flink-tests/src/test/java/org/apache/flink/test/accumulators/AccumulatorIterativeITCase.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.accumulators;

import org.apache.flink.api.common.accumulators.IntCounter;
import org.apache.flink.api.common.functions.RichGroupReduceFunction;
import org.apache.flink.api.java.ExecutionEnvironment;
import org.apache.flink.api.java.io.DiscardingOutputFormat;
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;

/** Test accumulator within iteration. */
public class AccumulatorIterativeITCase extends JavaProgramTestBase {
    private static final int NUM_ITERATIONS = 3;
    private static final int NUM_SUBTASKS = 1;
    private static final String ACC_NAME = "test";

    @Override
    protected boolean skipCollectionExecution() {
        return true;
    }

    @Override
    protected void testProgram() throws Exception {
        ExecutionEnvironment env = ExecutionEnvironment.getExecutionEnvironment();
        env.setParallelism(NUM_SUBTASKS);

        IterativeDataSet<Integer> iteration = env.fromElements(1, 2, 3).iterate(NUM_ITERATIONS);

        iteration
                .closeWith(iteration.reduceGroup(new SumReducer()))
                .output(new DiscardingOutputFormat<Integer>());

        Assert.assertEquals(NUM_ITERATIONS * 6, (int) env.execute().getAccumulatorResult(ACC_NAME));
    }

    static final class SumReducer extends RichGroupReduceFunction<Integer, Integer> {

        private static final long serialVersionUID = 1L;

        private IntCounter testCounter = new IntCounter();

        @Override
        public void open(Configuration config) throws Exception {
            getRuntimeContext().addAccumulator(ACC_NAME, this.testCounter);
        }

        @Override
        public void reduce(Iterable<Integer> values, Collector<Integer> out) {
            // Compute the sum
            int sum = 0;

            for (Integer value : values) {
                sum += value;
                testCounter.add(value);
            }
            out.collect(sum);
        }
    }
}