co.cask.cdap.internal.app.runtime.batch.dataset.DataSetInputFormat.java Source code

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/*
 * Copyright  2014-2015 Cask Data, Inc.
 *
 * 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 co.cask.cdap.internal.app.runtime.batch.dataset;

import co.cask.cdap.api.data.batch.BatchReadable;
import co.cask.cdap.api.data.batch.Split;
import co.cask.cdap.api.data.batch.SplitReader;
import co.cask.cdap.app.metrics.MapReduceMetrics;
import co.cask.cdap.internal.app.runtime.batch.BasicMapReduceContext;
import co.cask.cdap.internal.app.runtime.batch.MapReduceContextConfig;
import co.cask.cdap.internal.app.runtime.batch.MapReduceContextProvider;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.mapreduce.InputFormat;
import org.apache.hadoop.mapreduce.InputSplit;
import org.apache.hadoop.mapreduce.Job;
import org.apache.hadoop.mapreduce.JobContext;
import org.apache.hadoop.mapreduce.RecordReader;
import org.apache.hadoop.mapreduce.TaskAttemptContext;

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

/**
 * An {@link InputFormat} that reads from dataset.
 * @param <KEY> Type of key.
 * @param <VALUE> Type of value.
 */
public final class DataSetInputFormat<KEY, VALUE> extends InputFormat<KEY, VALUE> {

    public static final String HCONF_ATTR_INPUT_DATASET = "input.dataset.name";

    public static void setInput(Job job, String inputDatasetName) {
        job.setInputFormatClass(DataSetInputFormat.class);
        job.getConfiguration().set(DataSetInputFormat.HCONF_ATTR_INPUT_DATASET, inputDatasetName);
    }

    @Override
    public List<InputSplit> getSplits(final JobContext context) throws IOException, InterruptedException {
        MapReduceContextConfig mrContextConfig = new MapReduceContextConfig(context.getConfiguration());
        List<Split> splits = mrContextConfig.getInputSelection();
        List<InputSplit> list = new ArrayList<>();
        for (Split split : splits) {
            list.add(new DataSetInputSplit(split));
        }
        return list;
    }

    @SuppressWarnings("unchecked")
    @Override
    public RecordReader<KEY, VALUE> createRecordReader(final InputSplit split, final TaskAttemptContext context)
            throws IOException, InterruptedException {

        DataSetInputSplit inputSplit = (DataSetInputSplit) split;

        Configuration conf = context.getConfiguration();
        // we don't currently allow datasets as the format between map and reduce stages, otherwise we'll have to
        // pass in the stage here instead of hardcoding mapper.
        MapReduceContextProvider contextProvider = new MapReduceContextProvider(context,
                MapReduceMetrics.TaskType.Mapper);
        BasicMapReduceContext mrContext = contextProvider.get();
        mrContext.getMetricsCollectionService().startAndWait();
        String dataSetName = getInputName(conf);
        BatchReadable<KEY, VALUE> inputDataset = mrContext.getDataset(dataSetName);
        SplitReader<KEY, VALUE> splitReader = inputDataset.createSplitReader(inputSplit.getSplit());

        // the record reader now owns the context and will close it
        return new DataSetRecordReader<>(splitReader, contextProvider);
    }

    private String getInputName(Configuration conf) {
        return conf.get(HCONF_ATTR_INPUT_DATASET);
    }
}