Mercurial > hg > LightPIT / file revision

 /*

  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.

  * 

  * Copyright 2017 Mike Becker. All rights reserved.

  * 

  * Redistribution and use in source and binary forms, with or without

  * modification, are permitted provided that the following conditions are met:

  *

  *   1. Redistributions of source code must retain the above copyright

  *      notice, this list of conditions and the following disclaimer.

  *

  *   2. Redistributions in binary form must reproduce the above copyright

  *      notice, this list of conditions and the following disclaimer in the

  *      documentation and/or other materials provided with the distribution.

  *

  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"

  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE

  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE

  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE

  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR

  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF

  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS

  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN

  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)

  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE

  * POSSIBILITY OF SUCH DAMAGE.

  * 

  */

 package de.uapcore.lightpit;

 import de.uapcore.lightpit.entities.CoreDAOFactory;

 import de.uapcore.lightpit.entities.ModuleDao;

 import java.sql.Connection;

 import java.sql.SQLException;

 import java.util.Collection;

 import java.util.Collections;

 import java.util.HashMap;

 import java.util.List;

 import java.util.Map;

 import java.util.Map.Entry;

 import java.util.Optional;

 import java.util.concurrent.CopyOnWriteArrayList;

 import java.util.concurrent.atomic.AtomicBoolean;

 import java.util.stream.Collectors;

 import javax.servlet.Registration;

 import javax.servlet.ServletContext;

 import javax.servlet.ServletContextEvent;

 import javax.servlet.ServletContextListener;

 import javax.servlet.annotation.WebListener;

 import org.slf4j.Logger;

 import org.slf4j.LoggerFactory;

 /**

  * Scans registered servlets for LightPIT modules.

  */

 @WebListener

 public final class ModuleManager implements ServletContextListener {

     private static final Logger LOG = LoggerFactory.getLogger(ModuleManager.class);

     /**

      * The attribute name in the servlet context under which an instance of this class can be found.

      */

     public static final String SC_ATTR_NAME = ModuleManager.class.getName();

     private ServletContext sc;

     /**

      * This flag is true, when synchronization is needed.

      */

     private final AtomicBoolean dirty = new AtomicBoolean(true);

     private final CopyOnWriteArrayList<Menu> mainMenu = new CopyOnWriteArrayList<>();

     private final List<Menu> immutableMainMenu = Collections.unmodifiableList(mainMenu);

     /**

      * Maps class names to module information.

      */

     private final Map<String, LightPITModule> registeredModules = new HashMap<>();

     @Override

     public void contextInitialized(ServletContextEvent sce) {

         sc = sce.getServletContext();

         reloadAll();

         sc.setAttribute(SC_ATTR_NAME, this);

         LOG.info("Module manager injected into ServletContext.");

     }

     @Override

     public void contextDestroyed(ServletContextEvent sce) {

         unloadAll();

     }

     private Optional<LightPITModule> getModuleInfo(Registration reg) {

         try {

             final Class scclass = Class.forName(reg.getClassName());

             final boolean lpservlet = AbstractLightPITServlet.class.isAssignableFrom(scclass);

             final boolean lpmodule = scclass.isAnnotationPresent(LightPITModule.class);

             if (lpservlet && !lpmodule) {

                 LOG.warn(

                     "{} is a LightPIT Servlet but is missing the module annotation.",

                     reg.getClassName()

                 );

             } else if (!lpservlet && lpmodule) {

                 LOG.warn(

                     "{} is annotated as a LightPIT Module but does not extend {}.",

                     reg.getClassName(),

                     AbstractLightPITServlet.class.getSimpleName()

                 );

             }

             if (lpservlet && lpmodule) {

                 final Class<? extends AbstractLightPITServlet> clazz = scclass;

                 final LightPITModule moduleInfo = clazz.getAnnotation(LightPITModule.class);

                 return Optional.of(moduleInfo);

             } else {

                 return Optional.empty();

             }

         } catch (ClassNotFoundException ex) {

             LOG.error(

                     "Servlet registration refers to class {} which cannot be found by the class loader (Reason: {})",

                     reg.getClassName(),

                     ex.getMessage()

             );

             return Optional.empty();

         }        

     }

     private void handleServletRegistration(String name, Registration reg) {

         final Optional<LightPITModule> moduleInfo = getModuleInfo(reg);

         if (moduleInfo.isPresent()) {

             registeredModules.put(reg.getClassName(), moduleInfo.get());            

             LOG.info("Module detected: {}", name);

         } else {

             LOG.debug("Servlet {} is no module, skipping.", name);

         }

     }

     /**

      * Scans for modules and reloads them all.

      */

     public void reloadAll() {

         registeredModules.clear();

         sc.getServletRegistrations().forEach(this::handleServletRegistration);

         // TODO: implement dependency resolver

         dirty.set(true);

         LOG.info("Modules loaded.");

     }

     /**

      * Synchronizes module information with the database.

      * 

      * @param db interface to the database

      */

     public void syncWithDatabase(DatabaseFacade db) {

         if (dirty.compareAndSet(true, false)) {

             if (db.getDataSource().isPresent()) {

                 try (Connection conn = db.getDataSource().get().getConnection()) {

                     final ModuleDao moduleDao = CoreDAOFactory.getModuleDao(db.getSQLDialect());

                     final List<Entry<String, LightPITModule>> visibleModules =

                             moduleDao.syncRegisteredModuleClasses(conn, registeredModules.entrySet());

                     final List<Menu> updatedMenu = visibleModules

                             .stream()

                             .collect(Collectors.mapping(

                                     (mod) -> new Menu(

                                             mod.getKey(),

                                             new ResourceKey(mod.getValue().bundleBaseName(), mod.getValue().menuKey()),

                                             mod.getValue().modulePath()),

                                     Collectors.toList())

                             );

                     mainMenu.removeIf((e) -> !updatedMenu.contains(e));

                     mainMenu.addAllAbsent(updatedMenu);

                 } catch (SQLException ex) {

                     LOG.error("Unexpected SQL Exception", ex);

                 }

             } else {

                 LOG.warn("No datasource present. Cannot sync module information with database.");

             }

         } else {

             LOG.debug("Module information clean - no synchronization required.");

         }

     }

     /**

      * Unloads all found modules.

      */

     public void unloadAll() {

         mainMenu.clear();

         registeredModules.clear();

         LOG.info("All modules unloaded.");

     }

     /**

      * Returns the main menu.

      * @return a list of menus belonging to the main menu

      */

     public List<Menu> getMainMenu() {

         return immutableMainMenu;

     }

     /**

      * Returns an unmodifiable map of all registered modules.

      * 

      * The key is the classname of the module.

      * 

      * @return the map of registered modules

      */

     public Map<String, LightPITModule> getRegisteredModules() {

         return Collections.unmodifiableMap(registeredModules);

     }

 }