dependencymanager/core/src/main/java/org/apache/felix/dm/impl/AspectServiceImpl.java

/*
 * 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.
 */
package org.apache.felix.dm.impl;

import java.util.ArrayList;
import java.util.Dictionary;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Properties;
import java.util.Set;

import org.apache.felix.dm.Component;
import org.apache.felix.dm.ComponentStateListener;
import org.apache.felix.dm.Dependency;
import org.apache.felix.dm.DependencyManager;
import org.apache.felix.dm.DependencyService;
import org.apache.felix.dm.ServiceDependency;
import org.apache.felix.dm.impl.dependencies.ServiceDependencyImpl;
import org.osgi.framework.Constants;
import org.osgi.framework.ServiceReference;

/**
 * Aspect Service implementation. This class extends the FilterService in order to catch
 * some Service methods for configuring actual aspect service implementation.
 * 
 * @author <a href="mailto:dev@felix.apache.org">Felix Project Team</a>
 */
public class AspectServiceImpl extends FilterService {
    private final String m_add;
    private final String m_change;
    private final String m_remove;
    private final String m_swap;
    private final String m_aspectFilter;
    private final int m_ranking; // the aspect ranking

    public AspectServiceImpl(DependencyManager dm, Class aspectInterface, String aspectFilter, int ranking, String autoConfig, String add, String change, String remove, String swap)
    { 
        super(dm.createComponent()); // This service will be filtered by our super class, allowing us to take control.
        m_ranking = ranking;
        m_add = add;
        m_change = change;
        m_remove = remove;
        m_swap = swap;
        m_aspectFilter = aspectFilter;
        m_component.setImplementation(new AspectImpl(aspectInterface, autoConfig))
             .add(dm.createServiceDependency()
                  .setService(aspectInterface, createDependencyFilterForAspect(aspectFilter))
                  .setAutoConfig(false)
                  .setCallbacks("added", "removed"))
             .setCallbacks("init", null, "stop", null);
    }

    private String createDependencyFilterForAspect(String filter) {
        // we only want to match services which are not themselves aspects
        if (filter == null || filter.length() == 0) {
            return "(!(" + DependencyManager.ASPECT + "=*))";
        }
        else {
            return "(&(!(" + DependencyManager.ASPECT + "=*))" + filter + ")";
        }        
    }
    
    private Properties getServiceProperties(ServiceReference ref) {
        Properties props = new Properties();
        String[] keys = ref.getPropertyKeys();
        for (int i = 0; i < keys.length; i++) {
            String key = keys[i];
            if (key.equals(Constants.SERVICE_ID) || key.equals(Constants.SERVICE_RANKING) || key.equals(DependencyManager.ASPECT) || key.equals(Constants.OBJECTCLASS)) {
                // do not copy these
            }
            else {
                props.put(key, ref.getProperty(key));
            }
        }
        if (m_serviceProperties != null) {
            Enumeration e = m_serviceProperties.keys();
            while (e.hasMoreElements()) {
                Object key = e.nextElement();
                props.put(key, m_serviceProperties.get(key));
            }
        }
        // finally add our aspect property
        props.put(DependencyManager.ASPECT, ref.getProperty(Constants.SERVICE_ID));
        // and the ranking
        props.put(Constants.SERVICE_RANKING, Integer.valueOf(m_ranking));
        return props;
    }

    /**
     * This class is the Aspect Implementation. It will create the actual Aspect Service, and
     * will use the Aspect Service parameters provided by our enclosing class.
     */
    class AspectImpl extends AbstractDecorator {
        private final String m_autoConfig; // the aspect impl field name where to inject decorated service
        private final Class m_aspectInterface; // the service decorated by this aspect
      
        public AspectImpl(Class aspectInterface, String autoConfig) {
            m_aspectInterface = aspectInterface;
            m_autoConfig = autoConfig;
        }
        
        /**
         * Creates an aspect implementation component for a new original service.
         * @param param First entry contains the ref to the original service
         */
        public Component createService(Object[] params) {
            // Get the new original service reference.
            ServiceReference ref = (ServiceReference) params[0];
            List dependencies = m_component.getDependencies();
            // remove our internal dependency, replace it with one that points to the specific service that just was passed in.
            dependencies.remove(0);
            Properties serviceProperties = getServiceProperties(ref);
            String[] serviceInterfaces = getServiceInterfaces();
            
