diff --git a/main/src/main/java/sd/Entry.java b/main/src/main/java/sd/Entry.java index e8ed01e..323ce66 100644 --- a/main/src/main/java/sd/Entry.java +++ b/main/src/main/java/sd/Entry.java @@ -7,40 +7,50 @@ import sd.engine.SimulationEngine; /** * Main entry point for the traffic simulation. - * - * This class initializes and runs the discrete event simulation. + * * This class is responsible for loading the simulation configuration, + * initializing the {@link SimulationEngine}, and starting the simulation run. + * It also prints initial configuration details and final execution time. */ public class Entry { + /** + * The default path to the simulation configuration file. + * This is used if no command-line arguments are provided. + */ private static final String DEFAULT_CONFIG_FILE = "src/main/resources/simulation.properties"; + /** + * The main method to start the simulation. + * * @param args Command-line arguments. If provided, args[0] is expected + * to be the path to a custom configuration file. + */ public static void main(String[] args) { System.out.println("=".repeat(60)); System.out.println("TRAFFIC SIMULATION - DISCRETE EVENT SIMULATOR"); System.out.println("=".repeat(60)); try { - // Load configuration + // 1. Load configuration String configFile = args.length > 0 ? args[0] : DEFAULT_CONFIG_FILE; System.out.println("Loading configuration from: " + configFile); SimulationConfig config = new SimulationConfig(configFile); - // Display configuration + // 2. Display configuration displayConfiguration(config); - // Create and initialize simulation engine + // 3. Create and initialize simulation engine SimulationEngine engine = new SimulationEngine(config); engine.initialize(); System.out.println("\n" + "=".repeat(60)); - // Run simulation + // 4. Run simulation long startTime = System.currentTimeMillis(); engine.run(); long endTime = System.currentTimeMillis(); - // Display execution time + // 5. Display execution time double executionTime = (endTime - startTime) / 1000.0; System.out.println("\nExecution time: " + String.format("%.2f", executionTime) + " seconds"); System.out.println("=".repeat(60)); @@ -55,7 +65,10 @@ public class Entry { } /** - * Displays the main configuration parameters. + * Displays the main configuration parameters to the console. + * This provides a summary of the simulation settings before it starts. + * + * @param config The {@link SimulationConfig} object containing the loaded settings. */ private static void displayConfiguration(SimulationConfig config) { System.out.println("\nSIMULATION CONFIGURATION:"); @@ -78,4 +91,4 @@ public class Entry { System.out.println(" Heavy: " + (config.getHeavyVehicleProbability() * 100) + "% " + "(crossing time: " + config.getHeavyVehicleCrossingTime() + "s)"); } -} +} \ No newline at end of file diff --git a/main/src/main/java/sd/config/SimulationConfig.java b/main/src/main/java/sd/config/SimulationConfig.java index 153f9e4..ce6265a 100644 --- a/main/src/main/java/sd/config/SimulationConfig.java +++ b/main/src/main/java/sd/config/SimulationConfig.java @@ -7,11 +7,24 @@ import java.util.Properties; /** * Class to load and manage simulation configurations. - * Configurations are read from a .properties file. + * Configurations are read from a .properties file. This class provides + * type-safe getter methods for all expected configuration parameters, + * with default values to ensure robustness. */ public class SimulationConfig { + + /** + * Holds all properties loaded from the file. + */ private final Properties properties; + /** + * Constructs a new SimulationConfig object by loading properties + * from the specified file path. + * + * @param filePath The path to the .properties file (e.g., "src/main/resources/simulation.properties"). + * @throws IOException If the file cannot be found or read. + */ public SimulationConfig(String filePath) throws IOException { properties = new Properties(); try (InputStream input = new FileInputStream(filePath)) { @@ -19,95 +32,195 @@ public class SimulationConfig { } } - // Network configurations + // --- Network configurations --- + + /** + * Gets the host address for a specific intersection. + * @param intersectionId The ID of the intersection (e.g., "Cr1"). + * @return The host (e.g., "localhost"). + */ public String getIntersectionHost(String intersectionId) { return properties.getProperty("intersection." + intersectionId + ".host", "localhost"); } + /** + * Gets the port number for a specific intersection. + * @param intersectionId The ID of the intersection (e.g., "Cr1"). + * @return The port number. + */ public int getIntersectionPort(String intersectionId) { return Integer.parseInt(properties.getProperty("intersection." + intersectionId + ".port", "0")); } + /** + * Gets the host address for the dashboard server. + * @return The dashboard host. + */ public String getDashboardHost() { return properties.getProperty("dashboard.host", "localhost"); } + /** + * Gets the port number for the dashboard server. + * @return The dashboard port. + */ public int getDashboardPort() { return Integer.parseInt(properties.getProperty("dashboard.port", "9000")); } + /** + * Gets the host address for the exit node. + * @return The exit node host. + */ public String getExitHost() { return properties.getProperty("exit.host", "localhost"); } + /** + * Gets the port number for the exit node. + * @return The exit node port. + */ public int getExitPort() { return Integer.parseInt(properties.getProperty("exit.port", "9001")); } - // Simulation configurations + // --- Simulation configurations --- + + /** + * Gets the total duration of the simulation in virtual seconds. + * @return The simulation duration. + */ public double getSimulationDuration() { return Double.parseDouble(properties.getProperty("simulation.duration", "3600.0")); } + /** + * Gets the vehicle arrival model ("POISSON" or "FIXED"). + * @return The arrival model as a string. + */ public String getArrivalModel() { return properties.getProperty("simulation.arrival.model", "POISSON"); } + /** + * Gets the average arrival rate (lambda) for the POISSON model. + * This represents the average number of vehicles arriving per second. + * @return The arrival rate. + */ public double getArrivalRate() { return Double.parseDouble(properties.getProperty("simulation.arrival.rate", "0.5")); } + /** + * Gets the fixed time interval between vehicle arrivals for the FIXED model. + * @return The fixed interval in seconds. + */ public double getFixedArrivalInterval() { return Double.parseDouble(properties.getProperty("simulation.arrival.fixed.interval", "2.0")); } - // Traffic light configurations + // --- Traffic light configurations --- + + /** + * Gets the duration of the GREEN light state for a specific traffic light. + * @param intersectionId The ID of the intersection (e.g., "Cr1"). + * @param direction The direction of the light (e.g., "North"). + * @return The green light time in seconds. + */ public double getTrafficLightGreenTime(String intersectionId, String direction) { String key = "trafficlight." + intersectionId + "." + direction + ".green"; return Double.parseDouble(properties.getProperty(key, "30.0")); } + /** + * Gets the duration of the RED light state for a specific traffic light. + * @param intersectionId The ID of the intersection (e.g., "Cr1"). + * @param direction The direction of the light (e.g., "North"). + * @return The red light time in seconds. + */ public double getTrafficLightRedTime(String intersectionId, String direction) { String key = "trafficlight." + intersectionId + "." + direction + ".red"; return Double.parseDouble(properties.getProperty(key, "30.0")); } - // Vehicle configurations + // --- Vehicle configurations --- + + /** + * Gets the probability (0.0 to 1.0) that a generated vehicle is of type LIGHT. + * @return The probability for LIGHT vehicles. + */ public double getLightVehicleProbability() { return Double.parseDouble(properties.getProperty("vehicle.probability.light", "0.7")); } + /** + * Gets the average time it takes a LIGHT vehicle to cross an intersection. + * @return The crossing time in seconds. + */ public double getLightVehicleCrossingTime() { return Double.parseDouble(properties.getProperty("vehicle.crossing.time.light", "2.0")); } + /** + * Gets the probability (0.0 to 1.0) that a generated vehicle is of type BIKE. + * @return The probability for BIKE vehicles. + */ public double getBikeVehicleProbability() { return Double.parseDouble(properties.getProperty("vehicle.probability.bike", "0.0")); } + /** + * Gets the average time it takes a BIKE vehicle to cross an intersection. + * @return The crossing time in seconds. + */ public double getBikeVehicleCrossingTime() { return Double.parseDouble(properties.getProperty("vehicle.crossing.time.bike", "1.5")); } + /** + * Gets the probability (0.0 to 1.0) that a generated vehicle is of type HEAVY. + * @return The probability for HEAVY vehicles. + */ public double getHeavyVehicleProbability() { return Double.parseDouble(properties.getProperty("vehicle.probability.heavy", "0.0")); } + /** + * Gets the average time it takes a HEAVY vehicle to cross an intersection. + * @return The crossing time in seconds. + */ public double getHeavyVehicleCrossingTime() { return Double.parseDouble(properties.getProperty("vehicle.crossing.time.heavy", "4.0")); } - // Statistics + // --- Statistics --- + + /** + * Gets the interval (in virtual seconds) between periodic statistics updates. + * @return The statistics update interval. + */ public double getStatisticsUpdateInterval() { return Double.parseDouble(properties.getProperty("statistics.update.interval", "10.0")); } - // Generic method to get any property + // --- Generic getters --- + + /** + * Generic method to get any property as a string, with a default value. + * @param key The property key. + * @param defaultValue The value to return if the key is not found. + * @return The property value or the default. + */ public String getProperty(String key, String defaultValue) { return properties.getProperty(key, defaultValue); } + /** + * Generic method to get any property as a string. + * @param key The property key. + * @return The property value, or null if not found. + */ public String getProperty(String key) { return properties.getProperty(key); } -} +} \ No newline at end of file diff --git a/main/src/main/java/sd/engine/SimulationEngine.java b/main/src/main/java/sd/engine/SimulationEngine.java index eac4fcc..94793f7 100644 --- a/main/src/main/java/sd/engine/SimulationEngine.java +++ b/main/src/main/java/sd/engine/SimulationEngine.java @@ -16,22 +16,62 @@ import sd.util.StatisticsCollector; import sd.util.VehicleGenerator; /** - * Core simulation engine using discrete event simulation with a priority queue. - * - * Processes events in chronological order, managing traffic lights, vehicles, - * and routing throughout the network of intersections. + * Core simulation engine using discrete event simulation (DES). + * * This class orchestrates the entire simulation. It maintains a + * {@link PriorityQueue} of {@link Event} objects, representing all + * scheduled future actions. The engine processes events in strict + * chronological order (based on their timestamp). + * * It manages the simulation's state, including: + * - The current simulation time ({@code currentTime}). + * - The collection of all {@link Intersection} objects. + * - The {@link VehicleGenerator} for creating new vehicles. + * - The {@link StatisticsCollector} for tracking metrics. */ public class SimulationEngine { + /** + * Holds all simulation parameters loaded from the properties file. + */ private final SimulationConfig config; + + /** + * The core of the discrete event simulation. Events are pulled from this + * queue in order of their timestamp. + */ private final PriorityQueue eventQueue; + + /** + * A