| /* |
| * 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.process.traversal.step.filter; |
| |
| import org.apache.tinkerpop.gremlin.process.traversal.Traversal; |
| import org.apache.tinkerpop.gremlin.process.traversal.Traverser; |
| import org.apache.tinkerpop.gremlin.process.traversal.step.Seedable; |
| import org.apache.tinkerpop.gremlin.process.traversal.traverser.TraverserRequirement; |
| import org.apache.tinkerpop.gremlin.structure.util.StringFactory; |
| |
| import java.util.Collections; |
| import java.util.Random; |
| import java.util.Set; |
| |
| /** |
| * @author Marko A. Rodriguez (http://markorodriguez.com) |
| */ |
| public final class CoinStep<S> extends FilterStep<S> implements Seedable { |
| |
| private final Random random = new Random(); |
| private final double probability; |
| |
| public CoinStep(final Traversal.Admin traversal, final double probability) { |
| super(traversal); |
| this.probability = probability; |
| } |
| |
| @Override |
| public void resetSeed(final long seed) { |
| random.setSeed(seed); |
| } |
| |
| @Override |
| protected boolean filter(final Traverser.Admin<S> traverser) { |
| long newBulk = 0l; |
| if (traverser.bulk() < 100) { |
| for (int i = 0; i < traverser.bulk(); i++) { |
| if (this.probability >= random.nextDouble()) |
| newBulk++; |
| } |
| } else { |
| newBulk = Math.round(this.probability * traverser.bulk()); |
| } |
| if (0 == newBulk) return false; |
| traverser.setBulk(newBulk); |
| return true; |
| } |
| |
| @Override |
| public String toString() { |
| return StringFactory.stepString(this, this.probability); |
| } |
| |
| @Override |
| public int hashCode() { |
| return super.hashCode() ^ Double.hashCode(this.probability); |
| } |
| |
| @Override |
| public Set<TraverserRequirement> getRequirements() { |
| return Collections.singleton(TraverserRequirement.BULK); |
| } |
| } |