app.py

import sys
import os
import shutil
import warnings
import spaces
from threading import Thread
from transformers import TextIteratorStreamer
from functools import partial
from huggingface_hub import snapshot_download

import gradio as gr
import torch
import numpy as np
from model import Rank1
import math

print(f"NumPy version: {np.__version__}")
print(f"PyTorch version: {torch.__version__}")

# Suppress CUDA initialization warning
warnings.filterwarnings("ignore", category=UserWarning, message="Can't initialize NVML")

MODEL_PATH = None
reranker = None
    
@spaces.GPU
def process_input(query: str, passage: str) -> tuple[str, str, str]:
    """Process input through the reranker and return formatted outputs."""
    global MODEL_PATH
    global reranker
    prompt = f"Determine if the following passage is relevant to the query. Answer only with 'true' or 'false'.\n" \
        f"Query: {query}\n" \
        f"Passage: {passage}\n" \
        "<think>"

    reranker.model = reranker.model.to("cuda")
    inputs = reranker.tokenizer(
        prompt,
        return_tensors="pt",
        truncation=True,
        max_length=reranker.context_size
    ).to("cuda")

    streamer = TextIteratorStreamer(
        reranker.tokenizer,
        skip_prompt=True,
        skip_special_tokens=False
    )
    
    current_text = "<think>"
    generation_output = None
    
    def generate_with_output():
        nonlocal generation_output
        generation_output = reranker.model.generate(
            **inputs,
            generation_config=reranker.generation_config,
            stopping_criteria=reranker.stopping_criteria,
            return_dict_in_generate=True,
            output_scores=True,
            streamer=streamer
        )
    
    thread = Thread(target=generate_with_output)
    thread.start()
    
    # Stream tokens as they're generated
    for new_text in streamer:
        current_text += new_text
        yield (
            "Processing...",
            "Processing...",
            current_text
        )
    
    thread.join()
    
    # Add the stopping sequence and calculate final scores
    if "</think>" not in current_text:
        current_text += "\n" + reranker.stopping_criteria[0].matched_sequence
    
    with torch.no_grad():
        final_scores = generation_output.scores[-1][0]
        true_logit = final_scores[reranker.true_token].item()
        false_logit = final_scores[reranker.false_token].item()
        true_score = math.exp(true_logit)
        false_score = math.exp(false_logit)
        score = true_score / (true_score + false_score)
    
    yield (
        score > 0.5,
        score,
        current_text
    )


# Example inputs
examples = [
    [
        "What movies were directed by James Cameron?",
        "Avatar: The Way of Water is a 2022 American epic science fiction film directed by James Cameron.",
    ],
    [
        "What movies were directed by James Cameron?",
        "Common symptoms of COVID-19 include fever, cough, fatigue, loss of taste or smell, and difficulty breathing.",
    ]
]

theme = gr.themes.Soft(
    primary_hue="indigo",
    font=["Inter", "ui-sans-serif", "system-ui", "sans-serif"],
    neutral_hue="slate",
    radius_size="lg",
)

with gr.Blocks(theme=theme, css=".red-text { color: red; }") as demo:
    gr.Markdown("# Rank1: Test Time Compute in Reranking")
    gr.HTML('NOTE: for demo purposes this is a <span style="color: red;">quantized</span> model limited to a <span style="color: red;">1024</span> context length. HF spaces cannot use vLLM so this is <span style="color: red;">significantly slower</span>')
    gr.HTML('📄 Paper Link: <a href="https://arxiv.org/abs/2502.18418" target="_blank">https://arxiv.org/abs/2502.18418</a>')

    with gr.Row():
        with gr.Column():
            query_input = gr.Textbox(
                label="Query",
                placeholder="Enter your search query here",
                lines=2
            )
            passage_input = gr.Textbox(
                label="Passage",
                placeholder="Enter the passage to check for relevance",
                lines=6
            )
            submit_button = gr.Button("Check Relevance")
        
        with gr.Column():
            relevance_output = gr.Textbox(label="Relevance")
            confidence_output = gr.Textbox(label="Confidence")
            reasoning_output = gr.Textbox(
                label="Model Reasoning",
                lines=10,
                interactive=False
            )
    
    gr.Examples(
        examples=examples,
        inputs=[query_input, passage_input],
        outputs=[relevance_output, confidence_output, reasoning_output],
        fn=process_input,
        cache_examples=True,
    )
    
    submit_button.click(
        fn=process_input,
        inputs=[query_input, passage_input],
        outputs=[relevance_output, confidence_output, reasoning_output],
        api_name="predict",
        queue=True
    )

if __name__ == "__main__":
    # download model first, so we don't have to wait for it
    MODEL_PATH = snapshot_download(
        repo_id="orionweller/rank1-7b-awq",
    )
    print(f"Downloaded model to: {MODEL_PATH}")
    reranker = Rank1(model_name_or_path=MODEL_PATH)
    demo.launch(share=False)