更新transformer代码

PyTorch/NLP/new-Transformer/fairseq/data/noising.py

+# 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 numpy as np
+import torch
+from fairseq.data import data_utils
+
+
+class WordNoising(object):
+    """Generate a noisy version of a sentence, without changing words themselves."""
+
+    def __init__(self, dictionary, bpe_cont_marker="@@", bpe_end_marker=None):
+        self.dictionary = dictionary
+        self.bpe_end = None
+        if bpe_cont_marker:
+            self.bpe_end = np.array(
+                [
+                    not self.dictionary[i].endswith(bpe_cont_marker)
+                    for i in range(len(self.dictionary))
+                ]
+            )
+        elif bpe_end_marker:
+            self.bpe_end = np.array(
+                [
+                    self.dictionary[i].endswith(bpe_end_marker)
+                    for i in range(len(self.dictionary))
+                ]
+            )
+
+        self.get_word_idx = (
+            self._get_bpe_word_idx if self.bpe_end is not None else self._get_token_idx
+        )
+
+    def noising(self, x, lengths, noising_prob=0.0):
+        raise NotImplementedError()
+
+    def _get_bpe_word_idx(self, x):
+        """
+        Given a list of BPE tokens, for every index in the tokens list,
+        return the index of the word grouping that it belongs to.
+        For example, for input x corresponding to ["how", "are", "y@@", "ou"],
+        return [[0], [1], [2], [2]].
+        """
+        # x: (T x B)
+        bpe_end = self.bpe_end[x]
+
+        if x.size(0) == 1 and x.size(1) == 1:
+            # Special case when we only have one word in x. If x = [[N]],
+            # bpe_end is a scalar (bool) instead of a 2-dim array of bools,
+            # which makes the sum operation below fail.
+            return np.array([[0]])
+
+        # do a reduce front sum to generate word ids
+        word_idx = bpe_end[::-1].cumsum(0)[::-1]
+        word_idx = word_idx.max(0)[None, :] - word_idx
+        return word_idx
+
+    def _get_token_idx(self, x):
+        """
+        This is to extend noising functions to be able to apply to non-bpe
+        tokens, e.g. word or characters.
+        """
+        x = torch.t(x)
+        word_idx = np.array([range(len(x_i)) for x_i in x])
+        return np.transpose(word_idx)
+
+
+class WordDropout(WordNoising):
+    """Randomly drop input words. If not passing blank_idx (default is None),
+    then dropped words will be removed. Otherwise, it will be replaced by the
+    blank_idx."""
+
+    def __init__(
+        self,
+        dictionary,
+        default_dropout_prob=0.1,
+        bpe_cont_marker="@@",
+        bpe_end_marker=None,
+    ):
+        super().__init__(dictionary, bpe_cont_marker, bpe_end_marker)
+        self.default_dropout_prob = default_dropout_prob
+
+    def noising(self, x, lengths, dropout_prob=None, blank_idx=None):
+        if dropout_prob is None:
+            dropout_prob = self.default_dropout_prob
+        # x: (T x B), lengths: B
+        if dropout_prob == 0:
+            return x, lengths
+
+        assert 0 < dropout_prob < 1
+
+        # be sure to drop entire words
+        word_idx = self.get_word_idx(x)
+        sentences = []
+        modified_lengths = []
+        for i in range(lengths.size(0)):
+            # Since dropout probabilities need to apply over non-pad tokens,
+            # it is not trivial to generate the keep mask without consider
+            # input lengths; otherwise, this could be done outside the loop
+
+            # We want to drop whole words based on word_idx grouping
+            num_words = max(word_idx[:, i]) + 1
+
+            # ith example: [x0, x1, ..., eos, pad, ..., pad]
+            # We should only generate keep probs for non-EOS tokens. Thus if the
+            # input sentence ends in EOS, the last word idx is not included in
+            # the dropout mask generation and we append True to always keep EOS.
+            # Otherwise, just generate the dropout mask for all word idx
+            # positions.
+            has_eos = x[lengths[i] - 1, i] == self.dictionary.eos()
+            if has_eos:  # has eos?
+                keep = np.random.rand(num_words - 1) >= dropout_prob
+                keep = np.append(keep, [True])  # keep EOS symbol
+            else:
+                keep = np.random.rand(num_words) >= dropout_prob
+
+            words = x[: lengths[i], i].tolist()
+
+            # TODO: speed up the following loop
+            # drop words from the input according to keep
+            new_s = [
+                w if keep[word_idx[j, i]] else blank_idx for j, w in enumerate(words)
+            ]
+            new_s = [w for w in new_s if w is not None]
+            # we need to have at least one word in the sentence (more than the
+            # start / end sentence symbols)
+            if len(new_s) <= 1:
+                # insert at beginning in case the only token left is EOS
+                # EOS should be at end of list.
+                new_s.insert(0, words[np.random.randint(0, len(words))])
+            assert len(new_s) >= 1 and (
+                not has_eos  # Either don't have EOS at end or last token is EOS
+                or (len(new_s) >= 2 and new_s[-1] == self.dictionary.eos())
+            ), "New sentence is invalid."
+            sentences.append(new_s)
+            modified_lengths.append(len(new_s))
+        # re-construct input
+        modified_lengths = torch.LongTensor(modified_lengths)
+        modified_x = torch.LongTensor(
+            modified_lengths.max(), modified_lengths.size(0)
+        ).fill_(self.dictionary.pad())
+        for i in range(modified_lengths.size(0)):
+            modified_x[: modified_lengths[i], i].copy_(torch.LongTensor(sentences[i]))
+
+        return modified_x, modified_lengths
+
+
+class WordShuffle(WordNoising):
+    """Shuffle words by no more than k positions."""
+
+    def __init__(
+        self,
+        dictionary,
+        default_max_shuffle_distance=3,
+        bpe_cont_marker="@@",
+        bpe_end_marker=None,
+    ):
+        super().__init__(dictionary, bpe_cont_marker, bpe_end_marker)
+        self.default_max_shuffle_distance = 3
+
+    def noising(self, x, lengths, max_shuffle_distance=None):
+        if max_shuffle_distance is None:
+            max_shuffle_distance = self.default_max_shuffle_distance
+        # x: (T x B), lengths: B
+        if max_shuffle_distance == 0:
+            return x, lengths
+
+        # max_shuffle_distance < 1 will return the same sequence
+        assert max_shuffle_distance > 1
+
+        # define noise word scores
+        noise = np.random.uniform(
+            0,
+            max_shuffle_distance,
+            size=(x.size(0), x.size(1)),
+        )
+        noise[0] = -1  # do not move start sentence symbol
+        # be sure to shuffle entire words
+        word_idx = self.get_word_idx(x)
+        x2 = x.clone()
+        for i in range(lengths.size(0)):
+            length_no_eos = lengths[i]
+            if x[lengths[i] - 1, i] == self.dictionary.eos():
+                length_no_eos = lengths[i] - 1
+            # generate a random permutation
+            scores = word_idx[:length_no_eos, i] + noise[word_idx[:length_no_eos, i], i]
+            # ensure no reordering inside a word
+            scores += 1e-6 * np.arange(length_no_eos.item())
+            permutation = scores.argsort()
+            # shuffle words
+            x2[:length_no_eos, i].copy_(
+                x2[:length_no_eos, i][torch.from_numpy(permutation)]
+            )
+        return x2, lengths
+
+
+class UnsupervisedMTNoising(WordNoising):
+    """
+    Implements the default configuration for noising in UnsupervisedMT
+    (github.com/facebookresearch/UnsupervisedMT)
+    """
+
+    def __init__(
+        self,
+        dictionary,
+        max_word_shuffle_distance,
+        word_dropout_prob,
+        word_blanking_prob,
+        bpe_cont_marker="@@",
+        bpe_end_marker=None,
+    ):
+        super().__init__(dictionary)
+        self.max_word_shuffle_distance = max_word_shuffle_distance
+        self.word_dropout_prob = word_dropout_prob
+        self.word_blanking_prob = word_blanking_prob
+
+        self.word_dropout = WordDropout(
+            dictionary=dictionary,
+            bpe_cont_marker=bpe_cont_marker,
+            bpe_end_marker=bpe_end_marker,
+        )
+        self.word_shuffle = WordShuffle(
+            dictionary=dictionary,
+            bpe_cont_marker=bpe_cont_marker,
+            bpe_end_marker=bpe_end_marker,
+        )
+
+    def noising(self, x, lengths):
+        # 1. Word Shuffle
+        noisy_src_tokens, noisy_src_lengths = self.word_shuffle.noising(
+            x=x,
+            lengths=lengths,
+            max_shuffle_distance=self.max_word_shuffle_distance,
+        )
+        # 2. Word Dropout
+        noisy_src_tokens, noisy_src_lengths = self.word_dropout.noising(
+            x=noisy_src_tokens,
+            lengths=noisy_src_lengths,
+            dropout_prob=self.word_dropout_prob,
+        )
+        # 3. Word Blanking
+        noisy_src_tokens, noisy_src_lengths = self.word_dropout.noising(
+            x=noisy_src_tokens,
+            lengths=noisy_src_lengths,
+            dropout_prob=self.word_blanking_prob,
+            blank_idx=self.dictionary.unk(),
+        )
+
+        return noisy_src_tokens
+
+
+class NoisingDataset(torch.utils.data.Dataset):
+    def __init__(
+        self,
+        src_dataset,
+        src_dict,
+        seed,
+        noiser=None,
+        noising_class=UnsupervisedMTNoising,
+        **kwargs
+    ):
+        """
+        Wrap a :class:`~torch.utils.data.Dataset` and apply noise to the
+        samples based on the supplied noising configuration.
+
+        Args:
+            src_dataset (~torch.utils.data.Dataset): dataset to wrap.
+                to build self.src_dataset --
+                a LanguagePairDataset with src dataset as the source dataset and
+                None as the target dataset. Should NOT have padding so that
+                src_lengths are accurately calculated by language_pair_dataset
+                collate function.
+                We use language_pair_dataset here to encapsulate the tgt_dataset
+                so we can re-use the LanguagePairDataset collater to format the
+                batches in the structure that SequenceGenerator expects.
+            src_dict (~fairseq.data.Dictionary): source dictionary
+            seed (int): seed to use when generating random noise
+            noiser (WordNoising): a pre-initialized :class:`WordNoising`
+                instance. If this is None, a new instance will be created using
+                *noising_class* and *kwargs*.
+            noising_class (class, optional): class to use to initialize a
+                default :class:`WordNoising` instance.
+            kwargs (dict, optional): arguments to initialize the default
+                :class:`WordNoising` instance given by *noiser*.
+        """
+        self.src_dataset = src_dataset
+        self.src_dict = src_dict
+        self.seed = seed
+        self.noiser = (
+            noiser
+            if noiser is not None
+            else noising_class(
+                dictionary=src_dict,
+                **kwargs,
+            )
+        )
+        self.sizes = src_dataset.sizes
+
+    def __getitem__(self, index):
+        """
+        Returns a single noisy sample. Multiple samples are fed to the collater
+        create a noising dataset batch.
+        """
+        src_tokens = self.src_dataset[index]
+        src_lengths = torch.LongTensor([len(src_tokens)])
+        src_tokens = src_tokens.unsqueeze(0)
+
+        # Transpose src tokens to fit expected shape of x in noising function
+        # (batch size, sequence length) -> (sequence length, batch size)
+        src_tokens_t = torch.t(src_tokens)
+
+        with data_utils.numpy_seed(self.seed + index):
+            noisy_src_tokens = self.noiser.noising(src_tokens_t, src_lengths)
+
+        # Transpose back to expected src_tokens format
+        # (sequence length, 1) -> (1, sequence length)
+        noisy_src_tokens = torch.t(noisy_src_tokens)
+        return noisy_src_tokens[0]
+
+    def __len__(self):
+        """
+        The length of the noising dataset is the length of src.
+        """
+        return len(self.src_dataset)
+
+    @property
+    def supports_prefetch(self):
+        return self.src_dataset.supports_prefetch
+
+    def prefetch(self, indices):
+        if self.src_dataset.supports_prefetch:
+            self.src_dataset.prefetch(indices)

