org.apache.carbondata.hadoop.CarbonRecordReader.java Source code

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Here is the source code for org.apache.carbondata.hadoop.CarbonRecordReader.java

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/*
 * 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.carbondata.hadoop;

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;

import org.apache.carbondata.common.CarbonIterator;
import org.apache.carbondata.core.cache.dictionary.Dictionary;
import org.apache.carbondata.core.carbon.datastore.block.TableBlockInfo;
import org.apache.carbondata.core.util.CarbonUtil;
import org.apache.carbondata.hadoop.readsupport.CarbonReadSupport;
import org.apache.carbondata.scan.executor.QueryExecutorFactory;
import org.apache.carbondata.scan.executor.exception.QueryExecutionException;
import org.apache.carbondata.scan.model.QueryModel;
import org.apache.carbondata.scan.result.BatchResult;
import org.apache.carbondata.scan.result.iterator.ChunkRowIterator;

import org.apache.hadoop.mapreduce.InputSplit;
import org.apache.hadoop.mapreduce.RecordReader;
import org.apache.hadoop.mapreduce.TaskAttemptContext;

/**
 * Reads the data from Carbon store.
 */
public class CarbonRecordReader<T> extends RecordReader<Void, T> {

    private QueryModel queryModel;

    private CarbonReadSupport<T> readSupport;

    private CarbonIterator<Object[]> carbonIterator;

    public CarbonRecordReader(QueryModel queryModel, CarbonReadSupport<T> readSupport) {
        this.queryModel = queryModel;
        this.readSupport = readSupport;
    }

    @Override
    public void initialize(InputSplit split, TaskAttemptContext context) throws IOException, InterruptedException {
        CarbonInputSplit carbonInputSplit = (CarbonInputSplit) split;
        List<TableBlockInfo> tableBlockInfoList = new ArrayList<TableBlockInfo>();
        tableBlockInfoList.add(new TableBlockInfo(carbonInputSplit.getPath().toString(),
                carbonInputSplit.getStart(), carbonInputSplit.getSegmentId(), carbonInputSplit.getLocations(),
                carbonInputSplit.getLength()));
        queryModel.setTableBlockInfos(tableBlockInfoList);
        readSupport.intialize(queryModel.getProjectionColumns(), queryModel.getAbsoluteTableIdentifier());
        try {
            carbonIterator = new ChunkRowIterator((CarbonIterator<BatchResult>) QueryExecutorFactory
                    .getQueryExecutor(queryModel).execute(queryModel));
        } catch (QueryExecutionException e) {
            throw new InterruptedException(e.getMessage());
        }
    }

    @Override
    public boolean nextKeyValue() {
        return carbonIterator.hasNext();

    }

    @Override
    public Void getCurrentKey() throws IOException, InterruptedException {
        return null;
    }

    @Override
    public T getCurrentValue() throws IOException, InterruptedException {
        return readSupport.readRow(carbonIterator.next());
    }

    @Override
    public float getProgress() throws IOException, InterruptedException {
        // TODO : Implement it based on total number of rows it is going to retrive.
        return 0;
    }

    @Override
    public void close() throws IOException {
        // clear dictionary cache
        Map<String, Dictionary> columnToDictionaryMapping = queryModel.getColumnToDictionaryMapping();
        if (null != columnToDictionaryMapping) {
            for (Map.Entry<String, Dictionary> entry : columnToDictionaryMapping.entrySet()) {
                CarbonUtil.clearDictionaryCache(entry.getValue());
            }
        }
        // close read support
        readSupport.close();
    }
}