hf_chat.py

# Copyright 2022 MosaicML LLM Foundry authors
# SPDX-License-Identifier: Apache-2.0

import time
import warnings
from argparse import ArgumentParser, ArgumentTypeError, Namespace
from contextlib import nullcontext
from typing import Any, Dict, List, Optional, Union

import torch
from transformers import (
    AutoConfig,
    AutoModelForCausalLM,
    AutoTokenizer,
    PreTrainedModel,
    PreTrainedTokenizerBase,
    StoppingCriteria,
    StoppingCriteriaList,
    TextStreamer,
)

from llmfoundry.utils.exceptions import ChatTemplateError

DEFAULT_SYSTEM_PROMPT = 'You are a friendly chatbot who aims to be helpful and honest.'


class ChatMessage:
    """A class that contains a chat message.

    Please see ChatML format for more information:
    https://huggingface.co/docs/transformers/main/en/chat_templating#how-do-i-use-chat-templates
    """

    def __init__(self, role: str, content: str) -> None:
        self.role = role
        self.content = content

    def to_dict(self,) -> Dict[str, str]:
        return {'role': self.role, 'content': self.content}

    def __repr__(self) -> str:
        return f"{{ 'role': {self.role}, 'content': {self.content} }}"


class Conversation:
    """A class for interacting with a chat-tuned LLM.

    Args:
        model: The model to use for inference.
        tokenizer: The tokenizer to use for inference.
        system_prompt: The system prompt to use for the conversation.
        chat_format: The chat format to use for the conversation.
        generate_kwargs: The keyword arguments to pass to `model.generate`.
        stop_tokens: The tokens to stop generation on.

    Attributes:
        model: The model to use for inference.
        tokenizer: The tokenizer to use for inference.
        streamer: The streamer to use for inference.
        generate_kwargs: The keyword arguments to pass to `model.generate`.
        system_prompt: The system prompt used in the conversation chat.
        history: The conversation history.
        cli_instructions: The instructions to display to the user.
    """

    def __init__(
        self,
        model: PreTrainedModel,
        tokenizer: PreTrainedTokenizerBase,
        generate_kwargs: Dict[str, Any],
        system_prompt: str,
        stop_tokens: Optional[List[str]] = None,
    ) -> None:
        if stop_tokens is None:
            stop_tokens = ['<|endoftext|>', '<|im_end|>']
        self.model = model
        self.tokenizer = tokenizer

        stop_token_ids = self.tokenizer.convert_tokens_to_ids(stop_tokens)
        if len(stop_token_ids) != len(stop_tokens):
            warnings.warn(
                f'Not all stop tokens were found in the tokenizer vocabulary: {stop_tokens}\n'
                + 'Generation may stop or continue unexpectedly.',
            )

        class StopOnTokens(StoppingCriteria):

            def __call__(
                self,
                input_ids: torch.LongTensor,
                scores: torch.FloatTensor,
                **kwargs: Any,
            ) -> bool:
                del kwargs  # unused
                for stop_id in stop_token_ids:
                    if input_ids[0][-1] == stop_id:
                        return True
                return False

        self.streamer = TextStreamer(
            tokenizer,
            skip_prompt=True,
            skip_special_tokens=True,
        )
        self.generate_kwargs = {
            **generate_kwargs,
            'stopping_criteria':
                StoppingCriteriaList([StopOnTokens()]),
            'streamer':
                self.streamer,
        }
        self.history = []
        system_prompt_msg = ChatMessage('system', system_prompt)
        self.history.append(system_prompt_msg)

        self.cli_instructions = (
            'Enter your message below.\n- Hit return twice to send input to the model\n'
            +
            "- Type 'clear' to restart the conversation\n- Type 'history' to see the conversation\n"
            +
            "- Type 'history_fmt' to see the conversation\n- Type 'quit' to end\n- Type 'system' to change the system prompt\n"
        )

    def _history_to_chat_conversation(self) -> List[Dict[str, str]]:
        msg_history = [chat_msg.to_dict() for chat_msg in self.history]
        return msg_history

    def _history_as_formatted_str(self) -> str:
        chat_conversation = self._history_to_chat_conversation()
        try:
            return self.tokenizer.apply_chat_template(
                chat_conversation,
                tokenize=False,
                add_generation_prompt=False,
            )
        except Exception as e:
            raise ChatTemplateError(
                inner_message=str(e),
                template=self.tokenizer.chat_template,
                sample=chat_conversation,
            )

