1 /* 2 * Licensed to the Apache Software Foundation (ASF) under one 3 * or more contributor license agreements. See the NOTICE file 4 * distributed with this work for additional information 5 * regarding copyright ownership. The ASF licenses this file 6 * to you under the Apache License, Version 2.0 (the 7 * "License"); you may not use this file except in compliance 8 * with the License. You may obtain a copy of the License at 9 * 10 * http://www.apache.org/licenses/LICENSE-2.0 11 * 12 * Unless required by applicable law or agreed to in writing, software 13 * distributed under the License is distributed on an "AS IS" BASIS, 14 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 15 * See the License for the specific language governing permissions and 16 * limitations under the License. 17 */ 18 package org.apache.giraph.reducers.impl; 19 20 import java.io.DataInput; 21 import java.io.DataOutput; 22 import java.io.IOException; 23 24 import org.apache.giraph.reducers.ReduceOperation; 25 import org.apache.giraph.writable.kryo.KryoWritableWrapper; 26 27 /** 28 * Reduce operation which wraps reduced value in KryoWritableWrapper, 29 * so we don't need to worry about it being writable 30 * 31 * @param <S> Single value type 32 * @param <R> Reduced value type 33 */ 34 public abstract class KryoWrappedReduceOperation<S, R> 35 implements ReduceOperation<S, KryoWritableWrapper<R>> { 36 /** 37 * Look at ReduceOperation.reduce. 38 * 39 * @param reduceInto Partial value into which to reduce and store the result 40 * @param valueToReduce Single value to be reduced 41 */ 42 public abstract void reduce(R reduceInto, S valueToReduce); 43 44 /** 45 * Look at ReduceOperation.reduceMerge. 46 * 47 * @param reduceInto Partial value into which to reduce and store the result 48 * @param valueToReduce Partial value to be reduced 49 */ 50 public abstract void reduceMerge(R reduceInto, R valueToReduce); 51 52 /** 53 * Look at ReduceOperation.createValue. 54 * 55 * @return Neutral value 56 */ 57 public abstract R createValue(); 58 59 @Override 60 public final KryoWritableWrapper<R> createInitialValue() { 61 return new KryoWritableWrapper<>(createValue()); 62 } 63 64 @Override 65 public final KryoWritableWrapper<R> reduce( 66 KryoWritableWrapper<R> wrapper, S value) { 67 reduce(wrapper.get(), value); 68 return wrapper; 69 } 70 71 @Override 72 public final KryoWritableWrapper<R> reduceMerge( 73 KryoWritableWrapper<R> wrapper, 74 KryoWritableWrapper<R> wrapperToReduce) { 75 reduceMerge(wrapper.get(), wrapperToReduce.get()); 76 return wrapper; 77 } 78 79 @Override 80 public void write(DataOutput dataOutput) throws IOException { 81 } 82 83 @Override 84 public void readFields(DataInput dataInput) throws IOException { 85 } 86 }