PyTorch/NLP/new-Transformer/fairseq/data/num_samples_dataset.py

+# 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.
+
+from . import FairseqDataset
+
+
+class NumSamplesDataset(FairseqDataset):
+    def __getitem__(self, index):
+        return 1
+
+    def __len__(self):
+        return 0
+
+    def collater(self, samples):
+        return sum(samples)

PyTorch/NLP/new-Transformer/fairseq/data/numel_dataset.py

+# 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 numpy as np
+import torch
+
+from . import BaseWrapperDataset
+
+
+class NumelDataset(BaseWrapperDataset):
+    def __init__(self, dataset, reduce=False):
+        super().__init__(dataset)
+        self.reduce = reduce
+
+    def __getitem__(self, index):
+        item = self.dataset[index]
+        if torch.is_tensor(item):
+            return torch.numel(item)
+        else:
+            return np.size(item)
+
+    def __len__(self):
+        return len(self.dataset)
+
+    def collater(self, samples):
+        if self.reduce:
+            return sum(samples)
+        else:
+            return torch.tensor(samples)

PyTorch/NLP/new-Transformer/fairseq/data/offset_tokens_dataset.py

+# 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.
+
+from . import BaseWrapperDataset
+
+
+class OffsetTokensDataset(BaseWrapperDataset):
+    def __init__(self, dataset, offset):
+        super().__init__(dataset)
+        self.offset = offset
+
+    def __getitem__(self, idx):
+        return self.dataset[idx] + self.offset

PyTorch/NLP/new-Transformer/fairseq/data/pad_dataset.py

+# 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.
+
+from fairseq.data import data_utils
+
+from . import BaseWrapperDataset
+
+
+class PadDataset(BaseWrapperDataset):
+    def __init__(self, dataset, pad_idx, left_pad, pad_length=None):
+        super().__init__(dataset)
+        self.pad_idx = pad_idx
+        self.left_pad = left_pad
+        self.pad_length = pad_length
+
+    def collater(self, samples):
+        return data_utils.collate_tokens(
+            samples, self.pad_idx, left_pad=self.left_pad, pad_to_length=self.pad_length
+        )
+
+
+class LeftPadDataset(PadDataset):
+    def __init__(self, dataset, pad_idx):
+        super().__init__(dataset, pad_idx, left_pad=True)
+
+
+class RightPadDataset(PadDataset):
+    def __init__(self, dataset, pad_idx):
+        super().__init__(dataset, pad_idx, left_pad=False)

