| /** |
| * 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.heron.examples.streamlet; |
| |
| import java.io.Serializable; |
| import java.text.DecimalFormat; |
| import java.time.Duration; |
| import java.util.Arrays; |
| import java.util.List; |
| import java.util.concurrent.ThreadLocalRandom; |
| import java.util.logging.Logger; |
| |
| import org.apache.heron.examples.streamlet.utils.StreamletUtils; |
| import org.apache.heron.streamlet.Builder; |
| import org.apache.heron.streamlet.Config; |
| import org.apache.heron.streamlet.KeyValue; |
| import org.apache.heron.streamlet.Runner; |
| import org.apache.heron.streamlet.WindowConfig; |
| |
| /** |
| * This topology shows an example usage of a reduce function. A source streamlet emits smart watch readings every 10 |
| * seconds from one of several joggers. Those readings provide * The processing graph then converts those smart watch |
| * readings to a KeyValue object, which is passed to a reduce function that calculates a per-jogger total number of feet |
| * run in the last minute. The reduced value is then used to provide a per-runner average pace (feet per minute) and the |
| * result is logged using a consume operation (which allows for a formatted log). |
| */ |
| public final class SmartWatchTopology { |
| private SmartWatchTopology() { |
| } |
| |
| private static final Logger LOG = |
| Logger.getLogger(SmartWatchTopology.class.getName()); |
| |
| private static final List<String> JOGGERS = Arrays.asList( |
| "bill", |
| "ted" |
| ); |
| |
| private static class SmartWatchReading implements Serializable { |
| private static final long serialVersionUID = -6555650939020508026L; |
| private final String joggerId; |
| private final int feetRun; |
| |
| SmartWatchReading() { |
| StreamletUtils.sleep(1000); |
| this.joggerId = StreamletUtils.randomFromList(JOGGERS); |
| this.feetRun = ThreadLocalRandom.current().nextInt(200, 400); |
| } |
| |
| String getJoggerId() { |
| return joggerId; |
| } |
| |
| int getFeetRun() { |
| return feetRun; |
| } |
| } |
| |
| public static void main(String[] args) throws Exception { |
| Builder processingGraphBuilder = Builder.newBuilder(); |
| |
| processingGraphBuilder.newSource(SmartWatchReading::new) |
| .setName("incoming-watch-readings") |
| .reduceByKeyAndWindow( |
| // Key extractor |
| reading -> reading.getJoggerId(), |
| // Value extractor |
| reading -> reading.getFeetRun(), |
| // The time window (1 minute of clock time) |
| WindowConfig.TumblingTimeWindow(Duration.ofSeconds(10)), |
| // The reduce function (produces a cumulative sum) |
| (cumulative, incoming) -> cumulative + incoming |
| ) |
| .setName("reduce-to-total-distance-per-jogger") |
| .map(keyWindow -> { |
| // The per-key result of the previous reduce step |
| long totalFeetRun = keyWindow.getValue(); |
| |
| // The amount of time elapsed |
| long startTime = keyWindow.getKey().getWindow().getStartTime(); |
| long endTime = keyWindow.getKey().getWindow().getEndTime(); |
| long timeLengthMillis = endTime - startTime; // Cast to float to use as denominator |
| |
| // The feet-per-minute calculation |
| float feetPerMinute = totalFeetRun / (float) (timeLengthMillis / 1000); |
| |
| // Reduce to two decimal places |
| String paceString = new DecimalFormat("#.##").format(feetPerMinute); |
| |
| // Return a per-jogger average pace |
| return new KeyValue<>(keyWindow.getKey().getKey(), paceString); |
| }) |
| .setName("calculate-average-speed") |
| .consume(kv -> { |
| String logMessage = String.format("(runner: %s, avgFeetPerMinute: %s)", |
| kv.getKey(), |
| kv.getValue()); |
| |
| LOG.info(logMessage); |
| }); |
| |
| Config config = Config.defaultConfig(); |
| |
| // Fetches the topology name from the first command-line argument |
| String topologyName = StreamletUtils.getTopologyName(args); |
| |
| // Finally, the processing graph and configuration are passed to the Runner, which converts |
| // the graph into a Heron topology that can be run in a Heron cluster. |
| new Runner().run(topologyName, config, processingGraphBuilder); |
| } |
| } |