=self.full_name(),
                        size=d_key * n_head,
                        bias_attr=False,
                        num_flatten_dims=2)
        self._v_fc = FC(name_scope=self.full_name(),
                        size=d_value * n_head,
                        bias_attr=False,
                        num_flatten_dims=2)
        self._proj_fc = FC(name_scope=self.full_name(),
                           size=self._d_model,
                           bias_attr=False,
                           num_flatten_dims=2)

    def forward(self, queries, keys, values, attn_bias):
        """
        forward
        :param queries:
        :param keys:
        :param values:
        :param attn_bias:
        :return:
        """
        # compute q ,k ,v
        keys = queries if keys is None else keys
        values = keys if values is None else values

        q = self._q_fc(queries)
        k = self._k_fc(keys)
        v = self._v_fc(values)

        # split head
        reshaped_q = fluid.layers.reshape(
            x=q, shape=[0, 0, self._n_head, self._d_key], inplace=False)
        transpose_q = fluid.layers.transpose(x=reshaped_q, perm=[0, 2, 1, 3])
        reshaped_k = fluid.layers.reshape(
            x=k, shape=[0, 0, self._n_head, self._d_key], inplace=False)
        transpose_k = fluid.layers.transpose(x=reshaped_k, perm=[0, 2, 1, 3])
        reshaped_v = fluid.layers.reshape(
            x=v, shape=[0, 0, self._n_head, self._d_value], inplace=False)
        transpose_v = fluid.layers.transpose(x=reshaped_v, perm=[0, 2, 1, 3])

        # scale dot product attention
        product = fluid.layers.matmul(
            x=transpose_q,
            y=transpose_k,
            transpose_y=True,
            alpha=self._d_model**-0.5)
        if attn_bias:
            product += attn_bias
        weights = fluid.layers.softmax(product)
        if self._dropout_rate:
            weights_droped = fluid.layers.dropout(
                weights,
                dropout_prob=self._dropout_rate,
                seed=ModelHyperParams.dropout_seed,
                is_test=False)
            out = fluid.layers.matmul(weights_droped, transpose_v)
        else:
            out = fluid.layers.matmul(weights, transpose_v)

        # combine heads
        if len(out.shape) != 4:
            raise ValueError("Input(x) should be a 4-D Tensor.")
        trans_x = fluid.layers.transpose(out, perm=[0, 2, 1, 3])
        final_out = fluid.layers.reshape(
            x=trans_x,
            shape=[0, 0, trans_x.shape[2] * trans_x.shape[3]],
            inplace=False)

        # fc to output
        proj_out = self._proj_fc(final_out)
        return proj_out


class EncoderSubLayer(Layer):
    """
    EncoderSubLayer
    """

    def __init__(self,
                 name_scope,
                 n_head,
                 d_key,
                 d_value,
                 d_model,
                 d_inner_hid,
                 prepostprocess_dropout,
                 attention_dropout,
                 relu_dropout,
                 preprocess_cmd="n",
                 postprocess_cmd="da"):

        super(EncoderSubLayer, self).__init__(name_scope)
        self._preprocess_cmd = preprocess_cmd
        self._postprocess_cmd = postprocess_cmd
        self._prepostprocess_dropout = prepostprocess_dropout

        self._preprocess_layer = PrePostProcessLayer(self.full_name(),
                                                     self._preprocess_cmd, 3)
        self._multihead_attention_layer = MultiHeadAttentionLayer(
            self.full_name(), d_key, d_value, d_model, n_head,
            attention_dropout)
        self._postprocess_layer = PrePostProcessLayer(
            self.full_name(), self._postprocess_cmd, None)
        self._preprocess_layer2 = PrePostProcessLayer(self.full_name(),
                                                      self._preprocess_cmd, 3)
        self._positionwise_feed_forward = PositionwiseFeedForwardLayer(
            self.full_name(), d_inner_hid, d_model, relu_dropout)
        self._postprocess_layer2 = PrePostProcessLayer(
            self.full_name(), self._postprocess_cmd, None)