PyTorch/NLP/new-Transformer/fairseq/data/plasma_utils.py

+# 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 hashlib
+import json
+import subprocess
+import tempfile
+from typing import Hashable
+
+try:
+    import pyarrow.plasma as plasma
+
+    PYARROW_AVAILABLE = True
+except ImportError:
+    plasma = None
+    PYARROW_AVAILABLE = False
+
+
+class PlasmaArray:
+    """
+    Wrapper around numpy arrays that automatically moves the data to shared
+    memory upon serialization. This is particularly helpful when passing numpy
+    arrays through multiprocessing, so that data is not unnecessarily
+    duplicated or pickled.
+    """
+
+    def __init__(self, array):
+        super().__init__()
+        self.array = array
+        self.disable = array.nbytes < 134217728  # disable for arrays <128MB
+        self.object_id = None
+        self.path = None
+
+        # variables with underscores shouldn't be pickled
+        self._client = None
+        self._server = None
+        self._server_tmp = None
+        self._plasma = None
+
+    @property
+    def plasma(self):
+        if self._plasma is None and not self.disable:
+            self._plasma = plasma
+        return self._plasma
+
+    def start_server(self):
+        if self.plasma is None or self._server is not None:
+            return
+        assert self.object_id is None
+        assert self.path is None
+        self._server_tmp = tempfile.NamedTemporaryFile()
+        self.path = self._server_tmp.name
+        self._server = subprocess.Popen(
+            ["plasma_store", "-m", str(int(1.05 * self.array.nbytes)), "-s", self.path]
+        )
+
+    @property
+    def client(self):
+        if self._client is None:
+            assert self.path is not None
+            self._client = self.plasma.connect(self.path, num_retries=200)
+        return self._client
+
+    def __getstate__(self):
+        """Called on pickle load"""
+        if self.plasma is None:
+            return self.__dict__
+        if self.object_id is None:
+            self.start_server()
+            self.object_id = self.client.put(self.array)
+        state = self.__dict__.copy()
+        del state["array"]
+        state["_client"] = None
+        state["_server"] = None
+        state["_server_tmp"] = None
+        state["_plasma"] = None
+        return state
+
+    def __setstate__(self, state):
+        """Called on pickle save"""
+        self.__dict__.update(state)
+        if self.plasma is None:
+            return
+        self.array = self.client.get(self.object_id)
+
+    def __del__(self):
+        if self._server is not None:
+            self._server.kill()
+            self._server = None
+            self._server_tmp.close()
+            self._server_tmp = None
+
+
+DEFAULT_PLASMA_PATH = "/tmp/plasma"
+
+
+class PlasmaView:
+    """Interface to write and read from shared memory. Whereas PlasmaArray writes to plasma on serialization,
+    PlasmaView writes to shared memory on instantiation."""
+
+    def __init__(self, array, split_path: str, hash_data: Hashable, plasma_path=None):
+        """
+        Args:
+            array: numpy array to store. This can be read with ``PlasmaView().array``
+            split_path: the path whence the data was read, used for hashing
+            hash_data: other metadata about the array that can be used to create a unique key.
+                as of writing, the 3 callers in ``TokenBlockDataset`` use::
+
+                    hash_data = ((block_size, document_sep_len, str(break_mode), len(dataset)), 0|1|2)
+
+
+        """
+        assert PYARROW_AVAILABLE
+        assert split_path is not None
+        if plasma_path is None:
+            plasma_path = DEFAULT_PLASMA_PATH
+
+        self.path = plasma_path
+        self.split_path = split_path
+        self._client = None  # Initialize lazily for pickle. plasma clients should not be deep copied or serialized.
+        self._n = None
+
+        self.object_id = self.get_object_id(self.split_path, hash_data)
+        try:
+            self.client.put(array, object_id=self.object_id)
+        except plasma.PlasmaObjectExists:
+            pass
+
+    @property
+    def client(self):
+        if self._client is None:
+            self._client = plasma.connect(self.path, num_retries=200)
+        return self._client
+
+    @property
+    def array(self):
+        """Fetch a read only view of an np.array, stored in plasma."""
+        ret = self.client.get(self.object_id)
+        return ret
+
+    @staticmethod
+    def get_object_id(split_path: str, hash_data: Hashable):
+        """Returns plasma.ObjectID from hashing split_path and object_num."""
+        hash = hashlib.blake2b(bytes(split_path, "utf-8"), digest_size=20)
+        harg = json.dumps(hash_data).encode("utf-8")
+        hash.update(harg)
+        return plasma.ObjectID(hash.digest())
+
+    def __getstate__(self):
+        """Called on pickle save"""
+        self.disconnect()
+        state = self.__dict__.copy()
+        assert state["_client"] is None
+        assert "object_id" in state
+        return state
+
+    def __setstate__(self, state):
+        """Called on pickle load"""
+        self.__dict__.update(state)
+
+    def __del__(self):
+        self.disconnect()
+
+    def disconnect(self):
+        if self._client is not None:
+            self._client.disconnect()
+            self._client = None
+
+    def __len__(self):
+        """Save reads by caching len"""
+        if self._n is None:
+            self._n = len(self.array)
+        return self._n
+
+
+GB100 = (1024**3) * 100
+
+
+class PlasmaStore:
+    def __init__(self, path=DEFAULT_PLASMA_PATH, nbytes: int = GB100):
+
+        self.server = self.start(path, nbytes)
+
+    def __del__(self):
+        self.server.kill()
+
+    @staticmethod
+    def start(path=DEFAULT_PLASMA_PATH, nbytes: int = GB100) -> subprocess.Popen:
+        if not PYARROW_AVAILABLE:
+            raise ImportError("please run pip install pyarrow to use --use_plasma_view")
+        # best practice is to allocate more space than we need. The limitation seems to be the size of /dev/shm
+        _server = subprocess.Popen(["plasma_store", "-m", str(nbytes), "-s", path])
+        plasma.connect(path, num_retries=200)  # If we can't connect we fail immediately
+        return _server

PyTorch/NLP/new-Transformer/fairseq/data/prepend_dataset.py

+# 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 numpy as np
+import torch
+
+from . import BaseWrapperDataset
+
+
+class PrependDataset(BaseWrapperDataset):
+    def __init__(self, dataset, prepend_getter, ensure_first_token_is=None):
+        super().__init__(dataset)
+        self.prepend_getter = prepend_getter
+        self.ensure_first_token = ensure_first_token_is
+
+    def __getitem__(self, idx):
+        item = self.dataset[idx]
+        is_tuple = isinstance(item, tuple)
+        src = item[0] if is_tuple else item
+
+        assert self.ensure_first_token is None or src[0] == self.ensure_first_token
+        prepend_idx = self.prepend_getter(self.dataset, idx)
+        assert isinstance(prepend_idx, int)
+        src[0] = prepend_idx
+        item = tuple((src,) + item[1:]) if is_tuple else src
+        return item

