Function atomic_transaction

api/database.py:505–536

Context manager for atomic SQLite transactions. Acquires a write lock immediately via BEGIN IMMEDIATE (configured by engine event hooks), preventing stale reads in read-modify-write patterns. This is essential for preventing race conditions in parallel mode. Args: session_m

(session_maker)

@contextmanager
def atomic_transaction(session_maker):
    """Context manager for atomic SQLite transactions.

    Acquires a write lock immediately via BEGIN IMMEDIATE (configured by
    engine event hooks), preventing stale reads in read-modify-write patterns.
    This is essential for preventing race conditions in parallel mode.

    Args:
        session_maker: SQLAlchemy sessionmaker

    Yields:
        SQLAlchemy session with automatic commit/rollback

    Example:
        with atomic_transaction(session_maker) as session:
            # All reads in this block are protected by write lock
            feature = session.query(Feature).filter(...).first()
            feature.priority = new_priority
            # Commit happens automatically on exit
    """
    session = session_maker()
    try:
        yield session
        session.commit()
    except Exception:
        try:
            session.rollback()
        except Exception:
            pass  # Don't let rollback failure mask original error
        raise
    finally:
        session.close()