Fine-tuning/backend/app/services/inference_service.py

import json
from pathlib import Path
from typing import Any

from app.config import get_settings
from app.core.db import async_session, TrainingJobModel
from app.core.logging import logger
from sqlalchemy import select

settings = get_settings()


async def generate(
    adapter_path: str,
    prompt: str,
    max_new_tokens: int = 256,
    temperature: float = 0.8,
    top_p: float = 0.95,
    repetition_penalty: float = 1.1,
    do_sample: bool = True,
) -> dict[str, Any]:
    """使用已训练的 adapter 生成文本。"""
    try:
        import torch
        from transformers import AutoModelForCausalLM, AutoTokenizer

        # 推断 base model
        base_model_id = _get_base_model_id(adapter_path)
        if not base_model_id:
            # 尝试从训练记录中获取
            return {"error": "无法找到基础模型信息，请确保训练任务已完成"}

        # 加载 tokenizer
        tokenizer = AutoTokenizer.from_pretrained(adapter_path, trust_remote_code=True)
        if tokenizer.pad_token is None:
            tokenizer.pad_token = tokenizer.eos_token

        # 加载 base model + adapter
        from peft import PeftModel

        base_model = AutoModelForCausalLM.from_pretrained(
            base_model_id,
            torch_dtype=torch.float16,
            device_map="auto",
        )
        model = PeftModel.from_pretrained(base_model, adapter_path)
        model.eval()

        # Tokenize prompt
        inputs = tokenizer(prompt, return_tensors="pt").to(model.device)

        # Generate
        with torch.no_grad():
            outputs = model.generate(
                **inputs,
                max_new_tokens=max_new_tokens,
                temperature=temperature,
                top_p=top_p,
                repetition_penalty=repetition_penalty,
                do_sample=do_sample,
                pad_token_id=tokenizer.eos_token_id,
            )

        # Decode
        generated_text = tokenizer.decode(outputs[0], skip_special_tokens=True)
        generated_only = tokenizer.decode(outputs[0][inputs["input_ids"].shape[1]:], skip_special_tokens=True)

        return {
            "prompt": prompt,
            "generated_text": generated_text,
            "generated_only": generated_only,
            "tokens_generated": outputs.shape[1] - inputs["input_ids"].shape[1],
        }

    except Exception as e:
        logger.error(f"Inference failed: {e}")
        return {"error": str(e)}


def _get_base_model_id(adapter_path: str) -> str | None:
    """从 adapter config 中获取 base model ID。"""
    config_path = Path(adapter_path) / "adapter_config.json"
    if config_path.exists():
        with open(config_path) as f:
            cfg = json.load(f)
        return cfg.get("base_model_name_or_path")
    return None


async def get_available_adapters() -> list[dict[str, Any]]:
    """列出所有已训练的 adapter。"""
    adapters_dir = settings.adapters_dir
    if not adapters_dir.exists():
        return []

    result = []
    for d in adapters_dir.iterdir():
        if not d.is_dir():
            continue
        adapter_config = d / "adapter_config.json"
        if adapter_config.exists():
            with open(adapter_config) as f:
                cfg = json.load(f)
            result.append({
                "id": d.name,
                "path": str(d),
                "base_model": cfg.get("base_model_name_or_path", "unknown"),
                "peft_type": cfg.get("peft_type", "unknown"),
            })
    return result