    def forward(self, enc_input, attn_bias):
        """
        forward
        :param enc_input:
        :param attn_bias:
        :return:
        """
        pre_process_multihead = self._preprocess_layer(
            None, enc_input, self._preprocess_cmd, self._prepostprocess_dropout)
        attn_output = self._multihead_attention_layer(pre_process_multihead,
                                                      None, None, attn_bias)
        attn_output = self._postprocess_layer(enc_input, attn_output,
                                              self._postprocess_cmd,
                                              self._prepostprocess_dropout)
        pre_process2_output = self._preprocess_layer2(
            None, attn_output, self._preprocess_cmd,
            self._prepostprocess_dropout)
        ffd_output = self._positionwise_feed_forward(pre_process2_output)
        return self._postprocess_layer2(attn_output, ffd_output,
                                        self._postprocess_cmd,
                                        self._prepostprocess_dropout)


class EncoderLayer(Layer):
    """
    encoder
    """

    def __init__(self,
                 name_scope,
                 n_layer,
                 n_head,
                 d_key,
                 d_value,
                 d_model,
                 d_inner_hid,
                 prepostprocess_dropout,
                 attention_dropout,
                 relu_dropout,
                 preprocess_cmd="n",
                 postprocess_cmd="da"):

        super(EncoderLayer, self).__init__(name_scope)
        self._preprocess_cmd = preprocess_cmd
        self._encoder_sublayers = list()
        self._prepostprocess_dropout = prepostprocess_dropout
        self._n_layer = n_layer
        self._preprocess_layer = PrePostProcessLayer(self.full_name(),
                                                     self._preprocess_cmd, 3)
        for i in range(n_layer):
            self._encoder_sublayers.append(
                self.add_sublayer(
                    'esl_%d' % i,
                    EncoderSubLayer(
                        self.full_name(), n_head, d_key, d_value, d_model,
                        d_inner_hid, prepostprocess_dropout, attention_dropout,
                        relu_dropout, preprocess_cmd, postprocess_cmd)))

    def forward(self, enc_input, attn_bias):
        """
        forward
        :param enc_input:
        :param attn_bias:
        :return:
        """
        for i in range(self._n_layer):
            enc_output = self._encoder_sublayers[i](enc_input, attn_bias)
            enc_input = enc_output

        return self._preprocess_layer(None, enc_output, self._preprocess_cmd,
                                      self._prepostprocess_dropout)


class PrepareEncoderDecoderLayer(Layer):
    """
    PrepareEncoderDecoderLayer
    """

    def __init__(self,
                 name_scope,
                 src_vocab_size,
                 src_emb_dim,
                 src_max_len,
                 dropout_rate,
                 word_emb_param_name=None,
                 pos_enc_param_name=None):
        super(PrepareEncoderDecoderLayer, self).__init__(name_scope)
        self._src_max_len = src_max_len
        self._src_emb_dim = src_emb_dim
        self._src_vocab_size = src_vocab_size
        self._dropout_rate = dropout_rate
        self._input_emb = Embedding(
            name_scope=self.full_name(),
            size=[src_vocab_size, src_emb_dim],
            padding_idx=0,
            param_attr=fluid.ParamAttr(
                name=word_emb_param_name,
                initializer=fluid.initializer.Normal(0., src_emb_dim**-0.5)))

        if pos_enc_param_name is pos_enc_param_names[0]:
            pos_inp = pos_inp1
        else:
            pos_inp = pos_inp2
        self._pos_emb = Embedding(
            name_scope=self.full_name(),
            size=[self._src_max_len, src_emb_dim],
            param_attr=fluid.ParamAttr(
                name=pos_enc_param_name,
                initializer=fluid.initializer.NumpyArrayInitializer(pos_inp),
                trainable=False))

