org.apache.hama.bsp.KeyValueLineRecordReader.java Source code

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Here is the source code for org.apache.hama.bsp.KeyValueLineRecordReader.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.hama.bsp;

import java.io.IOException;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.Text;

/**
 * This class treats a line in the input as a key/value pair separated by a
 * separator character. The separator can be specified in config file under the
 * attribute name key.value.separator.in.input.line. The default separator is
 * the tab character ('\t').
 */
public class KeyValueLineRecordReader implements RecordReader<Text, Text> {

    private final LineRecordReader lineRecordReader;

    private byte separator = (byte) '\t';

    private LongWritable dummyKey;

    private Text innerValue;

    @SuppressWarnings("rawtypes")
    public Class getKeyClass() {
        return Text.class;
    }

    public Text createKey() {
        return new Text();
    }

    public Text createValue() {
        return new Text();
    }

    public KeyValueLineRecordReader(Configuration job, FileSplit split) throws IOException {

        lineRecordReader = new LineRecordReader(job, split);
        dummyKey = lineRecordReader.createKey();
        innerValue = lineRecordReader.createValue();
        String sepStr = job.get("key.value.separator.in.input.line", "\t");
        this.separator = (byte) sepStr.charAt(0);
    }

    public static int findSeparator(byte[] utf, int start, int length, byte sep) {
        for (int i = start; i < (start + length); i++) {
            if (utf[i] == sep) {
                return i;
            }
        }
        return -1;
    }

    /** Read key/value pair in a line. */
    public synchronized boolean next(Text key, Text value) throws IOException {
        Text tKey = key;
        Text tValue = value;
        byte[] line = null;
        int lineLen = -1;
        if (lineRecordReader.next(dummyKey, innerValue)) {
            line = innerValue.getBytes();
            lineLen = innerValue.getLength();
        } else {
            return false;
        }
        if (line == null)
            return false;
        int pos = findSeparator(line, 0, lineLen, this.separator);
        if (pos == -1) {
            tKey.set(line, 0, lineLen);
            tValue.set("");
        } else {
            int keyLen = pos;
            byte[] keyBytes = new byte[keyLen];
            System.arraycopy(line, 0, keyBytes, 0, keyLen);
            int valLen = lineLen - keyLen - 1;
            byte[] valBytes = new byte[valLen];
            System.arraycopy(line, pos + 1, valBytes, 0, valLen);
            tKey.set(keyBytes);
            tValue.set(valBytes);
        }
        return true;
    }

    public float getProgress() {
        return lineRecordReader.getProgress();
    }

    public synchronized long getPos() throws IOException {
        return lineRecordReader.getPos();
    }

    public synchronized void close() throws IOException {
        lineRecordReader.close();
    }
}