Provide a constant for graceful shutdown's smart lifecyle phase

In order to provide a single constant for graceful shutdown's smart
lifecycle, this commit replaces the package-private reactive and
servlet-specific implementations with a single public implementation
that can be used by both web stacks. This new public implementation
provides a constant for its smart lifecycle phase.

Closes gh-24255

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/web/context/WebServerGracefulShutdownLifecycle.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2020 the original author or authors.
+ * Copyright 2012-2021 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -14,24 +14,35 @@
  * limitations under the License.
  */
 
-package org.springframework.boot.web.servlet.context;
+package org.springframework.boot.web.context;
 
 import org.springframework.boot.web.server.WebServer;
 import org.springframework.context.SmartLifecycle;
 
 /**
- * {@link SmartLifecycle} to trigger {@link WebServer} graceful shutdown in a
- * {@link ServletWebServerApplicationContext}.
+ * {@link SmartLifecycle} to trigger {@link WebServer} graceful shutdown.
  *
  * @author Andy Wilkinson
+ * @since 2.5.0
  */
-class WebServerGracefulShutdownLifecycle implements SmartLifecycle {
+public final class WebServerGracefulShutdownLifecycle implements SmartLifecycle {
+
+	/**
+	 * {@link SmartLifecycle#getPhase() SmartLifecycle phase} in which graceful shutdown
+	 * of the web server is performed.
+	 */
+	public static final int SMART_LIFECYCLE_PHASE = SmartLifecycle.DEFAULT_PHASE;
 
 	private final WebServer webServer;
 
 	private volatile boolean running;
 
-	WebServerGracefulShutdownLifecycle(WebServer webServer) {
+	/**
+	 * Creates a new {@code WebServerGracefulShutdownLifecycle} that will gracefully shut
+	 * down the given {@code webServer}.
+	 * @param webServer web server to shut down gracefully
+	 */
+	public WebServerGracefulShutdownLifecycle(WebServer webServer) {
 		this.webServer = webServer;
 	}
 
@@ -56,4 +67,9 @@ class WebServerGracefulShutdownLifecycle implements SmartLifecycle {
 		return this.running;
 	}
 
+	@Override
+	public int getPhase() {
+		return SMART_LIFECYCLE_PHASE;
+	}
+
 }

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/web/reactive/context/ReactiveWebServerApplicationContext.java

@@ -21,6 +21,7 @@ import org.springframework.beans.factory.support.DefaultListableBeanFactory;
 import org.springframework.boot.availability.AvailabilityChangeEvent;
 import org.springframework.boot.availability.ReadinessState;
 import org.springframework.boot.web.context.ConfigurableWebServerApplicationContext;
+import org.springframework.boot.web.context.WebServerGracefulShutdownLifecycle;
 import org.springframework.boot.web.reactive.server.ReactiveWebServerFactory;
 import org.springframework.boot.web.server.WebServer;
 import org.springframework.context.ApplicationContextException;
@@ -92,7 +93,7 @@ public class ReactiveWebServerApplicationContext extends GenericReactiveWebAppli
 			boolean lazyInit = getBeanFactory().getBeanDefinition(webServerFactoryBeanName).isLazyInit();
 			this.serverManager = new WebServerManager(this, webServerFactory, this::getHttpHandler, lazyInit);
 			getBeanFactory().registerSingleton("webServerGracefulShutdown",
-					new WebServerGracefulShutdownLifecycle(this.serverManager));
+					new WebServerGracefulShutdownLifecycle(this.serverManager.getWebServer()));
 			getBeanFactory().registerSingleton("webServerStartStop",
 					new WebServerStartStopLifecycle(this.serverManager));
 			createWebServer.end();

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/web/reactive/context/WebServerGracefulShutdownLifecycle.java

@@ -1,59 +0,0 @@
-/*
- * Copyright 2012-2020 the original author or authors.
- *
- * 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
- *
- *      https://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 org.springframework.boot.web.reactive.context;
-
-import org.springframework.boot.web.server.WebServer;
-import org.springframework.context.SmartLifecycle;
-
-/**
- * {@link SmartLifecycle} to trigger {@link WebServer} graceful shutdown in a
- * {@link ReactiveWebServerApplicationContext}.
- *
- * @author Andy Wilkinson
- */
-class WebServerGracefulShutdownLifecycle implements SmartLifecycle {
-
-	private final WebServerManager serverManager;
-
-	private volatile boolean running;
-
-	WebServerGracefulShutdownLifecycle(WebServerManager serverManager) {
-		this.serverManager = serverManager;
-	}
-
-	@Override
-	public void start() {
-		this.running = true;
-	}
-
-	@Override
-	public void stop() {
-		throw new UnsupportedOperationException("Stop must not be invoked directly");
-	}
-
-	@Override
-	public void stop(Runnable callback) {
-		this.running = false;
-		this.serverManager.shutDownGracefully(callback);
-	}
-
-	@Override
-	public boolean isRunning() {
-		return this.running;
-	}
-
-}

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/web/reactive/context/WebServerManager.java

@@ -21,6 +21,7 @@ import java.util.function.Supplier;
 import reactor.core.publisher.Mono;
 
 import org.springframework.boot.web.reactive.server.ReactiveWebServerFactory;
+import org.springframework.boot.web.server.GracefulShutdownCallback;
 import org.springframework.boot.web.server.WebServer;
 import org.springframework.http.server.reactive.HttpHandler;
 import org.springframework.http.server.reactive.ServerHttpRequest;
@@ -56,8 +57,8 @@ class WebServerManager {
 				.publishEvent(new ReactiveWebServerInitializedEvent(this.webServer, this.applicationContext));
 	}
 
-	void shutDownGracefully(Runnable callback) {
-		this.webServer.shutDownGracefully((result) -> callback.run());
+	void shutDownGracefully(GracefulShutdownCallback callback) {
+		this.webServer.shutDownGracefully(callback);
 	}
 
 	void stop() {

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/web/servlet/context/ServletWebServerApplicationContext.java

@@ -40,6 +40,7 @@ import org.springframework.beans.factory.support.DefaultListableBeanFactory;
 import org.springframework.boot.availability.AvailabilityChangeEvent;
 import org.springframework.boot.availability.ReadinessState;
 import org.springframework.boot.web.context.ConfigurableWebServerApplicationContext;
+import org.springframework.boot.web.context.WebServerGracefulShutdownLifecycle;
 import org.springframework.boot.web.server.WebServer;
 import org.springframework.boot.web.servlet.FilterRegistrationBean;
 import org.springframework.boot.web.servlet.ServletContextInitializer;