        # use in dygraph_mode to fit different length batch
        # self._pos_emb._w = to_variable(
        #     position_encoding_init(self._src_max_len, self._src_emb_dim))

    def forward(self, src_word, src_pos):
        """
        forward
        :param src_word:
        :param src_pos:
        :return:
        """
        # print("here")
        # print(self._input_emb._w._numpy().shape)
        src_word_emb = self._input_emb(src_word)

        src_word_emb = fluid.layers.scale(
            x=src_word_emb, scale=self._src_emb_dim**0.5)
        # # TODO change this to fit dynamic length input
        src_pos_emb = self._pos_emb(src_pos)
        src_pos_emb.stop_gradient = True
        enc_input = src_word_emb + src_pos_emb
        return fluid.layers.dropout(
            enc_input,
            dropout_prob=self._dropout_rate,
            seed=ModelHyperParams.dropout_seed,
            is_test=False) if self._dropout_rate else enc_input


class WrapEncoderLayer(Layer):
    """
    encoderlayer
    """

    def __init__(self, name_cope, src_vocab_size, max_length, n_layer, n_head,
                 d_key, d_value, d_model, d_inner_hid, prepostprocess_dropout,
                 attention_dropout, relu_dropout, preprocess_cmd,
                 postprocess_cmd, weight_sharing):
        """
        The wrapper assembles together all needed layers for the encoder.
        """
        super(WrapEncoderLayer, self).__init__(name_cope)

        self._prepare_encoder_layer = PrepareEncoderDecoderLayer(
            self.full_name(),
            src_vocab_size,
            d_model,
            max_length,
            prepostprocess_dropout,
            word_emb_param_name=word_emb_param_names[0],
            pos_enc_param_name=pos_enc_param_names[0])
        self._encoder = EncoderLayer(
            self.full_name(), n_layer, n_head, d_key, d_value, d_model,
            d_inner_hid, prepostprocess_dropout, attention_dropout,
            relu_dropout, preprocess_cmd, postprocess_cmd)

    def forward(self, enc_inputs):
        """forward"""
        src_word, src_pos, src_slf_attn_bias = enc_inputs
        enc_input = self._prepare_encoder_layer(src_word, src_pos)
        enc_output = self._encoder(enc_input, src_slf_attn_bias)
        return enc_output


class DecoderSubLayer(Layer):
    """
    decoder
    """

    def __init__(self,
                 name_scope,
                 n_head,
                 d_key,
                 d_value,
                 d_model,
                 d_inner_hid,
                 prepostprocess_dropout,
                 attention_dropout,
                 relu_dropout,
                 preprocess_cmd,
                 postprocess_cmd,
                 cache=None,
                 gather_idx=None):
        super(DecoderSubLayer, self).__init__(name_scope)
        self._postprocess_cmd = postprocess_cmd
        self._preprocess_cmd = preprocess_cmd
        self._prepostprcess_dropout = prepostprocess_dropout
        self._pre_process_layer = PrePostProcessLayer(self.full_name(),
                                                      preprocess_cmd, 3)
        self._multihead_attention_layer = MultiHeadAttentionLayer(
            self.full_name(),
            d_key,
            d_value,
            d_model,
            n_head,
            attention_dropout,
            cache=cache,
            gather_idx=gather_idx)
        self._post_process_layer = PrePostProcessLayer(self.full_name(),
                                                       postprocess_cmd, None)
        self._pre_process_layer2 = PrePostProcessLayer(self.full_name(),
                                                       preprocess_cmd, 3)
        self._multihead_attention_layer2 = MultiHeadAttentionLayer(
            self.full_name(),
            d_key,
            d_value,
            d_model,
            n_head,
            attention_dropout,
            cache=cache,
            gather_idx=gather_idx,
            static_kv=True)
        self._post_process_layer2 = PrePostProcessLayer(self.full_name(),
                                                        postprocess_cmd, None)
        self._pre_process_layer3 = PrePostProcessLayer(self.full_name(),
                                                       preprocess_cmd, 3)
        self._positionwise_feed_forward_layer = PositionwiseFeedForwardLayer(
            self.full_name(), d_inner_hid, d_model, relu_dropout)
        self._post_process_layer3 = PrePostProcessLayer(self.full_name(),
                                                        postprocess_cmd, None)

