hadoop VirtualRecordReader 源码
haddop VirtualRecordReader 代码
文件路径：/hadoop-tools/hadoop-dynamometer/hadoop-dynamometer-workload/src/main/java/org/apache/hadoop/tools/dynamometer/workloadgenerator/VirtualRecordReader.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.workloadgenerator;
import java.io.IOException;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.io.NullWritable;
import org.apache.hadoop.mapreduce.InputSplit;
import org.apache.hadoop.mapreduce.RecordReader;
import org.apache.hadoop.mapreduce.TaskAttemptContext;
/**
* A simple fake record reader which simply runs for some time duration.
*/
@SuppressWarnings("unchecked")
public class VirtualRecordReader<K, V> extends RecordReader<K, V> {
private int durationMs;
private long startTimestampInMs;
private long endTimestampInMs;
private int numRows = 1;
@Override
public void initialize(InputSplit split, TaskAttemptContext context)
throws IOException, InterruptedException {
Configuration conf = context.getConfiguration();
durationMs = conf.getInt(CreateFileMapper.DURATION_MIN_KEY, 0) * 60 * 1000;
startTimestampInMs = conf.getInt(WorkloadDriver.START_TIMESTAMP_MS, 0);
endTimestampInMs = startTimestampInMs + durationMs;
}
// The map function per split should be invoked only once.
@Override
public boolean nextKeyValue() throws IOException, InterruptedException {
if (numRows > 0) {
numRows--;
return true;
} else {
return false;
}
}
@Override
public K getCurrentKey() throws IOException, InterruptedException {
return (K) NullWritable.get();
}
@Override
public V getCurrentValue() throws IOException, InterruptedException {
return (V) NullWritable.get();
}
@Override
public float getProgress() throws IOException, InterruptedException {
long remainingMs = endTimestampInMs - System.currentTimeMillis();
return (remainingMs * 100.0f) / durationMs;
}
@Override
public void close() throws IOException {
// do Nothing
}
};
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