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.hadoop.mapred;
20
21 import java.io.IOException;
22
23
24 import org.apache.hadoop.conf.Configuration;
25 import org.apache.hadoop.fs.FileSystem;
26 import org.apache.hadoop.fs.Path;
27 import org.apache.hadoop.io;
28 import org.apache.hadoop.util.ReflectionUtils;
29
30 /** An {@link RecordReader} for {@link SequenceFile}s. */
31 public class SequenceFileRecordReader implements RecordReader {
32 private SequenceFile.Reader in;
33 private long start;
34 private long end;
35 private boolean more = true;
36 protected Configuration conf;
37
38 public SequenceFileRecordReader(Configuration conf, FileSplit split)
39 throws IOException {
40 Path path = split.getPath();
41 FileSystem fs = path.getFileSystem(conf);
42 this.in = new SequenceFile.Reader(fs, path, conf);
43 this.end = split.getStart() + split.getLength();
44 this.conf = conf;
45
46 if (split.getStart() > in.getPosition())
47 in.sync(split.getStart()); // sync to start
48
49 this.start = in.getPosition();
50 more = start < end;
51 }
52
53
54 /** The class of key that must be passed to {@link
55 * #next(Writable,Writable)}.. */
56 public Class getKeyClass() { return in.getKeyClass(); }
57
58 /** The class of value that must be passed to {@link
59 * #next(Writable,Writable)}.. */
60 public Class getValueClass() { return in.getValueClass(); }
61
62 public WritableComparable createKey() {
63 return (WritableComparable) ReflectionUtils.newInstance(getKeyClass(),
64 conf);
65 }
66
67 public Writable createValue() {
68 return (Writable) ReflectionUtils.newInstance(getValueClass(), conf);
69 }
70
71 public synchronized boolean next(Writable key, Writable value)
72 throws IOException {
73 if (!more) return false;
74 long pos = in.getPosition();
75 boolean eof = in.next(key, value);
76 if (pos >= end && in.syncSeen()) {
77 more = false;
78 } else {
79 more = eof;
80 }
81 return more;
82 }
83
84 protected synchronized boolean next(Writable key)
85 throws IOException {
86 if (!more) return false;
87 long pos = in.getPosition();
88 boolean eof = in.next(key);
89 if (pos >= end && in.syncSeen()) {
90 more = false;
91 } else {
92 more = eof;
93 }
94 return more;
95 }
96
97 protected synchronized void getCurrentValue(Writable value)
98 throws IOException {
99 in.getCurrentValue(value);
100 }
101
102 /**
103 * Return the progress within the input split
104 * @return 0.0 to 1.0 of the input byte range
105 */
106 public float getProgress() throws IOException {
107 if (end == start) {
108 return 0.0f;
109 } else {
110 return Math.min(1.0f, (in.getPosition() - start) / (float)(end - start));
111 }
112 }
113
114 public synchronized long getPos() throws IOException {
115 return in.getPosition();
116 }
117
118 protected synchronized void seek(long pos) throws IOException {
119 in.seek(pos);
120 }
121 public synchronized void close() throws IOException { in.close(); }
122
123 }
124
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