feat: BAEL-5947 External Debugging with JMXTerm (#13847)

* feat: BAEL-5947 External Debugging with JMXTerm

* fix: Removed a faulty test

* fix: Change Random to ThreadLocalRandom

* fix: Renamed a method

* fix: Formatting fix

core-java-modules/core-java-perf/src/main/java/com/baeldung/jmxterm/AbstractPlayerMBean.java

@@ -0,0 +1,16 @@
+package com.baeldung.jmxterm;
+
+import java.util.UUID;
+
+public abstract class AbstractPlayerMBean implements PlayerMBean{
+
+    private final UUID id;
+
+    protected AbstractPlayerMBean() {
+        this.id = UUID.randomUUID();
+    }
+
+    String getId() {
+        return getName() + id.toString();
+    }
+}

core-java-modules/core-java-perf/src/main/java/com/baeldung/jmxterm/BroadcastingGuessGame.java

@@ -0,0 +1,42 @@
+package com.baeldung.jmxterm;
+
+import javax.management.ListenerNotFoundException;
+import javax.management.MBeanNotificationInfo;
+import javax.management.Notification;
+import javax.management.NotificationBroadcaster;
+import javax.management.NotificationBroadcasterSupport;
+import javax.management.NotificationFilter;
+import javax.management.NotificationListener;
+
+public abstract class BroadcastingGuessGame implements NotificationBroadcaster, GuessGameMBean {
+    private final NotificationBroadcasterSupport broadcaster =
+        new NotificationBroadcasterSupport();
+
+    private long notificationSequence = 0;
+
+    private final MBeanNotificationInfo[] notificationInfo;
+
+    protected BroadcastingGuessGame() {
+        this.notificationInfo = new MBeanNotificationInfo[]{
+            new MBeanNotificationInfo(new String[]{"game"}, Notification.class.getName(), "Game notification")
+        };
+    }
+
+    protected void notifyAboutWinner(Player winner) {
+        String message = "Winner is " + winner.getName() + " with score " + winner.getScore();
+        Notification notification = new Notification("game.winner", this, notificationSequence++, message);
+        broadcaster.sendNotification(notification);
+    }
+
+    public void addNotificationListener(NotificationListener listener, NotificationFilter filter, Object handback) {
+        broadcaster.addNotificationListener(listener, filter, handback);
+    }
+
+    public void removeNotificationListener(NotificationListener listener) throws ListenerNotFoundException {
+        broadcaster.removeNotificationListener(listener);
+    }
+
+    public MBeanNotificationInfo[] getNotificationInfo() {
+        return notificationInfo;
+    }
+}

core-java-modules/core-java-perf/src/main/java/com/baeldung/jmxterm/GameRunner.java

@@ -0,0 +1,19 @@
+package com.baeldung.jmxterm;
+
+import java.util.Arrays;
+import java.util.List;
+
+public class GameRunner {
+
+    public static void main(String[] args) {
+        MBeanGameServer mBeanGameServer = new MBeanGameServer();
+        Player bob = new Player("Bob");
+        Player alice = new Player("Alice");
+        Player john = new Player("John");
+        List<Player> players = Arrays.asList(bob, alice, john);
+        GuessGame guessGame = new GuessGame(players);
+        mBeanGameServer.registerGame(guessGame);
+        guessGame.start();
+    }
+
+}

core-java-modules/core-java-perf/src/main/java/com/baeldung/jmxterm/GuessGame.java

@@ -0,0 +1,80 @@
+package com.baeldung.jmxterm;
+
+import static com.baeldung.jmxterm.RandomNumbergenerator.generateRandomNumber;
+
+import java.util.List;
+import java.util.logging.Level;
+import java.util.logging.Logger;
+
+public class GuessGame extends BroadcastingGuessGame {
+
+
+    public static final int SECOND = 1000;
+    private static final Logger log = Logger.getLogger(GuessGame.class.getCanonicalName());
+    private final List<Player> players;
+    private volatile boolean isFinished = false;
+    private volatile boolean isPaused = false;
+
+
+    public GuessGame(List<Player> players) {
+        this.players = players;
+        log.setLevel(Level.WARNING);
+    }
+
+    public void start() {
+        int randomNumber = generateRandomNumber();
+        while (!isFinished) {
+            waitASecond();
+            while (!isPaused && !isFinished) {
+                log.info("Current random number is " + randomNumber);
+                waitASecond();
+                for (Player player : players) {
+                    int guess = player.guessNumber();
+                    if (guess == randomNumber) {
+                        log.info("Players " + player.getName() + " " + guess + " is correct");
+                        player.incrementScore();
+                        notifyAboutWinner(player);
+                        randomNumber = generateRandomNumber();
+                        break;
+                    }
+                    log.info("Player " + player.getName() + " guessed incorrectly with " + guess);
+                }
+                log.info("\n");
+            }
+            if (isPaused) {
+                log.info("Game is paused");
+            }
+            if (isFinished) {
+                log.info("Game is finished");
+            }
+        }
+    }
+
+    @Override
+    public void finishGame() {
+        isFinished = true;
+    }
+
+    @Override
+    public void pauseGame() {
+        isPaused = true;
+    }
+
+    @Override
+    public void unpauseGame() {
+        isPaused = false;
+    }
+
+    public List<Player> getPlayers() {
+        return players;
+    }
+
+    private void waitASecond() {
+        try {
+            Thread.sleep(SECOND);
+        } catch (InterruptedException e) {
+            e.printStackTrace();
+        }
+    }
+
+}

