hadoop SequenceFileAsBinaryInputFormat 源码
haddop SequenceFileAsBinaryInputFormat 代码
文件路径:/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapred/SequenceFileAsBinaryInputFormat.java
/**
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.hadoop.mapred;
import java.io.IOException;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.BytesWritable;
import org.apache.hadoop.io.DataOutputBuffer;
import org.apache.hadoop.io.SequenceFile;
/**
* InputFormat reading keys, values from SequenceFiles in binary (raw)
* format.
*/
@InterfaceAudience.Public
@InterfaceStability.Stable
public class SequenceFileAsBinaryInputFormat
extends SequenceFileInputFormat<BytesWritable,BytesWritable> {
public SequenceFileAsBinaryInputFormat() {
super();
}
public RecordReader<BytesWritable,BytesWritable> getRecordReader(
InputSplit split, JobConf job, Reporter reporter)
throws IOException {
return new SequenceFileAsBinaryRecordReader(job, (FileSplit)split);
}
/**
* Read records from a SequenceFile as binary (raw) bytes.
*/
public static class SequenceFileAsBinaryRecordReader
implements RecordReader<BytesWritable,BytesWritable> {
private SequenceFile.Reader in;
private long start;
private long end;
private boolean done = false;
private DataOutputBuffer buffer = new DataOutputBuffer();
private SequenceFile.ValueBytes vbytes;
public SequenceFileAsBinaryRecordReader(Configuration conf, FileSplit split)
throws IOException {
Path path = split.getPath();
FileSystem fs = path.getFileSystem(conf);
this.in = new SequenceFile.Reader(fs, path, conf);
this.end = split.getStart() + split.getLength();
if (split.getStart() > in.getPosition())
in.sync(split.getStart()); // sync to start
this.start = in.getPosition();
vbytes = in.createValueBytes();
done = start >= end;
}
public BytesWritable createKey() {
return new BytesWritable();
}
public BytesWritable createValue() {
return new BytesWritable();
}
/**
* Retrieve the name of the key class for this SequenceFile.
* @see org.apache.hadoop.io.SequenceFile.Reader#getKeyClassName
*/
public String getKeyClassName() {
return in.getKeyClassName();
}
/**
* Retrieve the name of the value class for this SequenceFile.
* @see org.apache.hadoop.io.SequenceFile.Reader#getValueClassName
*/
public String getValueClassName() {
return in.getValueClassName();
}
/**
* Read raw bytes from a SequenceFile.
*/
public synchronized boolean next(BytesWritable key, BytesWritable val)
throws IOException {
if (done) return false;
long pos = in.getPosition();
boolean eof = -1 == in.nextRawKey(buffer);
if (!eof) {
key.set(buffer.getData(), 0, buffer.getLength());
buffer.reset();
in.nextRawValue(vbytes);
vbytes.writeUncompressedBytes(buffer);
val.set(buffer.getData(), 0, buffer.getLength());
buffer.reset();
}
return !(done = (eof || (pos >= end && in.syncSeen())));
}
public long getPos() throws IOException {
return in.getPosition();
}
public void close() throws IOException {
in.close();
}
/**
* Return the progress within the input split
* @return 0.0 to 1.0 of the input byte range
*/
public float getProgress() throws IOException {
if (end == start) {
return 0.0f;
} else {
return Math.min(1.0f, (float)((in.getPosition() - start) /
(double)(end - start)));
}
}
}
}
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