package org.apache.turbine.services;

 /*

  * Licensed to the Apache Software Foundation (ASF) under one

  * or more contributor license agreements.  See the NOTICE file

  * distributed with this work for additional information

  * regarding copyright ownership.  The ASF licenses this file

  * to you 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.

  */

 import java.util.ArrayList;

 import java.util.Iterator;

 import java.util.LinkedHashMap;

 import java.util.LinkedHashSet;

 import java.util.Map;

 import java.util.Set;

 import java.util.concurrent.ConcurrentHashMap;

 import java.util.concurrent.locks.ReentrantLock;

 import org.apache.commons.configuration2.Configuration;

 import org.apache.commons.lang3.StringUtils;

 import org.apache.logging.log4j.LogManager;

 import org.apache.logging.log4j.Logger;

 /**

  * A generic implementation of a <code>ServiceBroker</code> which

  * provides:

  *

  * <ul>

  * <li>Maintaining service name to class name mapping, allowing

  * pluggable service implementations.</li>

  * <li>Providing <code>Services</code> with a configuration based on

  * system wide configuration mechanism.</li>

  * <li>Integration of TurbineServiceProviders for looking up

  * non-local services</li>

  * </ul>

  *

  * @author <a href="mailto:burton@apache.org">Kevin Burton</a>

  * @author <a href="mailto:krzewski@e-point.pl">Rafal Krzewski</a>

  * @author <a href="mailto:dlr@finemaltcoding.com">Daniel Rall</a>

  * @author <a href="mailto:jvanzyl@apache.org">Jason van Zyl</a>

  * @author <a href="mailto:mpoeschl@marmot.at">Martin Poeschl</a>

  * @author <a href="mailto:hps@intermeta.de">Henning P. Schmiedehausen</a>

  * @version $Id: BaseServiceBroker.java 1854787 2019-03-04 18:30:25Z tv $

  */

 public abstract class BaseServiceBroker implements ServiceBroker

 {

     /**

      * Mapping of Service names to class names, keep order.

      */

     private final Map<String, Class<?>> mapping = new LinkedHashMap<String, Class<?>>();

     /**

      * A repository of Service instances.

      */

     private final ConcurrentHashMap<String, Service> services = new ConcurrentHashMap<String, Service>();

     /**

      * Lock access during service initialization

      */

     private final ReentrantLock serviceLock = new ReentrantLock();

     /**

      * Configuration for the services broker.

      * The configuration should be set by the application

      * in which the services framework is running.

      */

     private Configuration configuration;

     /**

      * A prefix for <code>Service</code> properties in

      * TurbineResource.properties.

      */

     public static final String SERVICE_PREFIX = "services.";

     /**

      * A <code>Service</code> property determining its implementing

      * class name .

      */

     public static final String CLASSNAME_SUFFIX = ".classname";

     /**

      * These are objects that the parent application

      * can provide so that application specific

      * services have a mechanism to retrieve specialized

      * information. For example, in Turbine there are services

      * that require the RunData object: these services can

      * retrieve the RunData object that Turbine has placed

      * in the service manager. This alleviates us of

      * the requirement of having init(Object) all

      * together.

      */

     private final ConcurrentHashMap<String, Object> serviceObjects = new ConcurrentHashMap<String, Object>();

     /** Logging */

     private static final Logger log = LogManager.getLogger(BaseServiceBroker.class);

     /**

      * Application root path as set by the

      * parent application.

      */

     private String applicationRoot;

     /**

      * mapping from service names to instances of TurbineServiceProviders

      */

     private final ConcurrentHashMap<String, Service> serviceProviderInstanceMap = new ConcurrentHashMap<String, Service>();

     /**

      * Default constructor, protected as to only be usable by subclasses.

      *

      * This constructor does nothing.

      */

     protected BaseServiceBroker()

     {

         // nothing to do

     }

     /**

      * Set the configuration object for the services broker.

      * This is the configuration that contains information

      * about all services in the care of this service

      * manager.

