MapReduceBatchReadableInputFormat.java

/*
 * Copyright © 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;

import co.cask.cdap.api.data.batch.BatchReadable;
import co.cask.cdap.internal.app.runtime.batch.dataset.AbstractBatchReadableInputFormat;
import org.apache.hadoop.mapreduce.InputFormat;
import org.apache.hadoop.mapreduce.TaskAttemptContext;

import java.util.Map;

/**
 * An {@link InputFormat} for reading data from {@link BatchReadable} for MapReduce.
 * @param <KEY> Type of key.
 * @param <VALUE> Type of value.
 */
public final class MapReduceBatchReadableInputFormat<KEY, VALUE> extends AbstractBatchReadableInputFormat<KEY, VALUE> {

  @Override
  protected BatchReadable<KEY, VALUE> createBatchReadable(TaskAttemptContext context,
                                                          String datasetName, Map<String, String> datasetArgs) {

    MapReduceClassLoader classLoader = MapReduceClassLoader.getFromConfiguration(context.getConfiguration());
    BasicMapReduceTaskContext<?, ?> taskContext = classLoader.getTaskContextProvider().get(context);
    return taskContext.getBatchReadable(datasetName, datasetArgs);
  }
}