PyTorch/NLP/new-Transformer/fairseq/data/prepend_token_dataset.py

+# 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 numpy as np
+import torch
+
+from . import BaseWrapperDataset
+
+
+class PrependTokenDataset(BaseWrapperDataset):
+    def __init__(self, dataset, token=None):
+        super().__init__(dataset)
+        self.token = token
+        if token is not None:
+            self._sizes = np.array(dataset.sizes) + 1
+        else:
+            self._sizes = dataset.sizes
+
+    def __getitem__(self, idx):
+        item = self.dataset[idx]
+        if self.token is not None:
+            item = torch.cat([item.new([self.token]), item])
+        return item
+
+    @property
+    def sizes(self):
+        return self._sizes
+
+    def num_tokens(self, index):
+        n = self.dataset.num_tokens(index)
+        if self.token is not None:
+            n += 1
+        return n
+
+    def size(self, index):
+        n = self.dataset.size(index)
+        if self.token is not None:
+            n += 1
+        return n

PyTorch/NLP/new-Transformer/fairseq/data/raw_label_dataset.py

+# 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
+
+from . import FairseqDataset
+
+
+class RawLabelDataset(FairseqDataset):
+    def __init__(self, labels):
+        super().__init__()
+        self.labels = labels
+
+    def __getitem__(self, index):
+        return self.labels[index]
+
+    def __len__(self):
+        return len(self.labels)
+
+    def collater(self, samples):
+        return torch.tensor(samples)

PyTorch/NLP/new-Transformer/fairseq/data/replace_dataset.py

+# 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.
+
+from . import BaseWrapperDataset
+
+
+class ReplaceDataset(BaseWrapperDataset):
+    """Replaces tokens found in the dataset by a specified replacement token
+
+    Args:
+        dataset (~torch.utils.data.Dataset): dataset to replace tokens in
+        replace_map(Dictionary[int,int]): map of token to replace -> replacement token
+        offsets (List[int]): do not replace tokens before (from left if pos, right if neg) this offset. should be
+        as many as the number of objects returned by the underlying dataset __getitem__ method.
+    """
+
+    def __init__(self, dataset, replace_map, offsets):
+        super().__init__(dataset)
+        assert len(replace_map) > 0
+        self.replace_map = replace_map
+        self.offsets = offsets
+
+    def __getitem__(self, index):
+        item = self.dataset[index]
+        is_tuple = isinstance(item, tuple)
+        srcs = item if is_tuple else [item]
+
+        for offset, src in zip(self.offsets, srcs):
+            for k, v in self.replace_map.items():
+                src_off = src[offset:] if offset >= 0 else src[:offset]
+                src_off.masked_fill_(src_off == k, v)
+
+        item = srcs if is_tuple else srcs[0]
+        return item

PyTorch/NLP/new-Transformer/fairseq/data/resampling_dataset.py

+# 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 logging
+
+import numpy as np
+
+from fairseq.data import BaseWrapperDataset, plasma_utils
+
+logger = logging.getLogger(__name__)
+
+
+class ResamplingDataset(BaseWrapperDataset):
+    """Randomly samples from a given dataset at each epoch.
+
+    Sampling is done with or without replacement, depending on the "replace"
+    parameter.
+
+    Optionally, the epoch size can be rescaled. This is potentially desirable
+    to increase per-epoch coverage of the base dataset (since sampling with
+    replacement means that many items in the dataset will be left out). In the
+    case of sampling without replacement, size_ratio should be strictly less
+    than 1.
+
+    Args:
+        dataset (~torch.utils.data.Dataset): dataset on which to sample.
+        weights (List[float]): list of probability weights
+            (default: None, which corresponds to uniform sampling).
+        replace (bool): sampling mode; True for "with replacement", or False
+            for "without replacement" (default: True)
+        size_ratio (float): the ratio to subsample to; must be positive
+            (default: 1.0).
+        batch_by_size (bool): whether or not to batch by sequence length
+            (default: True).
+        seed (int): RNG seed to use (default: 0).
+        epoch (int): starting epoch number (default: 1).
+    """
+
+    def __init__(
+        self,
+        dataset,
+        weights=None,
+        replace=True,
+        size_ratio=1.0,
+        batch_by_size=True,
+        seed=0,
+        epoch=1,
+    ):
+        super().__init__(dataset)
+
+        if weights is None:
+            self.weights = None
+
+        else:
+            assert len(weights) == len(dataset)
+            weights_arr = np.array(weights, dtype=np.float64)
+            weights_arr /= weights_arr.sum()
+            self.weights = plasma_utils.PlasmaArray(weights_arr)
+
+        self.replace = replace
+
+        assert size_ratio > 0.0
+        if not self.replace:
+            assert size_ratio < 1.0
+        self.size_ratio = float(size_ratio)
+        self.actual_size = np.ceil(len(dataset) * self.size_ratio).astype(int)
+
+        self.batch_by_size = batch_by_size
+        self.seed = seed
+
+        self._cur_epoch = None
+        self._cur_indices = None
+
+        self.set_epoch(epoch)
+
+    def __getitem__(self, index):
+        return self.dataset[self._cur_indices.array[index]]
+
+    def __len__(self):
+        return self.actual_size
+
+    @property
+    def sizes(self):
+        if isinstance(self.dataset.sizes, list):
+            return [s[self._cur_indices.array] for s in self.dataset.sizes]
+        return self.dataset.sizes[self._cur_indices.array]
+
+    def num_tokens(self, index):
+        return self.dataset.num_tokens(self._cur_indices.array[index])
+
+    def size(self, index):
+        return self.dataset.size(self._cur_indices.array[index])
+
+    def ordered_indices(self):
+        if self.batch_by_size:
+            order = [
+                np.arange(len(self)),
+                self.sizes,
+            ]  # No need to handle `self.shuffle == True`
+            return np.lexsort(order)
+        else:
+            return np.arange(len(self))
+
+    def prefetch(self, indices):
+        self.dataset.prefetch(self._cur_indices.array[indices])
+
+    @property
+    def can_reuse_epoch_itr_across_epochs(self):
+        return False
+
+    def set_epoch(self, epoch):
+        logger.debug("ResamplingDataset.set_epoch: {}".format(epoch))
+        super().set_epoch(epoch)
+
+        if epoch == self._cur_epoch:
+            return
+
+        self._cur_epoch = epoch
+
+        # Generate a weighted sample of indices as a function of the
+        # random seed and the current epoch.
+
+        rng = np.random.RandomState(
+            [
+                42,  # magic number
+                self.seed % (2**32),  # global seed
+                self._cur_epoch,  # epoch index
+            ]
+        )
+        self._cur_indices = plasma_utils.PlasmaArray(
+            rng.choice(
+                len(self.dataset),
+                self.actual_size,
+                replace=self.replace,
+                p=(None if self.weights is None else self.weights.array),
+            )
+        )

