chore: initial commit

db_async_singleton.py

@@ -0,0 +1,33 @@
+# db_async_singleton.py
+import asyncio
+from sqlalchemy.ext.asyncio import create_async_engine
+from sqlalchemy import text
+
+class AsyncDB:
+    def __init__(self, engine):
+        self.engine = engine
+
+    async def query_json(self, sql: str, params: dict):
+        async with self.engine.connect() as conn:
+            result = await conn.execute(text(sql), params)
+            rows = [tuple(r) for r in result]
+            return {"rows": rows}
+
+_ENGINE = None
+
+async def _make_engine_async(conn_str: str):
+    return create_async_engine(conn_str, pool_pre_ping=True, future=True)
+
+def get_db(loop: asyncio.AbstractEventLoop, conn_str: str) -> AsyncDB:
+    """Crea l'engine UNA volta, dentro il loop globale, e restituisce il client."""
+    global _ENGINE
+    if _ENGINE is None:
+        fut = asyncio.run_coroutine_threadsafe(_make_engine_async(conn_str), loop)
+        _ENGINE = fut.result()
+    return AsyncDB(_ENGINE)
+
+async def dispose_async():
+    global _ENGINE
+    if _ENGINE is not None:
+        await _ENGINE.dispose()
+        _ENGINE = None