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 19 package org.apache.giraph.utils; 20 21 import org.apache.hadoop.io.Writable; 22 import org.apache.hadoop.io.WritableComparable; 23 24 import java.io.IOException; 25 import javax.annotation.concurrent.NotThreadSafe; 26 27 /** 28 * Special iterator that reuses vertex ids and messages bytes so that the 29 * lifetime of the object is only until next() is called. 30 * 31 * Vertex id ownership can be released if desired through 32 * releaseCurrentVertexId(). This optimization allows us to cut down 33 * on the number of objects instantiated and garbage collected. Messages 34 * can only be copied to an ExtendedDataOutput object 35 * 36 * @param <I> vertexId type parameter 37 * @param <M> message type parameter 38 */ 39 @NotThreadSafe 40 public abstract class ByteStructVertexIdMessageBytesIterator<I 41 extends WritableComparable, M extends Writable> 42 extends ByteStructVertexIdDataIterator<I, M> 43 implements VertexIdMessageBytesIterator<I, M> { 44 /** Last message offset */ 45 protected int messageOffset = -1; 46 /** Number of bytes in the last message */ 47 protected int messageBytes = -1; 48 49 /** 50 * Constructor with vertexIdData 51 * 52 * @param vertexIdData vertexIdData 53 */ 54 public ByteStructVertexIdMessageBytesIterator( 55 AbstractVertexIdData<I, M> vertexIdData) { 56 super(vertexIdData); 57 } 58 59 /** 60 * Moves to the next element in the iteration. 61 */ 62 @Override 63 public void next() { 64 if (vertexId == null) { 65 vertexId = vertexIdData.getConf().createVertexId(); 66 } 67 68 try { 69 vertexId.readFields(extendedDataInput); 70 messageBytes = extendedDataInput.readInt(); 71 messageOffset = extendedDataInput.getPos(); 72 if (extendedDataInput.skipBytes(messageBytes) != messageBytes) { 73 throw new IllegalStateException("next: Failed to skip " + 74 messageBytes); 75 } 76 } catch (IOException e) { 77 throw new IllegalStateException("next: IOException", e); 78 } 79 } 80 }