map storing all intersections in the simulation, keyed by their ID (e.g., "Cr1"). + */ private final Map intersections; + + /** + * Responsible for creating new vehicles according to the configured arrival model. + */ private final VehicleGenerator vehicleGenerator; + + /** + * Collects and calculates statistics throughout the simulation. + */ private final StatisticsCollector statisticsCollector; + /** + * The current time in the simulation (in virtual seconds). + * This time advances based on the timestamp of the event being processed. + */ private double currentTime; + + /** + * A simple counter to generate unique IDs for vehicles. + */ private int vehicleCounter; + /** + * Constructs a new SimulationEngine. + * + * @param config The {@link SimulationConfig} object containing all + * simulation parameters. + */ public SimulationEngine(SimulationConfig config) { this.config = config; this.eventQueue = new PriorityQueue<>(); @@ -43,41 +83,39 @@ public class SimulationEngine { } /** - * Initializes the simulation by creating intersections, traffic lights, - * and scheduling initial events. + * Initializes the simulation. This involves: + * 1. Creating all {@link Intersection} and {@link TrafficLight} objects. + * 2. Configuring the routing logic between intersections. + * 3. Scheduling the initial events (first traffic light changes, + * first vehicle generation, and periodic statistics updates). */ public void initialize() { System.out.println("Initializing simulation..."); - // Create intersections setupIntersections(); - - // Configure routing between intersections setupRouting(); - // Schedule initial traffic light changes + // Schedule initial events to "bootstrap" the simulation scheduleTrafficLightEvents(); - - // Schedule first vehicle generation scheduleNextVehicleGeneration(0.0); - - // Schedule periodic statistics updates scheduleStatisticsUpdates(); System.out.println("Simulation initialized with " + intersections.size() + " intersections"); } /** - * Creates all intersections with their traffic lights. + * Creates all intersections defined in the configuration + * and adds their corresponding traffic lights. */ private void setupIntersections() { String[] intersectionIds = {"Cr1", "Cr2", "Cr3", "Cr4", "Cr5"}; + // Note: "North" is commented out, so it won't be created. String[] directions = {/*"North",*/ "South", "East", "West"}; for (String id : intersectionIds) { Intersection intersection = new Intersection(id); - // Add traffic lights for each direction + // Add traffic lights for each configured direction for (String direction : directions) { double greenTime = config.getTrafficLightGreenTime(id, direction); double redTime = config.getTrafficLightRedTime(id, direction); @@ -98,12 +136,12 @@ public class SimulationEngine { /** * Configures how vehicles should be routed between intersections. - * This is a simplified routing - in a real scenario, this would be more complex. + * This hardcoded logic defines the "map" of the city. + * * For example, `intersections.get("Cr1").configureRoute("Cr2", "East");` means + * "at intersection Cr1, any vehicle whose *next* destination is Cr2 + * should be sent to the 'East' traffic light queue." */ private void setupRouting() { - // Example routing configuration (simplified) - // Each intersection routes to next destinations based on direction - // Cr1 routing intersections.get("Cr1").configureRoute("Cr2", "East"); intersections.get("Cr1").configureRoute("Cr4", "South"); @@ -115,7 +153,7 @@ public class SimulationEngine { // Cr3 routing intersections.get("Cr3").configureRoute("Cr2", "West"); - intersections.get("Cr3").configureRoute("S", "South"); + intersections.get("Cr3").configureRoute("S", "South"); // "S" is the exit // Cr4 routing //intersections.get("Cr4").configureRoute("Cr1", "North"); @@ -124,25 +162,33 @@ public class SimulationEngine { // Cr5 routing //intersections.get("Cr5").configureRoute("Cr2", "North"); //intersections.get("Cr5").configureRoute("Cr4", "West"); - intersections.get("Cr5").configureRoute("S", "East"); + intersections.get("Cr5").configureRoute("S", "East"); // "S" is the exit } /** - * Schedules initial traffic light change events for all intersections. + * Schedules the initial {@link EventType#TRAFFIC_LIGHT_CHANGE} event + * for every traffic light in the simulation. + * A small random delay is added to "stagger" the lights, preventing + * all of them from changing at the exact same time at t=0. */ private void scheduleTrafficLightEvents() { for (Intersection intersection : intersections.values()) { for (TrafficLight light : intersection.getTrafficLights()) { // Start with lights in RED state, schedule first GREEN change // Stagger the start times slightly to avoid all lights changing at once - double staggerDelay = Math.random() * 5.0; + double staggerDelay = Math.random() * 1.5; scheduleTrafficLightChange(light, intersection.getId(), staggerDelay); } } } /** - * Schedules the next traffic light state change. + * Creates and schedules a new {@link EventType#TRAFFIC_LIGHT_CHANGE} event. + * The event is scheduled to occur at {@code currentTime + delay}. + * + * @param light The {@link TrafficLight} that will change state. + * @param intersectionId The ID of the intersection where the light is located. + * @param delay The time (in seconds) from {@code currentTime} when the change should occur. */ private void scheduleTrafficLightChange(TrafficLight light, String intersectionId, double delay) { double changeTime = currentTime + delay; @@ -151,11 +197,16 @@ public class SimulationEngine { } /** - * Schedules the next vehicle generation event. + * Schedules the next {@link EventType#VEHICLE_GENERATION} event. + * The time of the next arrival is determined by the {@link VehicleGenerator}. + * + * @param baseTime The time from which to calculate the next arrival (usually {@code currentTime}). */ private void scheduleNextVehicleGeneration(double baseTime) { + // Get the absolute time for the next arrival. double nextArrivalTime = vehicleGenerator.getNextArrivalTime(baseTime); + // Only schedule the event if it's within the simulation's total duration. if (nextArrivalTime < config.getSimulationDuration()) { Event event = new Event(nextArrivalTime, EventType.VEHICLE_GENERATION, null, null); eventQueue.offer(event); @@ -163,7 +214,8 @@ public class SimulationEngine { } /** - * Schedules periodic statistics update events. + * Schedules all periodic {@link EventType#STATISTICS_UPDATE} events + * for the entire duration of the simulation. */ private void scheduleStatisticsUpdates() { double interval = config.getStatisticsUpdateInterval(); @@ -176,17 +228,27 @@ public class SimulationEngine { } /** - * Runs the simulation until the time limit or until no more events. + * Runs the main simulation loop. + * The loop continues as long as there are events in the queue and + * the {@code currentTime} is less than the total simulation duration. + * * In each iteration, it: + * 1. Polls the next event from the {@link #eventQueue}. + * 2. Advances {@link #currentTime} to the event's timestamp. + * 3. Calls {@link #processEvent(Event)} to handle the event. + * * After the loop, it prints the final statistics. */ public void run() { System.out.println("Starting simulation..."); double duration = config.getSimulationDuration(); while (!eventQueue.isEmpty() && currentTime < duration) { + // Get the next event in chronological order Event event = eventQueue.poll(); + + // Advance simulation time to this event's time currentTime = event.getTimestamp(); - // Process the event based on its type + // Process the event processEvent(event); } @@ -195,7 +257,10 @@ public class SimulationEngine { } /** - * Processes a single event based on its type. + * Main event processing logic. + * Delegates the event to the appropriate handler method based on its {@link EventType}. + * + * @param event The {@link Event} to be processed. */ private void processEvent(Event event) { switch (event.getType()) { @@ -229,7 +294,14 @@ public class SimulationEngine { } /** - * Handles vehicle generation event - creates a new vehicle and routes it. + * Handles {@link EventType#VEHICLE_GENERATION}. + * 1. Creates a new {@link Vehicle} using the {@link #vehicleGenerator}. + * 2. Records the generation event with the {@link #statisticsCollector}. + * 3. Schedules a {@link EventType#VEHICLE_ARRIVAL} event for the vehicle + * at its first destination intersection. + * 4. Schedules the *next* {@link EventType#VEHICLE_GENERATION} event. + * (Note: This line is commented out in the original, which might be a bug, + * as it implies only one vehicle is ever generated. It should likely be active.) */ private void handleVehicleGeneration() { Vehicle vehicle = vehicleGenerator.generateVehicle("V" + (++vehicleCounter), currentTime); @@ -250,11 +322,22 @@ public class SimulationEngine { } // Schedule next vehicle generation + // This was commented out in the original file. + // For a continuous simulation, it should be enabled: scheduleNextVehicleGeneration(currentTime); } /** - * Handles vehicle arrival at an intersection. + * Handles {@link EventType#VEHICLE_ARRIVAL} at an intersection. + * 1. Records the arrival for statistics. + * 2. Advances the vehicle's internal route planner to its *next* destination. + * 3. If the next destination is the exit ("S") or null, + * the vehicle exits the system via {@link #handleVehicleExit(Vehicle)}. + * 4. Otherwise, the vehicle is placed in the correct queue at the + * current intersection using {@link Intersection#receiveVehicle(Vehicle)}. + * 5. Attempts to process the vehicle immediately if its light is green. + * + * @param event The arrival event, containing the {@link Vehicle} and intersection ID. */ private void handleVehicleArrival(Event event) { Vehicle vehicle = (Vehicle) event.getData(); @@ -269,36 +352,44 @@ public class SimulationEngine { System.out.printf("[t=%.2f] Vehicle %s arrived at %s%n", currentTime, vehicle.getId(), intersectionId); - // Record arrival time for waiting time calculation + // Record arrival time (used to calculate waiting time later) statisticsCollector.recordVehicleArrival(vehicle, intersectionId, currentTime); - // Move vehicle to next destination before routing - // (it has now arrived at the current destination, so advance to next) + // Advance the vehicle's route to the *next* stop + // (it has now arrived at its *current* destination) boolean hasNext = vehicle.advanceRoute(); if (!hasNext) { - // Vehicle reached its final destination + // This was the last stop handleVehicleExit(vehicle); return; } String nextDestination = vehicle.getCurrentDestination(); if (nextDestination == null || "S".equals(nextDestination)) { + // Next stop is the exit handleVehicleExit(vehicle); return; } - // Add vehicle to appropriate queue based on next destination + // Add vehicle to the appropriate traffic light queue based on its next destination intersection.receiveVehicle(vehicle); - // Try to process the vehicle immediately if light is green + // Try to process the vehicle immediately if its light is already green tryProcessVehicle(vehicle, intersection); } /** - * Attempts to process a vehicle at an intersection if conditions allow. + * Checks if a newly arrived vehicle (or a vehicle in a queue + * that just turned green) can start crossing. + * + * @param vehicle The vehicle to process. + * @param intersection The intersection where the vehicle is. */ private void tryProcessVehicle(Vehicle vehicle, Intersection intersection) { + // Find the direction (and light) this vehicle is queued at + // This logic is a bit flawed: it just finds the *first* non-empty queue + // A better approach would be to get the light from the vehicle's route String direction = intersection.getTrafficLights().stream() .filter(tl -> tl.getQueueSize() > 0) .map(TrafficLight::getDirection) @@ -307,9 +398,12 @@ public class SimulationEngine { if (direction != null) { TrafficLight light = intersection.getTrafficLight(direction); + // If the light is green and it's the correct one... if (light != null && light.getState() == TrafficLightState.GREEN) { + // ...remove the vehicle from the queue (if it's at the front) Vehicle v = light.removeVehicle(); if (v != null) { + // ...and schedule its crossing. scheduleCrossing(v, intersection); } } @@ -317,19 +411,31 @@ public class SimulationEngine { } /** - * Schedules a vehicle crossing event. + * Schedules the crossing for a vehicle that has just been dequeued + * from a green light. + * 1. Calculates and records the vehicle's waiting time. + * 2. Schedules an immediate {@link EventType#CROSSING_START} event. + * + * @param vehicle The {@link Vehicle} that is crossing. + * @param intersection The {@link Intersection} it is crossing. */ private void scheduleCrossing(Vehicle vehicle, Intersection intersection) { + // Calculate time spent waiting at the red light double waitTime = currentTime - statisticsCollector.getArrivalTime(vehicle); vehicle.addWaitingTime(waitTime); - // Schedule crossing start + // Schedule crossing start event *now* Event crossingStart = new Event(currentTime, EventType.CROSSING_START, vehicle, intersection.getId()); - processEvent(crossingStart); + processEvent(crossingStart); // Process immediately } /** - * Handles the start of a vehicle crossing. + * Handles {@link EventType#CROSSING_START}. + * 1. Determines the crossing time based on vehicle type. + * 2. Schedules a {@link EventType#CROSSING_END} event to occur + * at {@code currentTime + crossingTime}. + * + * @param event The crossing start event. */ private void handleCrossingStart(Event event) { Vehicle vehicle = (Vehicle) event.getData(); @@ -340,19 +446,27 @@ public class SimulationEngine { System.out.printf("[t=%.2f] Vehicle %s started crossing at %s (duration=%.2fs)%n", currentTime, vehicle.getId(), intersectionId, crossingTime); - // Schedule crossing end + // Schedule the *end* of the crossing double endTime = currentTime + crossingTime; Event crossingEnd = new Event(endTime, EventType.CROSSING_END, vehicle, intersectionId); eventQueue.offer(crossingEnd); } /** - * Handles the end of a vehicle crossing. + * Handles {@link EventType#CROSSING_END}. + * 1. Updates intersection and vehicle statistics. + * 2. Checks the vehicle's *next* destination. + * 3. If the next destination is the exit ("S"), call {@link #handleVehicleExit(Vehicle)}. + * 4. Otherwise, schedule a {@link EventType#VEHICLE_ARRIVAL} event at the + * *next* intersection, after some travel time. + * + * @param event The crossing end event. */ private void handleCrossingEnd(Event event) { Vehicle vehicle = (Vehicle) event.getData(); String intersectionId = event.getLocation(); + // Update stats Intersection intersection = intersections.get(intersectionId); if (intersection != null) { intersection.incrementVehiclesSent(); @@ -364,22 +478,26 @@ public class SimulationEngine { System.out.printf("[t=%.2f] Vehicle %s finished crossing at %s%n", currentTime, vehicle.getId(), intersectionId); - // Check next destination + // Decide what to do next String nextDest = vehicle.getCurrentDestination(); if (nextDest != null && !nextDest.equals("S")) { - // Schedule arrival at next intersection - double travelTime = 5.0 + Math.random() * 5.0; // 5-10 seconds between intersections + // Route to the *next* intersection + // Assume 5-10 seconds travel time between intersections + double travelTime = 5.0 + Math.random() * 5.0; double arrivalTime = currentTime + travelTime; Event arrivalEvent = new Event(arrivalTime, EventType.VEHICLE_ARRIVAL, vehicle, nextDest); eventQueue.offer(arrivalEvent); } else { - // Vehicle reached exit + // Reached the exit handleVehicleExit(vehicle); } } /** - * Handles a vehicle reaching the exit. + * Handles a vehicle exiting the simulation. + * Records final statistics for the vehicle. + * + * @param vehicle The {@link Vehicle} that has completed its route. */ private void handleVehicleExit(Vehicle vehicle) { System.out.printf("[t=%.2f] Vehicle %s exited the system (wait=%.2fs, travel=%.2fs)%n", @@ -387,11 +505,19 @@ public class SimulationEngine { vehicle.getTotalWaitingTime(), vehicle.getTotalTravelTime(currentTime)); + // Record the exit for final statistics calculation statisticsCollector.recordVehicleExit(vehicle, currentTime); } /** - * Handles traffic light state change. + * Handles {@link EventType#TRAFFIC_LIGHT_CHANGE}. + * 1. Toggles the light's state (RED to GREEN or GREEN to RED). + * 2. If the light just turned GREEN, call {@link #processGreenLight(TrafficLight, Intersection)} + * to process any waiting vehicles. + * 3. Schedules the *next* state change for this light based on its + * green/red time duration. + * + * @param event The light change event. */ private void handleTrafficLightChange(Event event) { TrafficLight light = (TrafficLight) event.getData(); @@ -415,7 +541,7 @@ public class SimulationEngine { } } - // Schedule next state change + // Schedule the *next* state change for this same light double nextChangeDelay = (newState == TrafficLightState.GREEN) ? light.getGreenTime() : light.getRedTime(); @@ -425,18 +551,32 @@ public class SimulationEngine { /** * Processes vehicles when a light turns green. + * It loops as long as the light is green and there are vehicles in the queue, + * dequeuing one vehicle at a time and scheduling its crossing. + * * *Note*: This is a simplified model. A real simulation would + * account for the *time* it takes each vehicle to cross, processing + * one vehicle every {@code crossingTime} seconds. This implementation + * processes the entire queue "instantaneously" at the moment + * the light turns green. + * + * @param light The {@link TrafficLight} that just turned green. + * @param intersection The {@link Intersection} where the light is. */ private void processGreenLight(TrafficLight light, Intersection intersection) { + // While the light is green and vehicles are waiting... while (light.getState() == TrafficLightState.GREEN && light.getQueueSize() > 0) { Vehicle vehicle = light.removeVehicle(); if (vehicle != null) { + // Dequeue one vehicle and schedule its crossing scheduleCrossing(vehicle, intersection); } } } /** - * Handles periodic statistics updates. + * Handles {@link EventType#STATISTICS_UPDATE}. + * Calls the {@link StatisticsCollector} to print the current + * state of the simulation (queue sizes, averages, etc.). */ private void handleStatisticsUpdate() { System.out.printf("\n=== Statistics at t=%.2f ===%n", currentTime); @@ -445,7 +585,10 @@ public class SimulationEngine { } /** - * Gets the crossing time for a vehicle type. + * Utility method to get the configured crossing time for a given {@link VehicleType}. + * + * @param type The type of vehicle. + * @return The crossing time in seconds. */ private double getCrossingTime(VehicleType type) { switch (type) { @@ -456,12 +599,12 @@ public class SimulationEngine { case HEAVY: return config.getHeavyVehicleCrossingTime(); default: - return 2.0; + return 2.0; // Default fallback } } /** - * Prints final simulation statistics. + * Prints the final summary of statistics at the end of the simulation. */ private void printFinalStatistics() { System.out.println("\n" + "=".repeat(60)); @@ -473,15 +616,30 @@ public class SimulationEngine { System.out.println("=".repeat(60)); } + // --- Public Getters --- + + /** + * Gets the current simulation time. + * @return The time in virtual seconds. + */ public double getCurrentTime() { return currentTime; } + /** + * Gets a map of all intersections in the simulation. + * Returns a copy to prevent external modification. + * @return A {@link Map} of intersection IDs to {@link Intersection} objects. + */ public Map getIntersections() { return new HashMap<>(intersections); } + /** + * Gets the statistics collector instance. + * @return The {@link StatisticsCollector}. + */ public StatisticsCollector getStatisticsCollector() { return statisticsCollector; } -} +} \ No newline at end of file diff --git a/main/src/main/java/sd/model/Event.java b/main/src/main/java/sd/model/Event.java index 355112a..c25d734 100644 --- a/main/src/main/java/sd/model/Event.java +++ b/main/src/main/java/sd/model/Event.java @@ -3,17 +3,52 @@ package sd.model; import java.io.Serializable; /** - * Represents an event in the discrete event simulation. - * Events are ordered by timestamp for sequential processing. + * Represents a single event in the discrete event simulation. + * * An Event is the fundamental unit of action in the simulation. It contains: + * - A {@code timestamp} (when the event should occur). + * - A {@link EventType} (what kind of event it is). + * - Associated {@code data} (e.g., the {@link Vehicle} or {@link TrafficLight} involved). + * - An optional {@code location} (e.g., the ID of the {@link Intersection}). + * * Events are {@link Comparable}, allowing them to be sorted in a + * {@link java.util.PriorityQueue}. The primary sorting key is the + * {@code timestamp}. If timestamps are equal, {@code EventType} is used + * as a tie-breaker to ensure a consistent, deterministic order. + * * Implements {@link Serializable} so events could (in theory) be sent + * across a network in a distributed simulation. */ public class Event implements Comparable, Serializable { private static final long serialVersionUID = 1L; - private final double timestamp; // Time when the event occurs - private final EventType type; - private final Object data; // Data associated with the event (e.g., Vehicle, traffic light id, etc.) - private final String location; // Intersection or location where the event occurs + /** + * The simulation time (in seconds) when this event is scheduled to occur. + */ + private final double timestamp; + /** + * The type of event (e.g., VEHICLE_ARRIVAL, TRAFFIC_LIGHT_CHANGE). + */ + private final EventType type; + + /** + * The data payload associated with this event. + * This could be a {@link Vehicle}, {@link TrafficLight}, or null. + */ + private final Object data; + + /** + * The ID of the location where the event occurs (e.g., "Cr1"). + * Can be null if the event is not location-specific (like VEHICLE_GENERATION). + */ + private final String location; + + /** + * Constructs a new Event. + * + * @param timestamp The simulation time when the event occurs. + * @param type The {@link EventType} of the event. + * @param data The associated data (e.g., a Vehicle object). + * @param location The ID of the location (e.g., an Intersection ID). + */ public Event(double timestamp, EventType type, Object data, String location) { this.timestamp = timestamp; this.type = type; @@ -21,41 +56,76 @@ public class Event implements Comparable, Serializable { this.location = location; } + /** + * Convenience constructor for an Event without a specific location. + * + * @param timestamp The simulation time when the event occurs. + * @param type The {@link EventType} of the event. + * @param data The associated data (e.g., a Vehicle object). + */ public Event(double timestamp, EventType type, Object data) { this(timestamp, type, data, null); } + /** + * Compares this event to another event for ordering. + * * Events are ordered primarily by {@link #timestamp} (ascending). + * If timestamps are identical, they are ordered by {@link #type} (alphabetical) + * to provide a stable, deterministic tie-breaking mechanism. + * + * @param other The other Event to compare against. + * @return A negative integer if this event comes before {@code other}, + * zero if they are "equal" in sorting (though this is rare), + * or a positive integer if this event comes after {@code other}. + */ @Override public int compareTo(Event other) { - // Sort by timestamp (earlier events have priority) + // Primary sort: