File size: 9,387 Bytes
71e47a3
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
import math

import torch
import transformers
from transformers import LogitsWarper
from transformers.generation.logits_process import (
    LogitNormalization,
    LogitsProcessor,
    LogitsProcessorList,
    TemperatureLogitsWarper
)

global_scores = None


class TailFreeLogitsWarper(LogitsWarper):
    def __init__(self, tfs: float, filter_value: float = -float("Inf"), min_tokens_to_keep: int = 1):
        tfs = float(tfs)
        if tfs < 0 or tfs > 1.0:
            raise ValueError(f"`tfs` has to be a float >= 0 and <= 1, but is {tfs}")
        self.tfs = tfs
        self.filter_value = filter_value
        self.min_tokens_to_keep = min_tokens_to_keep

    def __call__(self, input_ids: torch.LongTensor, scores: torch.FloatTensor) -> torch.FloatTensor:
        sorted_logits, sorted_indices = torch.sort(scores, descending=True)
        probs = sorted_logits.softmax(dim=-1)

        # Compute second derivative normalized CDF
        d2 = probs.diff().diff().abs()
        normalized_d2 = d2 / d2.sum(dim=-1, keepdim=True)
        normalized_d2_cdf = normalized_d2.cumsum(dim=-1)

        # Remove tokens with CDF value above the threshold (token with 0 are kept)
        sorted_indices_to_remove = normalized_d2_cdf > self.tfs

        # Centre the distribution around the cutoff as in the original implementation of the algorithm
        sorted_indices_to_remove = torch.cat(
            (
                torch.zeros(scores.shape[0], 1, dtype=torch.bool, device=scores.device),
                sorted_indices_to_remove,
                torch.ones(scores.shape[0], 1, dtype=torch.bool, device=scores.device),
            ),
            dim=-1,
        )

        if self.min_tokens_to_keep > 1:
            # Keep at least min_tokens_to_keep
            sorted_indices_to_remove[..., : self.min_tokens_to_keep] = 0

        indices_to_remove = sorted_indices_to_remove.scatter(1, sorted_indices, sorted_indices_to_remove)
        scores = scores.masked_fill(indices_to_remove, self.filter_value)
        return scores


class TopALogitsWarper(LogitsWarper):
    def __init__(self, top_a: float, filter_value: float = -float("Inf"), min_tokens_to_keep: int = 1):
        top_a = float(top_a)
        if top_a < 0 or top_a > 1.0:
            raise ValueError(f"`top_a` has to be a float >= 0 and <= 1, but is {top_a}")
        self.top_a = top_a
        self.filter_value = filter_value
        self.min_tokens_to_keep = min_tokens_to_keep

    def __call__(self, input_ids: torch.LongTensor, scores: torch.FloatTensor) -> torch.FloatTensor:
        sorted_logits, sorted_indices = torch.sort(scores, descending=True)
        probs = sorted_logits.softmax(dim=-1)

        # Remove tokens with probability less than top_a*(max(probs))^2 (token with 0 are kept)
        probs_max = probs[..., 0, None]
        sorted_indices_to_remove = probs < probs_max * probs_max * self.top_a

        if self.min_tokens_to_keep > 1:
            # Keep at least min_tokens_to_keep
            sorted_indices_to_remove[..., : self.min_tokens_to_keep] = 0

        indices_to_remove = sorted_indices_to_remove.scatter(1, sorted_indices, sorted_indices_to_remove)
        scores = scores.masked_fill(indices_to_remove, self.filter_value)
        return scores


class MirostatLogitsWarper(LogitsWarper):
    def __init__(self, mirostat_mode: int, mirostat_tau: float, mirostat_eta: float, filter_value: float = -float("Inf"), min_tokens_to_keep: int = 1):
        if mirostat_mode not in [2]:
            raise ValueError(f"`mirostat` has to be a an integer 2, but is {mirostat_mode}")
        self.mirostat_mode = mirostat_mode
        self.mirostat_eta = mirostat_eta
        self.mirostat_tau = mirostat_tau
        self.filter_value = filter_value
        self.min_tokens_to_keep = min_tokens_to_keep
        self.mu = 2 * self.mirostat_tau
        self.e = 0

    def __call__(self, input_ids: torch.LongTensor, scores: torch.FloatTensor) -> torch.FloatTensor:
        logits = scores[0]
        sorted_logits, sorted_indices = torch.sort(logits, descending=True)
        prob_original = torch.softmax(sorted_logits, dim=-1).tolist()  # candidates

        # Truncate the words with surprise values greater than mu
        for i, candidate in enumerate(prob_original):
            if candidate > 0 and -math.log2(candidate) > self.mu:
                if (i == 0):
                    sorted_logits = sorted_logits[:1]
                else:
                    sorted_logits = sorted_logits[:i]
                break

