presto-main/src/main/java/io/prestosql/cost/CostCalculatorUsingExchanges.java/CostEstimator/calculateJoinCost
class CostEstimator:        private LocalCostEstimate calculateJoinCost(PlanNode join, PlanNode probe, PlanNode build, boolean replicated)
        {
            LocalCostEstimate joinInputCost = calculateJoinInputCost(
                    probe,
                    build,
                    stats,
                    types,
                    replicated,
                    taskCountEstimator.estimateSourceDistributedTaskCount());
            LocalCostEstimate joinOutputCost = calculateJoinOutputCost(join);
            return addPartialComponents(joinInputCost, joinOutputCost);
        }