Fix: Implement proper state management in MonitorService

src/main/java/org/springframework/samples/petclinic/system/MonitorService.java

@@ -0,0 +1,95 @@
+package org.springframework.samples.petclinic.system;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.stereotype.Service;
+
+import java.util.concurrent.atomic.AtomicBoolean;
+
+/**
+ * Monitor service for system health checking
+ */
+@Service
+public class MonitorService {
+    private static final Logger logger = LoggerFactory.getLogger(MonitorService.class);
+
+    private final AtomicBoolean isRunning = new AtomicBoolean(false);
+    private final AtomicBoolean isHealthy = new AtomicBoolean(true);
+
+    /**
+     * Start the monitoring service
+     * @return true if service started successfully, false if already running
+     */
+    public boolean start() {
+        if (isRunning.compareAndSet(false, true)) {
+            logger.info("Monitor service started successfully");
+            return true;
+        }
+        logger.warn("Monitor service already running");
+        return false;
+    }
+
+    /**
+     * Stop the monitoring service
+     * @return true if service stopped successfully, false if already stopped
+     */
+    public boolean stop() {
+        if (isRunning.compareAndSet(true, false)) {
+            logger.info("Monitor service stopped successfully");
+            return true;
+        }
+        logger.warn("Monitor service already stopped");
+        return false;
+    }
+
+    /**
+     * Check system health
+     * @return true if system is healthy
+     */
+    public boolean monitor() {
+        try {
+            if (!isRunning.get()) {
+                logger.warn("Cannot monitor: service not running");
+                return false;
+            }
+
+            // Perform actual health check logic here
+            boolean currentHealth = performHealthCheck();
+            isHealthy.set(currentHealth);
+
+            if (currentHealth) {
+                logger.info("System health check passed");
+            } else {
+                logger.warn("System health check failed");
+            }
+
+            return currentHealth;
+        } catch (Exception e) {
+            logger.error("Error during health monitoring", e);
+            isHealthy.set(false);
+            return false;
+        }
+    }
+
+    /**
+     * Get current system health status
+     * @return true if system is healthy
+     */
+    public boolean isHealthy() {
+        return isHealthy.get();
+    }
+
+    /**
+     * Check if service is currently running
+     * @return true if service is running
+     */
+    public boolean isRunning() {
+        return isRunning.get();
+    }
+
+    private boolean performHealthCheck() {
+        // Implement actual health check logic here
+        // For now, return true to indicate healthy state
+        return true;
+    }
+}