| /* |
| * 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.tinkerpop.gremlin.tinkergraph.process.traversal.strategy.optimization; |
| |
| import org.apache.tinkerpop.gremlin.process.traversal.Step; |
| import org.apache.tinkerpop.gremlin.process.traversal.Traversal; |
| import org.apache.tinkerpop.gremlin.process.traversal.TraversalStrategy; |
| import org.apache.tinkerpop.gremlin.process.traversal.step.TraversalParent; |
| import org.apache.tinkerpop.gremlin.process.traversal.step.map.CountGlobalStep; |
| import org.apache.tinkerpop.gremlin.process.traversal.step.map.GraphStep; |
| import org.apache.tinkerpop.gremlin.process.traversal.step.map.NoOpBarrierStep; |
| import org.apache.tinkerpop.gremlin.process.traversal.step.sideEffect.AggregateGlobalStep; |
| import org.apache.tinkerpop.gremlin.process.traversal.step.sideEffect.IdentityStep; |
| import org.apache.tinkerpop.gremlin.process.traversal.step.sideEffect.SideEffectStep; |
| import org.apache.tinkerpop.gremlin.process.traversal.step.util.CollectingBarrierStep; |
| import org.apache.tinkerpop.gremlin.process.traversal.step.util.EmptyStep; |
| import org.apache.tinkerpop.gremlin.process.traversal.strategy.AbstractTraversalStrategy; |
| import org.apache.tinkerpop.gremlin.process.traversal.util.TraversalHelper; |
| import org.apache.tinkerpop.gremlin.structure.Element; |
| import org.apache.tinkerpop.gremlin.tinkergraph.process.traversal.step.map.TinkerCountGlobalStep; |
| |
| import java.util.Collections; |
| import java.util.List; |
| import java.util.Set; |
| |
| /** |
| * This strategy will do a direct {@link org.apache.tinkerpop.gremlin.tinkergraph.structure.TinkerHelper#getVertices} |
| * size call if the traversal is a count of the vertices and edges of the graph or a one-to-one map chain thereof. |
| * |
| * @author Marko A. Rodriguez (http://markorodriguez.com) |
| * @example <pre> |
| * g.V().count() // is replaced by TinkerCountGlobalStep |
| * g.V().map(out()).count() // is replaced by TinkerCountGlobalStep |
| * g.E().label().count() // is replaced by TinkerCountGlobalStep |
| * </pre> |
| */ |
| public final class TinkerGraphCountStrategy extends AbstractTraversalStrategy<TraversalStrategy.ProviderOptimizationStrategy> implements TraversalStrategy.ProviderOptimizationStrategy { |
| |
| private static final TinkerGraphCountStrategy INSTANCE = new TinkerGraphCountStrategy(); |
| |
| private TinkerGraphCountStrategy() { |
| } |
| |
| @Override |
| public void apply(final Traversal.Admin<?, ?> traversal) { |
| if (!(traversal.isRoot()) || TraversalHelper.onGraphComputer(traversal)) |
| return; |
| final List<Step> steps = traversal.getSteps(); |
| if (steps.size() < 2 || |
| !(steps.get(0) instanceof GraphStep) || |
| 0 != ((GraphStep) steps.get(0)).getIds().length || |
| !(steps.get(steps.size() - 1) instanceof CountGlobalStep)) |
| return; |
| |
| for (int i = 1; i < steps.size() - 1; i++) { |
| final Step current = steps.get(i); |
| // used to include "current instanceof MapStep" but they will not necessarily emit an element as |
| // demonstrated in https://issues.apache.org/jira/browse/TINKERPOP-1958 |
| // |
| // used to include "current instanceof CollectingBarrierStep" but those steps like sample() can filter |
| // demonstrated in https://issues.apache.org/jira/browse/TINKERPOP-1958 |
| if (!(current instanceof IdentityStep || |
| current instanceof NoOpBarrierStep) || |
| (current instanceof TraversalParent && |
| TraversalHelper.anyStepRecursively(s -> (s instanceof SideEffectStep || s instanceof AggregateGlobalStep), (TraversalParent) current))) |
| return; |
| } |
| final Class<? extends Element> elementClass = ((GraphStep<?, ?>) steps.get(0)).getReturnClass(); |
| TraversalHelper.removeAllSteps(traversal); |
| traversal.addStep(new TinkerCountGlobalStep<>(traversal, elementClass)); |
| } |
| |
| @Override |
| public Set<Class<? extends ProviderOptimizationStrategy>> applyPost() { |
| return Collections.singleton(TinkerGraphStepStrategy.class); |
| } |
| |
| public static TinkerGraphCountStrategy instance() { |
| return INSTANCE; |
| } |
| } |