AverageVehicleSpeedBolt.java

/*
 * #!
 * %
 * Copyright (C) 2014 - 2016 Humboldt-Universität zu Berlin
 * %
 * Licensed 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 de.hub.cs.dbis.lrb.operators;

import java.util.HashMap;
import java.util.Map;
import java.util.Map.Entry;

import org.apache.commons.lang3.tuple.MutablePair;
import org.apache.commons.lang3.tuple.Pair;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import backtype.storm.task.OutputCollector;
import backtype.storm.task.TopologyContext;
import backtype.storm.topology.OutputFieldsDeclarer;
import backtype.storm.topology.base.BaseRichBolt;
import backtype.storm.tuple.Fields;
import backtype.storm.tuple.Tuple;
import backtype.storm.tuple.Values;
import de.hub.cs.dbis.aeolus.utils.TimestampMerger;
import de.hub.cs.dbis.lrb.types.PositionReport;
import de.hub.cs.dbis.lrb.types.internal.AvgVehicleSpeedTuple;
import de.hub.cs.dbis.lrb.types.util.SegmentIdentifier;
import de.hub.cs.dbis.lrb.util.AvgValue;
import de.hub.cs.dbis.lrb.util.Time;





/**
 * {@link AverageVehicleSpeedBolt} computes the average speed of a vehicle within an express way-segment (single
 * direction) every minute. The input is expected to be of type {@link PositionReport}, to be ordered by timestamp, and
 * must be grouped by vehicle. A new average speed computation is trigger each time a vehicle changes the express way,
 * segment or direction as well as each 60 seconds (ie, changing 'minute number' [see {@link Time#getMinute(short)}]).<br />
 * <br />
 * <strong>Input schema:</strong> {@link PositionReport}<br />
 * <strong>Output schema:</strong> {@link AvgVehicleSpeedTuple}
 * 
 * @author msoyka
 * @author mjsax
 */
public class AverageVehicleSpeedBolt extends BaseRichBolt {
	private final static long serialVersionUID = 5537727428628598519L;
	private static final Logger LOGGER = LoggerFactory.getLogger(AverageVehicleSpeedBolt.class);
	
	/** The storm provided output collector. */
	private OutputCollector collector;
	
	/** Internally (re)used object to access individual attributes. */
	private final PositionReport inputPositionReport = new PositionReport();
	/** Internally (re)used object. */
	private final SegmentIdentifier segment = new SegmentIdentifier();
	
	/**
	 * Maps each vehicle to its average speed value that corresponds to the current 'minute number' and specified
	 * segment.
	 */
	private final Map<Integer, Pair<AvgValue, SegmentIdentifier>> avgSpeedsMap = new HashMap<Integer, Pair<AvgValue, SegmentIdentifier>>();
	
	/** The currently processed 'minute number'. */
	private short currentMinute = 1;
	
	
	
	@Override
	public void prepare(@SuppressWarnings("rawtypes") Map stormConf, TopologyContext context, OutputCollector collector) {
		this.collector = collector;
	}
	
	@Override
	public void execute(Tuple input) {
		if(input.getSourceStreamId().equals(TimestampMerger.FLUSH_STREAM_ID)) {
			if(input.getValue(0) == null) {
				this.flushBuffer();
				this.collector.emit(TimestampMerger.FLUSH_STREAM_ID, new Values((Object)null));
			}
			this.collector.ack(input);
			return;
		}
		
		this.inputPositionReport.clear();
		this.inputPositionReport.addAll(input.getValues());
		LOGGER.trace(this.inputPositionReport.toString());
		
		Integer vid = this.inputPositionReport.getVid();
		short minute = this.inputPositionReport.getMinuteNumber();
		int speed = this.inputPositionReport.getSpeed().intValue();
		this.segment.set(this.inputPositionReport);
		
		assert (minute >= this.currentMinute);
		
		if(minute > this.currentMinute) {
			// emit all values for last minute
			// (because input tuples are ordered by ts, we can close the last minute safely)
			this.flushBuffer();
			this.collector.emit(TimestampMerger.FLUSH_STREAM_ID, new Values(new Short(minute)));
			
			this.avgSpeedsMap.clear();
			this.currentMinute = minute;
		}
		
		Pair<AvgValue, SegmentIdentifier> vehicleEntry = this.avgSpeedsMap.get(vid);
		if(vehicleEntry != null && !vehicleEntry.getRight().equals(this.segment)) {
			SegmentIdentifier segId = vehicleEntry.getRight();
			
			// VID, Minute-Number, X-Way, Segment, Direction, Avg(speed)
			this.collector.emit(new AvgVehicleSpeedTuple(vid, new Short(this.currentMinute), segId.getXWay(), segId
				.getSegment(), segId.getDirection(), vehicleEntry.getLeft().getAverage()));
			
			// set to null to get new vehicle entry below
			vehicleEntry = null;
		}
		
		
		if(vehicleEntry == null) {
			vehicleEntry = new MutablePair<AvgValue, SegmentIdentifier>(new AvgValue(speed), this.segment.copy());
			this.avgSpeedsMap.put(vid, vehicleEntry);
		} else {
			vehicleEntry.getLeft().updateAverage(speed);
		}
		
		this.collector.ack(input);
	}
	
	private void flushBuffer() {
		for(Entry<Integer, Pair<AvgValue, SegmentIdentifier>> entry : this.avgSpeedsMap.entrySet()) {
			Pair<AvgValue, SegmentIdentifier> value = entry.getValue();
			SegmentIdentifier segId = value.getRight();
			
			// VID, Minute-Number, X-Way, Segment, Direction, Avg(speed)
			this.collector.emit(new AvgVehicleSpeedTuple(entry.getKey(), new Short(this.currentMinute),
				segId.getXWay(), segId.getSegment(), segId.getDirection(), value.getLeft().getAverage()));
		}
	}
	
	@Override
	public void declareOutputFields(OutputFieldsDeclarer declarer) {
		declarer.declare(AvgVehicleSpeedTuple.getSchema());
		declarer.declareStream(TimestampMerger.FLUSH_STREAM_ID, new Fields("ts"));
	}
	
}