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

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Here is the source code for co.cask.cdap.etl.spark.function.JoinOnFunction.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.BatchJoiner;
import co.cask.cdap.etl.api.batch.BatchJoinerRuntimeContext;
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 BatchJoiner to perform the joinOn part of the join.
 * Non-serializable fields are lazily created since this is used in a Spark closure.
 *
 * @param <JOIN_KEY> the type of join key
 * @param <INPUT_RECORD> the type of input records to the join stage
 */
public class JoinOnFunction<JOIN_KEY, INPUT_RECORD>
        implements PairFlatMapFunction<INPUT_RECORD, JOIN_KEY, INPUT_RECORD> {

    private final PluginFunctionContext pluginFunctionContext;
    private final String inputStageName;
    private transient TrackedTransform<INPUT_RECORD, Tuple2<JOIN_KEY, INPUT_RECORD>> joinFunction;
    private transient DefaultEmitter<Tuple2<JOIN_KEY, INPUT_RECORD>> emitter;

    public JoinOnFunction(PluginFunctionContext pluginFunctionContext, String inputStageName) {
        this.pluginFunctionContext = pluginFunctionContext;
        this.inputStageName = inputStageName;
    }

    @Override
    public Iterable<Tuple2<JOIN_KEY, INPUT_RECORD>> call(INPUT_RECORD input) throws Exception {
        if (joinFunction == null) {
            BatchJoiner<JOIN_KEY, INPUT_RECORD, Object> joiner = pluginFunctionContext.createPlugin();
            BatchJoinerRuntimeContext context = pluginFunctionContext.createBatchRuntimeContext();
            joiner.initialize(context);
            joinFunction = new TrackedTransform<>(new JoinOnTransform<>(joiner, inputStageName),
                    pluginFunctionContext.createStageMetrics(), TrackedTransform.RECORDS_IN, null,
                    pluginFunctionContext.getDataTracer());
            emitter = new DefaultEmitter<>();
        }
        emitter.reset();
        joinFunction.transform(input, emitter);
        return emitter.getEntries();
    }

    private static class JoinOnTransform<INPUT, JOIN_KEY>
            implements Transformation<INPUT, Tuple2<JOIN_KEY, INPUT>> {
        private final BatchJoiner<JOIN_KEY, INPUT, ?> joiner;
        private final String inputStageName;

        JoinOnTransform(BatchJoiner<JOIN_KEY, INPUT, ?> joiner, String inputStageName) {
            this.joiner = joiner;
            this.inputStageName = inputStageName;
        }

        @Override
        public void transform(final INPUT inputValue, Emitter<Tuple2<JOIN_KEY, INPUT>> emitter) throws Exception {
            emitter.emit(new Tuple2<>(joiner.joinOn(inputStageName, inputValue), inputValue));
        }
    }
}