hadoop XMLParserMapper 源码
haddop XMLParserMapper 代码
文件路径：/hadoop-tools/hadoop-dynamometer/hadoop-dynamometer-blockgen/src/main/java/org/apache/hadoop/tools/dynamometer/blockgenerator/XMLParserMapper.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.tools.dynamometer.blockgenerator;
import java.io.IOException;
import java.util.List;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Mapper;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* This Mapper class generates a list of {@link BlockInfo}'s from a given
* fsimage.
*
* Input: fsimage in XML format. It should be generated using
* {@code org.apache.hadoop.hdfs.tools.offlineImageViewer.OfflineImageViewer}.
*
* Output: list of all {@link BlockInfo}'s
*/
public class XMLParserMapper
extends Mapper<LongWritable, Text, IntWritable, BlockInfo> {
private static final Logger LOG =
LoggerFactory.getLogger(XMLParserMapper.class);
@Override
public void setup(Mapper.Context context) {
Configuration conf = context.getConfiguration();
numDataNodes = conf.getInt(GenerateBlockImagesDriver.NUM_DATANODES_KEY, -1);
parser = new XMLParser();
}
// Blockindexes should be generated serially
private int blockIndex = 0;
private int numDataNodes;
private XMLParser parser;
/**
* Read the input XML file line by line, and generate list of blocks. The
* actual parsing logic is handled by {@link XMLParser}. This mapper just
* delegates to that class and then writes the blocks to the corresponding
* index to be processed by reducers.
*/
@Override
public void map(LongWritable lineNum, Text line,
Mapper<LongWritable, Text, IntWritable, BlockInfo>.Context context)
throws IOException, InterruptedException {
List<BlockInfo> blockInfos = parser.parseLine(line.toString());
for (BlockInfo blockInfo : blockInfos) {
for (short i = 0; i < blockInfo.getReplication(); i++) {
context.write(new IntWritable((blockIndex + i) % numDataNodes),
blockInfo);
}
blockIndex++;
if (blockIndex % 1000000 == 0) {
LOG.info("Processed " + blockIndex + " blocks");
}
}
}
}
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