    def forward(self, dec_input, enc_output, slf_attn_bias, dec_enc_attn_bias):
        """
        forward
        :param dec_input:
        :param enc_output:
        :param slf_attn_bias:
        :param dec_enc_attn_bias:
        :return:
        """
        pre_process_rlt = self._pre_process_layer(
            None, dec_input, self._preprocess_cmd, self._prepostprcess_dropout)
        slf_attn_output = self._multihead_attention_layer(pre_process_rlt, None,
                                                          None, slf_attn_bias)
        slf_attn_output_pp = self._post_process_layer(
            dec_input, slf_attn_output, self._postprocess_cmd,
            self._prepostprcess_dropout)
        pre_process_rlt2 = self._pre_process_layer2(None, slf_attn_output_pp,
                                                    self._preprocess_cmd,
                                                    self._prepostprcess_dropout)
        enc_attn_output_pp = self._multihead_attention_layer2(
            pre_process_rlt2, enc_output, enc_output, dec_enc_attn_bias)
        enc_attn_output = self._post_process_layer2(
            slf_attn_output_pp, enc_attn_output_pp, self._postprocess_cmd,
            self._prepostprcess_dropout)
        pre_process_rlt3 = self._pre_process_layer3(None, enc_attn_output,
                                                    self._preprocess_cmd,
                                                    self._prepostprcess_dropout)
        ffd_output = self._positionwise_feed_forward_layer(pre_process_rlt3)
        dec_output = self._post_process_layer3(enc_attn_output, ffd_output,
                                               self._postprocess_cmd,
                                               self._prepostprcess_dropout)
        return dec_output


class DecoderLayer(Layer):
    """
    decoder
    """

    def __init__(self,
                 name_scope,
                 n_layer,
                 n_head,
                 d_key,
                 d_value,
                 d_model,
                 d_inner_hid,
                 prepostprocess_dropout,
                 attention_dropout,
                 relu_dropout,
                 preprocess_cmd,
                 postprocess_cmd,
                 caches=None,
                 gather_idx=None):
        super(DecoderLayer, self).__init__(name_scope)
        self._pre_process_layer = PrePostProcessLayer(self.full_name(),
                                                      preprocess_cmd, 3)
        self._decoder_sub_layers = list()
        self._n_layer = n_layer
        self._preprocess_cmd = preprocess_cmd
        self._prepostprocess_dropout = prepostprocess_dropout
        for i in range(n_layer):
            self._decoder_sub_layers.append(
                self.add_sublayer(
                    'dsl_%d' % i,
                    DecoderSubLayer(
                        self.full_name(),
                        n_head,
                        d_key,
                        d_value,
                        d_model,
                        d_inner_hid,
                        prepostprocess_dropout,
                        attention_dropout,
                        relu_dropout,
                        preprocess_cmd,
                        postprocess_cmd,
                        cache=None if caches is None else caches[i],
                        gather_idx=gather_idx)))

    def forward(self, dec_input, enc_output, dec_slf_attn_bias,
                dec_enc_attn_bias):
        """
        forward
        :param dec_input:
        :param enc_output:
        :param dec_slf_attn_bias:
        :param dec_enc_attn_bias:
        :return:
        """
        for i in range(self._n_layer):
            tmp_dec_output = self._decoder_sub_layers[i](
                dec_input, enc_output, dec_slf_attn_bias, dec_enc_attn_bias)
            dec_input = tmp_dec_output

        dec_output = self._pre_process_layer(None, tmp_dec_output,
                                             self._preprocess_cmd,
                                             self._prepostprocess_dropout)
        return dec_output


