app.py

import gradio as gr
import spaces
from transformers import (
    AutoModelForCausalLM,
    AutoTokenizer,
    AutoModelForSequenceClassification,
)
import torch

chat_model_name = "sapienzanlp/Minerva-7B-instruct-v1.0"
chat_model = AutoModelForCausalLM.from_pretrained(
    chat_model_name, torch_dtype=torch.bfloat16, device_map="auto"
)
chat_tokenizer = AutoTokenizer.from_pretrained(chat_model_name)

moderator_model_name = "saiteki-kai/QA-DeBERTa-v3-large"
moderator_model = AutoModelForSequenceClassification.from_pretrained(
    moderator_model_name, device_map="auto"
)
moderator_tokenizer = AutoTokenizer.from_pretrained(moderator_model_name)


def generate_responses(model, tokenizer, prompts):
    messages = [[{"role": "user", "content": message}] for message in prompts]

    texts = tokenizer.apply_chat_template(
        messages, tokenize=False, add_generation_prompt=True
    )

    with torch.inference_mode():
        model_inputs = tokenizer(texts, padding=True, return_tensors="pt").to(model.device)
        generated_ids = model.generate(
            **model_inputs,
            do_sample=False,
            temperature=0,
            repetition_penalty=1.0,
            max_new_tokens=512,
        )

    prompt_lengths = (model_inputs.input_ids != tokenizer.pad_token_id).sum(dim=1)
    generated_ids = [
        output_ids[length:] for length, output_ids in zip(prompt_lengths, generated_ids)
    ]
    responses = tokenizer.batch_decode(generated_ids, skip_special_tokens=True)

    return responses


def classify_pairs(model, tokenizer, prompts, responses):
    texts = [
        prompt + "[SEP]" + response for prompt, response in zip(prompts, responses)
    ]

    with torch.inference_mode():
        input_ids = tokenizer(texts, padding=True, max_length=512).to(model.device)
        outputs = model(**input_ids)

    return outputs


@spaces.GPU()
def generate(prompts: list[str]) -> list[dict[str, str | float]]:
    responses = generate_responses(chat_model, chat_tokenizer, prompts)
    scores = classify_pairs(moderator_model, moderator_tokenizer, prompts, responses)

    return [
        {"prompt": prompt, "response": response, "score": score}
        for prompt, response, score in zip(prompts, responses, scores)
    ]


with gr.Blocks() as demo:
    gr.Markdown("Welcome")
    gr.api(generate, api_name="scores", batch=False)

demo.queue()
demo.launch()