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Apache Hadoop MapReduce Streaming
/**
* 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.streaming.mapreduce;
import java.io.IOException;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FSDataInputStream;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.RecordReader;
import org.apache.hadoop.mapreduce.TaskAttemptContext;
import org.apache.hadoop.mapreduce.lib.input.FileSplit;
import org.apache.hadoop.streaming.StreamUtil;
/**
* Shared functionality for hadoopStreaming formats. A custom reader can be
* defined to be a RecordReader with the constructor below and is selected with
* the option bin/hadoopStreaming -inputreader ...
*
* @see StreamXmlRecordReader
*/
public abstract class StreamBaseRecordReader extends RecordReader {
protected static final Log LOG = LogFactory
.getLog(StreamBaseRecordReader.class.getName());
// custom JobConf properties for this class are prefixed with this namespace
final static String CONF_NS = "stream.recordreader.";
public StreamBaseRecordReader(FSDataInputStream in, FileSplit split,
TaskAttemptContext context, Configuration conf, FileSystem fs)
throws IOException {
in_ = in;
split_ = split;
start_ = split_.getStart();
length_ = split_.getLength();
end_ = start_ + length_;
splitName_ = split_.getPath().getName();
this.context_ = context;
conf_ = conf;
fs_ = fs;
statusMaxRecordChars_ = conf.getInt(CONF_NS + "statuschars", 200);
}
// / RecordReader API
/**
* Read a record. Implementation should call numRecStats at the end
*/
public abstract boolean next(Text key, Text value) throws IOException;
/** Returns the current position in the input. */
public synchronized long getPos() throws IOException {
return in_.getPos();
}
/** Close this to future operations. */
public synchronized void close() throws IOException {
in_.close();
}
public float getProgress() throws IOException {
if (end_ == start_) {
return 1.0f;
} else {
return ((float) (in_.getPos() - start_)) / ((float) (end_ - start_));
}
}
public Text createKey() {
return new Text();
}
public Text createValue() {
return new Text();
}
// / StreamBaseRecordReader API
/**
* Implementation should seek forward in_ to the first byte of the next
* record. The initial byte offset in the stream is arbitrary.
*/
public abstract void seekNextRecordBoundary() throws IOException;
void numRecStats(byte[] record, int start, int len) throws IOException {
numRec_++;
if (numRec_ == nextStatusRec_) {
String recordStr = new String(record, start, Math.min(len,
statusMaxRecordChars_), "UTF-8");
nextStatusRec_ += 100;// *= 10;
String status = getStatus(recordStr);
LOG.info(status);
context_.setStatus(status);
}
}
long lastMem = 0;
String getStatus(CharSequence record) {
long pos = -1;
try {
pos = getPos();
} catch (IOException io) {
}
String recStr;
if (record.length() > statusMaxRecordChars_) {
recStr = record.subSequence(0, statusMaxRecordChars_) + "...";
} else {
recStr = record.toString();
}
String unqualSplit = split_.getPath().getName() + ":" + split_.getStart()
+ "+" + split_.getLength();
String status = "HSTR " + StreamUtil.getHost() + " " + numRec_ + ". pos="
+ pos + " " + unqualSplit + " Processing record=" + recStr;
status += " " + splitName_;
return status;
}
FSDataInputStream in_;
FileSplit split_;
long start_;
long end_;
long length_;
String splitName_;
TaskAttemptContext context_;
Configuration conf_;
FileSystem fs_;
int numRec_ = 0;
int nextStatusRec_ = 1;
int statusMaxRecordChars_;
}