class WrapDecoderLayer(Layer):
    """
    decoder
    """

    def __init__(self,
                 name_scope,
                 trg_vocab_size,
                 max_length,
                 n_layer,
                 n_head,
                 d_key,
                 d_value,
                 d_model,
                 d_inner_hid,
                 prepostprocess_dropout,
                 attention_dropout,
                 relu_dropout,
                 preprocess_cmd,
                 postprocess_cmd,
                 weight_sharing,
                 caches=None,
                 gather_idx=None):
        """
        The wrapper assembles together all needed layers for the encoder.
        """
        super(WrapDecoderLayer, self).__init__(name_scope)

        self._prepare_decoder_layer = PrepareEncoderDecoderLayer(
            self.full_name(),
            trg_vocab_size,
            d_model,
            max_length,
            prepostprocess_dropout,
            word_emb_param_name=word_emb_param_names[1],
            pos_enc_param_name=pos_enc_param_names[1])
        self._decoder_layer = DecoderLayer(
            self.full_name(),
            n_layer,
            n_head,
            d_key,
            d_value,
            d_model,
            d_inner_hid,
            prepostprocess_dropout,
            attention_dropout,
            relu_dropout,
            preprocess_cmd,
            postprocess_cmd,
            caches=caches,
            gather_idx=gather_idx)
        self._weight_sharing = weight_sharing
        if not weight_sharing:
            self._fc = FC(self.full_name(),
                          size=trg_vocab_size,
                          bias_attr=False)

    def forward(self, dec_inputs=None, enc_output=None):
        """
        forward
        :param dec_inputs:
        :param enc_output:
        :return:
        """
        trg_word, trg_pos, trg_slf_attn_bias, trg_src_attn_bias = dec_inputs
        dec_input = self._prepare_decoder_layer(trg_word, trg_pos)
        dec_output = self._decoder_layer(dec_input, enc_output,
                                         trg_slf_attn_bias, trg_src_attn_bias)

        dec_output_reshape = fluid.layers.reshape(
            dec_output, shape=[-1, dec_output.shape[-1]], inplace=False)

        if self._weight_sharing:
            predict = fluid.layers.matmul(
                x=dec_output_reshape,
                y=self._prepare_decoder_layer._input_emb._w,
                transpose_y=True)
        else:
            predict = self._fc(dec_output_reshape)

        if dec_inputs is None:
            # Return probs for independent decoder program.
            predict_out = fluid.layers.softmax(predict)
            return predict_out
        return predict


class TransFormer(Layer):
    """
    model
    """

    def __init__(self, name_scope, src_vocab_size, trg_vocab_size, max_length,
                 n_layer, n_head, d_key, d_value, d_model, d_inner_hid,
                 prepostprocess_dropout, attention_dropout, relu_dropout,
                 preprocess_cmd, postprocess_cmd, weight_sharing,
                 label_smooth_eps):
        super(TransFormer, self).__init__(name_scope)
        self._label_smooth_eps = label_smooth_eps
        self._trg_vocab_size = trg_vocab_size
        if weight_sharing:
            assert src_vocab_size == trg_vocab_size, (
                "Vocabularies in source and target should be same for weight sharing."
            )
        self._wrap_encoder_layer = WrapEncoderLayer(
            self.full_name(), src_vocab_size, max_length, n_layer, n_head,
            d_key, d_value, d_model, d_inner_hid, prepostprocess_dropout,
            attention_dropout, relu_dropout, preprocess_cmd, postprocess_cmd,
            weight_sharing)
        self._wrap_decoder_layer = WrapDecoderLayer(
            self.full_name(), trg_vocab_size, max_length, n_layer, n_head,
            d_key, d_value, d_model, d_inner_hid, prepostprocess_dropout,
            attention_dropout, relu_dropout, preprocess_cmd, postprocess_cmd,
            weight_sharing)