PyTorch/NLP/new-Transformer/fairseq/data/roll_dataset.py

+# 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
+
+from . import BaseWrapperDataset
+
+
+class RollDataset(BaseWrapperDataset):
+    def __init__(self, dataset, shifts):
+        super().__init__(dataset)
+        self.shifts = shifts
+
+    def __getitem__(self, index):
+        item = self.dataset[index]
+        return torch.roll(item, self.shifts)

PyTorch/NLP/new-Transformer/fairseq/data/round_robin_zip_datasets.py

+# 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 logging
+from collections import OrderedDict
+from typing import Dict, Sequence
+
+import numpy as np
+
+from . import FairseqDataset, LanguagePairDataset
+
+logger = logging.getLogger(__name__)
+
+
+class RoundRobinZipDatasets(FairseqDataset):
+    """Zip multiple :class:`~fairseq.data.FairseqDataset` instances together.
+
+    Shorter datasets are repeated in a round-robin fashion to match the length
+    of the longest one.
+
+    Args:
+        datasets (Dict[~fairseq.data.FairseqDataset]): a dictionary of
+            :class:`~fairseq.data.FairseqDataset` instances.
+        eval_key (str, optional): a key used at evaluation time that causes
+            this instance to pass-through batches from *datasets[eval_key]*.
+    """
+
+    def __init__(self, datasets, eval_key=None):
+        super().__init__()
+        if isinstance(datasets, dict):
+            datasets = OrderedDict(datasets)
+        assert isinstance(datasets, OrderedDict)
+        assert datasets, "Can't make a RoundRobinZipDatasets out of nothing"
+        for dataset in datasets.values():
+            assert isinstance(dataset, FairseqDataset)
+
+        self.datasets = datasets
+        self.eval_key = eval_key
+
+        self.longest_dataset_key = max(datasets, key=lambda k: len(datasets[k]))
+        self.longest_dataset = datasets[self.longest_dataset_key]
+        self._ordered_indices: Dict[str, Sequence[int]] = None
+
+    def _map_index(self, key, index):
+        assert (
+            self._ordered_indices is not None
+        ), "Must call RoundRobinZipDatasets.ordered_indices() first"
+        o = self._ordered_indices[key]
+        return o[index % len(o)]
+
+    def __getitem__(self, index):
+        if self.eval_key is None:
+            return OrderedDict(
+                [
+                    (key, dataset[self._map_index(key, index)])
+                    for key, dataset in self.datasets.items()
+                ]
+            )
+        else:
+            # at evaluation time it's useful to pass-through batches from a single key
+            return self.datasets[self.eval_key][self._map_index(self.eval_key, index)]
+
+    def __len__(self):
+        if self._ordered_indices is not None:
+            return len(self._ordered_indices[self.longest_dataset_key])
+        return len(self.longest_dataset)
+
+    def collater(self, samples):
+        """Merge a list of samples to form a mini-batch."""
+        if len(samples) == 0:
+            return None
+        if self.eval_key is None:
+            return OrderedDict(
+                [
+                    (key, dataset.collater([sample[key] for sample in samples]))
+                    for key, dataset in self.datasets.items()
+                ]
+            )
+        else:
+            # at evaluation time it's useful to pass-through batches from a single key
+            return self.datasets[self.eval_key].collater(samples)
+
+    def num_tokens(self, index):
+        """Return an example's length (number of tokens), used for batching."""
+        # TODO make it configurable whether to use max() or sum() here
+        return max(
+            dataset.num_tokens(self._map_index(key, index))
+            for key, dataset in self.datasets.items()
+        )
+
+    def size(self, index):
+        """Return an example's size as a float or tuple. This value is used when
+        filtering a dataset with ``--max-positions``."""
+        return {
+            key: dataset.size(self._map_index(key, index))
+            for key, dataset in self.datasets.items()
+        }
+
+    def ordered_indices(self):
+        """Ordered indices for batching."""
+        if self._ordered_indices is None:
+            # Call the underlying dataset's ordered_indices() here, so that we
+            # get the same random ordering as we would have from using the
+            # underlying sub-datasets directly.
+            self._ordered_indices = OrderedDict(
+                [
+                    (key, dataset.ordered_indices())
+                    for key, dataset in self.datasets.items()
+                ]
+            )
+        return np.arange(len(self))
+
+    def filter_indices_by_size(self, indices, max_positions=None):
+        """
+        Filter each sub-dataset independently, then update the round robin to work
+        on the filtered sub-datasets.
+        """
+
+        def _deep_until_language_pair(dataset):
+            if isinstance(dataset, LanguagePairDataset):
+                return dataset
+            if hasattr(dataset, "tgt_dataset"):
+                return _deep_until_language_pair(dataset.tgt_dataset)
+            if hasattr(dataset, "dataset"):
+                return _deep_until_language_pair(dataset.dataset)
+            raise Exception(f"Don't know how to unwrap this dataset: {dataset}")
+
+        if not isinstance(max_positions, dict):
+            max_positions = {k: max_positions for k in self.datasets.keys()}
+        ignored_some = False
+        for key, dataset in self.datasets.items():
+            dataset = _deep_until_language_pair(dataset)
+            self._ordered_indices[key], ignored = dataset.filter_indices_by_size(
+                self._ordered_indices[key], max_positions[key]
+            )
+            if len(ignored) > 0:
+                ignored_some = True
+                logger.warning(
+                    f"{len(ignored)} samples from {key} have invalid sizes and will be skipped, "
+                    f"max_positions={max_positions[key]}, first few sample ids={ignored[:10]}"
+                )
+        # Since we are modifying in place the _ordered_indices,
+        # it's not possible anymore to return valid ignored indices.
+        # Hopefully the extra debug information print above should be enough to debug.
+        # Ideally we would receive ignore_invalid_inputs so that we could have
+        # a proper error message.
+        return (np.arange(len(self)), [0] if ignored_some else [])
+
+    @property
+    def supports_prefetch(self):
+        return all(
+            getattr(dataset, "supports_prefetch", False)
+            for dataset in self.datasets.values()
+        )
+
+    def prefetch(self, indices):
+        for key, dataset in self.datasets.items():
+            dataset.prefetch([self._map_index(key, index) for index in indices])

