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 * Input format for reading single edges. Provides access to 30 * ImmutableClassesGiraphConfiguration. 31 * 32 * It's guaranteed that whatever parameters are set in the configuration are 33 * also going to be available in all method arguments related to this input 34 * format (context in getSplits and createEdgeReader; methods invoked on 35 * EdgeReader). So if backing input format relies on some parameters from 36 * configuration, you can safely set them for example in 37 * {@link #setConf(org.apache.giraph.conf.ImmutableClassesGiraphConfiguration)}. 38 * 39 * @param <I> Vertex id 40 * @param <E> Edge data 41 */ 42 public abstract class EdgeInputFormat<I extends WritableComparable, 43 E extends Writable> extends GiraphInputFormat<I, Writable, E> { 44 /** 45 * Create an edge reader for a given split. The framework will call 46 * {@link EdgeReader#initialize(InputSplit, TaskAttemptContext)} before 47 * the split is used. 48 * 49 * @param split the split to be read 50 * @param context the information about the task 51 * @return a new record reader 52 * @throws IOException 53 */ 54 public abstract EdgeReader<I, E> createEdgeReader( 55 InputSplit split, 56 TaskAttemptContext context) throws IOException; 57 }