org.apache.hadoop.streaming.mapreduce.StreamBaseRecordReader.java Source code

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Here is the source code for org.apache.hadoop.streaming.mapreduce.StreamBaseRecordReader.java

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/**
 * 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<Text, Text> {

    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_;

}