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.utils; 19 20 import java.util.Iterator; 21 import org.apache.hadoop.io.Writable; 22 23 /** 24 * This iterable is designed to deserialize a byte array on the fly to 25 * provide new copies of writable objects when desired. It does not reuse 26 * objects, and instead creates a new one for every next(). 27 * 28 * @param <T> Type that extends Writable that will be iterated 29 */ 30 public abstract class ByteStructIterable<T extends Writable> implements 31 Iterable<T> { 32 /** Factory for data input */ 33 protected final Factory<? extends ExtendedDataInput> dataInputFactory; 34 35 /** 36 * Constructor 37 * 38 * @param dataInputFactory Factory for data inputs 39 */ 40 public ByteStructIterable( 41 Factory<? extends ExtendedDataInput> dataInputFactory) { 42 this.dataInputFactory = dataInputFactory; 43 } 44 45 /** 46 * Must be able to create the writable object 47 * 48 * @return New writable 49 */ 50 protected abstract T createWritable(); 51 52 @Override 53 public Iterator<T> iterator() { 54 return new ByteStructIterator<T>(dataInputFactory.create()) { 55 @Override 56 protected T createWritable() { 57 return ByteStructIterable.this.createWritable(); 58 } 59 }; 60 } 61 }