PyTorch/NLP/new-Transformer/fairseq/data/shorten_dataset.py

+# 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 numpy as np
+from fairseq.data import data_utils
+
+from . import BaseWrapperDataset
+
+
+class TruncateDataset(BaseWrapperDataset):
+    """Truncate a sequence by returning the first truncation_length tokens"""
+
+    def __init__(self, dataset, truncation_length):
+        super().__init__(dataset)
+        assert truncation_length is not None
+        self.truncation_length = truncation_length
+        self.dataset = dataset
+
+    def __getitem__(self, index):
+        item = self.dataset[index]
+        item_len = item.size(0)
+        if item_len > self.truncation_length:
+            item = item[: self.truncation_length]
+        return item
+
+    @property
+    def sizes(self):
+        return np.minimum(self.dataset.sizes, self.truncation_length)
+
+    def __len__(self):
+        return len(self.dataset)
+
+
+class RandomCropDataset(TruncateDataset):
+    """Truncate a sequence by returning a random crop of truncation_length tokens"""
+
+    def __init__(self, dataset, truncation_length, seed=1):
+        super().__init__(dataset, truncation_length)
+        self.seed = seed
+        self.epoch = 0
+
+    @property
+    def can_reuse_epoch_itr_across_epochs(self):
+        return True  # only the crop changes, not item sizes
+
+    def set_epoch(self, epoch, **unused):
+        super().set_epoch(epoch)
+        self.epoch = epoch
+
+    def __getitem__(self, index):
+        with data_utils.numpy_seed(self.seed, self.epoch, index):
+            item = self.dataset[index]
+            item_len = item.size(0)
+            excess = item_len - self.truncation_length
+            if excess > 0:
+                start_idx = np.random.randint(0, excess)
+                item = item[start_idx : start_idx + self.truncation_length]
+            return item
+
+
+def maybe_shorten_dataset(
+    dataset,
+    split,
+    shorten_data_split_list,
+    shorten_method,
+    tokens_per_sample,
+    seed,
+):
+    truncate_split = (
+        split in shorten_data_split_list.split(",") or len(shorten_data_split_list) == 0
+    )
+    if shorten_method == "truncate" and truncate_split:
+        dataset = TruncateDataset(dataset, tokens_per_sample)
+    elif shorten_method == "random_crop" and truncate_split:
+        dataset = RandomCropDataset(dataset, tokens_per_sample, seed)
+    return dataset

PyTorch/NLP/new-Transformer/fairseq/data/sort_dataset.py

+# 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 numpy as np
+
+from . import BaseWrapperDataset
+
+
+class SortDataset(BaseWrapperDataset):
+    def __init__(self, dataset, sort_order):
+        super().__init__(dataset)
+        if not isinstance(sort_order, (list, tuple)):
+            sort_order = [sort_order]
+        self.sort_order = sort_order
+
+        assert all(len(so) == len(dataset) for so in sort_order)
+
+    def ordered_indices(self):
+        return np.lexsort(self.sort_order)

PyTorch/NLP/new-Transformer/fairseq/data/strip_token_dataset.py

+# 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.
+
+from . import BaseWrapperDataset
+
+
+class StripTokenDataset(BaseWrapperDataset):
+    def __init__(self, dataset, id_to_strip):
+        super().__init__(dataset)
+        self.id_to_strip = id_to_strip
+
+    def __getitem__(self, index):
+        item = self.dataset[index]
+        while len(item) > 0 and item[-1] == self.id_to_strip:
+            item = item[:-1]
+        while len(item) > 0 and item[0] == self.id_to_strip:
+            item = item[1:]
+        return item

PyTorch/NLP/new-Transformer/fairseq/data/subsample_dataset.py

+# 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 logging
+
+import numpy as np
+
+from . import BaseWrapperDataset
+
+
+logger = logging.getLogger(__name__)
+
+
+class SubsampleDataset(BaseWrapperDataset):
+    """Subsamples a given dataset by a specified ratio. Subsampling is done on the number of examples
+
+    Args:
+        dataset (~torch.utils.data.Dataset): dataset to subsample
+        size_ratio(float): the ratio to subsample to. must be between 0 and 1 (exclusive)
+    """
+
+    def __init__(self, dataset, size_ratio, shuffle=False):
+        super().__init__(dataset)
+        assert size_ratio < 1
+        self.actual_size = np.ceil(len(dataset) * size_ratio).astype(int)
+        self.indices = np.random.choice(
+            list(range(len(self.dataset))), self.actual_size, replace=False
+        )
+        self.shuffle = shuffle
+        logger.info(
+            "subsampled dataset from {} to {} (ratio={})".format(
+                len(self.dataset), self.actual_size, size_ratio
+            )
+        )
+
+    def __getitem__(self, index):
+        return self.dataset[self.indices[index]]
+
+    def __len__(self):
+        return self.actual_size
+
+    def collater(self, samples):
+        return self.dataset.collater(samples)
+
+    @property
+    def sizes(self):
+        return self.dataset.sizes[self.indices]
+
+    @property
+    def name(self):
+        return self.dataset.name
+
+    def num_tokens(self, index):
+        return self.dataset.num_tokens(self.indices[index])
+
+    def size(self, index):
+        return self.dataset.size(self.indices[index])
+
+    def ordered_indices(self):
+        """Return an ordered list of indices. Batches will be constructed based
+        on this order."""
+        if self.shuffle:
+            order = [np.random.permutation(len(self))]
+        else:
+            order = [np.arange(len(self))]
+        order.append(self.sizes)
+        return np.lexsort(order)
+
+    def prefetch(self, indices):
+        self.dataset.prefetch(self.indices[indices])

PyTorch/NLP/new-Transformer/fairseq/data/text_compressor.py

+# 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.
+
+from enum import Enum
+
+
+class TextCompressionLevel(Enum):
+    none = 0
+    low = 1
+    high = 2
+
+
+class TextCompressor(object):
+    def __init__(
+        self, level: TextCompressionLevel, max_input_byte_length: int = 2**16
+    ):
+        self.level = level
+        self.max_input_length = max_input_byte_length
+
+    def compress(self, text: str) -> bytes:
+        if self.level == TextCompressionLevel.low:
+            import zlib
+
+            # zlib: built-in, fast
+            return zlib.compress(text.encode(), level=0)
+        elif self.level == TextCompressionLevel.high:
+            try:
+                import unishox2
+
+                # unishox2: optimized for short text but slower
+            except ImportError:
+                raise ImportError(
+                    "Please install unishox2 for the text compression feature: "
+                    "pip install unishox2-py3"
+                )
+            assert len(text.encode()) <= self.max_input_length
+            return unishox2.compress(text)[0]
+        else:
+            return text.encode()
+
+    def decompress(self, compressed: bytes) -> str:
+        if self.level == TextCompressionLevel.low:
+            import zlib
+
+            return zlib.decompress(compressed).decode()
+        elif self.level == TextCompressionLevel.high:
+            try:
+                import unishox2
+            except ImportError:
+                raise ImportError(
+                    "Please install unishox2 for the text compression feature: "
+                    "pip install unishox2-py3"
+                )
+            return unishox2.decompress(compressed, self.max_input_length)
+        else:
+            return compressed.decode()