    def turn(self, user_inp: str) -> None:
        self.history.append(ChatMessage('user', user_inp))
        chat_conversation = self._history_to_chat_conversation()
        try:
            tokenized_chat = self.tokenizer.apply_chat_template(
                chat_conversation,
                tokenize=True,
                add_generation_prompt=True,
                return_tensors='pt',
            )
        except Exception as e:
            raise ChatTemplateError(
                inner_message=str(e),
                template=self.tokenizer.chat_template,
                sample=chat_conversation,
            )
        tokenized_chat = tokenized_chat.to(self.model.device)
        # also stream to stdout
        maybe_synchronize()
        start = time.time()
        print(f'Assistant:')
        output_ids = self.model.generate(tokenized_chat, **self.generate_kwargs)
        maybe_synchronize()
        end = time.time()
        print(f'\nTook {end - start:.2f} seconds')
        new_tokens = output_ids[0, len(tokenized_chat[0]):]
        assistant_response = self.tokenizer.decode(
            new_tokens,
            skip_special_tokens=True,
        )
        self.history.append(ChatMessage('assistant', assistant_response))

    def __call__(self) -> None:
        print(self.cli_instructions)
        while True:
            print('User:')
            user_inp_lines = []
            while True:
                line = input()
                if line.strip() == '':
                    break
                user_inp_lines.append(line)
            user_inp = '\n'.join(user_inp_lines)
            if user_inp.lower() == 'quit':
                break
            elif user_inp.lower() == 'clear':
                self.history = self.history[:1]  # keep system prompt
                continue
            elif user_inp == 'history':
                print(f'history: {self.history}')
                continue
            elif user_inp == 'history_fmt':
                print(f'history: {self._history_as_formatted_str()}')
                continue
            elif user_inp == 'system':
                print('Enter a new system prompt:')
                new_system = input()
                self.history[0].content = new_system
                continue
            self.turn(user_inp)


def get_dtype(dtype: str):
    if dtype == 'fp32':
        return torch.float32
    elif dtype == 'fp16':
        return torch.float16
    elif dtype == 'bf16':
        return torch.bfloat16
    else:
        raise NotImplementedError(
            f'dtype {dtype} is not supported. ' +
            'We only support fp32, fp16, and bf16 currently',
        )


def str2bool(v: Union[str, bool]):
    if isinstance(v, bool):
        return v
    if v.lower() in ('yes', 'true', 't', 'y', '1'):
        return True
    elif v.lower() in ('no', 'false', 'f', 'n', '0'):
        return False
    else:
        raise ArgumentTypeError('Boolean value expected.')


def str_or_bool(v: Union[str, bool]):
    if isinstance(v, bool):
        return v
    if v.lower() in ('yes', 'true', 't', 'y', '1'):
        return True
    elif v.lower() in ('no', 'false', 'f', 'n', '0'):
        return False
    else:
        return v


def parse_args() -> Namespace:
    """Parse commandline arguments."""
    parser = ArgumentParser(
        description='Load a HF CausalLM Model and use it to generate text.',
    )
    parser.add_argument('-n', '--name_or_path', type=str, required=True)
    parser.add_argument('--max_new_tokens', type=int, default=512)
    parser.add_argument('--max_seq_len', type=int, default=None)
    parser.add_argument('--temperature', type=float, default=1.0)
    parser.add_argument('--top_k', type=int, default=50)
    parser.add_argument('--top_p', type=float, default=1.0)
    parser.add_argument(
        '--do_sample',
        type=str2bool,
        nargs='?',
        const=True,
        default=True,
    )
    parser.add_argument(
        '--use_cache',
        type=str2bool,
        nargs='?',
        const=True,
        default=True,
    )
    parser.add_argument('--eos_token_id', type=str, default=None)
    parser.add_argument('--pad_token_id', type=str, default=None)
    parser.add_argument(
        '--model_dtype',
        type=str,
        choices=['fp32', 'fp16', 'bf16'],
        default=None,
    )
    parser.add_argument(
        '--autocast_dtype',
        type=str,
        choices=['fp32', 'fp16', 'bf16'],
        default=None,
    )
    parser.add_argument(
        '--warmup',
        type=str2bool,
        nargs='?',
        const=True,
        default=True,
    )
    parser.add_argument(
        '--trust_remote_code',
        type=str2bool,
        nargs='?',
        const=True,
        default=True,
    )
    parser.add_argument(
        '--use_auth_token',
        type=str_or_bool,
        nargs='?',
        const=True,
        default=None,
    )
    parser.add_argument('--revision', type=str, default=None)
    parser.add_argument('--device', type=str, default=None)
    parser.add_argument('--device_map', type=str, default=None)
    parser.add_argument('--attn_impl', type=str, default=None)
    parser.add_argument('--seed', type=int, default=42)
    parser.add_argument(
        '--system_prompt',
        type=str,
        default=DEFAULT_SYSTEM_PROMPT,
    )
    parser.add_argument(
        '--stop_tokens',
        type=str,
        default='<|endoftext|> <|im_end|>',
        help=
        'A string of tokens to stop generation on; will be split on spaces.',
    )
    return parser.parse_args()


