138 lines
4.9 KiB
Python
138 lines
4.9 KiB
Python
from threading import Thread
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from transformers import AutoTokenizer, AutoModelForCausalLM, pipeline, TextIteratorStreamer
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from typing import Iterator, Optional, Callable
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from xml_schema_validator import XmlLogitsProcessor
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import sys
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import torch
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from . import LlmEngine
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from .. import util
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class LocalLlmEngine(LlmEngine):
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def __init__(
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self,
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model_path: str,
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temperature: float,
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token_limit: int,
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xml_schema_text: Optional[str] = None,
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api_token: Optional[str] = None,
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):
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"""
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Initialize the LLM Engine with a model path.
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Args:
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model_path: Path to the model weights to be used.
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temperature: Temperature for sampling
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token_limit: Maximum number of tokens to generate
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xml_schema_text: Optional XML schema to validate against
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api_token: Huggingface API key
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"""
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self._temperature = temperature
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self._token_limit = token_limit
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self._tokenizer = AutoTokenizer.from_pretrained(model_path, token=api_token)
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model = AutoModelForCausalLM.from_pretrained(
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model_path,
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return_dict=True,
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low_cpu_mem_usage=True,
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torch_dtype=torch.bfloat16,
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device_map="auto",
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trust_remote_code=True,
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token=api_token,
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)
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if self._tokenizer.pad_token_id is None:
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self._tokenizer.pad_token_id = self._tokenizer.eos_token_id
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if model.config.pad_token_id is None:
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model.config.pad_token_id = model.config.eos_token_id
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self._pipeline = pipeline(
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"text-generation",
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model=model,
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tokenizer=self._tokenizer,
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torch_dtype=torch.bfloat16,
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device_map="auto",
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return_full_text=False,
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)
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if xml_schema_text:
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self._logits_processor = XmlLogitsProcessor(self._tokenizer, xml_schema_text)
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else:
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self._logits_processor = None
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def infer(self, system_prompt: str, main_context: str, continuation_text: str, should_stop: Callable[[], bool] = lambda: False) -> Iterator[str]:
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"""
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Run inference using the system prompt and main context.
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Args:
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system_prompt: The system prompt string
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main_context: The main context string after templating
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continuation_text: Part of the response that is already generated
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should_stop: Callback that returns True when inference should stop
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Returns:
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Iterator[str]: An iterator that yields the generated text.
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"""
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messages = [
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{"role": "system", "content": system_prompt},
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{"role": "user", "content": main_context},
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{"role": "assistant", "content": continuation_text},
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]
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prompt = self._tokenizer.apply_chat_template(
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messages, tokenize=False,
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add_generation_prompt=False,
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)
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streamer = TextIteratorStreamer(
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self._tokenizer,
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skip_prompt=True
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)
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generation_kwargs = {
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"text_inputs": prompt,
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"do_sample": True,
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"temperature": self._temperature,
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"max_new_tokens": self.token_limit(),
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"streamer": streamer,
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}
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if self._logits_processor:
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generation_kwargs["logits_processor"] = [self._logits_processor.copy()]
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generation_thread = Thread(
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target=self._pipeline,
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kwargs=generation_kwargs
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)
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generation_thread.start()
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for text in util.stop_before_value(streamer, self._tokenizer.eos_token):
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yield text
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if should_stop():
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break
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generation_thread.join()
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def token_count(self, system_prompt: str, main_context: str) -> int:
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"""
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Count tokens for the given system prompt and main context.
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Args:
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system_prompt: The system prompt string
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main_context: The main context string
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Returns:
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int: Total number of tokens
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"""
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messages = [
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{"role": "system", "content": system_prompt},
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{"role": "user", "content": main_context}
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]
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prompt = self._tokenizer.apply_chat_template(
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messages, tokenize=False, add_generation_prompt=True
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)
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return len(self._tokenizer.encode(prompt))
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def token_limit(self) -> int:
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"""
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Get the model's context window size.
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Returns:
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int: Maximum number of tokens the model can process
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"""
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if self._token_limit is not None:
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return self._token_limit
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else:
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return self._pipeline.model.config.max_position_embeddings
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