Add Mirostat v2 sampling to transformer models (#2571)

modules/sampler_hijack.py

@@ -1,7 +1,11 @@
+import math
+
 import torch
 import transformers
 from transformers import LogitsWarper
-from transformers.generation.logits_process import LogitNormalization, LogitsProcessorList
+from transformers.generation.logits_process import (LogitNormalization,
+                                                    LogitsProcessorList,
+                                                    TemperatureLogitsWarper)
 
 
 class TailFreeLogitsWarper(LogitsWarper):
@@ -70,11 +74,63 @@ class TopALogitsWarper(LogitsWarper):
         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)
+
+        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
+
+
 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:
@@ -92,6 +148,9 @@ 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)
 
 
 def hijack_samplers():

modules/text_generation.py

@@ -193,7 +193,7 @@ def _generate_reply(question, state, eos_token=None, stopping_strings=None, is_c
 
 def generate_reply_HF(question, original_question, seed, state, eos_token=None, stopping_strings=None, is_chat=False):
     generate_params = {}
-    for k in ['max_new_tokens', 'do_sample', 'temperature', 'top_p', 'typical_p', 'repetition_penalty', 'encoder_repetition_penalty', 'top_k', 'min_length', 'no_repeat_ngram_size', 'num_beams', 'penalty_alpha', 'length_penalty', 'early_stopping', 'tfs', 'top_a']:
+    for k in ['max_new_tokens', 'do_sample', 'temperature', 'top_p', 'typical_p', 'repetition_penalty', 'encoder_repetition_penalty', 'top_k', 'min_length', 'no_repeat_ngram_size', 'num_beams', 'penalty_alpha', 'length_penalty', 'early_stopping', 'tfs', 'top_a', 'mirostat_mode', 'mirostat_tau', 'mirostat_eta']:
         generate_params[k] = state[k]
 
     for k in ['epsilon_cutoff', 'eta_cutoff']:

server.py

@@ -504,7 +504,7 @@ def create_settings_menus(default_preset):
                         shared.gradio['early_stopping'] = gr.Checkbox(value=generate_params['early_stopping'], label='early_stopping')
 
                     with gr.Column():
-                        gr.Markdown('Mirostat (for llama.cpp)')
+                        gr.Markdown('Mirostat (mode=1 is only for llama.cpp)')
                         shared.gradio['mirostat_mode'] = gr.Slider(0, 2, step=1, value=generate_params['mirostat_mode'], label='mirostat_mode')
                         shared.gradio['mirostat_tau'] = gr.Slider(0, 10, step=0.01, value=generate_params['mirostat_tau'], label='mirostat_tau')
                         shared.gradio['mirostat_eta'] = gr.Slider(0, 1, step=0.01, value=generate_params['mirostat_eta'], label='mirostat_eta')