presto-main/src/main/java/io/prestosql/operator/ExchangeOperator.java/ExchangeOperatorFactory/createOperator
class ExchangeOperatorFactory:        @Override
        public SourceOperator createOperator(DriverContext driverContext)
        {
            checkState(!closed, "Factory is already closed");
            OperatorContext operatorContext = driverContext.addOperatorContext(operatorId, sourceId, ExchangeOperator.class.getSimpleName());
            if (exchangeClient == null) {
                exchangeClient = exchangeClientSupplier.get(driverContext.getPipelineContext().localSystemMemoryContext());
            }

            return new ExchangeOperator(
                    operatorContext,
                    sourceId,
                    serdeFactory.createPagesSerde(),
                    exchangeClient);
        }