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171 lines
4.4 KiB
Markdown
171 lines
4.4 KiB
Markdown
# 异步数据库操作指南
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## 概述
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本指南介绍如何在MoviePilot项目中实现异步数据库操作，而无需重写现有的同步数据库模块。
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## 方案优势
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1. **最小化改动**: 不需要重写现有的同步数据库操作代码
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2. **渐进式迁移**: 可以逐步将需要异步的操作迁移到异步版本
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3. **向后兼容**: 现有的同步代码继续正常工作
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4. **性能提升**: 通过线程池执行同步数据库操作，避免阻塞事件循环
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## 核心组件
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### 1. 异步适配器 (`app/db/async_adapter.py`)
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提供以下功能：
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- `async_db_operation`: 将同步函数包装为异步函数
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- `async_db_session`: 为异步操作提供数据库会话
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- `AsyncDbOper`: 异步数据库操作基类
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- `to_async_db_oper`: 将同步操作类转换为异步版本
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- `AsyncDbSession`: 异步数据库会话上下文管理器
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### 2. 异步操作类 (`app/db/async_user_oper.py`)
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展示如何创建异步版本的数据库操作类。
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## 使用方法
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### 方法1: 使用装饰器自动转换
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```python
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from app.db.user_oper import UserOper
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from app.db.async_adapter import to_async_db_oper
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# 自动将同步类转换为异步版本
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AsyncUserOper = to_async_db_oper(UserOper)
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# 使用异步版本
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async def example():
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async_user_oper = AsyncUserOper()
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users = await async_user_oper.list()
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return users
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```
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### 方法2: 手动创建异步方法
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```python
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from app.db.async_adapter import async_db_operation
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class AsyncUserOperManual:
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def __init__(self, db: Session = None):
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self._sync_oper = UserOper(db)
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@async_db_operation
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def list(self) -> List[User]:
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return self._sync_oper.list()
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@async_db_operation
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def add(self, **kwargs):
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return self._sync_oper.add(**kwargs)
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```
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### 方法3: 使用异步上下文管理器
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```python
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from app.db.async_adapter import AsyncDbSession
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async def example():
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async with AsyncDbSession() as db:
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# 直接使用同步操作，但在线程池中执行
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from functools import partial
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users = await asyncio.get_event_loop().run_in_executor(
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None, partial(lambda db: db.query(User).all(), db)
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)
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return users
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```
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### 方法4: 装饰器包装单个函数
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```python
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from app.db.async_adapter import async_db_operation
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@async_db_operation
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def get_user_by_name_sync(db: Session, name: str) -> User:
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return db.query(User).filter(User.name == name).first()
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async def example():
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async with AsyncDbSession() as db:
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user = await get_user_by_name_sync(db, "admin")
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return user
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```
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## 在FastAPI中使用
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### 依赖注入
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```python
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async def get_current_user_async_dependency(
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token_data: schemas.TokenPayload = Depends(verify_token)
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) -> User:
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async with AsyncDbSession() as db:
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from functools import partial
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user = await asyncio.get_event_loop().run_in_executor(
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None, partial(User.get, db, rid=token_data.sub)
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)
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if not user:
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raise HTTPException(status_code=403, detail="用户不存在")
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return user
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@router.get("/me/async")
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async def get_current_user_async(
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current_user: User = Depends(get_current_user_async_dependency)
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):
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return current_user
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```
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### API端点
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```python
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@router.get("/users/async")
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async def get_users_async():
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async_user_oper = AsyncUserOper()
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users = await async_user_oper.list()
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return users
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```
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## 并发操作
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### 批量操作
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```python
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@router.post("/users/batch-async")
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async def create_users_batch_async(users_data: List[schemas.UserCreate]):
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async_user_oper = AsyncUserOper()
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# 并发创建用户
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tasks = []
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for user_data in users_data:
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task = async_user_oper.add(**user_data.dict())
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tasks.append(task)
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# 等待所有任务完成
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await asyncio.gather(*tasks)
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# 获取创建的用户列表
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all_users = await async_user_oper.list()
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return all_users[-len(users_data):]
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```
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### 复杂查询
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```python
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@router.get("/users/stats/async")
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async def get_user_stats_async():
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async_user_oper = AsyncUserOper()
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# 并发执行多个数据库查询
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users_task = async_user_oper.list()
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active_users_task = async_user_oper.get_active_users()
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# 等待所有查询完成
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users, active_users = await asyncio.gather(users_task, active_users_task)
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return {
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"total_users": len(users),
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"active_users": len(active_users),
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"inactive_users": len(users) - len(active_users)
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}
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``` |