feature:基本框架

config/database/mysql.py

@@ -0,0 +1,51 @@
+"""MySQL 会话（懒）：首次访问才创建 AsyncEngine + 连接池，不随应用启动初始化。
+
+引擎/会话工厂都是函数式访问，第一次调用时建出单例；dispose 清理已建对象。
+"""
+from sqlalchemy import text
+from sqlalchemy.ext.asyncio import async_sessionmaker, create_async_engine
+
+from config.settings import settings
+
+_engine = None
+_sessionmaker = None
+
+
+def get_engine():
+    global _engine
+    if _engine is None:
+        _engine = create_async_engine(
+            settings.mysql.url,
+            pool_size=settings.mysql.pool_size,
+            max_overflow=settings.mysql.max_overflow,
+            pool_recycle=settings.mysql.pool_recycle,
+            pool_pre_ping=True,  # 取/还连接时探测，自动剔除死连接
+            pool_timeout=settings.mysql.pool_timeout,
+            connect_args={"connect_timeout": settings.mysql.connect_timeout},
+        )
+    return _engine
+
+
+def get_session_factory():
+    global _sessionmaker
+    if _sessionmaker is None:
+        _sessionmaker = async_sessionmaker(bind=get_engine(), expire_on_commit=False)
+    return _sessionmaker
+
+
+async def init_db() -> None:
+    """手动预热入口（registry.init_db 逐库调用；不随应用启动自动执行）。"""
+    get_engine()
+
+
+async def dispose() -> None:
+    global _engine, _sessionmaker
+    if _engine is not None:
+        await _engine.dispose()
+        _engine = None
+        _sessionmaker = None
+
+
+async def check_health() -> None:
+    async with get_engine().connect() as conn:
+        await conn.execute(text("SELECT 1"))