      *

      * @param configuration Broker configuration.

      */

     public void setConfiguration(Configuration configuration)

     {

         this.configuration = configuration;

     }

     /**

      * Get the configuration for this service manager.

      *

      * @return Broker configuration.

      */

     public Configuration getConfiguration()

     {

         return configuration;

     }

     /**

      * Initialize this service manager.

      * @throws InitializationException if the initialization fails

      */

     public void init() throws InitializationException

     {

         // Check:

         //

         // 1. The configuration has been set.

         // 2. Make sure the application root has been set.

         // FIXME: Make some service framework exceptions to throw in

         // the event these requirements aren't satisfied.

         // Create the mapping between service names

         // and their classes.

         initMapping();

         // Start services that have their 'earlyInit'

         // property set to 'true'.

         initServices(false);

     }

     /**

      * Set an application specific service object

      * that can be used by application specific

      * services.

      *

      * @param name name of service object

      * @param value value of service object

      */

     public void setServiceObject(String name, Object value)

     {

         serviceObjects.put(name, value);

     }

     /**

      * Get an application specific service object.

      *

      * @param name the name of the service object

      * @return Object application specific service object

      */

     public Object getServiceObject(String name)

     {

         return serviceObjects.get(name);

     }

     /**

      * Check recursively if the given checkIfc interface is among the implemented

      * interfaces

      *

      * @param checkIfc interface to check for

      * @param interfaces interfaces to scan

      * @return true if the interface is implemented

      */

     private boolean checkForInterface(Class<?> checkIfc, Class<?>[] interfaces)

     {

         for (Class<?> ifc : interfaces)

         {

             if (ifc == checkIfc)

             {

                 return true;

             }

             Class<?>[] subInterfaces = ifc.getInterfaces();

             if (checkForInterface(checkIfc, subInterfaces))

             {

                 return true;

             }

         }

         return false;

     }

     /**

      * Creates a mapping between Service names and class names.

      *

      * The mapping is built according to settings present in

      * TurbineResources.properties.  The entries should have the

      * following form:

      *

      * <pre>

      * services.MyService.classname=com.mycompany.MyServiceImpl

      * services.MyOtherService.classname=com.mycompany.MyOtherServiceImpl

      * </pre>

      *

      * <br>

      *

      * Generic ServiceBroker provides no Services.

      * @throws InitializationException if a service class could not be found

      */

     protected void initMapping() throws InitializationException

     {

         // we need to temporarily store the earlyInit flags to avoid

         // ConcurrentModificationExceptions

         Map<String, String> earlyInitFlags = new LinkedHashMap<String, String>();

         /*

          * These keys returned in an order that corresponds

          * to the order the services are listed in

          * the TR.props.

          */

         for (Iterator<String> keys = configuration.getKeys(); keys.hasNext();)

         {

             String key = keys.next();

             String[] keyParts = StringUtils.split(key, ".");

             if (keyParts.length == 3

                     && (keyParts[0] + ".").equals(SERVICE_PREFIX)

                     && ("." + keyParts[2]).equals(CLASSNAME_SUFFIX))

             {

                 String serviceKey = keyParts[1];

                 log.info("Added Mapping for Service: {}", serviceKey);

                 if (!mapping.containsKey(serviceKey))

                 {

                     String className = configuration.getString(key);

                     try

                     {

                         Class<?> clazz = Class.forName(className);

                         mapping.put(serviceKey, clazz);

                         // detect TurbineServiceProviders

                         if (checkForInterface(TurbineServiceProvider.class, clazz.getInterfaces()))

                         {

                             log.info("Found a TurbineServiceProvider: {} - initializing it early", serviceKey);

                             earlyInitFlags.put(SERVICE_PREFIX + serviceKey + ".earlyInit", "true");

                         }

                     }

                     // those two errors must be passed to the VM

                     catch (ThreadDeath t)

                     {

                         throw t;

                     }

                     catch (OutOfMemoryError t)

                     {

                         throw t;

                     }

                     catch (ClassNotFoundException | NoClassDefFoundError e)

                     {

                         throw new InitializationException("Class " + className +

                             " is unavailable. Check your jars and classes.", e);

                     }

                 }

             }

         }

         for (Map.Entry<String, String> entry : earlyInitFlags.entrySet())

         {

             configuration.setProperty(entry.getKey(), entry.getValue());

         }

     }

     /**

      * Determines whether a service is registered in the configured

      * <code>TurbineResources.properties</code>.

