| /* |
| * 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, |
| * 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 org.apache.flink.training.solutions.longrides; |
| |
| import org.apache.flink.api.common.state.ValueState; |
| import org.apache.flink.api.common.state.ValueStateDescriptor; |
| 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.training.exercises.common.datatypes.TaxiRide; |
| import org.apache.flink.training.exercises.common.sources.TaxiRideGenerator; |
| import org.apache.flink.training.exercises.common.utils.ExerciseBase; |
| import org.apache.flink.util.Collector; |
| |
| /** |
| * Solution to the "Long Ride Alerts" exercise of the Flink training in the docs. |
| * |
| * <p>The goal for this exercise is to emit START events for taxi rides that have not been matched |
| * by an END event during the first 2 hours of the ride. |
| */ |
| public class LongRidesSolution extends ExerciseBase { |
| |
| /** |
| * Main method. |
| * |
| * @throws Exception which occurs during job execution. |
| */ |
| public static void main(String[] args) throws Exception { |
| |
| // set up streaming execution environment |
| StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment(); |
| env.setParallelism(ExerciseBase.parallelism); |
| |
| // start the data generator |
| DataStream<TaxiRide> rides = env.addSource(rideSourceOrTest(new TaxiRideGenerator())); |
| |
| DataStream<TaxiRide> longRides = |
| rides.keyBy((TaxiRide ride) -> ride.rideId).process(new MatchFunction()); |
| |
| printOrTest(longRides); |
| |
| env.execute("Long Taxi Rides"); |
| } |
| |
| private static class MatchFunction extends KeyedProcessFunction<Long, TaxiRide, TaxiRide> { |
| |
| private ValueState<TaxiRide> rideState; |
| |
| @Override |
| public void open(Configuration config) { |
| ValueStateDescriptor<TaxiRide> stateDescriptor = |
| new ValueStateDescriptor<>("ride event", TaxiRide.class); |
| rideState = getRuntimeContext().getState(stateDescriptor); |
| } |
| |
| @Override |
| public void processElement(TaxiRide ride, Context context, Collector<TaxiRide> out) |
| throws Exception { |
| TaxiRide previousRideEvent = rideState.value(); |
| |
| if (previousRideEvent == null) { |
| rideState.update(ride); |
| if (ride.isStart) { |
| context.timerService().registerEventTimeTimer(getTimerTime(ride)); |
| } |
| } else { |
| if (!ride.isStart) { |
| // it's an END event, so event saved was the START event and has a timer |
| // the timer hasn't fired yet, and we can safely kill the timer |
| context.timerService().deleteEventTimeTimer(getTimerTime(previousRideEvent)); |
| } |
| // both events have now been seen, we can clear the state |
| rideState.clear(); |
| } |
| } |
| |
| @Override |
| public void onTimer(long timestamp, OnTimerContext context, Collector<TaxiRide> out) |
| throws Exception { |
| |
| // if we get here, we know that the ride started two hours ago, and the END hasn't been |
| // processed |
| out.collect(rideState.value()); |
| rideState.clear(); |
| } |
| |
| private long getTimerTime(TaxiRide ride) { |
| return ride.startTime.plusSeconds(120 * 60).toEpochMilli(); |
| } |
| } |
| } |