        if weight_sharing:
            self._wrap_decoder_layer._prepare_decoder_layer._input_emb._w = self._wrap_encoder_layer._prepare_encoder_layer._input_emb._w

    def forward(self, enc_inputs, dec_inputs, label, weights):
        """
        forward
        :param enc_inputs:
        :param dec_inputs:
        :param label:
        :param weights:
        :return:
        """
        enc_output = self._wrap_encoder_layer(enc_inputs)
        predict = self._wrap_decoder_layer(dec_inputs, enc_output)
        if self._label_smooth_eps:
            label_out = fluid.layers.label_smooth(
                label=fluid.layers.one_hot(
                    input=label, depth=self._trg_vocab_size),
                epsilon=self._label_smooth_eps)

        cost = fluid.layers.softmax_with_cross_entropy(
            logits=predict,
            label=label_out,
            soft_label=True if self._label_smooth_eps else False)
        weighted_cost = cost * weights
        sum_cost = fluid.layers.reduce_sum(weighted_cost)
        token_num = fluid.layers.reduce_sum(weights)
        token_num.stop_gradient = True
        avg_cost = sum_cost / token_num
        return sum_cost, avg_cost, predict, token_num


def train():
    """
    train models
    :return:
    """

    trainer_count = fluid.dygraph.parallel.Env().nranks
    place = fluid.CUDAPlace(fluid.dygraph.parallel.Env().dev_id) \
        if args.use_data_parallel else fluid.CUDAPlace(0)
    with fluid.dygraph.guard(place):
        if args.use_data_parallel:
            strategy = fluid.dygraph.parallel.prepare_context()

        transformer = TransFormer(
            'transformer', ModelHyperParams.src_vocab_size,
            ModelHyperParams.trg_vocab_size, ModelHyperParams.max_length + 1,
            ModelHyperParams.n_layer, ModelHyperParams.n_head,
            ModelHyperParams.d_key, ModelHyperParams.d_value,
            ModelHyperParams.d_model, ModelHyperParams.d_inner_hid,
            ModelHyperParams.prepostprocess_dropout,
            ModelHyperParams.attention_dropout, ModelHyperParams.relu_dropout,
            ModelHyperParams.preprocess_cmd, ModelHyperParams.postprocess_cmd,
            ModelHyperParams.weight_sharing, TrainTaskConfig.label_smooth_eps)

        optimizer = fluid.optimizer.SGD(learning_rate=0.003)

        if args.use_data_parallel:
            transformer = fluid.dygraph.parallel.DataParallel(transformer,
                                                              strategy)

        reader = paddle.batch(
            wmt16.train(ModelHyperParams.src_vocab_size,
                        ModelHyperParams.trg_vocab_size),
            batch_size=TrainTaskConfig.batch_size)
        if args.use_data_parallel:
            reader = fluid.contrib.reader.distributed_batch_reader(reader)

        for i in range(200):
            dy_step = 0
            for batch in reader():
                np_values = prepare_batch_input(
                    batch, ModelHyperParams.src_pad_idx,
                    ModelHyperParams.trg_pad_idx, ModelHyperParams.n_head)

                enc_inputs, dec_inputs, label, weights = create_data(np_values)
                dy_sum_cost, dy_avg_cost, dy_predict, dy_token_num = transformer(
                    enc_inputs, dec_inputs, label, weights)

                if args.use_data_parallel:
                    dy_avg_cost = transformer.scale_loss(dy_avg_cost)
                    dy_avg_cost.backward()
                    transformer.apply_collective_grads()
                else:
                    dy_avg_cost.backward()

                optimizer.minimize(dy_avg_cost)
                transformer.clear_gradients()
                dy_step = dy_step + 1
                if dy_step % 10 == 0:
                    print("pass num : {}, batch_id: {}, dy_graph avg loss: {}".
                          format(i, dy_step, dy_avg_cost.numpy()))
            print("pass : {} finished".format(i))


if __name__ == '__main__':
    train()