      *

      * @param serviceName The name of the service whose existence to check.

      * @return Registration predicate for the desired services.

      */

     @Override

     public boolean isRegistered(String serviceName)

     {

         return (services.get(serviceName) != null);

     }

     /**

      * Returns an Iterator over all known service names.

      *

      * @return An Iterator of service names.

      */

     public Iterator<String> getServiceNames()

     {

         return mapping.keySet().iterator();

     }

     /**

      * Returns an Iterator over all known service names beginning with

      * the provided prefix.

      *

      * @param prefix The prefix against which to test.

      * @return An Iterator of service names which match the prefix.

      */

     public Iterator<String> getServiceNames(String prefix)

     {

         Set<String> keys = new LinkedHashSet<String>(mapping.keySet());

         for(Iterator<String> key = keys.iterator(); key.hasNext();)

         {

             if (!key.next().startsWith(prefix))

             {

                 key.remove();

             }

         }

         return keys.iterator();

     }

     /**

      * Performs early initialization of specified service.

      *

      * @param name The name of the service (generally the

      * <code>SERVICE_NAME</code> constant of the service's interface

      * definition).

      * @throws InitializationException Initialization of this

      * service was not successful.

      */

     @Override

     public synchronized void initService(String name)

             throws InitializationException

     {

         // Calling getServiceInstance(name) assures that the Service

         // implementation has its name and broker reference set before

         // initialization.

         Service instance = getServiceInstance(name);

         if (!instance.getInit())

         {

             // this call might result in an indirect recursion

             instance.init();

         }

     }

     /**

      * Performs early initialization of all services.  Failed early

      * initialization of a Service may be non-fatal to the system,

      * thus any exceptions are logged and the initialization process

      * continues.

      */

     public void initServices()

     {

         try

         {

             initServices(false);

         }

         catch (InstantiationException | InitializationException notThrown)

         {

             log.debug("Caught non fatal exception", notThrown);

         }

     }

     /**

      * Performs early initialization of all services. You can decide

      * to handle failed initializations if you wish, but then

      * after one service fails, the other will not have the chance

      * to initialize.

      *

      * @param report <code>true</code> if you want exceptions thrown.

      * @throws InstantiationException if the service could not be instantiated

      * @throws InitializationException if the service could not be initialized

      */

     public void initServices(boolean report)

             throws InstantiationException, InitializationException

     {

         if (report)

         {

             // Throw exceptions

             for (Iterator<String> names = getServiceNames(); names.hasNext();)

             {

                 doInitService(names.next());

             }

         }

         else

         {

             // Eat exceptions

             for (Iterator<String> names = getServiceNames(); names.hasNext();)

             {

                 try

                 {

                     doInitService(names.next());

                 }

                         // In case of an exception, file an error message; the

                         // system may be still functional, though.

                 catch (InstantiationException | InitializationException e)

                 {

                     log.error(e);

                 }

             }

         }

         log.info("Finished initializing all services!");

     }

     /**

      * Internal utility method for use in {@link #initServices(boolean)}

      * to prevent duplication of code.

      */

     private void doInitService(String name)

             throws InstantiationException, InitializationException

     {

         // Only start up services that have their earlyInit flag set.

         if (getConfiguration(name).getBoolean("earlyInit", false))

         {

             log.info("Start Initializing service (early): {}", name);

             initService(name);

             log.info("Finish Initializing service (early): {}", name);

         }

     }

     /**

      * Shuts down a <code>Service</code>, releasing resources

      * allocated by an <code>Service</code>, and returns it to its

      * initial (uninitialized) state.