core-java-modules/core-java-perf/src/main/java/com/baeldung/jmxterm/GuessGameMBean.java

@@ -0,0 +1,8 @@
+package com.baeldung.jmxterm;
+
+public interface GuessGameMBean {
+
+    void finishGame();
+    void pauseGame();
+    void unpauseGame();
+}

core-java-modules/core-java-perf/src/main/java/com/baeldung/jmxterm/MBeanGameServer.java

@@ -0,0 +1,37 @@
+package com.baeldung.jmxterm;
+
+import java.lang.management.ManagementFactory;
+import javax.management.InstanceAlreadyExistsException;
+import javax.management.MBeanRegistrationException;
+import javax.management.MBeanServer;
+import javax.management.MalformedObjectNameException;
+import javax.management.NotCompliantMBeanException;
+import javax.management.ObjectName;
+
+public class MBeanGameServer {
+
+    public static final String ID_FORMAT = "com.baeldung.jmxterm:type=%s,id=%s";
+    private final MBeanServer server = ManagementFactory.getPlatformMBeanServer();
+
+    public void registerPlayer(AbstractPlayerMBean player) {
+        registerBean(player, "player", player.getId());
+    }
+
+    public void registerGame(GuessGame guessGame) {
+        registerBean(guessGame, "game", "singlegame");
+        guessGame.getPlayers().forEach(this::registerPlayer);
+    }
+
+    private void registerBean(Object bean, String type, String id) {
+        try {
+            ObjectName name = new ObjectName(String.format(ID_FORMAT, type, id));
+            server.registerMBean(bean, name);
+        } catch (InstanceAlreadyExistsException |
+                 MBeanRegistrationException |
+                 NotCompliantMBeanException |
+                 MalformedObjectNameException e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+}

core-java-modules/core-java-perf/src/main/java/com/baeldung/jmxterm/Player.java

@@ -0,0 +1,33 @@
+package com.baeldung.jmxterm;
+
+import static com.baeldung.jmxterm.RandomNumbergenerator.*;
+
+public class Player extends AbstractPlayerMBean {
+    private final String name;
+    private int score = 0;
+
+    public Player(String name) {
+        super();
+        this.name = name;
+    }
+
+    @Override
+    public int guessNumber() {
+        return generateRandomNumber();
+    }
+
+    public void incrementScore() {
+        score++;
+    }
+
+    @Override
+    public int getScore() {
+        return score;
+    }
+
+    @Override
+    public String getName() {
+        return name;
+    }
+
+}

core-java-modules/core-java-perf/src/main/java/com/baeldung/jmxterm/PlayerMBean.java

@@ -0,0 +1,10 @@
+package com.baeldung.jmxterm;
+
+public interface PlayerMBean {
+
+    int guessNumber();
+
+    int getScore();
+
+    String getName();
+}

core-java-modules/core-java-perf/src/main/java/com/baeldung/jmxterm/RandomNumbergenerator.java

@@ -0,0 +1,18 @@
+package com.baeldung.jmxterm;
+
+import java.util.concurrent.ThreadLocalRandom;
+
+public class RandomNumbergenerator {
+
+    private static final int MIN = 0;
+    private static final int MAX = 10;
+
+    private static final ThreadLocalRandom RANDOM = ThreadLocalRandom.current();
+
+    private RandomNumbergenerator() {
+    }
+    public static int generateRandomNumber() {
+        return RANDOM.nextInt(MIN, MAX + 1);
+    }
+
+}

core-java-modules/core-java-perf/src/test/java/com/baeldung/jmxterm/PlayerUnitTest.java

@@ -0,0 +1,21 @@
+package com.baeldung.jmxterm;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+import org.junit.jupiter.api.Test;
+
+class PlayerUnitTest {
+
+    @Test
+    void givenNewPlayer_thenScoreIsZero() {
+        Player player = new Player("John");
+        assertEquals(0, player.getScore());
+    }
+
+    @Test
+    void givenNewPlayer_whenIncrementScore_thenScoreIsOne() {
+        Player player = new Player("John");
+        player.incrementScore();
+        assertEquals(1, player.getScore());
+    }
+}