| /* |
| * 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.beam.sdk.io.common; |
| |
| import java.io.IOException; |
| import java.io.ObjectInputStream; |
| import java.io.ObjectOutputStream; |
| import java.io.Serializable; |
| import java.nio.charset.StandardCharsets; |
| import java.util.List; |
| import org.apache.beam.sdk.coders.CannotProvideCoderException; |
| import org.apache.beam.sdk.coders.Coder; |
| import org.apache.beam.sdk.coders.CoderRegistry; |
| import org.apache.beam.sdk.coders.SerializableCoder; |
| import org.apache.beam.sdk.transforms.Combine.CombineFn; |
| import org.apache.beam.vendor.guava.v26_0_jre.com.google.common.collect.Lists; |
| import org.apache.beam.vendor.guava.v26_0_jre.com.google.common.hash.HashCode; |
| import org.apache.beam.vendor.guava.v26_0_jre.com.google.common.hash.Hashing; |
| |
| /** Custom Function for Hashing. The combiner is combineUnordered, and accumulator is a HashCode. */ |
| public class HashingFn extends CombineFn<String, HashingFn.Accum, String> { |
| |
| /** Serializable Class to store the HashCode of input String. */ |
| public static class Accum implements Serializable { |
| HashCode hashCode = null; |
| |
| public Accum(HashCode value) { |
| this.hashCode = value; |
| } |
| |
| private void readObject(ObjectInputStream in) throws IOException, ClassNotFoundException { |
| in.defaultReadObject(); |
| } |
| |
| private void writeObject(ObjectOutputStream out) throws IOException { |
| out.defaultWriteObject(); |
| } |
| |
| @Override |
| public boolean equals(Object o) { |
| if (this == o) { |
| return true; |
| } |
| if (o == null || getClass() != o.getClass()) { |
| return false; |
| } |
| |
| Accum accum = (Accum) o; |
| |
| return hashCode != null ? hashCode.equals(accum.hashCode) : accum.hashCode == null; |
| } |
| |
| @Override |
| public int hashCode() { |
| return hashCode != null ? hashCode.hashCode() : 0; |
| } |
| } |
| |
| @Override |
| public Accum addInput(Accum accum, String input) { |
| List<HashCode> elementHashes = Lists.newArrayList(); |
| if (accum.hashCode != null) { |
| elementHashes.add(accum.hashCode); |
| } |
| HashCode inputHashCode = Hashing.murmur3_128().hashString(input, StandardCharsets.UTF_8); |
| elementHashes.add(inputHashCode); |
| accum.hashCode = Hashing.combineUnordered(elementHashes); |
| return accum; |
| } |
| |
| @Override |
| public Accum mergeAccumulators(Iterable<Accum> accums) { |
| Accum merged = createAccumulator(); |
| List<HashCode> elementHashes = Lists.newArrayList(); |
| for (Accum accum : accums) { |
| if (accum.hashCode != null) { |
| elementHashes.add(accum.hashCode); |
| } |
| } |
| merged.hashCode = Hashing.combineUnordered(elementHashes); |
| return merged; |
| } |
| |
| @Override |
| public String extractOutput(Accum accum) { |
| // Return the combined hash code of list of elements in the Pcollection. |
| String consolidatedHash = ""; |
| if (accum.hashCode != null) { |
| consolidatedHash = accum.hashCode.toString(); |
| } |
| return consolidatedHash; |
| } |
| |
| @Override |
| public Coder<Accum> getAccumulatorCoder(CoderRegistry registry, Coder<String> inputCoder) |
| throws CannotProvideCoderException { |
| return SerializableCoder.of(Accum.class); |
| } |
| |
| @Override |
| public Coder<String> getDefaultOutputCoder(CoderRegistry registry, Coder<String> inputCoder) { |
| return inputCoder; |
| } |
| |
| @Override |
| public Accum createAccumulator() { |
| return new Accum(null); |
| } |
| } |