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/*
* Copyright 2011 LinkedIn
*
* Licensed 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 com.linkedin.haivvreo;
import org.apache.avro.Schema;
import org.apache.avro.file.DataFileReader;
import org.apache.avro.generic.GenericData;
import org.apache.avro.generic.GenericDatumReader;
import org.apache.avro.generic.GenericRecord;
import org.apache.avro.mapred.FsInput;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.hive.ql.exec.Utilities;
import org.apache.hadoop.hive.ql.plan.MapWork;
import org.apache.hadoop.hive.ql.plan.PartitionDesc;
import org.apache.hadoop.io.NullWritable;
import org.apache.hadoop.mapred.*;
import java.io.IOException;
import java.util.Map;
import java.util.Properties;
/**
* RecordReader optimized against Avro GenericRecords that returns to record
* as the value of the k-v pair, as Hive requires.
*/
public class AvroGenericRecordReader implements RecordReader<NullWritable, AvroGenericRecordWritable>, JobConfigurable {
private static final Log LOG = LogFactory.getLog(AvroGenericRecordReader.class);
final private org.apache.avro.file.FileReader<GenericRecord> reader;
final private long start;
final private long stop;
protected JobConf jobConf;
public AvroGenericRecordReader(JobConf job, FileSplit split, Reporter reporter) throws IOException {
this.jobConf = job;
Schema latest;
try {
latest = getSchema(job, split);
} catch (HaivvreoException e) {
throw new IOException(e);
}
GenericDatumReader<GenericRecord> gdr = new GenericDatumReader<GenericRecord>();
if(latest != null) gdr.setExpected(latest);
this.reader = new DataFileReader<GenericRecord>(new FsInput(split.getPath(), job), gdr);
this.reader.sync(split.getStart());
this.start = reader.tell();
this.stop = split.getStart() + split.getLength();
}
/**
* Attempt to retrieve the reader schema. Haivvreo has a couple opportunities
* to provide this, depending on whether or not we're just selecting data
* or running with a MR job.
* @return Reader schema for the Avro object, or null if it has not been provided.
* @throws HaivvreoException
*/
private Schema getSchema(JobConf job, FileSplit split) throws HaivvreoException, IOException {
FileSystem fs = split.getPath().getFileSystem(job);
// Inside of a MR job, we can pull out the actual properties
if(HaivvreoUtils.insideMRJob(job)) {
MapWork mapWork = Utilities.getMapWork(job);
// Iterate over the Path -> Partition descriptions to find the partition
// that matches our input split.
for (Map.Entry<String,PartitionDesc> pathsAndParts: mapWork.getPathToPartitionInfo().entrySet()){
String partitionPath = pathsAndParts.getKey();
if(pathIsInPartition(split.getPath().makeQualified(fs), partitionPath)) {
if(LOG.isInfoEnabled()) LOG.info("Matching partition " + partitionPath + " with input split " + split);
Properties props = pathsAndParts.getValue().getProperties();
if(props.containsKey(HaivvreoUtils.SCHEMA_LITERAL) || props.containsKey(HaivvreoUtils.SCHEMA_URL)) {
return HaivvreoUtils.determineSchemaOrThrowException(job, props);
} else
return null; // If it's not in this property, it won't be in any others
}
}
if(LOG.isInfoEnabled()) LOG.info("Unable to match filesplit " + split + " with a partition.");
}
// In "select * from table" situations (non-MR), Haivvreo can add things to the job
// It's safe to add this to the job since it's not *actually* a mapred job.
// Here the global state is confined to just this process.
String s = job.get(AvroSerDe.HAIVVREO_SCHEMA);
if(s != null) {
LOG.info("Found the avro schema in the job: " + s);
return Schema.parse(s);
}
// No more places to get the schema from. Give up. May have to re-encode later.
return null;
}
private boolean pathIsInPartition(Path split, String partitionPath) {
return split.toString().startsWith(partitionPath);
}
@Override
public boolean next(NullWritable nullWritable, AvroGenericRecordWritable record) throws IOException {
if(!reader.hasNext() || reader.pastSync(stop)) return false;
GenericData.Record r = (GenericData.Record)reader.next();
record.setRecord(r);
return true;
}
@Override
public NullWritable createKey() {
return NullWritable.get();
}
@Override
public AvroGenericRecordWritable createValue() {
return new AvroGenericRecordWritable();
}
@Override
public long getPos() throws IOException {
return reader.tell();
}
@Override
public void close() throws IOException {
reader.close();
}
@Override
public float getProgress() throws IOException {
return stop == start ? 0.0f
: Math.min(1.0f, (getPos() - start) / (float)(stop - start));
}
@Override
public void configure(JobConf jobConf) {
this.jobConf= jobConf;
}
}
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