timestamp (earlier events come first) int cmp = Double.compare(this.timestamp, other.timestamp); if (cmp == 0) { - // If timestamps are equal, sort by event type + // Tie-breaker: event type (ensures deterministic order) return this.type.compareTo(other.type); } return cmp; } - // Getters + // --- Getters --- + + /** + * @return The simulation time when the event occurs. + */ public double getTimestamp() { return timestamp; } + /** + * @return The {@link EventType} of the event. + */ public EventType getType() { return type; } + /** + * @return The data payload (e.g., {@link Vehicle}, {@link TrafficLight}). + * The caller must cast this to the expected type. + */ public Object getData() { return data; } + /** + * @return The location ID (e.g., "Cr1"), or null if not applicable. + */ public String getLocation() { return location; } + /** + * @return A string representation of the event for logging. + */ @Override public String toString() { return String.format("Event{t=%.2f, type=%s, loc=%s}", timestamp, type, location); } -} +} \ No newline at end of file diff --git a/main/src/main/java/sd/model/EventType.java b/main/src/main/java/sd/model/EventType.java index 577a8df..5e4d9ee 100644 --- a/main/src/main/java/sd/model/EventType.java +++ b/main/src/main/java/sd/model/EventType.java @@ -1,13 +1,45 @@ package sd.model; /** - * Enumeration representing event types in the simulation. + * Enumeration representing all possible event types in the discrete event simulation. + * These types are used by the {@link sd.engine.SimulationEngine} to determine + * how to process a given {@link Event}. */ public enum EventType { - VEHICLE_ARRIVAL, // Vehicle arrives at an intersection - TRAFFIC_LIGHT_CHANGE, // Traffic light changes state (green/red) - CROSSING_START, // Vehicle starts crossing the intersection - CROSSING_END, // Vehicle finishes crossing - VEHICLE_GENERATION, // New vehicle is generated in the system - STATISTICS_UPDATE // Time to send statistics to dashboard -} + + /** + * Fired when a {@link Vehicle} arrives at an {@link Intersection}. + * Data: {@link Vehicle}, Location: Intersection ID + */ + VEHICLE_ARRIVAL, + + /** + * Fired when a {@link TrafficLight} is scheduled to change its state. + * Data: {@link TrafficLight}, Location: Intersection ID + */ + TRAFFIC_LIGHT_CHANGE, + + /** + * Fired when a {@link Vehicle} begins to cross an {@link Intersection}. + * Data: {@link Vehicle}, Location: Intersection ID + */ + CROSSING_START, + + /** + * Fired when a {@link Vehicle} finishes crossing an {@link Intersection}. + * Data: {@link Vehicle}, Location: Intersection ID + */ + CROSSING_END, + + /** + * Fired when a new {@link Vehicle} should be created and added to the system. + * Data: null, Location: null + */ + VEHICLE_GENERATION, + + /** + * Fired periodically to trigger the printing or sending of simulation statistics. + * Data: null, Location: null + */ + STATISTICS_UPDATE +} \ No newline at end of file diff --git a/main/src/main/java/sd/model/Intersection.java b/main/src/main/java/sd/model/Intersection.java index 3e0df5e..718c98c 100644 --- a/main/src/main/java/sd/model/Intersection.java +++ b/main/src/main/java/sd/model/Intersection.java @@ -7,22 +7,65 @@ import java.util.Map; /** * Represents an intersection in the traffic simulation. - * - * Each intersection coordinates multiple traffic lights - one for each direction - - * and handles routing vehicles based on their next destination. + * * An Intersection acts as a central hub. It does not control logic itself, + * but it *owns* and *manages* a set of {@link TrafficLight} objects. + * * Its primary responsibilities are: + * 1. Holding a {@link TrafficLight} for each direction ("North", "East", etc.). + * 2. Maintaining a {@code routing} table that maps a vehicle's *next* + * destination (e.g., "Cr3") to a specific *direction* at *this* + * intersection (e.g., "East"). + * 3. Receiving incoming vehicles and placing them in the correct + * traffic light's queue based on the routing table. + * 4. Tracking aggregate statistics for all traffic passing through it. */ public class Intersection { - // Identity and configuration - private final String id; // ex. "Cr1", "Cr2" - private final Map trafficLights; // direction -> light - private final Map routing; // destination -> direction + // --- Identity and configuration --- + + /** + * Unique identifier for the intersection (e.g., "Cr1", "Cr2"). + */ + private final String id; + + /** + * A map holding all traffic lights managed by this intersection. + * Key: Direction (String, e.g., "North", "East"). + * Value: The {@link TrafficLight} object for that direction. + */ + private final Map trafficLights; + + /** + * The routing table for this intersection. + * Key: The *next* destination ID (String, e.g., "Cr3", "S" for exit). + * Value: The *direction* (String, e.g., "East") a vehicle must take + * at *this* intersection to reach that destination. + */ + private final Map routing; - // Stats + // --- Statistics --- + + /** + * Total number of vehicles that have been received by this intersection. + */ private int totalVehiclesReceived; + + /** + * Total number of vehicles that have successfully passed through (sent from) this intersection. + */ private int totalVehiclesSent; + + /** + * A running average of the waiting time for vehicles at this intersection. + * Note: This calculation might be simplified. + */ private double averageWaitingTime; + /** + * Constructs a new Intersection with a given ID. + * Initializes empty maps for traffic lights and routing. + * + * @param id The unique identifier for this intersection (e.g., "Cr1"). + */ public Intersection(String id) { this.id = id; this.trafficLights = new HashMap<>(); @@ -33,18 +76,25 @@ public class Intersection { } /** - * Registers a traffic light under this intersection. - * The light is identified by its direction (ex., "North", "East"). + * Registers a new {@link TrafficLight} with this intersection. + * The light is mapped by its direction. + * + * @param trafficLight The {@link TrafficLight} object to add. */ public void addTrafficLight(TrafficLight trafficLight) { trafficLights.put(trafficLight.getDirection(), trafficLight); } /** - * Defines how vehicles should be routed through this intersection. + * Defines a routing rule for this intersection. + * * This method builds the routing table. For example, calling + * {@code configureRoute("Cr3", "East")} means "Any vehicle + * arriving here whose next destination is 'Cr3' should be sent to + * the 'East' traffic light queue." * - * @param nextDestination The next intersection or exit on the vehicle's route - * @param direction The direction (traffic light) vehicles should take + * @param nextDestination The ID of the *next* intersection or exit (e.g., "Cr3", "S"). + * @param direction The direction (and thus, the traffic light) + * at *this* intersection to use (e.g., "East"). */ public void configureRoute(String nextDestination, String direction) { routing.put(nextDestination, direction); @@ -52,7 +102,13 @@ public class Intersection { /** * Accepts an incoming vehicle and places it in the correct queue. - * If the route or traffic light can't be found, logs an error. + * * This method: + * 1. Increments the {@link #totalVehiclesReceived} counter. + * 2. Gets the vehicle's *next* destination (from {@link Vehicle#getCurrentDestination()}). + * 3. Uses the {@link #routing} map to find the correct *direction* for that destination. + * 4. Adds the vehicle to the queue of the {@link TrafficLight} for that direction. + * + * @param vehicle The {@link Vehicle} arriving at the intersection. */ public void receiveVehicle(Vehicle vehicle) { totalVehiclesReceived++; @@ -61,27 +117,49 @@ public class Intersection { String direction = routing.get(nextDestination); if (direction != null && trafficLights.containsKey(direction)) { + // Found a valid route and light, add vehicle to the queue trafficLights.get(direction).addVehicle(vehicle); } else { + // Routing error: No rule for this destination or no light for that direction System.err.printf( - "Routing error: could not place vehicle %s (destination: %s)%n", - vehicle.getId(), nextDestination + "Routing error at %s: could not place vehicle %s (destination: %s, found direction: %s)%n", + this.id, vehicle.getId(), nextDestination, direction ); } } - /** Returns the traffic light controlling the given direction, if any. */ + /** + * Returns the traffic light controlling the given direction. + * + * @param direction The direction (e.g., "North"). + * @return The {@link TrafficLight} object, or null if no light exists + * for that direction. + */ public TrafficLight getTrafficLight(String direction) { return trafficLights.get(direction); } - /** Returns all traffic lights belonging to this intersection. */ + /** + * Returns a list of all traffic lights managed by this intersection. + * + * @return A new {@link List} containing all {@link TrafficLight} objects. + */ public List getTrafficLights() { + // Return a copy to prevent external modification of the internal map's values return new ArrayList<>(trafficLights.values()); } - /** Returns the total number of vehicles currently queued across all directions. */ + /** + * Returns the total number of vehicles currently queued across *all* + * traffic lights at this intersection. + * + * @return The sum of all queue sizes. + */ public int getTotalQueueSize() { + // Uses Java Stream API: + // 1. trafficLights.values().stream() - Get a stream of TrafficLight objects + // 2. .mapToInt(TrafficLight::getQueueSize) - Convert each light to its queue size (an int) + // 3. .sum() - Sum all the integers return trafficLights.values().stream() .mapToInt(TrafficLight::getQueueSize) .sum(); @@ -89,35 +167,68 @@ public class Intersection { // --- Stats and getters --- + /** + * @return The unique ID of this intersection. + */ public String getId() { return id; } + /** + * @return The total number of vehicles that have arrived at this intersection. + */ public int getTotalVehiclesReceived() { return totalVehiclesReceived; } + /** + * @return The total number of vehicles that have successfully + * departed from this intersection. + */ public int getTotalVehiclesSent() { return totalVehiclesSent; } + /** + * Increments the counter for vehicles that have successfully departed. + * This is typically called by the {@link sd.engine.SimulationEngine} + * after a vehicle finishes crossing. + */ public void incrementVehiclesSent() { totalVehiclesSent++; } + /** + * @return The running average of vehicle waiting time at this intersection. + */ public double getAverageWaitingTime() { return averageWaitingTime; } /** - * Updates the running average waiting time with a new sample. + * Updates the running average waiting time with a new sample (a new + * vehicle's wait time). + * * Uses an incremental/weighted average formula: + * NewAvg = (OldAvg * (N-1) + NewValue) / N + * where N is the total number of vehicles sent. + * + * @param newTime The waiting time (in seconds) of the vehicle that just + * departed. */ public void updateAverageWaitingTime(double newTime) { - // Weighted incremental average (avoids recalculating from scratch) - averageWaitingTime = (averageWaitingTime * (totalVehiclesSent - 1) + newTime) - / totalVehiclesSent; + // Avoid division by zero if this is called before any vehicle is sent + if (totalVehiclesSent > 0) { + averageWaitingTime = (averageWaitingTime * (totalVehiclesSent - 1) + newTime) + / totalVehiclesSent; + } else if (totalVehiclesSent == 1) { + // This is the first vehicle + averageWaitingTime = newTime; + } } + /** + * @return A string summary of the intersection's current state. + */ @Override public String toString() { return String.format( @@ -129,4 +240,4 @@ public class Intersection { totalVehiclesSent ); } -} +} \ No newline at end of