zzstoatzz.io
+34
-10
backend/src/backend/utilities/database.py
+34
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backend/src/backend/utilities/database.py
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from contextlib import asynccontextmanager
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from typing import Any
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from sqlalchemy.ext.asyncio import AsyncEngine, AsyncSession, create_async_engine
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from sqlalchemy.orm import sessionmaker
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from sqlalchemy.ext.asyncio import (
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AsyncEngine,
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AsyncSession,
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async_sessionmaker,
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create_async_engine,
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)
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from backend.config import settings
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# per-event-loop engine cache
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# per-event-loop engine and sessionmaker cache.
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# sessionmaker is cached alongside engine since it's bound to a specific engine.
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ENGINES: dict[tuple[Any, ...], AsyncEngine] = {}
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SESSION_MAKERS: dict[tuple[Any, ...], async_sessionmaker[AsyncSession]] = {}
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def get_engine() -> AsyncEngine:
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return ENGINES[cache_key]
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def get_session_maker() -> async_sessionmaker[AsyncSession]:
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"""retrieve a cached async sessionmaker.
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the sessionmaker is cached per event loop alongside the engine.
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this avoids recreating the sessionmaker on every db_session() call.
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returns:
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async_sessionmaker bound to the current event loop's engine
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"""
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loop = get_running_loop()
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cache_key = (loop, settings.database.url)
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if cache_key not in SESSION_MAKERS:
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engine = get_engine()
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SESSION_MAKERS[cache_key] = async_sessionmaker(
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bind=engine,
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class_=AsyncSession,
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expire_on_commit=False,
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)
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return SESSION_MAKERS[cache_key]
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@asynccontextmanager
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async def db_session() -> AsyncGenerator[AsyncSession, None]:
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"""get async database session."""
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engine = get_engine()
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async_session_maker = sessionmaker( # type: ignore
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bind=engine, # type: ignore
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class_=AsyncSession,
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expire_on_commit=False,
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)
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async with async_session_maker() as session:
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session_maker = get_session_maker()
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async with session_maker() as session:
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yield session
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