Impl #44 - Add CRaC support

org.eclipse.osgitech.rest.jetty/pom.xml

@@ -74,6 +74,10 @@
  <groupId>org.apache.felix</groupId>
  <artifactId>org.apache.felix.http.jetty</artifactId>
  </dependency>
+ <dependency>
+ <groupId>org.crac</groupId>
+ <artifactId>crac</artifactId>
+ </dependency>
  </dependencies>
 
  <build>
@@ -117,6 +121,27 @@
  </execution>
  </executions>
  </plugin>
+ <plugin>
+ <groupId>biz.aQute.bnd</groupId>
+ <artifactId>bnd-maven-plugin</artifactId>
+ <extensions>true</extensions>
+ <executions>
+ <execution>
+ <id>jar</id>
+ <goals>
+ <goal>jar</goal>
+ </goals>
+ <configuration>
+ <bnd><![CDATA[
+ Import-Package: org.crac.*;resolution:=optional, *
+ -noextraheaders: true
+ -noimportjava: true
+ -fixupmessages: The JAR is empty:
+ ]]></bnd>
+ </configuration>
+ </execution>
+ </executions>
+ </plugin>
  <plugin>
  <groupId>biz.aQute.bnd</groupId>
  <artifactId>bnd-resolver-maven-plugin</artifactId>

org.eclipse.osgitech.rest.jetty/src/main/java/org/eclipse/osgitech/rest/jetty/JettyBackedWhiteboardComponent.java

@@ -1,5 +1,5 @@
 /**
- * Copyright (c) 2012 - 2022 Data In Motion and others.
+ * Copyright (c) 2012 - 2024 Data In Motion and others.
  * All rights reserved. 
  * 
  * This program and the accompanying materials are made available under the terms of the 
@@ -10,6 +10,7 @@
  * Data In Motion - initial API and implementation
  * Stefan Bishof - API and implementation
  * Tim Ward - implementation
+ * Dirk Fauth - add CRaC support
  */
 package org.eclipse.osgitech.rest.jetty;
 
@@ -62,6 +63,10 @@ public class JettyBackedWhiteboardComponent {
  Logger logger = Logger.getLogger(JettyBackedWhiteboardComponent.class.getName());
 
  private JerseyServiceRuntime<WhiteboardServletContainer> serviceRuntime;
+
+ // need to keep a strong reference to avoid that the resource gets garbage collected
+ @SuppressWarnings("unused")
+ private JettyCracResource cracHandler;
 
  public enum State {
  INIT, STARTED, STOPPED, EXCEPTION
@@ -93,6 +98,17 @@ public void activate(BundleContext context, Map<String, Object> properties) thro
 
 
  serviceRuntime.start(getServiceRuntimeProperties(properties));
+
+ try {
+ Class.forName("org.crac.Resource");
+
+ // org.crac.Resource was found, so we create an instance of the JettyCracResource
+ cracHandler = new JettyCracResource(this);
+ } catch (ClassNotFoundException e) {
+ // org.crac.Resource could not be found
+ // we simply do nothing, as CRaC support is not available
+ }
+
  }
 
  private Map<String, Object> getServiceRuntimeProperties(Map<String, Object> properties) {
@@ -348,4 +364,12 @@ private void stopServer() {
  logger.log(Level.SEVERE, "Error stopping Jetty server", e);
  }
  }
+
+ /**
+ * 
+ * @return the Jetty server managed by this class. Can be <code>null</code>.
+ */
+ Server getJettyServer() {
+ return jettyServer;
+ }
 }

org.eclipse.osgitech.rest.jetty/src/main/java/org/eclipse/osgitech/rest/jetty/JettyCracResource.java

@@ -0,0 +1,65 @@
+/**
+ * Copyright (c) 2024 Dirk Fauth and others.
+ * All rights reserved. 
+ * 
+ * This program and the accompanying materials are made available under the terms of the 
+ * Eclipse Public License v2.0 which accompanies this distribution, and is available at
+ * http://www.eclipse.org/legal/epl-v20.html
+ * 
+ * Contributors:
+ * Dirk Fauth - initial API and implementation
+ */
+package org.eclipse.osgitech.rest.jetty;
+
+import java.util.Arrays;
+
+import org.crac.Context;
+import org.crac.Core;
+import org.crac.Resource;
+import org.eclipse.jetty.server.Server;
+import org.eclipse.jetty.util.component.LifeCycle;
+
+/**
+ * This class is used to add CRaC support to the jetty bundle by using the
+ * <code>org.crac</code> API. It adapts the examples and best practices from the
+ * CRaC documentation and the examples.
+ * 
+ * @see <a href="https://github.com/CRaC/org.crac">`org.crac` API</a>
+ * @see <a href=
+ * "https://docs.azul.com/core/crac/crac-tips-tricks#implementing-resource-as-inner-class">Implementing
+ * Resource as Inner Class</a>
+ * @see <a href=
+ * "https://github.com/CRaC/docs/blob/master/STEP-BY-STEP.md">Step-by-step
+ * CRaC support for a Jetty app</a>
+ * @see <a href=
+ * "https://github.com/CRaC/example-jetty/blob/master/src/main/java/com/example/App.java">CRaC
+ * example-jetty</a>
+ */
+public class JettyCracResource {
+
+ // the org.crac.Resource is implemented as an inner class and kept as a strong
+ // reference to avoid that it is garbage collected after the registration.
+ private Resource cracHandler;
+
+ public JettyCracResource(JettyBackedWhiteboardComponent jettyComponent) {
+ cracHandler = new Resource() {
+ @Override
+ public void beforeCheckpoint(Context<? extends Resource> context) {
+ Server jettyServer = jettyComponent.getJettyServer();
+ if (jettyServer != null && !jettyServer.isStopped()) {
+ // Stop the connectors only and keep the expensive application running
+ Arrays.asList(jettyServer.getConnectors()).forEach(c -> LifeCycle.stop(c));
+ }
+ }
+
+ @Override
+ public void afterRestore(Context<? extends Resource> context) {
+ Server jettyServer = jettyComponent.getJettyServer();
+ if (jettyServer != null && !jettyServer.isStopped()) {
+ Arrays.asList(jettyServer.getConnectors()).forEach(c -> LifeCycle.start(c));
+ }
+ }
+ };
+ Core.getGlobalContext().register(cracHandler);
+ }
+}

pom.xml

@@ -69,6 +69,7 @@
  <asm.version>9.5</asm.version>
  <jackson.version>2.15.2</jackson.version>
  <parsson.version>1.1.5</parsson.version>
+ <crac.version>1.5.0</crac.version>
  </properties>
 
  <modules>
@@ -464,6 +465,12 @@
  <artifactId>biz.aQute.bnd.annotation</artifactId>
  <version>6.4.0</version>
  </dependency>
+ <dependency>
+ <groupId>org.crac</groupId>
+ <artifactId>crac</artifactId>
+ <version>${crac.version}</version>
+ <scope>provided</scope>
+ </dependency>
  </dependencies>
  </dependencyManagement>