/*
* 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.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 org.slf4j.Logger;
import org.slf4j.LoggerFactory;
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> {
private static final Logger LOG = LoggerFactory.getLogger(DataSetInputFormat.class);
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);
List<Split> splits = mrContextConfig.getInputSelection();
List<InputSplit> list = new ArrayList<InputSplit>();
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 = (BatchReadable<KEY, VALUE>) 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<KEY, VALUE>(splitReader, mrContext, dataSetName);
}
private String getInputName(Configuration conf) {
return conf.get(HCONF_ATTR_INPUT_DATASET);
}
}