//cc CutLoadFunc A LoadFunc UDF to load tuple fields as column ranges
package com.hadoopbook.pig;
import java.io.IOException;
import java.util.List;
import org.apache.commons.logging.LogFactory;
import org.apache.commons.logging.Log;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.InputFormat;
import org.apache.hadoop.mapreduce.Job;
import org.apache.hadoop.mapreduce.RecordReader;
import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
import org.apache.hadoop.mapreduce.lib.input.TextInputFormat;
import org.apache.pig.LoadFunc;
import org.apache.pig.backend.executionengine.ExecException;
import org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.PigSplit;
import org.apache.pig.data.DataByteArray;
import org.apache.pig.data.Tuple;
import org.apache.pig.data.TupleFactory;
// vv CutLoadFunc
public class CutLoadFunc extends LoadFunc {
private static final Log LOG = LogFactory.getLog(CutLoadFunc.class);
private final List<Range> ranges;
private final TupleFactory tupleFactory = TupleFactory.getInstance();
private RecordReader reader;
public CutLoadFunc(String cutPattern) {
ranges = Range.parse(cutPattern);
}
@Override
public void setLocation(String location, Job job)
throws IOException {
FileInputFormat.setInputPaths(job, location);
}
@Override
public InputFormat getInputFormat() {
return new TextInputFormat();
}
@Override
public void prepareToRead(RecordReader reader, PigSplit split) {
this.reader = reader;
}
@Override
public Tuple getNext() throws IOException {
try {
if (!reader.nextKeyValue()) {
return null;
}
Text value = (Text) reader.getCurrentValue();
String line = value.toString();
Tuple tuple = tupleFactory.newTuple(ranges.size());
for (int i = 0; i < ranges.size(); i++) {
Range range = ranges.get(i);
if (range.getEnd() > line.length()) {
LOG.warn(String.format(
"Range end (%s) is longer than line length (%s)",
range.getEnd(), line.length()));
continue;
}
tuple.set(i, new DataByteArray(range.getSubstring(line)));
}
return tuple;
} catch (InterruptedException e) {
throw new ExecException(e);
}
}
}
// ^^ CutLoadFunc