      *

      * @param name The name of the <code>Service</code> to be

      * uninitialized.

      */

     @Override

     public synchronized void shutdownService(String name)

     {

         try

         {

             Service service = getServiceInstance(name);

             if (service != null && service.getInit())

             {

                 service.shutdown();

                 if (service.getInit() && service instanceof BaseService)

                 {

                     // BaseService::shutdown() does this by default,

                     // but could've been overriden poorly.

                     ((BaseService) service).setInit(false);

                 }

             }

         }

         catch (InstantiationException e)

         {

             // Assuming harmless -- log the error and continue.

             log.error("Shutdown of a nonexistent Service '"

                     + name + "' was requested", e);

         }

     }

     /**

      * Shuts down all Turbine services, releasing allocated resources and

      * returning them to their initial (uninitialized) state.

      */

     @Override

     public void shutdownServices()

     {

         log.info("Shutting down all services!");

         String serviceName = null;

         /*

          * Now we want to reverse the order of

          * this list. This functionality should be added to

          * the ExtendedProperties in the commons but

          * this will fix the problem for now.

          */

         ArrayList<String> reverseServicesList = new ArrayList<String>();

         for (Iterator<String> serviceNames = getServiceNames(); serviceNames.hasNext();)

         {

             serviceName = serviceNames.next();

             reverseServicesList.add(0, serviceName);

         }

         for (Iterator<String> serviceNames = reverseServicesList.iterator(); serviceNames.hasNext();)

         {

             serviceName = serviceNames.next();

             log.info("Shutting down service: {}", serviceName);

             shutdownService(serviceName);

         }

     }

     /**

      * Returns an instance of requested Service.

      *

      * @param name The name of the Service requested.

      * @return An instance of requested Service.

      * @throws InstantiationException if the service is unknown or

      * can't be initialized.

      */

     @Override

     public Object getService(String name) throws InstantiationException

     {

         Service service;

         if (this.isLocalService(name))

         {

                 try

                 {

                     service = getServiceInstance(name);

                     if (!service.getInit())

                     {

                         synchronized (service.getClass())

                         {

                             if (!service.getInit())

                             {

                                 log.info("Start Initializing service (late): {}", name);

                                 service.init();

                                 log.info("Finish Initializing service (late): {}", name);

                             }

                         }

                     }

                     if (!service.getInit())

                     {

                         // this exception will be caught & rethrown by this very method.

                         // getInit() returning false indicates some initialization issue,

                         // which in turn prevents the InitableBroker from passing a

                         // reference to a working instance of the initable to the client.

                         throw new InitializationException(

                                 "init() failed to initialize service " + name);

                     }

                     return service;

                 }

                 catch (InitializationException e)

                 {

                     throw new InstantiationException("Service " + name +

                             " failed to initialize", e);

                 }

         }

         else if (this.isNonLocalService(name))

         {

             return this.getNonLocalService(name);

         }

         else

         {

             throw new InstantiationException(

                 "ServiceBroker: unknown service " + name

                 + " requested");

         }

     }

     /**

      * Retrieves an instance of a Service without triggering late

      * initialization.

      *

      * Early initialization of a Service can require access to Service

      * properties.  The Service must have its name and serviceBroker

      * set by then.  Therefore, before calling

      * Initable.initClass(Object), the class must be instantiated with

      * InitableBroker.getInitableInstance(), and

      * Service.setServiceBroker() and Service.setName() must be

      * called.  This calls for two - level accessing the Services

      * instances.

      *

      * @param name The name of the service requested.

      *

      * @return the Service instance

      *

      * @throws InstantiationException The service is unknown or

      * can't be initialized.