        # Normalize the probabilities of the remaining words
        prob_topk = torch.softmax(sorted_logits, dim=0).to('cuda')

        prev_i = torch.multinomial(prob_topk, num_samples=1, replacement=True).to('cuda')

        observed_surprise = -math.log2(prob_topk[prev_i])
        self.e = observed_surprise - self.mirostat_tau

        # Update mu using the learning rate and error
        self.mu -= self.mirostat_eta * self.e

        sorted_indices_to_remove = torch.ones_like(scores[0], dtype=torch.bool)
        sorted_indices_to_remove[prev_i] = False

        indices_to_remove = sorted_indices_to_remove.unsqueeze(0).scatter(1, sorted_indices.unsqueeze(0), sorted_indices_to_remove.unsqueeze(0))
        scores = scores.masked_fill(indices_to_remove, self.filter_value)
        return scores


class SpyLogitsWarper(LogitsWarper):
    def __init__(self):
        pass

    def __call__(self, input_ids: torch.LongTensor, scores: torch.FloatTensor) -> torch.FloatTensor:
        global global_scores
        global_scores = scores
        return scores


class RepetitionPenaltyLogitsProcessorWithRange(LogitsProcessor):
    '''
    Copied from the transformers library
    '''

    def __init__(self, penalty: float, _range: int):
        if not isinstance(penalty, float) or not (penalty > 0):
            raise ValueError(f"`penalty` has to be a strictly positive float, but is {penalty}")

        self.penalty = penalty
        self._range = _range

    def __call__(self, input_ids: torch.LongTensor, scores: torch.FloatTensor) -> torch.FloatTensor:

        input_ids = input_ids[:, -self._range:]
        score = torch.gather(scores, 1, input_ids)

        # if score < 0 then repetition penalty has to be multiplied to reduce the previous token probability
        score = torch.where(score < 0, score * self.penalty, score / self.penalty)

        scores.scatter_(1, input_ids, score)
        return scores


def get_logits_warper_patch(self, generation_config):
    warpers = self._get_logits_warper_old(generation_config)
    warpers_to_add = LogitsProcessorList()
    min_tokens_to_keep = 2 if generation_config.num_beams > 1 else 1

    if generation_config.mirostat_mode is not None and generation_config.mirostat_mode == 2:
        warpers_to_add.append(MirostatLogitsWarper(mirostat_mode=generation_config.mirostat_mode, mirostat_eta=generation_config.mirostat_eta, mirostat_tau=generation_config.mirostat_tau, min_tokens_to_keep=min_tokens_to_keep))
        # We need to disable samplers other than temperature
        for warper in warpers:
            if not isinstance(warper, TemperatureLogitsWarper):
                warpers.remove(warper)
    else:
        if generation_config.tfs is not None and 0.0 <= generation_config.tfs <= 1.0:
            warpers_to_add.append(TailFreeLogitsWarper(tfs=generation_config.tfs, min_tokens_to_keep=min_tokens_to_keep))
        if generation_config.top_a is not None and 0.0 <= generation_config.top_a <= 1.0:
            warpers_to_add.append(TopALogitsWarper(top_a=generation_config.top_a, min_tokens_to_keep=min_tokens_to_keep))

    if warpers and isinstance(warpers[-1], LogitNormalization):
        warpers = warpers[:-1] + warpers_to_add + [warpers[-1]]
    else:
        warpers += warpers_to_add

    warpers.append(SpyLogitsWarper())
    return warpers


def get_logits_processor_patch(self, **kwargs):
    result = self._get_logits_processor_old(**kwargs)
    repetition_penalty_range = kwargs['generation_config'].repetition_penalty_range
    repetition_penalty = kwargs['generation_config'].repetition_penalty

    if repetition_penalty_range > 0:
        for i in range(len(result)):
            if result[i].__class__.__name__ == 'RepetitionPenaltyLogitsProcessor':
                result[i] = RepetitionPenaltyLogitsProcessorWithRange(repetition_penalty, repetition_penalty_range)

    return result


def generation_config_init_patch(self, **kwargs):
    self.__init___old(**kwargs)
    self.tfs = kwargs.pop("tfs", 1.0)
    self.top_a = kwargs.pop("top_a", 0.0)
    self.mirostat_mode = kwargs.pop("mirostat_mode", 0)
    self.mirostat_eta = kwargs.pop("mirostat_eta", 0.1)
    self.mirostat_tau = kwargs.pop("mirostat_tau", 5)
    self.repetition_penalty_range = kwargs.pop("repetition_penalty_range", 0)


def hijack_samplers():
    transformers.GenerationMixin._get_logits_warper_old = transformers.GenerationMixin._get_logits_warper
    transformers.GenerationMixin._get_logits_warper = get_logits_warper_patch

    transformers.GenerationMixin._get_logits_processor_old = transformers.GenerationMixin._get_logits_processor
    transformers.GenerationMixin._get_logits_processor = get_logits_processor_patch

    transformers.GenerationConfig.__init___old = transformers.GenerationConfig.__init__
    transformers.GenerationConfig.__init__ = generation_config_init_patch