65 lines
2.2 KiB
Python
65 lines
2.2 KiB
Python
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"""数据库连接管理。
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**为什么用同步引擎**：本项目并发极低（内部系统，营销人员数十人），
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异步拿不到吞吐收益；而重活——绩效批量核算、pandas 报表、Excel 导出——
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全是同步阻塞代码，放在异步路由里会卡死事件循环，且这类问题在开发期
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低并发下几乎不暴露。改用同步后，路由写 `def`，FastAPI 会**自动放入
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线程池执行**，天然规避上述陷阱，也不会阻塞事件循环。
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引擎采用**延迟创建**：应用启动时不连接 MySQL，
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这样 Docker 未启动时仍能运行服务、查看接口文档。
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"""
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from collections.abc import Generator
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from sqlalchemy import Engine, create_engine
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from sqlalchemy.orm import Session, sessionmaker
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from app.core.config import get_settings
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_engine: Engine | None = None
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_session_factory: sessionmaker[Session] | None = None
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def get_engine() -> Engine:
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"""获取同步引擎单例（首次调用时创建）。"""
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global _engine, _session_factory
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if _engine is None:
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settings = get_settings()
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_engine = create_engine(
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settings.database_url,
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# 连接池中的连接在使用前先探活，避免 MySQL 重启后取到死连接
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pool_pre_ping=True,
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pool_recycle=3600,
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echo=False,
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)
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_session_factory = sessionmaker(_engine, expire_on_commit=False)
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return _engine
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def get_session_factory() -> sessionmaker[Session]:
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"""获取会话工厂单例。"""
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get_engine()
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assert _session_factory is not None # get_engine 已确保初始化
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return _session_factory
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def get_db() -> Generator[Session, None, None]:
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"""FastAPI 依赖：提供一个数据库会话。
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只负责会话的创建与关闭，**事务边界由 service 层控制** ——
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这样一次请求内的多个仓储调用可以共处同一事务。
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"""
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factory = get_session_factory()
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with factory() as session:
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yield session
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def dispose_engine() -> None:
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"""关闭连接池。应用退出时调用。"""
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global _engine, _session_factory
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if _engine is not None:
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_engine.dispose()
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_engine = None
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_session_factory = None
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