Documentation

main/src/main/java/sd/ExitNodeProcess.java

@@ -20,58 +20,65 @@ import sd.protocol.MessageProtocol;
 import sd.protocol.SocketConnection;
 
 /**
- * Processo responsável pelo nó de saída do sistema de simulação de tráfego
- * distribuído.
- * 
- * Este processo representa o ponto final ("S") onde os veículos completam as
- * suas rotas.
- * As suas principais responsabilidades são:
- * - Receber veículos que terminam a sua rota vindos das interseções
- * - Calcular e agregar estatísticas finais dos veículos
- * - Enviar estatísticas periódicas para o dashboard
- * - Gerar relatórios finais ao terminar a simulação
+ * Represents the final Exit Node ("S") of the distributed traffic simulation.
+ *
+ * This process acts as a "sink" for all vehicles completing their routes.
+ * Unlike intersections, it does not route traffic but focuses on data collection.
+ * Its primary responsibilities are:
+ * - Accepting TCP connections from intersection processes.
+ * - Receiving {@link Vehicle} objects via the network.
+ * - Calculating final performance metrics (Total System Time, Waiting Time, Crossing Time).
+ * - Aggregating statistics by {@link VehicleType}.
+ * - Reporting real-time data to the Dashboard service via {@link SocketClient}.
+ * - Generating a final statistical report upon shutdown.
  */
 public class ExitNodeProcess {
 
+    // --- Configuration and Networking ---
     private final SimulationConfig config;
     private ServerSocket serverSocket;
+
+    /**
+     * Thread pool to handle concurrent incoming connections from multiple intersections.
+     */
     private final ExecutorService connectionHandlerPool;
 
     /**
-     * Flag para controlar a execução do processo (volatile para visibilidade entre
-     * threads)
+     * Volatile flag to control the lifecycle of the process.
      */
     private volatile boolean running;
 
-    /** Simulation start time (milliseconds) to calculate relative times */
+    /** * Simulation start time (in milliseconds) used to calculate relative arrival times. 
+     * This is synchronized with the Coordinator.
+     */
     private long simulationStartMillis;
 
-    /** Counter de veículos que completaram a rota */
+    // --- Statistics and Metrics ---
+
+    /** Total count of vehicles that have successfully completed their route. */
     private int totalVehiclesReceived;
 
-    /** Soma dos tempos no sistema de todos os veículos */
+    /** Accumulated time (in seconds) that all vehicles spent in the system. */
     private double totalSystemTime;
 
-    /** Soma dos tempos de espera de todos os veículos */
+   /** Accumulated time (in seconds) that all vehicles spent waiting at red lights. */
     private double totalWaitingTime;
 
-    /** Soma dos tempos de travessia de todos os veículos */
+   /** Accumulated time (in seconds) that all vehicles spent crossing intersections. */
     private double totalCrossingTime;
 
-    /** Contagem de veículos por tipo */
+   /** Counter of vehicles separated by {@link VehicleType}. */
     private final Map<VehicleType, Integer> vehicleTypeCount;
 
-    /** Tempo total de espera acumulado por tipo de veículo */
+    /** Accumulated wait time separated by {@link VehicleType}. */
     private final Map<VehicleType, Double> vehicleTypeWaitTime;
 
-    /** Socket para comunicação com o dashboard */
+    /** Client connection to send updates to the Dashboard. */
     private SocketClient dashboardClient;
 
-    /**
-     * Método para iniciar o processo
-     * 
-     * @param args Argumentos da linha de comandos. Se fornecido, args[0] deve ser
-     *             o caminho para um ficheiro de configuração personalizado.
+ /**
+     * Main entry point for the Exit Node process.
+     * * @param args Command line arguments. Optional args[0] for config file path.
      */
     public static void main(String[] args) {
         System.out.println("=".repeat(60));
@@ -101,14 +108,10 @@ public class ExitNodeProcess {
     }
 
     /**
-     * Constrói um novo processo de nó de saída.
-     * 
-     * Inicializa todas as estruturas de dados necessárias para recolher
-     * estatísticas
-     * e configura o pool de threads para processar as ligações concorrentes.
-     * 
-     * @param config Configuração da simulação contendo portas e endereços dos
-     *               serviços
+     * Constructs a new ExitNodeProcess.
+     * * Initializes all data structures required for statistics collection
+     * and sets up the thread pool for handling concurrent network connections.
+     * * @param config The loaded {@link SimulationConfig} containing ports and addresses.
      */
     public ExitNodeProcess(SimulationConfig config) {
         this.config = config;
@@ -133,12 +136,11 @@ public class ExitNodeProcess {
         System.out.println("  - Dashboard: " + config.getDashboardHost() + ":" + config.getDashboardPort());
     }
 
