presto-main/src/main/java/io/prestosql/operator/DriverFactory.java/DriverFactory/createDriver
class DriverFactory:    public synchronized Driver createDriver(DriverContext driverContext)
    {
        checkState(!closed, "DriverFactory is already closed");
        requireNonNull(driverContext, "driverContext is null");
        checkState(!closedLifespans.contains(driverContext.getLifespan()), "DriverFactory is already closed for driver group %s", driverContext.getLifespan());
        encounteredLifespans.add(driverContext.getLifespan());
        ImmutableList.Builder<Operator> operators = ImmutableList.builder();
        for (OperatorFactory operatorFactory : operatorFactories) {
            Operator operator = operatorFactory.createOperator(driverContext);
            operators.add(operator);
        }
        return Driver.createDriver(driverContext, operators.build());
    }