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211 lines
7.7 KiB
Python
211 lines
7.7 KiB
Python
"""Base interface for large language models to expose."""
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import json
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from abc import ABC, abstractmethod
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from pathlib import Path
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from typing import Any, Dict, List, Mapping, Optional, Union
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import yaml
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from pydantic import BaseModel, Extra, Field, validator
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import langchain
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from langchain.callbacks import get_callback_manager
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from langchain.callbacks.base import BaseCallbackManager
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from langchain.schema import Generation, LLMResult
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def _get_verbosity() -> bool:
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return langchain.verbose
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class BaseLLM(BaseModel, ABC):
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"""LLM wrapper should take in a prompt and return a string."""
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cache: Optional[bool] = None
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verbose: bool = Field(default_factory=_get_verbosity)
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"""Whether to print out response text."""
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callback_manager: BaseCallbackManager = Field(default_factory=get_callback_manager)
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class Config:
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"""Configuration for this pydantic object."""
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extra = Extra.forbid
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arbitrary_types_allowed = True
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@validator("callback_manager", pre=True, always=True)
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def set_callback_manager(
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cls, callback_manager: Optional[BaseCallbackManager]
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) -> BaseCallbackManager:
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"""If callback manager is None, set it.
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This allows users to pass in None as callback manager, which is a nice UX.
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"""
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return callback_manager or get_callback_manager()
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@validator("verbose", pre=True, always=True)
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def set_verbose(cls, verbose: Optional[bool]) -> bool:
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"""If verbose is None, set it.
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This allows users to pass in None as verbose to access the global setting.
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"""
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if verbose is None:
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return _get_verbosity()
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else:
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return verbose
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@abstractmethod
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def _generate(
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self, prompts: List[str], stop: Optional[List[str]] = None
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) -> LLMResult:
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"""Run the LLM on the given prompts."""
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def generate(
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self, prompts: List[str], stop: Optional[List[str]] = None
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) -> LLMResult:
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"""Run the LLM on the given prompt and input."""
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disregard_cache = self.cache is not None and not self.cache
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if langchain.llm_cache is None or disregard_cache:
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# This happens when langchain.cache is None, but self.cache is True
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if self.cache is not None and self.cache:
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raise ValueError(
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"Asked to cache, but no cache found at `langchain.cache`."
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)
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self.callback_manager.on_llm_start(
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{"name": self.__class__.__name__}, prompts, verbose=self.verbose
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)
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try:
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output = self._generate(prompts, stop=stop)
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except Exception as e:
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self.callback_manager.on_llm_error(e, verbose=self.verbose)
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raise e
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self.callback_manager.on_llm_end(output, verbose=self.verbose)
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return output
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params = self._llm_dict()
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params["stop"] = stop
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llm_string = str(sorted([(k, v) for k, v in params.items()]))
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missing_prompts = []
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missing_prompt_idxs = []
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existing_prompts = {}
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for i, prompt in enumerate(prompts):
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cache_val = langchain.llm_cache.lookup(prompt, llm_string)
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if isinstance(cache_val, list):
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existing_prompts[i] = cache_val
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else:
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missing_prompts.append(prompt)
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missing_prompt_idxs.append(i)
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self.callback_manager.on_llm_start(
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{"name": self.__class__.__name__}, missing_prompts, verbose=self.verbose
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)
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try:
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new_results = self._generate(missing_prompts, stop=stop)
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except Exception as e:
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self.callback_manager.on_llm_error(e, verbose=self.verbose)
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raise e
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self.callback_manager.on_llm_end(new_results, verbose=self.verbose)
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for i, result in enumerate(new_results.generations):
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existing_prompts[missing_prompt_idxs[i]] = result
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prompt = prompts[missing_prompt_idxs[i]]
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langchain.llm_cache.update(prompt, llm_string, result)
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generations = [existing_prompts[i] for i in range(len(prompts))]
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return LLMResult(generations=generations, llm_output=new_results.llm_output)
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def get_num_tokens(self, text: str) -> int:
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"""Get the number of tokens present in the text."""
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# TODO: this method may not be exact.
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# TODO: this method may differ based on model (eg codex).
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try:
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from transformers import GPT2TokenizerFast
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except ImportError:
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raise ValueError(
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"Could not import transformers python package. "
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"This is needed in order to calculate get_num_tokens. "
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"Please it install it with `pip install transformers`."
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)
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# create a GPT-3 tokenizer instance
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tokenizer = GPT2TokenizerFast.from_pretrained("gpt2")
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# tokenize the text using the GPT-3 tokenizer
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tokenized_text = tokenizer.tokenize(text)
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# calculate the number of tokens in the tokenized text
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return len(tokenized_text)
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def __call__(self, prompt: str, stop: Optional[List[str]] = None) -> str:
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"""Check Cache and run the LLM on the given prompt and input."""
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return self.generate([prompt], stop=stop).generations[0][0].text
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@property
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def _identifying_params(self) -> Mapping[str, Any]:
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"""Get the identifying parameters."""
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return {}
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def __str__(self) -> str:
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"""Get a string representation of the object for printing."""
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cls_name = f"\033[1m{self.__class__.__name__}\033[0m"
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return f"{cls_name}\nParams: {self._identifying_params}"
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@property
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@abstractmethod
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def _llm_type(self) -> str:
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"""Return type of llm."""
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def _llm_dict(self) -> Dict:
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"""Return a dictionary of the prompt."""
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starter_dict = dict(self._identifying_params)
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starter_dict["_type"] = self._llm_type
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return starter_dict
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def save(self, file_path: Union[Path, str]) -> None:
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"""Save the LLM.
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Args:
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file_path: Path to file to save the LLM to.
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Example:
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.. code-block:: python
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llm.save(file_path="path/llm.yaml")
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"""
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# Convert file to Path object.
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if isinstance(file_path, str):
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save_path = Path(file_path)
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else:
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save_path = file_path
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directory_path = save_path.parent
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directory_path.mkdir(parents=True, exist_ok=True)
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# Fetch dictionary to save
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prompt_dict = self._llm_dict()
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if save_path.suffix == ".json":
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with open(file_path, "w") as f:
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json.dump(prompt_dict, f, indent=4)
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elif save_path.suffix == ".yaml":
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with open(file_path, "w") as f:
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yaml.dump(prompt_dict, f, default_flow_style=False)
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else:
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raise ValueError(f"{save_path} must be json or yaml")
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class LLM(BaseLLM):
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"""LLM class that expect subclasses to implement a simpler call method.
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The purpose of this class is to expose a simpler interface for working
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with LLMs, rather than expect the user to implement the full _generate method.
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"""
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@abstractmethod
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def _call(self, prompt: str, stop: Optional[List[str]] = None) -> str:
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"""Run the LLM on the given prompt and input."""
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def _generate(
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self, prompts: List[str], stop: Optional[List[str]] = None
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) -> LLMResult:
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"""Run the LLM on the given prompt and input."""
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# TODO: add caching here.
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generations = []
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for prompt in prompts:
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text = self._call(prompt, stop=stop)
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generations.append([Generation(text=text)])
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return LLMResult(generations=generations)
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