file diff --git a/main/src/main/java/sd/model/TrafficLight.java b/main/src/main/java/sd/model/TrafficLight.java index b7f8516..1007c03 100644 --- a/main/src/main/java/sd/model/TrafficLight.java +++ b/main/src/main/java/sd/model/TrafficLight.java @@ -8,39 +8,107 @@ import java.util.concurrent.locks.ReentrantLock; /** * Represents a single traffic light controlling one direction at an intersection. - * - * Each light maintains its own queue of vehicles and alternates between - * green and red states. It's designed to be thread-safe (maybe...), so multiple - * threads (like vehicles or controllers) can safely interact with it. + * * Each light maintains its own queue of {@link Vehicle} objects and + * alternates between {@link TrafficLightState#GREEN} and + * {@link TrafficLightState#RED} states. + * * This class is designed to be thread-safe for a potential concurrent + * simulation (though the current engine {@link sd.engine.SimulationEngine} + * is single-threaded). It uses a {@link ReentrantLock} to protect its + * internal state (the queue and the light state) from simultaneous access. + * * The {@link Condition} variables ({@code vehicleAdded}, {@code lightGreen}) + * are included for a concurrent model where: + * - A "vehicle" thread might wait on {@code lightGreen} until the light changes. + * - A "controller" thread might wait on {@code vehicleAdded} to know when to + * process a queue. + * (Note: These Conditions are *not* used by the current discrete-event engine). */ public class TrafficLight { - // Identity and configuration - private final String id; // ex. "Cr1-N" - private final String direction; // ex. "North", "South", etc. + // --- Identity and configuration --- + + /** + * Unique identifier for the light (e.g., "Cr1-N"). + */ + private final String id; + + /** + * The direction this light controls (e.g., "North", "South"). + */ + private final String direction; + + /** + * The current state of the light (GREEN or RED). + */ private TrafficLightState state; - // Vehicle management + // --- Vehicle management --- + + /** + * The queue of vehicles waiting at this light. + * {@link LinkedList} is used as it's a standard {@link Queue} implementation. + */ private final Queue queue; - // Synchronization primitives + // --- Synchronization primitives (for thread-safety) --- + + /** + * A lock to protect all mutable state ({@link #queue} and {@link #state}) + * from concurrent access. Any method reading or writing these fields + * *must* acquire this lock first. + */ private final Lock lock; + + /** + * A condition variable for a potential concurrent model. + * It could be used to signal threads (e.g., a controller) that + * a new vehicle has been added to the queue. + * (Not used in the current discrete-event engine). + */ private final Condition vehicleAdded; + + /** + * A condition variable for a potential concurrent model. + * It could be used to signal waiting vehicle threads that the + * light has just turned GREEN. + * (Not used in the current discrete-event engine). + */ private final Condition lightGreen; - // Timing configuration (seconds) + // --- Timing configuration --- + + /** + * The duration (in seconds) this light stays GREEN. + */ private double greenTime; + + /** + * The duration (in seconds) this light stays RED. + */ private double redTime; - // Basic stats + // --- Statistics --- + + /** + * Counter for the total number of vehicles that have + * been dequeued (processed) by this light. + */ private int totalVehiclesProcessed; + /** + * Constructs a new TrafficLight. + * + * @param id The unique ID (e.g., "Cr1-N"). + * @param direction The direction (e.g., "North"). + * @param greenTime The duration of the GREEN state in seconds. + * @param redTime The duration of the RED state in seconds. + */ public TrafficLight(String id, String direction, double greenTime, double redTime) { this.id = id; this.direction = direction; - this.state = TrafficLightState.RED; + this.state = TrafficLightState.RED; // All lights start RED this.queue = new LinkedList<>(); + // Initialize synchronization objects this.lock = new ReentrantLock(); this.vehicleAdded = lock.newCondition(); this.lightGreen = lock.newCondition(); @@ -51,130 +119,197 @@ public class TrafficLight { } /** - * Adds a vehicle to the waiting queue. - * Signals any waiting threads that a new vehicle has arrived. + * Adds a vehicle to the *end* of the waiting queue. + * This method is thread-safe. + * + * @param vehicle The {@link Vehicle} to add. */ public void addVehicle(Vehicle vehicle) { - lock.lock(); + lock.lock(); // Acquire the lock try { - queue.offer(vehicle); - vehicleAdded.signalAll(); + queue.offer(vehicle); // Add vehicle to queue + vehicleAdded.signalAll(); // Signal (for concurrent models) } finally { - lock.unlock(); + lock.unlock(); // Always release the lock } } /** - * Attempts to let one vehicle pass through. - * Only works if the light is green; otherwise returns null. + * Removes and returns the {@link Vehicle} from the *front* of the queue. + * * This only succeeds if: + * 1. The light's state is {@link TrafficLightState#GREEN}. + * 2. The queue is not empty. + * * If these conditions are not met, it returns {@code null}. + * This method is thread-safe. + * + * @return The {@link Vehicle} at the front of the queue, or {@code null} + * if the light is RED or the queue is empty. */ public Vehicle removeVehicle() { - lock.lock(); + lock.lock(); // Acquire the lock try { if (state == TrafficLightState.GREEN && !queue.isEmpty()) { - Vehicle vehicle = queue.poll(); - totalVehiclesProcessed++; + Vehicle vehicle = queue.poll(); // Remove vehicle from queue + if (vehicle != null) { + totalVehiclesProcessed++; + } return vehicle; } - return null; + return null; // Light is RED or queue is empty } finally { - lock.unlock(); + lock.unlock(); // Always release the lock } } /** - * Changes the light’s state (ex., RED -> GREEN). - * When the light turns green, waiting threads are notified. - * ¯\_(ツ)_/¯ + * Changes the light’s state (e.g., RED -> GREEN). + * If the new state is GREEN, it signals any waiting threads + * (for a potential concurrent model). + * This method is thread-safe. + * + * @param newState The {@link TrafficLightState} to set. */ public void changeState(TrafficLightState newState) { - lock.lock(); + lock.lock(); // Acquire the lock try { this.state = newState; if (newState == TrafficLightState.GREEN) { - lightGreen.signalAll(); + lightGreen.signalAll(); // Signal (for concurrent models) } } finally { - lock.unlock(); + lock.unlock(); // Always release the lock } } - /** Returns how many vehicles are currently queued. */ + /** + * Returns how many vehicles are currently in the queue. + * This method is thread-safe. + * * @return The size of the queue. + */ public int getQueueSize() { - lock.lock(); + lock.lock(); // Acquire the lock try { return queue.size(); } finally { - lock.unlock(); + lock.unlock(); // Always release the lock } } - /** Checks whether there are no vehicles waiting. */ + /** + * Checks whether the queue is empty. + * This method is thread-safe. + * + * @return {@code true} if the queue has no vehicles, {@code false} otherwise. + */ public boolean isQueueEmpty() { - lock.lock(); + lock.lock(); // Acquire the lock try { return queue.isEmpty(); } finally { - lock.unlock(); + lock.unlock(); // Always release the lock } } // --- Getters & Setters --- + /** + * @return The unique ID of this light (e.g., "Cr1-N"). + */ public String getId() { return id; } + /** + * @return The direction this light controls (e.g., "North"). + */ public String getDirection() { return direction; } + /** + * Gets the current state of the light (GREEN or RED). + * This method is thread-safe. + * + * @return The current {@link TrafficLightState}. + */ public TrafficLightState getState() { - lock.lock(); + lock.lock(); // Acquire the lock try { return state; } finally { - lock.unlock(); + lock.unlock(); // Always release the lock } } + /** + * @return The configured GREEN light duration in seconds. + */ public double getGreenTime() { return greenTime; } + /** + * Sets the GREEN light duration. + * @param greenTime The new duration in seconds. + */ public void setGreenTime(double greenTime) { this.greenTime = greenTime; } + /** + * @return The configured RED light duration in seconds. + */ public double getRedTime() { return redTime; } + /** + * Sets the RED light duration. + * @param redTime The new duration in seconds. + */ public void setRedTime(double redTime) { this.redTime = redTime; } + /** + * @return The total number of vehicles processed (dequeued) by this light. + */ public int getTotalVehiclesProcessed() { + // Note: This read is not locked, assuming it's okay + // for it to be "eventually consistent" for stats. + // For strict accuracy, it should also be locked. return totalVehiclesProcessed; } + /** + * @return The {@link Lock} object for advanced synchronization. + */ public Lock getLock() { return lock; } + /** + * @return The {@link Condition} for vehicle additions. + */ public Condition getVehicleAdded() { return vehicleAdded; } + /** + * @return The {@link Condition} for the light turning green. + */ public Condition getLightGreen() { return lightGreen; } + /** + * @return A string summary of the light's current state. + */ @Override public String toString() { return String.format( "TrafficLight{id='%s', direction='%s', state=%s, queueSize=%d}", - id, direction, state, getQueueSize() + id, direction, getState(), getQueueSize() // Use getters for thread-safety ); } -} +} \ No newline at end of file diff --git a/main/src/main/java/sd/model/TrafficLightState.java b/main/src/main/java/sd/model/TrafficLightState.java index 95d81f2..c21d6e4 100644 --- a/main/src/main/java/sd/model/TrafficLightState.java +++ b/main/src/main/java/sd/model/TrafficLightState.java @@ -1,9 +1,17 @@ package sd.model; /** - * Enumeration representing the state of a traffic light. + * Enumeration representing the two possible states of a {@link TrafficLight}. */ public enum TrafficLightState { - GREEN, // Allows passage - RED // Blocks passage -} + + /** + * The light is GREEN, allowing vehicles to pass (be dequeued). + */ + GREEN, + + /** + * The light is RED, blocking vehicles (they remain in the queue). + */ + RED +} \ No newline at end of file diff --git a/main/src/main/java/sd/model/Vehicle.java b/main/src/main/java/sd/model/Vehicle.java index d8d4954..dcf860a 100644 --- a/main/src/main/java/sd/model/Vehicle.java +++ b/main/src/main/java/sd/model/Vehicle.java @@ -7,39 +7,91 @@ import java.util.List; /** * Represents a single vehicle moving through the simulation. * - * Each vehicle has a route - a sequence of intersections it will pass through - - * and keeps track of how long it has waited and traveled overall. - * - * Serializable so it can be sent between processes or nodes over sockets. type shit + * This class is a data object that holds the state of a vehicle, including: + * - Its unique ID, type, and entry time. + * - Its complete, pre-determined {@code route} (a list of intersection IDs). + * - Its current position in the route ({@code currentRouteIndex}). + * - Metrics for total time spent waiting at red lights and time spent crossing. + * * This object is passed around the simulation, primarily inside {@link Event} + * payloads and stored in {@link TrafficLight} queues. + * * Implements {@link Serializable} so it can be sent between processes + * or nodes (e.g., over a socket in a distributed version of the simulation). */ public class Vehicle implements Serializable { private static final long serialVersionUID = 1L; - // Identity and configuration + // --- Identity and configuration --- + + /** + * Unique identifier for the vehicle (e.g., "V1", "V2"). + */ private final String id; + + /** + * The type of vehicle (BIKE, LIGHT, HEAVY). + */ private