-    /**
-     * Inicializa o processo de ligação ao dashboard.
-     * 
-     * Tenta conectar-se ao dashboard. Se a ligação falhar, o processo
-     * continua a funcionar normalmente, mas sem enviar estatísticas.
-     * 
+   /**
+     * Initializes the connection to the external Dashboard service.
+     * * Attempts to establish a TCP connection to the dashboard. If successful,
+     * this connection will be used to stream live statistics.
+     * If the connection fails, the process logs a warning but continues operation.
      */
     public void initialize() {
         System.out.println("Connecting to dashboard...");
@@ -158,15 +160,12 @@ public class ExitNodeProcess {
     }
 
     /**
-     * Inicia o socket e começa a aceitar ligações.
-     * 
-     * Este é o loop principal do processo que:
-     * 1. Cria um socket na porta definida
-     * 2. Aguarda pelas ligações das interseções
-     * 3. Delega cada ligação a uma thread da pool para processamento assíncrono
-     * 
-     * @throws IOException Se o socket não puder ser criado ou houver erro na
-     *                     aceitação
+     * Starts the server socket and begins the main event loop.
+     * * This method:
+     * 1. Binds a {@link ServerSocket} to the configured exit port.
+     * 2. Enters a loop accepting incoming connections from Intersections.
+     * 3. Submits each new connection to the {@code connectionHandlerPool} for asynchronous processing.
+     * * @throws IOException If the server socket cannot be bound.
      */
     public void start() throws IOException {
         int port = config.getExitPort();
@@ -189,14 +188,12 @@ public class ExitNodeProcess {
         }
     }
 
-    /**
-     * Processa uma ligação recebida de uma interseção.
-     * 
-     * Mantém a ligação aberta e processa continuamente mensagens do tipo
-     * VEHICLE_TRANSFER. Cada mensagem representa um veículo que chegou ao nó de
-     * saída.
-     * 
-     * @param clientSocket Socket da ligação estabelecida com a interseção
+   /**
+     * Handles an active connection from an Intersection process.
+     * * Continuously reads {@link MessageProtocol} objects from the socket.
+     * Expects primarily {@link MessageType#VEHICLE_TRANSFER} messages containing
+     * {@link Vehicle} payloads.
+     * * @param clientSocket The accepted socket connection.
      */
     private void handleIncomingConnection(Socket clientSocket) {
         String clientAddress = clientSocket.getInetAddress().getHostAddress();
@@ -252,15 +249,14 @@ public class ExitNodeProcess {
     }
 
     /**
-     * Processa um veículo que chegou ao nó de saída.
-     * 
-     * Método sincronizado para garantir thread-safety ao atualizar as estatísticas.
-     * Calcula as métricas finais do veículo e atualiza:
-     * - Counters globais;
-     * - Estatísticas por tipo de veículo;
-     * - Faz update ao dashboard a cada 10 veículos.
-     * 
-     * @param vehicle Veículo que completou a sua rota
+     * Processes a vehicle that has completed its route.
+     * * This method is {@code synchronized} to ensure thread safety when updating
+     * shared statistical counters. It calculates final metrics:
+     * - System Time: Total time since entry.
+     * - Wait Time: Total time spent at red lights.
+     * - Crossing Time: Total time spent crossing intersections.
+     * * It triggers an immediate update to the Dashboard.
+     * * @param vehicle The vehicle that has arrived at the Exit Node.
      */
     private synchronized void processExitingVehicle(Vehicle vehicle) {
         totalVehiclesReceived++;
@@ -289,13 +285,10 @@ public class ExitNodeProcess {
     }
 
     /**
-     * Envia as estatísticas para o dashboard.
-     * 
-     * Prepara e envia uma mensagem STATS_UPDATE com:
-     * - O total de veículos processados;
-     * - A média dos tempos (sistema, espera, travessia);
-     * - As contagens e médias por cada tipo de veículo.
-     * 
+     * Sends current aggregated statistics to the Dashboard.
+     * * Constructs a {@link StatsUpdatePayload} containing global counters and
+     * per-type metrics, converting seconds to milliseconds as expected by the frontend.
+     * Wraps the payload in a {@link Message} and sends it via the dashboard client.
      */
     private void sendStatsToDashboard() {
         if (dashboardClient == null || !dashboardClient.isConnected()) {
@@ -346,15 +339,14 @@ public class ExitNodeProcess {
         }
     }
 
