co.cask.cdap.internal.app.runtime.spark.dataset.SparkDatasetInputFormat.java Source code

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/*
 * Copyright  2014 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.spark.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.api.dataset.Dataset;
import co.cask.cdap.api.spark.Spark;
import co.cask.cdap.internal.app.runtime.batch.dataset.DataSetInputSplit;
import co.cask.cdap.internal.app.runtime.spark.ExecutionSparkContext;
import co.cask.cdap.internal.app.runtime.spark.SparkContextProvider;
import com.google.common.reflect.TypeToken;
import com.google.gson.Gson;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.mapreduce.InputFormat;
import org.apache.hadoop.mapreduce.InputSplit;
import org.apache.hadoop.mapreduce.JobContext;
import org.apache.hadoop.mapreduce.RecordReader;
import org.apache.hadoop.mapreduce.TaskAttemptContext;

import java.io.IOException;
import java.lang.reflect.Type;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;

/**
 * An {@link InputFormat} for {@link Spark} jobs that reads from {@link Dataset}.
 *
 * @param <KEY>   Type of key.
 * @param <VALUE> Type of value.
 *                TODO: Refactor this and MapReduce DatasetInputFormat
 */
public final class SparkDatasetInputFormat<KEY, VALUE> extends InputFormat<KEY, VALUE> {

    private static final Gson GSON = new Gson();
    private static final Type ARGS_TYPE = new TypeToken<Map<String, String>>() {
    }.getType();

    // Set of job configuration keys for setting configurations into job conf.
    private static final String INPUT_DATASET_NAME = "input.spark.dataset.name";
    private static final String INPUT_DATASET_ARGS = "input.spark.dataset.args";

    /**
     * Sets the configurations for the dataset name and configurations for the input format.
     */
    public static void setDataset(Configuration configuration, String dataset, Map<String, String> arguments) {
        configuration.set(INPUT_DATASET_NAME, dataset);
        configuration.set(INPUT_DATASET_ARGS, GSON.toJson(arguments, ARGS_TYPE));
    }

    @Override
    public List<InputSplit> getSplits(final JobContext context) throws IOException, InterruptedException {
        ExecutionSparkContext sparkContext = SparkContextProvider.getSparkContext();

        Configuration configuration = context.getConfiguration();
        Map<String, String> arguments = GSON.fromJson(configuration.get(INPUT_DATASET_ARGS), ARGS_TYPE);
        BatchReadable<?, ?> batchReadable = sparkContext.getBatchReadable(configuration.get(INPUT_DATASET_NAME),
                arguments);

        List<Split> splits = batchReadable.getSplits();
        List<InputSplit> list = new ArrayList<>(splits.size());
        for (Split split : splits) {
            list.add(new DataSetInputSplit(split));
        }
        return list;
    }

    @Override
    public RecordReader<KEY, VALUE> createRecordReader(InputSplit split, TaskAttemptContext context)
            throws IOException {
        DataSetInputSplit inputSplit = (DataSetInputSplit) split;
        BatchReadable<KEY, VALUE> batchReadable = getBatchReadable(context.getConfiguration());
        SplitReader<KEY, VALUE> splitReader = batchReadable.createSplitReader(inputSplit.getSplit());

        return new DatasetRecordReader<>(splitReader);
    }

    private BatchReadable<KEY, VALUE> getBatchReadable(Configuration configuration) {
        Map<String, String> args = GSON.fromJson(configuration.get(INPUT_DATASET_ARGS), ARGS_TYPE);
        return SparkContextProvider.getSparkContext().getBatchReadable(configuration.get(INPUT_DATASET_NAME), args);
    }
}