co.cask.cdap.etl.spark.function.AggregatorGroupByFunction.java Source code

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Here is the source code for co.cask.cdap.etl.spark.function.AggregatorGroupByFunction.java

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/*
 * Copyright  2016 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.etl.spark.function;

import co.cask.cdap.etl.api.Emitter;
import co.cask.cdap.etl.api.Transformation;
import co.cask.cdap.etl.api.batch.BatchAggregator;
import co.cask.cdap.etl.common.DefaultEmitter;
import co.cask.cdap.etl.common.TrackedTransform;
import org.apache.spark.api.java.function.PairFlatMapFunction;
import scala.Tuple2;

/**
 * Function that uses a BatchAggregator to perform the groupBy part of the aggregator.
 * Non-serializable fields are lazily created since this is used in a Spark closure.
 *
 * @param <GROUP_KEY> type of group key
 * @param <GROUP_VAL> type of group val
 */
public class AggregatorGroupByFunction<GROUP_KEY, GROUP_VAL>
        implements PairFlatMapFunction<GROUP_VAL, GROUP_KEY, GROUP_VAL> {
    private final PluginFunctionContext pluginFunctionContext;
    private transient TrackedTransform<GROUP_VAL, Tuple2<GROUP_KEY, GROUP_VAL>> groupByFunction;
    private transient DefaultEmitter<Tuple2<GROUP_KEY, GROUP_VAL>> emitter;

    public AggregatorGroupByFunction(PluginFunctionContext pluginFunctionContext) {
        this.pluginFunctionContext = pluginFunctionContext;
    }

    @Override
    public Iterable<Tuple2<GROUP_KEY, GROUP_VAL>> call(GROUP_VAL input) throws Exception {
        if (groupByFunction == null) {
            BatchAggregator<GROUP_KEY, GROUP_VAL, ?> aggregator = pluginFunctionContext.createPlugin();
            aggregator.initialize(pluginFunctionContext.createBatchRuntimeContext());
            groupByFunction = new TrackedTransform<>(new GroupByTransform<>(aggregator),
                    pluginFunctionContext.createStageMetrics(), TrackedTransform.RECORDS_IN, null,
                    pluginFunctionContext.getDataTracer());
            emitter = new DefaultEmitter<>();
        }
        emitter.reset();
        groupByFunction.transform(input, emitter);
        return emitter.getEntries();
    }

    private static class GroupByTransform<GROUP_KEY, GROUP_VAL>
            implements Transformation<GROUP_VAL, Tuple2<GROUP_KEY, GROUP_VAL>> {
        private final BatchAggregator<GROUP_KEY, GROUP_VAL, ?> aggregator;
        private final DefaultEmitter<GROUP_KEY> keyEmitter;

        GroupByTransform(BatchAggregator<GROUP_KEY, GROUP_VAL, ?> aggregator) {
            this.aggregator = aggregator;
            this.keyEmitter = new DefaultEmitter<>();
        }

        @Override
        public void transform(final GROUP_VAL inputValue, Emitter<Tuple2<GROUP_KEY, GROUP_VAL>> emitter)
                throws Exception {
            keyEmitter.reset();
            aggregator.groupBy(inputValue, keyEmitter);
            for (GROUP_KEY key : keyEmitter.getEntries()) {
                emitter.emit(new Tuple2<>(key, inputValue));
            }
        }
    }
}