-    /**
-     * Termina o processo
-     * 
-     * Executa a seguinte sequência:
-     * Imprime as estatísticas finais no terminal;
-     * Envia a última atualização de estatísticas ao dashboard;
-     * Fecha o socket;
-     * Aguarda pela finalização das threads;
-     * Fecha a ligação com o dashboard;
+   /**
+     * Gracefully shuts down the exit node process.
+     * * Sequence of operations:
+     * 1. Prints final statistics to the console.
+     * 2. Sends one last update to the dashboard.
+     * 3. Closes the server socket to stop accepting connections.
+     * 4. Shuts down the thread pool.
+     * 5. Closes the dashboard connection.
      */
     public void shutdown() {
         System.out.println("\n[Exit] Shutting down...");
@@ -390,15 +382,12 @@ public class ExitNodeProcess {
     }
 
     /**
-     * Imprime as estatísticas finais detalhadas no terminal
-     * 
-     * Gera um relatório com:
-     * Total de veículos que completaram a rota;
-     * Médias de tempo no sistema, espera e travessia;
-     * Distribuição e médias pelo tipo de veículo (BIKE, LIGHT, HEAVY);
-     * 
-     * Este método é chamado durante o shutdown para fornecer um resumo
-     * da simulação antes de terminar o processo.
+     * Prints a detailed statistical report to the console.
+     * * Included metrics:
+     * - Total vehicles processed.
+     * - Average System Time, Waiting Time, and Crossing Time.
+     * - Distribution count and percentage by Vehicle Type.
+     * - Average wait time by Vehicle Type.
      */
     private void printFinalStatistics() {
         System.out.println("\n=== EXIT NODE STATISTICS ===");

main/src/main/java/sd/protocol/MessageProtocol.java

@@ -1,7 +1,8 @@
 package sd.protocol;
 
 import java.io.Serializable;
-import sd.model.MessageType; // Assuming MessageType is in sd.model or sd.protocol
+
+import sd.model.MessageType; 
 
 /**
  * Interface defining the contract for all messages exchanged in the simulator.

main/src/main/java/sd/protocol/SocketConnection.java

@@ -23,9 +23,30 @@ import sd.serialization.SerializerFactory;
  */
 public class SocketConnection implements Closeable {
 
+    // --- Network Resources ---
+
+    /**
+     * The underlying TCP socket used for network communication.
+     */
     private final Socket socket;
+
+    /**
+     * The raw output stream for writing bytes to the network.
+     * Wrapped by {@link DataOutputStream} during message sending.
+     */
     private final OutputStream outputStream;
+
+    /**
+     * The raw input stream for reading bytes from the network.
+     * Wrapped by {@link DataInputStream} during message reception.
+     */
     private final InputStream inputStream;
+
+    // --- Serialization ---
+
+    /**
+     * The serializer strategy used to convert objects to/from byte arrays (e.g., JSON).
+     */
     private final MessageSerializer serializer;
 
     // --- Configuration for Retry Logic ---
@@ -159,7 +180,7 @@ public class SocketConnection implements Closeable {
         }
 
         try {
-            // Lê um prefixo de 4 bytes - indicador de tamanho
+           
             DataInputStream dataIn = new DataInputStream(inputStream);
             int length = dataIn.readInt();
             
@@ -167,11 +188,11 @@ public class SocketConnection implements Closeable {
                 throw new IOException("Invalid message length: " + length);
             }
             
-            // Ler dados da mensagem
+      
             byte[] data = new byte[length];
             dataIn.readFully(data);
             
-            // Deserialize do JSON - use concrete Message class, not interface
+            // JSON deserialization- use concrete Message class, not interface
             return serializer.deserialize(data, sd.model.Message.class);
             
         } catch (SerializationException e) {
@@ -179,7 +200,7 @@ public class SocketConnection implements Closeable {
         }
     }
 
-    /**
+  /**
      * Closes the socket and all streams (Input and Output).
      */
     @Override
@@ -190,7 +211,8 @@ public class SocketConnection implements Closeable {
     }
 
     /**
-     * @return true if the socket is still connected and not closed.
+     * Checks the current state of the connection.
+     * @return {@code true} if the socket is connected and currently open, {@code false} otherwise.
      */
     public boolean isConnected() {
         return socket != null && socket.isConnected() && !socket.isClosed();