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.io; 20 21 import org.apache.hadoop.io.Writable; 22 import org.apache.hadoop.io.WritableComparable; 23 import org.apache.hadoop.mapreduce.InputSplit; 24 import org.apache.hadoop.mapreduce.TaskAttemptContext; 25 26 import java.io.IOException; 27 28 /** 29 * 30 * Use this to load data for a BSP application. Note that the InputSplit must 31 * also implement Writable. 32 * 33 * It's guaranteed that whatever parameters are set in the configuration are 34 * also going to be available in all method arguments related to this input 35 * format (context in getSplits and createVertexReader; methods invoked on 36 * MappingReader). So if backing input format relies on some parameters from 37 * configuration, you can safely set them for example in 38 * {@link #setConf(org.apache.giraph.conf.ImmutableClassesGiraphConfiguration)}. 39 * 40 * @param <I> vertexId type 41 * @param <V> vertexValue type 42 * @param <E> edgeValue type 43 * @param <B> mappingTarget type 44 */ 45 @SuppressWarnings("unchecked") 46 public abstract class MappingInputFormat<I extends WritableComparable, 47 V extends Writable, E extends Writable, B extends Writable> 48 extends GiraphInputFormat<I, V, E> { 49 50 /** 51 * Create a vertex reader for a given split. Guaranteed to have been 52 * configured with setConf() prior to use. The framework will also call 53 * {@link VertexReader#initialize(InputSplit, 54 * org.apache.hadoop.mapreduce.TaskAttemptContext)} before 55 * the split is used. 56 * 57 * @param split the split to be read 58 * @param context the information about the task 59 * @return a new record reader 60 * @throws IOException 61 */ 62 public abstract MappingReader<I, V, E, B> createMappingReader( 63 InputSplit split, TaskAttemptContext context) throws IOException; 64 }