Function first_connect

lib/sqlalchemy/engine/create.py:731–759

(
            dbapi_connection: DBAPIConnection,
            connection_record: ConnectionPoolEntry,
        )

            event.listen(pool, "connect", builtin_on_connect)

        def first_connect(
            dbapi_connection: DBAPIConnection,
            connection_record: ConnectionPoolEntry,
        ) -> None:
            c = base.Connection(
                engine,
                connection=_AdhocProxiedConnection(
                    dbapi_connection, connection_record
                ),
                _has_events=False,
                # reconnecting will be a reentrant condition, so if the
                # connection goes away, Connection is then closed
                _allow_revalidate=False,
                # dont trigger the autobegin sequence
                # within the up front dialect checks
                _allow_autobegin=False,
            )
            c._execution_options = util.EMPTY_DICT

            try:
                dialect.initialize(c)
            finally:
                # note that "invalidated" and "closed" are mutually
                # exclusive in 1.4 Connection.
                if not c.invalidated and not c.closed:
                    # transaction is rolled back otherwise, tested by
                    # test/dialect/postgresql/test_dialect.py
                    # ::MiscBackendTest::test_initial_transaction_state
                    dialect.do_rollback(c.connection)

        # previously, the "first_connect" event was used here, which was then
        # scaled back if the "on_connect" handler were present.  now,