      */

     protected Service getServiceInstance(String name)

             throws InstantiationException

     {

         Service service = services.get(name);

         if (service == null)

         {

             serviceLock.lock();

             try

             {

                 // Double check

                 service = services.get(name);

                 if (service == null)

                 {

                     if (!this.isLocalService(name))

                     {

                         throw new InstantiationException(

                                 "ServiceBroker: unknown service " + name

                                 + " requested");

                     }

                     try

                     {

                         Class<?> clazz = mapping.get(name);

                         try

                         {

                             service = (Service) clazz.newInstance();

                             // check if the newly created service is also a

                             // service provider - if so then remember it

                             if (service instanceof TurbineServiceProvider)

                             {

                                 Service _service = this.serviceProviderInstanceMap.putIfAbsent(name,service);

                                 if (_service != null)

                                 {

                                     service = _service;

                                 }

                             }

                         }

                         // those two errors must be passed to the VM

                         catch (ClassCastException e)

                         {

                             throw new InstantiationException("Class " + clazz +

                                     " doesn't implement the Service interface", e);

                         }

                         catch (ThreadDeath t)

                         {

                             throw t;

                         }

                         catch (OutOfMemoryError t)

                         {

                             throw t;

                         }

                         catch (Throwable t)

                         {

                             throw new InstantiationException("Failed to instantiate " + clazz, t);

                         }

                     }

                     catch (InstantiationException e)

                     {

                         throw new InstantiationException(

                                 "Failed to instantiate service " + name, e);

                     }

                     service.setServiceBroker(this);

                     service.setName(name);

                     Service _service = services.putIfAbsent(name, service);

                     if (_service != null) // Unlikely

                     {

                         service = _service;

                     }

                 }

             }

             finally

             {

                 serviceLock.unlock();

             }

         }

         return service;

     }

     /**

      * Returns the configuration for the specified service.

      *

      * @param name The name of the service.

      * @return Configuration of requested Service.

      */

     @Override

     public Configuration getConfiguration(String name)

     {

         return configuration.subset(SERVICE_PREFIX + name);

     }

     /**

      * Set the application root.

      *

      * @param applicationRoot application root

      */

     public void setApplicationRoot(String applicationRoot)

     {

         this.applicationRoot = applicationRoot;

     }

     /**

      * Get the application root as set by

      * the parent application.

      *

      * @return String application root

      */

     @Override

     public String getApplicationRoot()

     {

         return applicationRoot;

     }

     /**

      * Determines if the requested service is managed by this

      * ServiceBroker.

      *

      * @param name The name of the Service requested.

      * @return true if the service is managed by the this ServiceBroker

      */

     protected boolean isLocalService(String name)

     {

         return this.mapping.containsKey(name);

     }

     /**

      * Determines if the requested service is managed by an initialized

      * TurbineServiceProvider. We use the service names to lookup

      * the TurbineServiceProvider to ensure that we get a fully

      * initialized service.

      *

      * @param name The name of the Service requested.

      * @return true if the service is managed by a TurbineServiceProvider

      */

     protected boolean isNonLocalService(String name)

     {

         TurbineServiceProvider turbineServiceProvider = null;

         for (Map.Entry<String, Service> entry : this.serviceProviderInstanceMap.entrySet())

         {

             turbineServiceProvider = (TurbineServiceProvider) this.getService(entry.getKey());

             if (turbineServiceProvider.exists(name))

             {

                 return true;

             }

         }

         return false;

     }

     /**

      * Get a non-local service managed by a TurbineServiceProvider.

      *

      * @param name The name of the Service requested.

      * @return the requested service

      * @throws InstantiationException the service couldn't be instantiated

      */

     protected Object getNonLocalService(String name)

             throws InstantiationException

     {

         TurbineServiceProvider turbineServiceProvider = null;

         for (Map.Entry<String, Service> entry : this.serviceProviderInstanceMap.entrySet())

         {

             turbineServiceProvider = (TurbineServiceProvider) this.getService(entry.getKey());

             if (turbineServiceProvider.exists(name))

             {

                 return turbineServiceProvider.get(name);

             }

         }

         throw new InstantiationException(

             "ServiceBroker: unknown non-local service " + name

             + " requested");

     }

 }