Enable APR optional support in Tomcat servers

This commits adds the AprLifecycleListener as a default
LifecycleListener in order to detect and use automatically the
tomcatnative library if it is available, for SSL support.

This feature can be useful for both performance reasons or for
supporting ALPN when using JDK8.

See gh-10043
Closes gh-9964

Author: bclozel

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/web/embedded/tomcat/TomcatReactiveWebServerFactory.java

@@ -24,7 +24,9 @@
 
 import org.apache.catalina.Context;
 import org.apache.catalina.Host;
+import org.apache.catalina.LifecycleListener;
 import org.apache.catalina.connector.Connector;
+import org.apache.catalina.core.AprLifecycleListener;
 import org.apache.catalina.loader.WebappLoader;
 import org.apache.catalina.startup.Tomcat;
 import org.apache.coyote.AbstractProtocol;
@@ -53,6 +55,8 @@ public class TomcatReactiveWebServerFactory extends AbstractReactiveWebServerFac
 
 	private String protocol = DEFAULT_PROTOCOL;
 
+	private List<LifecycleListener> contextLifecycleListeners = Arrays.asList(new AprLifecycleListener());
+
 	private List<TomcatContextCustomizer> tomcatContextCustomizers = new ArrayList<>();
 
 	private List<TomcatConnectorCustomizer> tomcatConnectorCustomizers = new ArrayList<>();
@@ -115,6 +119,9 @@ protected void prepareContext(Host host, TomcatHttpHandlerAdapter servlet) {
 	 * @param context the Tomcat context
 	 */
 	protected void configureContext(Context context) {
+		for (LifecycleListener lifecycleListener : this.contextLifecycleListeners) {
+			context.addLifecycleListener(lifecycleListener);
+		}
 		for (TomcatContextCustomizer customizer : this.tomcatContextCustomizers) {
 			customizer.customize(context);
 		}
@@ -211,6 +218,39 @@ public Collection<TomcatConnectorCustomizer> getTomcatConnectorCustomizers() {
 		return this.tomcatConnectorCustomizers;
 	}
 
+	/**
+	 * Set {@link LifecycleListener}s that should be applied to the Tomcat {@link Context}
+	 * . Calling this method will replace any existing listeners.
+	 * @param contextLifecycleListeners the listeners to set
+	 */
+	public void setContextLifecycleListeners(
+			Collection<? extends LifecycleListener> contextLifecycleListeners) {
+		Assert.notNull(contextLifecycleListeners,
+				"ContextLifecycleListeners must not be null");
+		this.contextLifecycleListeners = new ArrayList<>(contextLifecycleListeners);
+	}
+
+	/**
+	 * Returns a mutable collection of the {@link LifecycleListener}s that will be applied
+	 * to the Tomcat {@link Context} .
+	 * @return the context lifecycle listeners that will be applied
+	 */
+	public Collection<LifecycleListener> getContextLifecycleListeners() {
+		return this.contextLifecycleListeners;
+	}
+
+	/**
+	 * Add {@link LifecycleListener}s that should be added to the Tomcat {@link Context}.
+	 * @param contextLifecycleListeners the listeners to add
+	 */
+	public void addContextLifecycleListeners(
+			LifecycleListener... contextLifecycleListeners) {
+		Assert.notNull(contextLifecycleListeners,
+				"ContextLifecycleListeners must not be null");
+		this.contextLifecycleListeners.addAll(Arrays.asList(contextLifecycleListeners));
+	}
+
+
 	/**
 	 * Factory method called to create the {@link TomcatWebServer}. Subclasses can
 	 * override this method to return a different {@link TomcatWebServer} or apply

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/web/embedded/tomcat/TomcatServletWebServerFactory.java

@@ -50,6 +50,7 @@
 import org.apache.catalina.WebResourceSet;
 import org.apache.catalina.Wrapper;
 import org.apache.catalina.connector.Connector;
+import org.apache.catalina.core.AprLifecycleListener;
 import org.apache.catalina.loader.WebappLoader;
 import org.apache.catalina.session.StandardManager;
 import org.apache.catalina.startup.Tomcat;
@@ -122,7 +123,7 @@ public class TomcatServletWebServerFactory extends AbstractServletWebServerFacto
 
 	private List<Valve> contextValves = new ArrayList<>();
 