PyTorch/NLP/new-Transformer/fairseq/data/token_block_dataset.py

+# 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 numpy as np
+import torch
+from fairseq.data import FairseqDataset, plasma_utils
+from fairseq.data.indexed_dataset import best_fitting_int_dtype
+from typing import Tuple
+
+
+class TokenBlockDataset(FairseqDataset):
+    """Break a Dataset of tokens into blocks.
+
+    Args:
+        dataset (~torch.utils.data.Dataset): dataset to break into blocks
+        sizes (List[int]): sentence lengths (required for 'complete' and 'eos')
+        block_size (int): maximum block size (ignored in 'eos' break mode)
+        break_mode (str, optional): Mode used for breaking tokens. Values can
+            be one of:
+            - 'none': break tokens into equally sized blocks (up to block_size)
+            - 'complete': break tokens into blocks (up to block_size) such that
+                blocks contains complete sentences, although block_size may be
+                exceeded if some sentences exceed block_size
+            - 'complete_doc': similar to 'complete' mode, but do not
+                cross document boundaries
+            - 'eos': each block contains one sentence (block_size is ignored)
+        include_targets (bool, optional): return next tokens as targets
+            (default: False).
+        document_sep_len (int, optional): document separator size (required for
+            'complete_doc' break mode). Typically 1 if the sentences have eos
+            and 0 otherwise.
+    """
+
+    def __init__(
+        self,
+        dataset,
+        sizes,
+        block_size,
+        pad,
+        eos,
+        break_mode=None,
+        include_targets=False,
+        document_sep_len=1,
+        use_plasma_view=False,
+        split_path=None,
+        plasma_path=None,
+    ):
+
+        super().__init__()
+        self.dataset = dataset
+        self.pad = pad
+        self.eos = eos
+        self.include_targets = include_targets
+
+        assert len(dataset) > 0
+
+        assert len(dataset) == len(sizes)
+        _sizes, block_to_dataset_index, slice_indices = self._build_slice_indices(
+            sizes, break_mode, document_sep_len, block_size
+        )
+        if use_plasma_view:
+            plasma_id = (block_size, document_sep_len, str(break_mode), len(dataset))
+            self._slice_indices = plasma_utils.PlasmaView(
+                slice_indices, split_path, (plasma_id, 0), plasma_path=plasma_path
+            )
+            self._sizes = plasma_utils.PlasmaView(
+                _sizes, split_path, (plasma_id, 1), plasma_path=plasma_path
+            )
+            self._block_to_dataset_index = plasma_utils.PlasmaView(
+                block_to_dataset_index,
+                split_path,
+                (plasma_id, 2),
+                plasma_path=plasma_path,
+            )
+        else:
+            self._slice_indices = plasma_utils.PlasmaArray(slice_indices)
+            self._sizes = plasma_utils.PlasmaArray(_sizes)
+            self._block_to_dataset_index = plasma_utils.PlasmaArray(
+                block_to_dataset_index
+            )
+
+    @staticmethod
+    def _build_slice_indices(
+        sizes, break_mode, document_sep_len, block_size
+    ) -> Tuple[np.ndarray]:
+        """Use token_block_utils_fast to build arrays for indexing into self.dataset"""
+        try:
+            from fairseq.data.token_block_utils_fast import (
+                _get_slice_indices_fast,
+                _get_block_to_dataset_index_fast,
+            )
+        except ImportError:
+            raise ImportError(
+                "Please build Cython components with: `pip install --editable .` "
+                "or `python setup.py build_ext --inplace`"
+            )
+
+        if isinstance(sizes, list):
+            sizes = np.array(sizes, dtype=np.int64)
+        else:
+            if torch.is_tensor(sizes):
+                sizes = sizes.numpy()
+            sizes = sizes.astype(np.int64)
+
+        break_mode = break_mode if break_mode is not None else "none"
+
+        # For "eos" break-mode, block_size is not required parameters.
+        if break_mode == "eos" and block_size is None:
+            block_size = 0
+
+        slice_indices = _get_slice_indices_fast(
+            sizes, str(break_mode), block_size, document_sep_len
+        )
+        _sizes = slice_indices[:, 1] - slice_indices[:, 0]
+
+        # build index mapping block indices to the underlying dataset indices
+        if break_mode == "eos":
+            # much faster version for eos break mode
+            block_to_dataset_index = np.stack(
+                [
+                    np.arange(len(sizes)),  # starting index in dataset
+                    np.zeros(
+                        len(sizes), dtype=np.compat.long
+                    ),  # starting offset within starting index
+                    np.arange(len(sizes)),  # ending index in dataset
+                ],
+                1,
+            )
+        else:
+            block_to_dataset_index = _get_block_to_dataset_index_fast(
+                sizes,
+                slice_indices,
+            )
+        size_dtype = np.uint16 if block_size < 65535 else np.uint32
+        num_tokens = slice_indices[-1].max()
+        slice_indices_dtype = best_fitting_int_dtype(num_tokens)
+        slice_indices = slice_indices.astype(slice_indices_dtype)
+        _sizes = _sizes.astype(size_dtype)
+        block_to_dataset_index = block_to_dataset_index.astype(slice_indices_dtype)
+        return _sizes, block_to_dataset_index, slice_indices
+
+    @property
+    def slice_indices(self):
+        return self._slice_indices.array
+
+    @property
+    def sizes(self):
+        return self._sizes.array
+
+    @property
+    def block_to_dataset_index(self):
+        return self._block_to_dataset_index.array
+
+    def attr(self, attr: str, index: int):
+        start_ds_idx, _, _ = self.block_to_dataset_index[index]
+        return self.dataset.attr(attr, start_ds_idx)
+
+    def __getitem__(self, index):
+        start_ds_idx, start_offset, end_ds_idx = self.block_to_dataset_index[index]
+
+        buffer = torch.cat(
+            [self.dataset[idx] for idx in range(start_ds_idx, end_ds_idx + 1)]
+        )
+        slice_s, slice_e = self.slice_indices[index]
+        length = slice_e - slice_s
+        s, e = start_offset, start_offset + length
+        item = buffer[s:e]
+
+        if self.include_targets:
+            # *target* is the original sentence (=item)
+            # *source* is shifted right by 1 (maybe left-padded with eos)
+            # *past_target* is shifted right by 2 (left-padded as needed)
+            if s == 0:
+                source = torch.cat([item.new([self.eos]), buffer[0 : e - 1]])
+                past_target = torch.cat(
+                    [item.new([self.pad, self.eos]), buffer[0 : e - 2]]
+                )
+            else:
+                source = buffer[s - 1 : e - 1]
+                if s == 1:
+                    past_target = torch.cat([item.new([self.eos]), buffer[0 : e - 2]])
+                else:
+                    past_target = buffer[s - 2 : e - 2]
+
+            return source, item, past_target
+
+        return item
+
+    def __len__(self):
+        return len(self.slice_indices)
+
+    @property
+    def supports_prefetch(self):
+        return getattr(self.dataset, "supports_prefetch", False)
+
+    def prefetch(self, indices):
+        self.dataset.prefetch(
+            {
+                ds_idx
+                for index in indices
+                for start_ds_idx, _, end_ds_idx in [self.block_to_dataset_index[index]]
+                for ds_idx in range(start_ds_idx, end_ds_idx + 1)
+            }
+        )