def maybe_synchronize():
    if torch.cuda.is_available():
        torch.cuda.synchronize()


def main(args: Namespace) -> None:
    # Set device or device_map
    if args.device and args.device_map:
        raise ValueError('You can only set one of `device` and `device_map`.')
    if args.device is not None:
        device = args.device
        device_map = None
    else:
        device = None
        device_map = args.device_map or 'auto'
    print(f'Using {device=} and {device_map=}')

    # Set model_dtype
    if args.model_dtype is not None:
        model_dtype = get_dtype(args.model_dtype)
    else:
        model_dtype = torch.float32
    print(f'Using {model_dtype=}')

    # Grab config first
    print(f'Loading HF Config...')
    from_pretrained_kwargs = {
        'use_auth_token': args.use_auth_token,
        'trust_remote_code': args.trust_remote_code,
        'revision': args.revision,
    }
    try:
        config = AutoConfig.from_pretrained(
            args.name_or_path,
            **from_pretrained_kwargs,
        )
        if args.attn_impl is not None and hasattr(config, 'attn_config'):
            config.attn_config['attn_impl'] = args.attn_impl
        if hasattr(config, 'init_device') and device is not None:
            config.init_device = device
        if args.max_seq_len is not None and hasattr(config, 'max_seq_len'):
            config.max_seq_len = args.max_seq_len

    except Exception as e:
        raise RuntimeError(
            'If you are having auth problems, try logging in via `huggingface-cli login` '
            + 'or by setting the environment variable `export HF_TOKEN=... ' +
            'using your access token from https://huggingface.co/settings/tokens.',
        ) from e

    # Load HF Model
    print(f'Loading HF model with dtype={model_dtype}...')
    try:
        model = AutoModelForCausalLM.from_pretrained(
            args.name_or_path,
            config=config,
            torch_dtype=model_dtype,
            device_map=device_map,
            **from_pretrained_kwargs,
        )
        model.eval()
        print(f'n_params={sum(p.numel() for p in model.parameters())}')
        if device is not None:
            print(f'Placing model on {device=}...')
            model.to(device)
    except Exception as e:
        raise RuntimeError(
            'Unable to load HF model. ' +
            'If you are having auth problems, try logging in via `huggingface-cli login` '
            + 'or by setting the environment variable `export HF_TOKEN=... ' +
            'using your access token from https://huggingface.co/settings/tokens.',
        ) from e

    print('\nLoading HF tokenizer...')
    tokenizer = AutoTokenizer.from_pretrained(
        args.name_or_path,
        **from_pretrained_kwargs,
    )
    if tokenizer.pad_token_id is None:
        warnings.warn(
            'pad_token_id is not set for the tokenizer. Using eos_token_id as pad_token_id.',
        )
        tokenizer.pad_token = tokenizer.eos_token
    tokenizer.padding_side = 'left'

    generate_kwargs = {
        'max_new_tokens': args.max_new_tokens,
        'temperature': args.temperature,
        'top_p': args.top_p,
        'top_k': args.top_k,
        'use_cache': args.use_cache,
        'do_sample': args.do_sample,
        'eos_token_id': args.eos_token_id or tokenizer.eos_token_id,
        'pad_token_id': args.pad_token_id or tokenizer.eos_token_id,
    }
    # Autocast
    if args.autocast_dtype is not None:
        autocast_dtype = get_dtype(args.autocast_dtype)
        autocast_context = torch.autocast(model.device.type, autocast_dtype)
        print(f'Using autocast with dtype={autocast_dtype}...')
    else:
        autocast_context = nullcontext()
        print('NOT using autocast...')

    conversation = Conversation(
        model=model,
        tokenizer=tokenizer,
        system_prompt=args.system_prompt,
        generate_kwargs=generate_kwargs,
        stop_tokens=args.stop_tokens.split(),
    )

    # Warmup
    if args.warmup:
        print('Warming up...')
        with autocast_context:
            conversation.turn('Write a welcome message to the user.')
            conversation.history = conversation.history[:1
                                                       ]  # keep system prompt

    print('Starting conversation...')
    with autocast_context:
        conversation()


if __name__ == '__main__':
    main(parse_args())