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 java.io.IOException;
22
23 import org.apache.giraph.graph.Vertex;
24 import org.apache.giraph.worker.WorkerAggregatorDelegator;
25 import org.apache.hadoop.io.Writable;
26 import org.apache.hadoop.io.WritableComparable;
27 import org.apache.hadoop.mapreduce.InputSplit;
28 import org.apache.hadoop.mapreduce.TaskAttemptContext;
29
30 /**
31 * Analogous to Hadoop's RecordReader for vertices. Will read the
32 * vertices from an input split.
33 *
34 * @param <I> Vertex id
35 * @param <V> Vertex data
36 * @param <E> Edge data
37 */
38 @SuppressWarnings("rawtypes")
39 public abstract class VertexReader<I extends WritableComparable,
40 V extends Writable, E extends Writable> extends
41 WorkerAggregatorDelegator<I, V, E> {
42 /**
43 * Use the input split and context to setup reading the vertices.
44 * Guaranteed to be called prior to any other function.
45 *
46 * @param inputSplit Input split to be used for reading vertices.
47 * @param context Context from the task.
48 * @throws IOException
49 * @throws InterruptedException
50 */
51 public abstract void initialize(InputSplit inputSplit,
52 TaskAttemptContext context)
53 throws IOException, InterruptedException;
54
55 /**
56 *
57 * @return false iff there are no more vertices
58 * @throws IOException
59 * @throws InterruptedException
60 */
61 public abstract boolean nextVertex() throws IOException,
62 InterruptedException;
63
64 /**
65 * Get the current vertex.
66 *
67 * @return the current vertex which has been read.
68 * nextVertex() should be called first.
69 * @throws IOException
70 * @throws InterruptedException
71 */
72 public abstract Vertex<I, V, E> getCurrentVertex()
73 throws IOException, InterruptedException;
74
75 /**
76 * Close this {@link VertexReader} to future operations.
77 *
78 * @throws IOException
79 */
80 public abstract void close() throws IOException;
81
82 /**
83 * How much of the input has the {@link VertexReader} consumed i.e.
84 * has been processed by?
85 *
86 * @return Progress from <code>0.0</code> to <code>1.0</code>.
87 * @throws IOException
88 * @throws InterruptedException
89 */
90 public abstract float getProgress() throws IOException, InterruptedException;
91 }