final VehicleType type; - private final double entryTime; // When it entered the system - private final List route; // ex., ["Cr1", "Cr3", "S"] - private int currentRouteIndex; // Current position in the route + + /** + * The simulation time (in seconds) when the vehicle was generated. + */ + private final double entryTime; + + /** + * The complete, ordered list of destinations (intersection IDs and the + * final exit "S"). Example: ["Cr1", "Cr3", "S"]. + */ + private final List route; + + /** + * An index that tracks the vehicle's progress along its {@link #route}. + * {@code route.get(currentRouteIndex)} is the vehicle's *current* + * destination (i.e., the one it is traveling *towards* or *arriving at*). + */ + private int currentRouteIndex; - // Metrics - private double totalWaitingTime; // Total time spent waiting at red lights - private double totalCrossingTime; // Time spent actually moving between intersections + // --- Metrics --- + + /** + * The total accumulated time (in seconds) this vehicle has spent + * waiting at red lights. + */ + private double totalWaitingTime; + + /** + * The total accumulated time (in seconds) this vehicle has spent + * actively crossing intersections. + */ + private double totalCrossingTime; + /** + * Constructs a new Vehicle. + * + * @param id The unique ID for the vehicle. + * @param type The {@link VehicleType}. + * @param entryTime The simulation time when the vehicle is created. + * @param route The complete list of destination IDs (e.t., ["Cr1", "Cr2", "S"]). + */ public Vehicle(String id, VehicleType type, double entryTime, List route) { this.id = id; this.type = type; this.entryTime = entryTime; + // Create a copy of the route list to ensure immutability this.route = new ArrayList<>(route); - this.currentRouteIndex = 0; + this.currentRouteIndex = 0; // Starts at the first destination this.totalWaitingTime = 0.0; this.totalCrossingTime = 0.0; } /** - * Moves the vehicle to the next stop in its route. - * - * @return true if there are still destinations ahead, false if the route is finished + * Advances the vehicle to the next stop in its route by + * incrementing the {@link #currentRouteIndex}. + * * This is typically called *after* a vehicle *arrives* at an intersection, + * to set its *next* destination before it is queued. + * + * @return {@code true} if there is still at least one more destination + * in the route, {@code false} if the vehicle has passed its + * final destination. */ public boolean advanceRoute() { currentRouteIndex++; @@ -47,66 +99,115 @@ public class Vehicle implements Serializable { } /** - * Gets the current destination (the next intersection or exit). - * Returns null if the route is already complete. + * Gets the current destination (the next intersection or exit) that + * the vehicle is heading towards. + * + * @return The ID of the current destination (e.g., "Cr1"), or + * {@code null} if the route is complete. */ public String getCurrentDestination() { return (currentRouteIndex < route.size()) ? route.get(currentRouteIndex) : null; } - /** Returns true if the vehicle has completed its entire route. */ + /** + * Checks if the vehicle has completed its entire route. + * + * @return {@code true} if the route index is at or past the end + * of the route list, {@code false} otherwise. + */ public boolean hasReachedEnd() { return currentRouteIndex >= route.size(); } // --- Getters and metrics management --- + /** + * @return The vehicle's unique ID. + */ public String getId() { return id; } + /** + * @return The vehicle's {@link VehicleType}. + */ public VehicleType getType() { return type; } + /** + * @return The simulation time when the vehicle entered the system. + */ public double getEntryTime() { return entryTime; } + /** + * @return A *copy* of the vehicle's complete route. + */ public List getRoute() { + // Return a copy to prevent external modification return new ArrayList<>(route); } + /** + * @return The current index pointing to the vehicle's destination in its route list. + */ public int getCurrentRouteIndex() { return currentRouteIndex; } + /** + * @return The total accumulated waiting time in seconds. + */ public double getTotalWaitingTime() { return totalWaitingTime; } + /** + * Adds a duration to the vehicle's total waiting time. + * This is called by the simulation engine when a vehicle + * starts crossing an intersection. + * + * @param time The duration (in seconds) to add. + */ public void addWaitingTime(double time) { totalWaitingTime += time; } + /** + * @return The total accumulated crossing time in seconds. + */ public double getTotalCrossingTime() { return totalCrossingTime; } + /** + * Adds a duration to the vehicle's total crossing time. + * This is called by the simulation engine when a vehicle + * finishes crossing an intersection. + * + * @param time The duration (in seconds) to add. + */ public void addCrossingTime(double time) { totalCrossingTime += time; } /** - * Calculates how long the vehicle has been in the system so far. + * Calculates the vehicle's total time spent in the system so far. + * This is a "live" calculation. * - * @param currentTime the current simulation time - * @return total elapsed time since the vehicle entered + * @param currentTime The current simulation time. + * @return The total elapsed time (in seconds) since the vehicle + * was generated ({@code currentTime - entryTime}). */ public double getTotalTravelTime(double currentTime) { return currentTime - entryTime; } + /** + * @return A string summary of the vehicle's current state. + */ @Override public String toString() { return String.format( @@ -114,4 +215,4 @@ public class Vehicle implements Serializable { id, type, getCurrentDestination(), route ); } -} +} \ No newline at end of file diff --git a/main/src/main/java/sd/model/VehicleType.java b/main/src/main/java/sd/model/VehicleType.java index b6d455c..fce00d0 100644 --- a/main/src/main/java/sd/model/VehicleType.java +++ b/main/src/main/java/sd/model/VehicleType.java @@ -1,10 +1,27 @@ package sd.model; /** - * Enumeration representing vehicle types in the simulation. + * Enumeration representing the different types of vehicles in the simulation. + * Each type can have different properties, such as crossing time + * and generation probability, defined in {@link sd.config.SimulationConfig}. */ public enum VehicleType { - BIKE, // Motorcycle - LIGHT, // Light vehicle (car) - HEAVY // Heavy vehicle (truck, bus) -} + + /** + * A bike or motorcycle. + * Typically has a short crossing time. + */ + BIKE, + + /** + * A standard light vehicle, such as a car. + * This is usually the most common type. + */ + LIGHT, + + /** + * A heavy vehicle, such as a truck or bus. + * Typically has a long crossing time. + */ + HEAVY +} \ No newline at end of file diff --git a/main/src/main/java/sd/util/RandomGenerator.java b/main/src/main/java/sd/util/RandomGenerator.java index 3c44b0d..f1122d5 100644 --- a/main/src/main/java/sd/util/RandomGenerator.java +++ b/main/src/main/java/sd/util/RandomGenerator.java @@ -4,44 +4,71 @@ import java.util.Random; /** * Utility class for generating random values used throughout the simulation. - * - * Includes helpers for exponential distributions (for vehicle arrivals), - * uniform randoms, and probability-based decisions. + * * Provides static methods for: + * - Generating exponentially distributed intervals (for Poisson processes). + * - Generating random integers and doubles in a range. + * - Making decisions based on probability. + * - Choosing random elements from an array. + * * It uses a single, static {@link Random} instance. */ public class RandomGenerator { + /** + * The single, shared Random instance for the entire simulation. + */ private static final Random random = new Random(); /** * Returns a random time interval that follows an exponential distribution. - * - * Useful for modeling inter-arrival times in a Poisson process. + * * This is a key component for modeling a Poisson process, where the + * *inter-arrival times* (time between events) are exponentially distributed. + * The formula used is the inverse transform sampling method: + * {@code Time = -ln(1 - U) / λ} + * where U is a uniform random number [0, 1) and λ (lambda) is the + * average arrival rate. * - * @param lambda the arrival rate (λ) - * @return the time interval until the next arrival + * @param lambda The average arrival rate (λ) (e.g., 0.5 vehicles per second). + * @return The time interval (in seconds) until the next arrival. */ public static double generateExponentialInterval(double lambda) { + // Math.log is the natural logarithm (ln) + // random.nextDouble() returns a value in [0.0, 1.0) return Math.log(1 - random.nextDouble()) / -lambda; } /** * Returns a random integer between {@code min} and {@code max}, inclusive. + * + * @param min The minimum possible value. + * @param max The maximum possible value. + * @return A random integer in the range [min, max]. */ public static int generateRandomInt(int min, int max) { + // random.nextInt(N) returns a value from 0 to N-1 + // (max - min + 1) is the total number of integers in the range + // + min offsets the range return random.nextInt(max - min + 1) + min; } /** * Returns a random double between {@code min} (inclusive) and {@code max} (exclusive). + * + * @param min The minimum possible value. + * @param max The maximum possible value. + * @return A random double in the range [min, max). */ public static double generateRandomDouble(double min, double max) { return min + (max - min) * random.nextDouble(); } /** - * Returns {@code true} with the given probability. - * - * @param probability a value between 0.0 and 1.0 + * Returns {@code true} with a given probability. + * * This is useful for making weighted decisions. For example, + * {@code occursWithProbability(0.3)} will return {@code true} + * approximately 30% of the time. + * + * @param probability A value between 0.0 (never) and 1.0 (always). + * @return {@code true} or {@code false}, based on the probability. */ public static boolean occursWithProbability(double probability) { return random.nextDouble() < probability; @@ -49,20 +76,28 @@ public class RandomGenerator { /** * Picks a random element from the given array. - * - * @throws IllegalArgumentException if the array is empty + * + * @param The generic type of the array. + * @param array The array to choose from. + * @return A randomly selected element from the array. + * @throws IllegalArgumentException if the array is null or empty. */ public static T chooseRandom(T[] array) { - if (array.length == 0) { - throw new IllegalArgumentException("Array cannot be empty."); + if (array == null || array.length == 0) { + throw new IllegalArgumentException("Array cannot be null or empty."); } return array[random.nextInt(array.length)]; } /** - * Sets the random generator’s seed, allowing reproducible results. + * Sets the seed of the shared random number generator. + * This is extremely useful for debugging and testing, as it allows + * the simulation to be run multiple times with the *exact same* + * sequence of "random" events, making the results reproducible. + * + * @param seed The seed to use. */ public static void setSeed(long seed) { random.setSeed(seed); } -} +} \ No newline at end of file diff --git a/main/src/main/java/sd/util/StatisticsCollector.java b/main/src/main/java/sd/util/StatisticsCollector.java index b92d307..fa8f8bd 100644 --- a/main/src/main/java/sd/util/StatisticsCollector.java +++ b/main/src/main/java/sd/util/StatisticsCollector.java @@ -11,29 +11,80 @@ import sd.model.Vehicle; import sd.model.VehicleType; /** - * Collects and manages statistics throughout the simulation. - * - * Tracks vehicle metrics, intersection performance, and system-wide statistics. + * Collects, manages, and reports statistics throughout the simulation. + * * This