PyTorch/NLP/new-Transformer/fairseq/data/token_block_utils_fast.pyx

+# cython: language_level=3
+# 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 numpy as np
+import torch
+from itertools import chain
+from libc.math cimport ceil
+
+cimport cython
+cimport numpy as np
+
+from libc.stdint cimport int32_t, int64_t
+
+DTYPE = np.int64
+ctypedef int64_t DTYPE_t
+
+
+@cython.boundscheck(False)
+@cython.wraparound(False)
+@cython.nonecheck(False)
+cdef np.ndarray[DTYPE_t, ndim=2] _get_slice_indices_none_mode(np.ndarray[DTYPE_t, ndim=1] sizes, int block_size):
+    cdef DTYPE_t total_size = sizes.sum()
+    cdef DTYPE_t length = <DTYPE_t> ceil(total_size / <double> block_size)
+    cdef np.ndarray[DTYPE_t, ndim=2] slice_indices = np.zeros([length, 2], dtype=DTYPE)
+    cdef DTYPE_t[:, :] slice_indices_view = slice_indices
+    cdef DTYPE_t i
+    cdef DTYPE_t start
+    cdef DTYPE_t end
+    for i in range(length):
+        start = i * block_size
+        end = min(start + block_size, total_size)
+        slice_indices_view[i][0] = start
+        slice_indices_view[i][1] = end
+    return slice_indices
+
+
+cdef np.ndarray[DTYPE_t, ndim=2] _fast_convert_to_np_array(list list_of_list):
+    """
+    Faster function to convert DTYPE_t list of list.
+    Only fast when there are huge number of rows and low number of columns.
+    """
+    cdef np.ndarray[DTYPE_t, ndim=1] flat = np.fromiter(chain.from_iterable(list_of_list), DTYPE, -1)
+    return flat.reshape((len(list_of_list), -1))
+
+
+@cython.boundscheck(False)
+@cython.wraparound(False)
+@cython.nonecheck(False)
+cpdef np.ndarray[DTYPE_t, ndim=2] _get_slice_indices_fast(np.ndarray[DTYPE_t, ndim=1] sizes, str break_mode, int block_size, int document_sep_len):
+    cdef DTYPE_t tok_idx = 0
+    cdef DTYPE_t sz_idx = 0
+    cdef DTYPE_t curr_size = 0
+    cdef DTYPE_t i = 0
+    cdef DTYPE_t length
+    cdef DTYPE_t total_size
+    cdef DTYPE_t[:] sizes_view = sizes
+    cdef np.ndarray[DTYPE_t, ndim=2] slice_indices
+    cdef list slice_indices_list = []
+
+    if break_mode is None or break_mode == 'none':
+        slice_indices = _get_slice_indices_none_mode(sizes, block_size)
+    elif break_mode == 'complete':
+        while sz_idx < len(sizes_view):
+            if curr_size + sizes_view[sz_idx] <= block_size or curr_size == 0:
+                curr_size += sizes_view[sz_idx]
+                sz_idx += 1
+            else:
+                slice_indices_list.append((tok_idx, tok_idx + curr_size))
+                tok_idx += curr_size
+                curr_size = 0
+        if curr_size > 0:
+            slice_indices_list.append((tok_idx, tok_idx + curr_size))
+        slice_indices = _fast_convert_to_np_array(slice_indices_list)
+    elif break_mode == 'complete_doc':
+        while sz_idx < len(sizes_view):
+            if (
+                (curr_size + sizes_view[sz_idx] <= block_size or curr_size == 0)
+                # an empty sentence indicates end-of-document:
+                and sizes_view[sz_idx] != document_sep_len
+            ):
+                curr_size += sizes_view[sz_idx]
+                sz_idx += 1
+            else:
+                # Only keep non-empty documents.
+                if curr_size > 1:
+                    slice_indices_list.append((tok_idx, tok_idx + curr_size))
+                tok_idx += curr_size
+                curr_size = 0
+                if sizes_view[sz_idx] == document_sep_len:
+                    tok_idx += sizes_view[sz_idx]
+                    sz_idx += 1
+        if curr_size > 1:
+            slice_indices_list.append((tok_idx, tok_idx + curr_size))
+        slice_indices = _fast_convert_to_np_array(slice_indices_list)
+    elif break_mode == 'eos':
+        slice_indices = np.zeros((len(sizes), 2), dtype=DTYPE)
+        cumsum = sizes.cumsum(axis=0)
+        slice_indices[1:, 0] = cumsum[:cumsum.shape[0] - 1]
+        slice_indices[:, 1] = cumsum
+    else:
+        raise ValueError('Invalid break_mode: ' + break_mode)
+    return slice_indices
+
+
+@cython.boundscheck(False)
+@cython.wraparound(False)
+@cython.nonecheck(False)
+cpdef np.ndarray[DTYPE_t, ndim=2] _get_block_to_dataset_index_fast(np.ndarray[DTYPE_t, ndim=1] sizes, np.ndarray[DTYPE_t, ndim=2] slice_indices):
+    cdef DTYPE_t start_ds_idx
+    cdef DTYPE_t start_offset
+    cdef DTYPE_t end_ds_idx
+    cdef DTYPE_t i
+    cdef DTYPE_t s
+    cdef DTYPE_t e
+    cdef DatasetSearcher ds = DatasetSearcher(sizes)
+    cdef np.ndarray[DTYPE_t, ndim=2] block_to_dataset_index = np.zeros([len(slice_indices), 3], dtype=DTYPE)
+    cdef DTYPE_t[:, :] block_to_dataset_index_view = block_to_dataset_index
+    cdef DTYPE_t[:, :] slice_indices_view = slice_indices
+    cdef Py_ssize_t x_max = slice_indices.shape[0]
+
+    for i in range(x_max):
+        s = slice_indices_view[i][0]
+        e = slice_indices_view[i][1]
+        ds.seek(s)
+        start_ds_idx = ds.current_index
+        start_offset = ds.current_offset
+        if e <= s:
+            end_ds_idx = start_ds_idx
+        else:
+            ds.seek(e - 1)
+            end_ds_idx = ds.current_index
+        block_to_dataset_index_view[i][0] = start_ds_idx  # starting index in dataset
+        block_to_dataset_index_view[i][1] = start_offset  # starting offset within starting index
+        block_to_dataset_index_view[i][2] = end_ds_idx    # ending index in dataset
+    return block_to_dataset_index
+
+
+cdef class DatasetSearcher(object):
+    """Helper for mapping "flat" indices to indices and offsets in an
+    underlying dataset."""
+    cdef DTYPE_t current_i
+    cdef DTYPE_t current_offset
+    cdef DTYPE_t current_index
+    cdef DTYPE_t[:] sizes
+
+    def __init__(self, DTYPE_t[:] sizes):
+        self.sizes = sizes
+        self.reset()
+
+    cdef reset(self):
+        self.current_offset = 0     # offset within current index in underlying dataset
+        self.current_i = 0          # "flat" index
+        self.current_index = 0      # index in underlying dataset
+
+    @cython.boundscheck(False)
+    @cython.wraparound(False)
+    @cython.nonecheck(False)
+    cdef int step(self, DTYPE_t i):
+        cdef DTYPE_t to_consume
+        cdef DTYPE_t remaining
+        if i < self.current_i:
+            self.reset()
+        if i > self.current_i:
+            to_consume = i - self.current_i
+            remaining = self.sizes[self.current_index] - self.current_offset
+            if remaining > to_consume:
+                self.current_offset += to_consume
+                self.current_i += to_consume
+            else:
+                assert remaining >= 0
+                self.current_i += remaining
+                self.current_index += 1
+                self.current_offset = 0
+                return 1
+        return 0
+
+    @cython.boundscheck(False)
+    @cython.wraparound(False)
+    @cython.nonecheck(False)
+    cdef seek(self, DTYPE_t i):
+        cdef int not_done = 1
+        while not_done == 1:
+            not_done = self.step(i)
+        assert self.current_i == i