long-ride-alerts/src/main/java/org/apache/flink/training/exercises/longrides/LongRidesExercise.java

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 * to you under the Apache License, Version 2.0 (the
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 *     http://www.apache.org/licenses/LICENSE-2.0
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package org.apache.flink.training.exercises.longrides;

import org.apache.flink.annotation.VisibleForTesting;
import org.apache.flink.api.common.JobExecutionResult;
import org.apache.flink.api.common.eventtime.WatermarkStrategy;
import org.apache.flink.configuration.Configuration;
import org.apache.flink.streaming.api.datastream.DataStream;
import org.apache.flink.streaming.api.environment.StreamExecutionEnvironment;
import org.apache.flink.streaming.api.functions.KeyedProcessFunction;
import org.apache.flink.streaming.api.functions.sink.PrintSinkFunction;
import org.apache.flink.streaming.api.functions.sink.SinkFunction;
import org.apache.flink.streaming.api.functions.source.SourceFunction;
import org.apache.flink.training.exercises.common.datatypes.TaxiRide;
import org.apache.flink.training.exercises.common.sources.TaxiRideGenerator;
import org.apache.flink.training.exercises.common.utils.MissingSolutionException;
import org.apache.flink.util.Collector;

import java.time.Duration;

/**
 * The "Long Ride Alerts" exercise.
 *
 * <p>The goal for this exercise is to emit the rideIds for taxi rides with a duration of more than
 * two hours. You should assume that TaxiRide events can be lost, but there are no duplicates.
 *
 * <p>You should eventually clear any state you create.
 */
public class LongRidesExercise {
    private final SourceFunction<TaxiRide> source;
    private final SinkFunction<Long> sink;

    /** Creates a job using the source and sink provided. */
    public LongRidesExercise(SourceFunction<TaxiRide> source, SinkFunction<Long> sink) {
        this.source = source;
        this.sink = sink;
    }

    /**
     * Creates and executes the long rides pipeline.
     *
     * @return {JobExecutionResult}
     * @throws Exception which occurs during job execution.
     */
    public JobExecutionResult execute() throws Exception {

        // set up streaming execution environment
        StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();

        // start the data generator
        DataStream<TaxiRide> rides = env.addSource(source);

        // the WatermarkStrategy specifies how to extract timestamps and generate watermarks
        WatermarkStrategy<TaxiRide> watermarkStrategy =
                WatermarkStrategy.<TaxiRide>forBoundedOutOfOrderness(Duration.ofSeconds(60))
                        .withTimestampAssigner(
                                (ride, streamRecordTimestamp) -> ride.getEventTimeMillis());

        // create the pipeline
        rides.assignTimestampsAndWatermarks(watermarkStrategy)
                .keyBy(ride -> ride.rideId)
                .process(new AlertFunction())
                .addSink(sink);

        // execute the pipeline and return the result
        return env.execute("Long Taxi Rides");
    }

    /**
     * Main method.
     *
     * @throws Exception which occurs during job execution.
     */
    public static void main(String[] args) throws Exception {
        LongRidesExercise job =
                new LongRidesExercise(new TaxiRideGenerator(), new PrintSinkFunction<>());

        job.execute();
    }

    @VisibleForTesting
    public static class AlertFunction extends KeyedProcessFunction<Long, TaxiRide, Long> {

        @Override
        public void open(Configuration config) throws Exception {
            throw new MissingSolutionException();
        }

        @Override
        public void processElement(TaxiRide ride, Context context, Collector<Long> out)
                throws Exception {}

        @Override
        public void onTimer(long timestamp, OnTimerContext context, Collector<Long> out)
                throws Exception {}
    }
}