com.linkedin.haivvreo.AvroGenericRecordReader.java Source code

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Here is the source code for com.linkedin.haivvreo.AvroGenericRecordReader.java

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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.hive.ql.exec.Utilities;
import org.apache.hadoop.hive.ql.plan.MapredWork;
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 {
        // 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)
            return Schema.parse(s);

        // Inside of a MR job, we can pull out the actual properties
        if (Utilities.getHiveJobID(job) != null) {
            MapredWork mapRedWork = Utilities.getMapRedWork(job);

            // Iterate over the Path -> Partition descriptions to find the partition
            // that matches our input split.
            for (Map.Entry<String, PartitionDesc> pathsAndParts : mapRedWork.getPathToPartitionInfo().entrySet()) {
                String partitionPath = pathsAndParts.getKey();
                if (pathIsInPartition(split, 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(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.");
        }
        // No more places to get the schema from. Give up.  May have to re-encode later.
        return null;
    }

    private boolean pathIsInPartition(FileSplit split, String partitionPath) {
        return split.getPath().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;
    }
}