OZ-476: Add ShutdownHandler bean (#33)

commons/src/main/java/com/ozonehis/eip/utils/ShutdownHandler.java

@@ -0,0 +1,50 @@
+/*
+ * Copyright © 2021, Ozone HIS <[email protected]>
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+package com.ozonehis.eip.utils;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.beans.BeansException;
+import org.springframework.context.ApplicationContext;
+import org.springframework.context.ApplicationContextAware;
+import org.springframework.context.ConfigurableApplicationContext;
+import org.springframework.stereotype.Component;
+
+@Component
+public class ShutdownHandler implements ApplicationContextAware {
+
+    private ApplicationContext applicationContext;
+
+    public static boolean shuttingDown = false;
+
+    public static Logger LOGGER = LoggerFactory.getLogger(ShutdownHandler.class);
+
+    @Override
+    public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
+        this.applicationContext = applicationContext;
+    }
+
+    public void shutdown() {
+        ConfigurableApplicationContext configurableApplicationContext =
+                (ConfigurableApplicationContext) applicationContext;
+        configurableApplicationContext.close();
+        exitApplication();
+    }
+
+    public static synchronized void exitApplication() {
+        if (shuttingDown) {
+            LOGGER.info("Application is already shutting down");
+            return;
+        }
+        shuttingDown = true;
+        LOGGER.info("Shutting down the application...");
+
+        // Shutdown in a new thread to ensure other background shutdown threads complete too
+        new Thread(() -> System.exit(0)).start();
+    }
+}

commons/src/test/java/com/ozonehis/eip/utils/ShutdownHandlerTest.java

@@ -0,0 +1,62 @@
+/*
+ * Copyright © 2021, Ozone HIS <[email protected]>
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+package com.ozonehis.eip.utils;
+
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.times;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.mockito.Mockito;
+import org.slf4j.Logger;
+import org.springframework.context.ApplicationContext;
+import org.springframework.context.ConfigurableApplicationContext;
+
+public class ShutdownHandlerTest {
+
+    private ShutdownHandler shutdownHandler;
+    private ApplicationContext applicationContext;
+    private Logger logger;
+
+    @BeforeEach
+    public void setUp() {
+        shutdownHandler = new ShutdownHandler();
+        applicationContext = mock(ConfigurableApplicationContext.class);
+        shutdownHandler.setApplicationContext(applicationContext);
+        logger = mock(Logger.class);
+        ShutdownHandler.LOGGER = logger;
+    }
+
+    @Test
+    public void testShutdownCloseApplicationContext() {
+        shutdownHandler.shutdown();
+
+        Mockito.verify((ConfigurableApplicationContext) applicationContext, times(1))
+                .close();
+    }
+
+    @Test
+    public void testExitApplication() {
+        ShutdownHandler.shuttingDown = false;
+
+        ShutdownHandler.exitApplication();
+
+        // Since System.exit() cannot be directly tested, we can't validate that it was invoked.
+        // We can only verify that the logger is invoked.
+        Mockito.verify(logger, times(1)).info("Shutting down the application...");
+    }
+
+    @Test
+    public void testExitApplicationWhenAlreadyShuttingDown() {
+        ShutdownHandler.shuttingDown = true;
+
+        ShutdownHandler.exitApplication();
+
+        Mockito.verify(logger, times(1)).info("Application is already shutting down");
+    }
+}