-	private List<LifecycleListener> contextLifecycleListeners = new ArrayList<>();
+	private List<LifecycleListener> contextLifecycleListeners = Arrays.asList(new AprLifecycleListener());
 
 	private List<TomcatContextCustomizer> tomcatContextCustomizers = new ArrayList<>();
 

spring-boot-project/spring-boot/src/test/java/org/springframework/boot/web/embedded/tomcat/TomcatReactiveWebServerFactoryTests.java

@@ -19,13 +19,17 @@
 import java.util.Arrays;
 
 import org.apache.catalina.Context;
+import org.apache.catalina.LifecycleEvent;
+import org.apache.catalina.LifecycleListener;
 import org.apache.catalina.connector.Connector;
+import org.apache.catalina.core.AprLifecycleListener;
 import org.junit.Test;
 import org.mockito.InOrder;
 
 import org.springframework.boot.web.reactive.server.AbstractReactiveWebServerFactoryTests;
 import org.springframework.http.server.reactive.HttpHandler;
 
+import static org.assertj.core.api.Assertions.assertThat;
 import static org.mockito.ArgumentMatchers.any;
 import static org.mockito.Mockito.inOrder;
 import static org.mockito.Mockito.mock;
@@ -60,6 +64,30 @@ public void tomcatCustomizers() throws Exception {
 		}
 	}
 
+	@Test
+	public void defaultTomcatListeners() throws Exception {
+		TomcatReactiveWebServerFactory factory = getFactory();
+		assertThat(factory.getContextLifecycleListeners())
+				.hasSize(1)
+				.first().isInstanceOf(AprLifecycleListener.class);
+	}
+
+	@Test
+	public void tomcatListeners() throws Exception {
+		TomcatReactiveWebServerFactory factory = getFactory();
+		LifecycleListener[] listeners = new LifecycleListener[4];
+		for (int i = 0; i < listeners.length; i++) {
+			listeners[i] = mock(LifecycleListener.class);
+		}
+		factory.setContextLifecycleListeners(Arrays.asList(listeners[0], listeners[1]));
+		factory.addContextLifecycleListeners(listeners[2], listeners[3]);
+		this.webServer = factory.getWebServer(mock(HttpHandler.class));
+		InOrder ordered = inOrder((Object[]) listeners);
+		for (LifecycleListener listener : listeners) {
+			ordered.verify(listener).lifecycleEvent(any(LifecycleEvent.class));
+		}
+	}
+
 	@Test
 	public void setNullConnectorCustomizersShouldThrowException() {
 		TomcatReactiveWebServerFactory factory = getFactory();

spring-boot-project/spring-boot/src/test/java/org/springframework/boot/web/embedded/tomcat/TomcatServletWebServerFactoryTests.java

@@ -37,6 +37,7 @@
 import org.apache.catalina.SessionIdGenerator;
 import org.apache.catalina.Valve;
 import org.apache.catalina.connector.Connector;
+import org.apache.catalina.core.AprLifecycleListener;
 import org.apache.catalina.core.StandardWrapper;
 import org.apache.catalina.startup.Tomcat;
 import org.apache.catalina.util.CharsetMapper;
@@ -102,6 +103,14 @@ public void tomcatEngineNames() throws Exception {
 		tomcatWebServer.stop();
 	}
 
+	@Test
+	public void defaultTomcatListeners() throws Exception {
+		TomcatServletWebServerFactory factory = getFactory();
+		assertThat(factory.getContextLifecycleListeners())
+				.hasSize(1)
+				.first().isInstanceOf(AprLifecycleListener.class);
+	}
+
 	@Test
 	public void tomcatListeners() throws Exception {
 		TomcatServletWebServerFactory factory = getFactory();