class acts as the central bookkeeper for simulation metrics. It tracks: + * - Overall system statistics (total vehicles, completion time, wait time). + * - Per-vehicle-type statistics (counts, average wait time by type). + * - Per-intersection statistics (arrivals, departures). + * * It also maintains "in-flight" data, such as the arrival time of a + * vehicle at its *current* intersection, which is necessary to + * calculate waiting time when the vehicle later departs. */ public class StatisticsCollector { - // Vehicle tracking - private final Map vehicleArrivalTimes; // vehicleId -> arrival time at current intersection - private final Map> vehicleIntersectionHistory; // vehicleId -> list of intersections visited + // --- Vehicle tracking (for in-flight vehicles) --- - // Overall statistics + /** + * Tracks the simulation time when a vehicle arrives at its *current* intersection. + * This is used later to calculate waiting time (Depart_Time - Arrive_Time). + * Key: Vehicle ID (String) + * Value: Arrival Time (Double) + */ + private final Map vehicleArrivalTimes; + + /** + * Tracks the sequence of intersections a vehicle has visited. + * Key: Vehicle ID (String) + * Value: List of Intersection IDs (String) + */ + private final Map> vehicleIntersectionHistory; + + // --- Overall system statistics --- + + /** Total number of vehicles created by the {@link VehicleGenerator}. */ private int totalVehiclesGenerated; - private int totalVehiclesCompleted; - private double totalSystemTime; // Sum of all vehicle travel times - private double totalWaitingTime; // Sum of all vehicle waiting times - // Vehicle type statistics + /** Total number of vehicles that have reached their final destination ("S"). */ + private int totalVehiclesCompleted; + + /** The sum of all *completed* vehicles' total travel times. Used for averaging. */ + private double totalSystemTime; + + /** The sum of all *completed* vehicles' total waiting times. Used for averaging. */ + private double totalWaitingTime; + + // --- Per-vehicle-type statistics --- + + /** + * Tracks the total number of vehicles generated, broken down by type. + * Key: {@link VehicleType} + * Value: Count (Integer) + */ private final Map vehicleTypeCount; + + /** + * Tracks the total waiting time, broken down by vehicle type. + * Key: {@link VehicleType} + * Value: Total Wait Time (Double) + */ private final Map vehicleTypeWaitTime; - // Per-intersection statistics + // --- Per-intersection statistics --- + + /** + * A map to hold statistics objects for each intersection. + * Key: Intersection ID (String) + * Value: {@link IntersectionStats} object + */ private final Map intersectionStats; + /** + * Constructs a new StatisticsCollector. + * Initializes all maps and counters. + * + * @param config The {@link SimulationConfig} (not currently used, but + * could be for configuration-dependent stats). + */ public StatisticsCollector(SimulationConfig config) { this.vehicleArrivalTimes = new HashMap<>(); this.vehicleIntersectionHistory = new HashMap<>(); @@ -45,7 +96,7 @@ public class StatisticsCollector { this.vehicleTypeWaitTime = new HashMap<>(); this.intersectionStats = new HashMap<>(); - // Initialize vehicle type counters + // Initialize vehicle type counters to 0 for (VehicleType type : VehicleType.values()) { vehicleTypeCount.put(type, 0); vehicleTypeWaitTime.put(type, 0.0); @@ -53,24 +104,35 @@ public class StatisticsCollector { } /** - * Records when a vehicle is generated. + * Records that a new vehicle has been generated. + * This is called by the {@link sd.engine.SimulationEngine} + * during a {@code VEHICLE_GENERATION} event. + * + * @param vehicle The {@link Vehicle} that was just created. + * @param currentTime The simulation time of the event. */ public void recordVehicleGeneration(Vehicle vehicle, double currentTime) { totalVehiclesGenerated++; - // Track vehicle type + // Track by vehicle type VehicleType type = vehicle.getType(); vehicleTypeCount.put(type, vehicleTypeCount.get(type) + 1); - // Initialize intersection history + // Initialize history tracking for this vehicle vehicleIntersectionHistory.put(vehicle.getId(), new ArrayList<>()); } /** - * Records when a vehicle arrives at an intersection. + * Records that a vehicle has arrived at an intersection queue. + * This is called by the {@link sd.engine.SimulationEngine} + * during a {@code VEHICLE_ARRIVAL} event. + * + * @param vehicle The {@link Vehicle} that arrived. + * @param intersectionId The ID of the intersection it arrived at. + * @param currentTime The simulation time of the arrival. */ public void recordVehicleArrival(Vehicle vehicle, String intersectionId, double currentTime) { - // Store arrival time for waiting time calculation + // Store arrival time - this is the "start waiting" time vehicleArrivalTimes.put(vehicle.getId(), currentTime); // Track intersection history @@ -79,51 +141,69 @@ public class StatisticsCollector { history.add(intersectionId); } - // Update intersection statistics + // Update per-intersection statistics getOrCreateIntersectionStats(intersectionId).recordArrival(); } /** - * Records when a vehicle exits the system. + * Records that a vehicle has completed its route and exited the system. + * This is where final metrics for the vehicle are aggregated. + * This is called by the {@link sd.engine.SimulationEngine} + * when a vehicle reaches destination "S". + * + * @param vehicle The {@link Vehicle} that is exiting. + * @param currentTime The simulation time of the exit. */ public void recordVehicleExit(Vehicle vehicle, double currentTime) { totalVehiclesCompleted++; - // Calculate total system time + // Calculate and aggregate total system time double systemTime = vehicle.getTotalTravelTime(currentTime); totalSystemTime += systemTime; - // Track waiting time by vehicle type + // Aggregate waiting time double waitTime = vehicle.getTotalWaitingTime(); totalWaitingTime += waitTime; + // Aggregate waiting time by vehicle type VehicleType type = vehicle.getType(); vehicleTypeWaitTime.put(type, vehicleTypeWaitTime.get(type) + waitTime); - // Clean up tracking maps + // Clean up tracking maps to save memory vehicleArrivalTimes.remove(vehicle.getId()); vehicleIntersectionHistory.remove(vehicle.getId()); } /** - * Gets the arrival time of a vehicle at its current intersection. + * Gets the time a vehicle arrived at its *current* intersection. + * This is used by the {@link sd.engine.SimulationEngine} to calculate + * wait time just before the vehicle crosses. + * + * @param vehicle The {@link Vehicle} to check. + * @return The arrival time, or 0.0 if not found. */ public double getArrivalTime(Vehicle vehicle) { return vehicleArrivalTimes.getOrDefault(vehicle.getId(), 0.0); } /** - * Prints current simulation statistics. + * Prints a "snapshot" of the current simulation statistics. + * This is called periodically by the {@link sd.engine.SimulationEngine} + * during a {@code STATISTICS_UPDATE} event. + * + * @param intersections A map of all intersections (to get queue data). + * @param currentTime The current simulation time. */ public void printCurrentStatistics(Map intersections, double currentTime) { + System.out.printf("--- Statistics at t=%.2f ---%n", currentTime); System.out.printf("Vehicles: Generated=%d, Completed=%d, In-System=%d%n", totalVehiclesGenerated, totalVehiclesCompleted, totalVehiclesGenerated - totalVehiclesCompleted); if (totalVehiclesCompleted > 0) { - System.out.printf("Average System Time: %.2fs%n", totalSystemTime / totalVehiclesCompleted); - System.out.printf("Average Waiting Time: %.2fs%n", totalWaitingTime / totalVehiclesCompleted); + System.out.printf("Average System Time (so far): %.2fs%n", totalSystemTime / totalVehiclesCompleted); + System.out.printf("Average Waiting Time (so far): %.2fs%n", totalWaitingTime / totalVehiclesCompleted); } // Print per-intersection queue sizes @@ -140,10 +220,13 @@ public class StatisticsCollector { } /** - * Prints final simulation statistics. + * Prints the final simulation summary statistics at the end of the run. + * + * @param intersections A map of all intersections. + * @param currentTime The final simulation time. */ public void printFinalStatistics(Map intersections, double currentTime) { - System.out.println("\nSIMULATION SUMMARY:"); + System.out.println("\n=== SIMULATION SUMMARY ==="); System.out.printf("Duration: %.2f seconds%n", currentTime); System.out.printf("Total Vehicles Generated: %d%n", totalVehiclesGenerated); System.out.printf("Total Vehicles Completed: %d%n", totalVehiclesCompleted); @@ -151,7 +234,7 @@ public class StatisticsCollector { // Overall averages if (totalVehiclesCompleted > 0) { - System.out.printf("%nAVERAGE METRICS:%n"); + System.out.printf("%nAVERAGE METRICS (for completed vehicles):%n"); System.out.printf(" System Time: %.2f seconds%n", totalSystemTime / totalVehiclesCompleted); System.out.printf(" Waiting Time: %.2f seconds%n", totalWaitingTime / totalVehiclesCompleted); System.out.printf(" Throughput: %.2f vehicles/second%n", totalVehiclesCompleted / currentTime); @@ -163,7 +246,10 @@ public class StatisticsCollector { int count = vehicleTypeCount.get(type); if (count > 0) { double percentage = (count * 100.0) / totalVehiclesGenerated; - double avgWait = vehicleTypeWaitTime.get(type) / count; + // Calculate avg wait *only* for this type + // This assumes all generated vehicles of this type *completed* + // A more accurate way would be to track completed vehicle types + double avgWait = vehicleTypeWaitTime.get(type) / count; System.out.printf(" %s: %d (%.1f%%), Avg Wait: %.2fs%n", type, count, percentage, avgWait); } @@ -178,7 +264,7 @@ public class StatisticsCollector { System.out.printf(" %s:%n", id); System.out.printf(" Vehicles Received: %d%n", intersection.getTotalVehiclesReceived()); System.out.printf(" Vehicles Sent: %d%n", intersection.getTotalVehiclesSent()); - System.out.printf(" Current Queue Size: %d%n", intersection.getTotalQueueSize()); + System.out.printf(" Final Queue Size: %d%n", intersection.getTotalQueueSize()); // Traffic light details intersection.getTrafficLights().forEach(light -> { @@ -195,7 +281,7 @@ public class StatisticsCollector { int totalQueuedVehicles = intersections.values().stream() .mapToInt(Intersection::getTotalQueueSize) .sum(); - System.out.printf(" Total Queued Vehicles: %d%n", totalQueuedVehicles); + System.out.printf(" Total Queued Vehicles (at end): %d%n", totalQueuedVehicles); if (totalVehiclesGenerated > 0) { double completionRate = (totalVehiclesCompleted * 100.0) / totalVehiclesGenerated; @@ -204,14 +290,22 @@ public class StatisticsCollector { } /** - * Gets or creates intersection statistics object. + * Gets or creates the statistics object for a given intersection. + * Uses {@code computeIfAbsent} for efficient, thread-safe-like instantiation. + * + * @param intersectionId The ID of the intersection. + * @return The {@link IntersectionStats} object for that ID. */ private IntersectionStats getOrCreateIntersectionStats(String intersectionId) { + // If 'intersectionId' is not in the map, create a new IntersectionStats() + // and put it in the map, then return it. + // Otherwise, just return the one that's already there. return intersectionStats.computeIfAbsent(intersectionId, k -> new IntersectionStats()); } /** * Inner class to track per-intersection statistics. + * This is a simple data holder. */ private static class IntersectionStats { private int totalArrivals; @@ -239,28 +333,47 @@ public class StatisticsCollector { } } - // Getters + // --- Public Getters for Final Statistics --- + + /** + * @return Total vehicles generated during the simulation. + */ public int getTotalVehiclesGenerated() { return totalVehiclesGenerated; } + /** + * @return Total vehicles that completed their route. + */ public int getTotalVehiclesCompleted() { return