flink-tests/src/test/java/org/apache/flink/test/broadcastvars/BroadcastVarInitializationITCase.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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,
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 * See the License for the specific language governing permissions and
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 */

package org.apache.flink.test.broadcastvars;

import org.apache.flink.api.common.functions.BroadcastVariableInitializer;
import org.apache.flink.api.common.functions.RichGroupReduceFunction;
import org.apache.flink.api.java.DataSet;
import org.apache.flink.api.java.ExecutionEnvironment;
import org.apache.flink.api.java.io.LocalCollectionOutputFormat;
import org.apache.flink.api.java.operators.IterativeDataSet;
import org.apache.flink.configuration.Configuration;
import org.apache.flink.test.util.JavaProgramTestBase;
import org.apache.flink.util.Collector;

import org.junit.Assert;

import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

/** Test {@link BroadcastVariableInitializer}. */
@SuppressWarnings("serial")
public class BroadcastVarInitializationITCase extends JavaProgramTestBase {

    @Override
    protected void testProgram() throws Exception {

        ExecutionEnvironment env = ExecutionEnvironment.getExecutionEnvironment();
        env.setParallelism(4);

        DataSet<Integer> data = env.fromElements(1, 2, 3, 4, 5, 6, 7, 8);

        IterativeDataSet<Integer> iteration = data.iterate(10);

        DataSet<Integer> result =
                data.reduceGroup(new PickOneAllReduce()).withBroadcastSet(iteration, "bc");

        final List<Integer> resultList = new ArrayList<Integer>();
        iteration.closeWith(result).output(new LocalCollectionOutputFormat<Integer>(resultList));

        env.execute();

        Assert.assertEquals(8, resultList.get(0).intValue());
    }

    private static class PickOneAllReduce extends RichGroupReduceFunction<Integer, Integer> {

        private Integer bcValue;

        @Override
        public void open(Configuration parameters) {
            this.bcValue =
                    getRuntimeContext()
                            .getBroadcastVariableWithInitializer("bc", new PickFirstInitializer());
        }

        @Override
        public void reduce(Iterable<Integer> records, Collector<Integer> out) {
            if (bcValue == null) {
                return;
            }
            final int x = bcValue;

            for (Integer y : records) {
                if (y > x) {
                    out.collect(y);
                    return;
                }
            }

            out.collect(bcValue);
        }
    }

    private static class PickFirstInitializer
            implements BroadcastVariableInitializer<Integer, Integer> {

        @Override
        public Integer initializeBroadcastVariable(Iterable<Integer> data) {
            Iterator<Integer> iter = data.iterator();
            return iter.hasNext() ? iter.next() : null;
        }
    }
}