feat: Fire an event when all hotswap operations have completed (#20364)…

… (#20373)

Co-authored-by: Artur <[email protected]>

flow-server/src/main/java/com/vaadin/flow/hotswap/HotswapCompleteEvent.java

@@ -0,0 +1,66 @@
+/*
+ * Copyright 2000-2024 Vaadin Ltd.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not
+ * use this file except in compliance with the License. You may obtain a copy of
+ * the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations under
+ * the License.
+ */
+
+package com.vaadin.flow.hotswap;
+
+import java.util.Set;
+
+import com.vaadin.flow.server.VaadinService;
+
+/*
+ * Event fired when hotswap has been completed.
+ */
+public class HotswapCompleteEvent {
+
+    private final Set<Class<?>> classes;
+    private final VaadinService vaadinService;
+    private final boolean redefined;
+
+    public HotswapCompleteEvent(VaadinService vaadinService,
+            Set<Class<?>> classes, boolean redefined) {
+        this.classes = classes;
+        this.vaadinService = vaadinService;
+        this.redefined = redefined;
+    }
+
+    /**
+     * Gets the classes that were updated.
+     *
+     * @return the updated classes
+     */
+    public Set<Class<?>> getClasses() {
+        return classes;
+    }
+
+    /**
+     * Checks if the classes were redefined (as opposed to being new classes).
+     *
+     * @return {@literal true} if the classes have been redefined by hotswap
+     */
+    public boolean isRedefined() {
+        return redefined;
+    }
+
+    /**
+     * Gets the Vaadin service.
+     *
+     * @return the vaadin service
+     */
+    public VaadinService getService() {
+        return vaadinService;
+    }
+
+}

flow-server/src/main/java/com/vaadin/flow/hotswap/Hotswapper.java

@@ -265,6 +265,17 @@ private void onHotswapInternal(HashSet<Class<?>> classes,
         if (forceBrowserReload || uiTreeNeedsRefresh) {
             triggerClientUpdate(refreshActions, forceBrowserReload);
         }
+
+        HotswapCompleteEvent event = new HotswapCompleteEvent(vaadinService,
+                classes, redefined);
+        for (VaadinHotswapper hotSwapper : hotSwappers) {
+            try {
+                hotSwapper.onHotswapComplete(event);
+            } catch (Exception ex) {
+                LOGGER.debug("Hotswap complete event handling failed for {}",
+                        hotSwapper, ex);
+            }
+        }
     }
 
     /**

flow-server/src/main/java/com/vaadin/flow/hotswap/VaadinHotswapper.java

@@ -98,4 +98,16 @@ default boolean onClassLoadEvent(VaadinSession vaadinSession,
         return false;
     }
 
+    /**
+     * Called by Vaadin hotswap entry point after all hotswap related operations
+     * have been completed.
+     *
+     * @param event
+     *            an event containing information about the hotswap operation.
+     */
+    default void onHotswapComplete(HotswapCompleteEvent event) {
+        // no-op by default
+        return;
+    }
+
 }

flow-server/src/test/java/com/vaadin/flow/hotswap/HotswapperTest.java

@@ -28,6 +28,7 @@
 import org.junit.Assert;
 import org.junit.Before;
 import org.junit.Test;
+import org.mockito.ArgumentCaptor;
 import org.mockito.Mockito;
 
 import com.vaadin.flow.component.Component;
@@ -157,6 +158,10 @@ public void onHotswap_noActiveSession_onlyGlobalHookCalled() {
         Mockito.verify(hillaHotswapper, never()).onClassLoadEvent(
                 isA(VaadinSession.class), anySet(), anyBoolean());
 
+        HotswapCompleteEvent hotswapCompleteEvent = new HotswapCompleteEvent(
+                service, classes, false);
+        assertOnHotswapCompleteInvoked(flowHotswapper, hotswapCompleteEvent);
+        assertOnHotswapCompleteInvoked(hillaHotswapper, hotswapCompleteEvent);
     }
 
     @Test
@@ -222,6 +227,10 @@ public void onHotswap_sessionHookCalledOnlyForActiveSessions()
         Mockito.verify(hillaHotswapper, never()).onClassLoadEvent(
                 isA(VaadinSession.class), anySet(), anyBoolean());
 
+        HotswapCompleteEvent hotswapCompleteEvent = new HotswapCompleteEvent(
+                service, classes, true);
+        assertOnHotswapCompleteInvoked(flowHotswapper, hotswapCompleteEvent);
+        assertOnHotswapCompleteInvoked(hillaHotswapper, hotswapCompleteEvent);
     }
 
     @Test
@@ -788,6 +797,18 @@ public Registration addServiceDestroyListener(
                 uiInitInstalled.get());
     }
 
+    private void assertOnHotswapCompleteInvoked(VaadinHotswapper hotswapper,
+            HotswapCompleteEvent event) {
+        var eventArgumentCaptor = ArgumentCaptor
+                .forClass(HotswapCompleteEvent.class);
+        Mockito.verify(hotswapper)
+                .onHotswapComplete(eventArgumentCaptor.capture());
+        HotswapCompleteEvent capturedEvent = eventArgumentCaptor.getValue();
+        Assert.assertEquals(event.getService(), capturedEvent.getService());
+        Assert.assertEquals(event.getClasses(), capturedEvent.getClasses());
+        Assert.assertEquals(event.isRedefined(), capturedEvent.isRedefined());
+    }
+
     @Tag("my-route")
     public static class MyRoute extends Component {
 
@@ -796,13 +817,15 @@ public static class MyRoute extends Component {
     @Tag("my-route-with-child")
     public static class MyRouteWithChild extends Component
             implements HasComponents {
+
         public MyRouteWithChild() {
             add(new MyComponent());
         }
     }
 
     @Tag("my-layout")
     public static class MyLayout extends Component implements RouterLayout {
+
     }
 
     @Tag("my-layout-with-child")
@@ -819,11 +842,13 @@ public void showRouterLayoutContent(HasElement content) {
     @Tag("my-nested-layout")
     public static class MyNestedLayout extends Component
             implements RouterLayout {
+
     }
 
     @Tag("my-nested-layout-with-child")
     public static class MyNestedLayoutWithChild extends Component
             implements HasComponents, RouterLayout {
+
         @Override
         public void showRouterLayoutContent(HasElement content) {
             RouterLayout.super.showRouterLayoutContent(content);

flow-test-generic/src/main/java/com/vaadin/flow/testutil/ClassesSerializableTest.java

@@ -113,6 +113,7 @@ protected Stream<String> getExcludedPatterns() {
                 "com\\.vaadin\\.flow\\.component\\.dnd\\.osgi\\.DndConnectorResource",
                 "com\\.vaadin\\.flow\\.component\\.internal\\.DeadlockDetectingCompletableFuture",
                 "com\\.vaadin\\.flow\\.function\\.VaadinApplicationInitializationBootstrap",
+                "com\\.vaadin\\.flow\\.hotswap\\.HotswapCompleteEvent",
                 "com\\.vaadin\\.flow\\.hotswap\\.Hotswapper",
                 "com\\.vaadin\\.flow\\.hotswap\\.VaadinHotswapper",
                 "com\\.vaadin\\.flow\\.internal\\.BrowserLiveReloadAccessor",