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.DataOutput; 25 26 /** 27 * Special iterator that reuses vertex ids and messages bytes so that the 28 * lifetime of the object is only until next() is called. 29 * 30 * Vertex id ownership can be released if desired through 31 * releaseCurrentVertexId(). This optimization allows us to cut down 32 * on the number of objects instantiated and garbage collected. Messages 33 * can only be copied to an ExtendedDataOutput object 34 * 35 * @param <I> vertexId type parameter 36 * @param <M> message type parameter 37 */ 38 public interface VertexIdMessageBytesIterator<I extends WritableComparable, 39 M extends Writable> extends VertexIdDataIterator<I, M> { 40 41 /** 42 * Write the current message to an ExtendedDataOutput object 43 * 44 * @param dataOutput Where the current message will be written to 45 */ 46 void writeCurrentMessageBytes(DataOutput dataOutput); 47 }