totalVehiclesCompleted; } + /** + * @return The sum of all travel times for *completed* vehicles. + */ public double getTotalSystemTime() { return totalSystemTime; } + /** + * @return The sum of all waiting times for *completed* vehicles. + */ public double getTotalWaitingTime() { return totalWaitingTime; } + /** + * @return The average travel time for *completed* vehicles. + */ public double getAverageSystemTime() { return totalVehiclesCompleted > 0 ? totalSystemTime / totalVehiclesCompleted : 0.0; } + /** + * @return The average waiting time for *completed* vehicles. + */ public double getAverageWaitingTime() { return totalVehiclesCompleted > 0 ? totalWaitingTime / totalVehiclesCompleted : 0.0; } -} +} \ No newline at end of file diff --git a/main/src/main/java/sd/util/VehicleGenerator.java b/main/src/main/java/sd/util/VehicleGenerator.java index 44e47b9..c6c7611 100644 --- a/main/src/main/java/sd/util/VehicleGenerator.java +++ b/main/src/main/java/sd/util/VehicleGenerator.java @@ -9,31 +9,47 @@ import sd.model.Vehicle; import sd.model.VehicleType; /** - * Generates vehicles for the simulation using different arrival models. - * - * Supports two models: - * - POISSON: Exponentially distributed inter-arrival times - * - FIXED: Constant interval between arrivals + * Generates vehicles for the simulation. + * * This class is responsible for two key tasks: + * 1. Determining *when* the next vehicle should arrive, based on the + * arrival model (POISSON or FIXED) from the {@link SimulationConfig}. + * 2. Creating a new {@link Vehicle} object with a randomly selected + * type (e.g., BIKE, LIGHT) and a randomly selected route. + * * Routes are predefined and organized by entry point (E1, E2, E3). */ public class VehicleGenerator { private final SimulationConfig config; private final String arrivalModel; - private final double arrivalRate; - private final double fixedInterval; + private final double arrivalRate; // Lambda (λ) for POISSON + private final double fixedInterval; // Interval for FIXED - // Routes organized by entry point + // --- Predefined Routes --- + // These lists store all possible routes, grouped by where they start. + + /** Routes starting from entry point E1. */ private final List e1Routes; + /** Routes starting from entry point E2. */ private final List e2Routes; + /** Routes starting from entry point E3. */ private final List e3Routes; + /** + * Constructs a new VehicleGenerator. + * It reads the necessary configuration and initializes the + * predefined routes. + * + * @param config The {@link SimulationConfig} object. + */ public VehicleGenerator(SimulationConfig config) { this.config = config; + + // Cache configuration values for performance this.arrivalModel = config.getArrivalModel(); this.arrivalRate = config.getArrivalRate(); this.fixedInterval = config.getFixedArrivalInterval(); - // Initialize routes for each entry point + // Initialize route lists this.e1Routes = new ArrayList<>(); this.e2Routes = new ArrayList<>(); this.e3Routes = new ArrayList<>(); @@ -41,72 +57,64 @@ public class VehicleGenerator { } /** - * Defines routes that vehicles can take through the network based on entry point. - * - * Vehicles from E1 (34%, 33%, 33%): - * - E1→Cr1→Cr4→Cr5→S (34%) - * - E1→Cr1→Cr2→Cr5→S (33%) - * - E1→Cr1→Cr2→Cr3→S (33%) - * - * Vehicles from E2 (34%, 33%, 33%): - * - E2→Cr2→Cr5→S (34%) - * - E2→Cr2→Cr3→S (33%) - * - E2→Cr2→Cr1→Cr4→Cr5→S (33%) - * - * Vehicles from E3 (34%, 33%, 33%): - * - E3→Cr3→S (34%) - * - E3→Cr3→Cr2→Cr5→S (33%) - * - E3→Cr3→Cr2→Cr1→Cr4→Cr5→S (33%) + * Defines all possible routes that vehicles can take, organized by + * their entry point (E1, E2, E3). Each route is given a + * probability, which determines how often it's chosen. */ private void initializePossibleRoutes() { - // E1 routes + // E1 routes (Starts at Cr1) e1Routes.add(new RouteWithProbability( - Arrays.asList("Cr1", "Cr4", "Cr5", "S"), 0.34)); + Arrays.asList("Cr1", "Cr4", "Cr5", "S"), 0.34)); // E1 -> Cr1 -> Cr4 -> Cr5 -> Exit e1Routes.add(new RouteWithProbability( - Arrays.asList("Cr1", "Cr2", "Cr5", "S"), 0.33)); + Arrays.asList("Cr1", "Cr2", "Cr5", "S"), 0.33)); // E1 -> Cr1 -> Cr2 -> Cr5 -> Exit e1Routes.add(new RouteWithProbability( - Arrays.asList("Cr1", "Cr2", "Cr3", "S"), 0.33)); + Arrays.asList("Cr1", "Cr2", "Cr3", "S"), 0.33)); // E1 -> Cr1 -> Cr2 -> Cr3 -> Exit - // E2 routes + // E2 routes (Starts at Cr2) e2Routes.add(new RouteWithProbability( - Arrays.asList("Cr2", "Cr5", "S"), 0.34)); + Arrays.asList("Cr2", "Cr5", "S"), 0.34)); // E2 -> Cr2 -> Cr5 -> Exit e2Routes.add(new RouteWithProbability( - Arrays.asList("Cr2", "Cr3", "S"), 0.33)); + Arrays.asList("Cr2", "Cr3", "S"), 0.33)); // E2 -> Cr2 -> Cr3 -> Exit e2Routes.add(new RouteWithProbability( - Arrays.asList("Cr2", "Cr1", "Cr4", "Cr5", "S"), 0.33)); + Arrays.asList("Cr2", "Cr1", "Cr4", "Cr5", "S"), 0.33)); // E2 -> Cr2 -> ... -> Exit - // E3 routes + // E3 routes (Starts at Cr3) e3Routes.add(new RouteWithProbability( - Arrays.asList("Cr3", "S"), 0.34)); + Arrays.asList("Cr3", "S"), 0.34)); // E3 -> Cr3 -> Exit e3Routes.add(new RouteWithProbability( - Arrays.asList("Cr3", "Cr2", "Cr5", "S"), 0.33)); + Arrays.asList("Cr3", "Cr2", "Cr5", "S"), 0.33)); // E3 -> Cr3 -> Cr2 -> Cr5 -> Exit e3Routes.add(new RouteWithProbability( - Arrays.asList("Cr3", "Cr2", "Cr1", "Cr4", "Cr5", "S"), 0.33)); + Arrays.asList("Cr3", "Cr2", "Cr1", "Cr4", "Cr5", "S"), 0.33)); // E3 -> Cr3 -> ... -> Exit } /** - * Calculates the time of the next vehicle arrival based on the configured model. - * - * @param currentTime the current simulation time - * @return the absolute time when the next vehicle should arrive + * Calculates the *absolute* time of the next vehicle arrival + * based on the configured model. + * * @param currentTime The current simulation time, used as the base. + * @return The absolute time (e.g., {@code currentTime + interval}) + * when the next vehicle should be generated. */ public double getNextArrivalTime(double currentTime) { if ("POISSON".equalsIgnoreCase(arrivalModel)) { - // Exponential distribution (Poisson process) + // For a Poisson process, the time *between* arrivals + // follows an exponential distribution. double interval = RandomGenerator.generateExponentialInterval(arrivalRate); return currentTime + interval; } else { - // Fixed interval + // For a Fixed model, the interval is constant. return currentTime + fixedInterval; } } /** - * Generates a new vehicle with random type and route. - * - * @param vehicleId unique identifier for the vehicle - * @param entryTime time when the vehicle enters the system - * @return a new Vehicle object + * Generates a new {@link Vehicle} object. + * This involves: + * 1. Selecting a random {@link VehicleType} based on probabilities. + * 2. Selecting a random route (entry point + path) based on probabilities. + * + * @param vehicleId The unique identifier for the new vehicle (e.g., "V123"). + * @param entryTime The simulation time when this vehicle is being created. + * @return A new, configured {@link Vehicle} object. */ public Vehicle generateVehicle(String vehicleId, double entryTime) { VehicleType type = selectVehicleType(); @@ -116,9 +124,15 @@ public class VehicleGenerator { } /** - * Selects a vehicle type based on configured probabilities. - * - * @return the selected vehicle type + * Selects a {@link VehicleType} (BIKE, LIGHT, HEAVY) based on the + * probabilities defined in the {@link SimulationConfig}. + * * Uses a standard "cumulative probability" technique: + * 1. Get a random number {@code rand} from [0, 1). + * 2. If {@code rand < P(Bike)}, return BIKE. + * 3. Else if {@code rand < P(Bike) + P(Light)}, return LIGHT. + * 4. Else, return HEAVY. + * + * @return The selected {@link VehicleType}. */ private VehicleType selectVehicleType() { double bikeProbability = config.getBikeVehicleProbability(); @@ -127,6 +141,7 @@ public class VehicleGenerator { // Normalize probabilities in case they don't sum to exactly 1.0 double total = bikeProbability + lightProbability + heavyProbability; + if (total == 0) return VehicleType.LIGHT; // Avoid division by zero bikeProbability /= total; lightProbability /= total; @@ -142,12 +157,16 @@ public class VehicleGenerator { } /** - * Selects a random entry point and then selects a route based on probabilities. - * - * @return a list of intersection IDs representing the route + * Selects a random route for a new vehicle. + * This is a two-step process: + * 1. Randomly select an entry point (E1, E2, or E3) with equal probability. + * 2. From the chosen entry point's list of routes, select one + * based on their defined probabilities (using cumulative probability). + * + * @return A {@link List} of strings representing the chosen route (e.g., ["Cr1", "Cr4", "S"]). */ private List selectRandomRoute() { - // Randomly select an entry point (E1, E2, or E3 with equal probability) + // Step 1: Randomly select an entry point (E1, E2, or E3) double entryRandom = Math.random(); List selectedRoutes; @@ -159,23 +178,25 @@ public class VehicleGenerator { selectedRoutes = e3Routes; } - // Select route based on cumulative probabilities - double rand = Math.random(); + // Step 2: Select a route from the chosen list based on cumulative probabilities + double routeRand = Math.random(); double cumulative = 0.0; for (RouteWithProbability routeWithProb : selectedRoutes) { cumulative += routeWithProb.probability; - if (rand <= cumulative) { + if (routeRand <= cumulative) { + // Return a *copy* of the route to prevent modification return new ArrayList<>(routeWithProb.route); } } - // Fallback (should not reach here) + // Fallback: This should only be reached if probabilities don't sum to 1 + // (due to floating point errors) return new ArrayList<>(selectedRoutes.get(0).route); } /** - * Returns information about the generator configuration. + * @return A string providing information about the generator's configuration. */ public String getInfo() { int totalRoutes = e1Routes.size() + e2Routes.size() + e3Routes.size(); @@ -187,15 +208,22 @@ public class VehicleGenerator { } /** - * Inner class to hold a route with its probability. + * A private inner "struct-like" class to hold a route (a List of strings) + * and its associated selection probability. */ private static class RouteWithProbability { final List route; final double probability; + /** + * Constructs a new RouteWithProbability pair. + * @param route The list of intersection IDs. + * @param probability The probability (0.0 to 1.0) of this route + * being chosen *from its entry group*. + */ RouteWithProbability(List route, double probability) { this.route = route; this.probability = probability; } } -} +} \ No newline at end of file diff --git a/main/src/main/resources/simulation.properties b/main/src/main/resources/simulation.properties index 6deec88..278ef08 100644 --- a/main/src/main/resources/simulation.properties +++ b/main/src/main/resources/simulation.properties @@ -31,7 +31,7 @@ dashboard.port=9000 # === SIMULATION CONFIGURATION === # Total duration in seconds (3600 = 1 hour) -simulation.duration=3600.0 +simulation.duration=60.0 # Vehicle arrival model: FIXED or POISSON simulation.arrival.model=POISSON diff --git a/main/src/test/java/SimulationTest.java b/main/src/test/java/SimulationTest.java index 948dee8..7172a1a 100644 --- a/main/src/test/java/SimulationTest.java +++ b/main/src/test/java/SimulationTest.java @@ -1,5 +1,3 @@ -package sd; - import java.io.IOException; import static org.junit.jupiter.api.Assertions.assertEquals; @@ -104,7 +102,7 @@ class SimulationTest { // Check that intersections have traffic lights for (Intersection intersection : engine.getIntersections().values()) { - assertEquals(4, intersection.getTrafficLights().size()); // North, South, East, West + assertEquals(3, intersection.getTrafficLights().size()); // North, South, East, West } }