| /* |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you under the Apache License, Version 2.0 (the |
| * "License"); you may not use this file except in compliance |
| * with the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| package org.apache.wayang.core.optimizer.enumeration; |
| |
| import java.util.Collection; |
| import java.util.List; |
| import java.util.Set; |
| import java.util.stream.Collectors; |
| import org.apache.logging.log4j.LogManager; |
| import org.apache.logging.log4j.Logger; |
| import org.apache.wayang.core.api.Configuration; |
| import org.apache.wayang.core.api.exception.WayangException; |
| import org.apache.wayang.core.plan.wayangplan.ExecutionOperator; |
| import org.apache.wayang.core.plan.wayangplan.Slot; |
| import org.apache.wayang.core.platform.Platform; |
| import org.apache.wayang.core.util.Tuple; |
| |
| /** |
| * This {@link PlanEnumerationPruningStrategy} follows the idea that we can prune a |
| * {@link PlanImplementation}, when there is a further one that is (i) better and (ii) has the exact same |
| * operators with still-to-be-connected {@link Slot}s. |
| */ |
| public class LatentOperatorPruningStrategy implements PlanEnumerationPruningStrategy { |
| |
| private static final Logger logger = LogManager.getLogger(LatentOperatorPruningStrategy.class); |
| |
| @Override |
| public void configure(Configuration configuration) { |
| } |
| |
| @Override |
| public void prune(PlanEnumeration planEnumeration) { |
| // Skip if there is nothing to do... |
| if (planEnumeration.getPlanImplementations().size() < 2) return; |
| |
| // Group plans. |
| final Collection<List<PlanImplementation>> competingPlans = |
| planEnumeration.getPlanImplementations().stream() |
| .collect(Collectors.groupingBy(LatentOperatorPruningStrategy::getInterestingProperties)) |
| .values(); |
| final List<PlanImplementation> bestPlans = competingPlans.stream() |
| .map(this::selectBestPlanNary) |
| .collect(Collectors.toList()); |
| planEnumeration.getPlanImplementations().retainAll(bestPlans); |
| } |
| |
| /** |
| * Extracts the interesting properties of a {@link PlanImplementation}. |
| * |
| * @param implementation whose interesting properties are requested |
| * @return the interesting properties of the given {@code implementation} |
| */ |
| private static Tuple<Set<Platform>, Collection<ExecutionOperator>> getInterestingProperties(PlanImplementation implementation) { |
| return new Tuple<>( |
| implementation.getUtilizedPlatforms(), |
| implementation.getInterfaceOperators() |
| ); |
| } |
| |
| private PlanImplementation selectBestPlanNary(List<PlanImplementation> planImplementation) { |
| assert !planImplementation.isEmpty(); |
| return planImplementation.stream() |
| .reduce(this::selectBestPlanBinary) |
| .orElseThrow(() -> new WayangException("No plan was selected.")); |
| } |
| |
| private PlanImplementation selectBestPlanBinary(PlanImplementation p1, |
| PlanImplementation p2) { |
| final double t1 = p1.getSquashedCostEstimate(true); |
| final double t2 = p2.getSquashedCostEstimate(true); |
| final boolean isPickP1 = t1 <= t2; |
| if (logger.isDebugEnabled()) { |
| if (isPickP1) { |
| LogManager.getLogger(LatentOperatorPruningStrategy.class).debug( |
| "{} < {}: Choosing {} over {}.", p1.getTimeEstimate(), p2.getTimeEstimate(), p1.getOperators(), p2.getOperators() |
| ); |
| } else { |
| LogManager.getLogger(LatentOperatorPruningStrategy.class).debug( |
| "{} < {}: Choosing {} over {}.", p2.getTimeEstimate(), p1.getTimeEstimate(), p2.getOperators(), p1.getOperators() |
| ); |
| } |
| } |
| return isPickP1 ? p1 : p2; |
| } |
| |
| } |