            ServiceDependency aspectDependency = (ServiceDependencyImpl) 
                    m_manager.createServiceDependency().setService(m_aspectInterface, createAspectFilter(ref)).setRequired(true);

//            aspectDependency.setDebug("AspectDependency#" + 
//                    (m_serviceImpl instanceof Class ? (((Class) m_serviceImpl).getSimpleName()) : m_serviceImpl));
            
            aspectDependency.setCallbacks(new CallbackProxy(aspectDependency, ref), 
                            m_add != null ? "addAspect" : null, 
                            "changeAspect", // We have to propagate in case aspect does not have a change callback
                            m_remove != null ? "removeAspect" : null, 
                            m_swap != null ? "swapAspect" : null);
            
            if (m_autoConfig != null) {
                aspectDependency.setAutoConfig(m_autoConfig);
            } else if (m_add == null && m_change == null && m_remove == null && m_swap == null) {
                // Since we have set callbacks, we must reactivate setAutoConfig because user has not specified any callbacks.
                aspectDependency.setAutoConfig(true);
            }
            
            Component service = m_manager.createComponent()
                .setInterface(serviceInterfaces, serviceProperties)
                .setImplementation(m_serviceImpl)
                .setFactory(m_factory, m_factoryCreateMethod) // if not set, no effect
                .setComposition(m_compositionInstance, m_compositionMethod) // if not set, no effect
                .setCallbacks(m_callbackObject, m_init, m_start, m_stop, m_destroy) // if not set, no effect
                .add(aspectDependency);
            
            configureAutoConfigState(service, m_component);
            
            for (int i = 0; i < dependencies.size(); i++) {
                service.add(((Dependency) dependencies.get(i)).createCopy());
            }

            for (int i = 0; i < m_stateListeners.size(); i++) {
                service.addStateListener((ComponentStateListener) m_stateListeners.get(i));
            }
            return service;                
        }
        
        /**
         * Modify some specific aspect service properties.
         */
        public void setServiceProperties(Dictionary props) {
            Map services = super.getServices();
            Iterator it = services.entrySet().iterator();
            while (it.hasNext()) {
                Map.Entry entry = (Map.Entry) it.next();
                ServiceReference originalServiceRef = (ServiceReference) entry.getKey();
                Component c = (Component) entry.getValue();
                // m_serviceProperties is already set to the new service properties; and the getServiceProperties will
                // merge m_serviceProperties with the original service properties.
                Dictionary newProps = getServiceProperties(originalServiceRef);                
                c.setServiceProperties(newProps);
            }
        }
                
        private String[] getServiceInterfaces() {
            List serviceNames = new ArrayList();
            // Of course, we provide the aspect interface.
            serviceNames.add(m_aspectInterface.getName());
            // But also append additional aspect implementation interfaces.
            if (m_serviceInterfaces != null) {
                for (int i = 0; i < m_serviceInterfaces.length; i ++) {
                    if (!m_serviceInterfaces[i].equals(m_aspectInterface.getName())) {
                        serviceNames.add(m_serviceInterfaces[i]);
                    }
                }
            }
            return (String[]) serviceNames.toArray(new String[serviceNames.size()]);
        }

        private String createAspectFilter(ServiceReference ref) {
            Long sid = (Long) ref.getProperty(Constants.SERVICE_ID);
            return "(&(|(!(" + Constants.SERVICE_RANKING + "=*))(" + Constants.SERVICE_RANKING + "<=" + (m_ranking - 1) + "))(|(" + Constants.SERVICE_ID + "=" + sid + ")(" + DependencyManager.ASPECT + "=" + sid + ")))";
        }
        
        public String toString() {
            return "Aspect for " + m_aspectInterface + ((m_aspectFilter != null) ? " with filter " + m_aspectFilter : "");
        }
    }
    
    class CallbackProxy {
        private final ServiceDependencyImpl m_aspectDependency;
        private final ServiceReference m_originalServiceRef;

        CallbackProxy(ServiceDependency aspectDependency, ServiceReference originalServiceRef) {
            m_aspectDependency = (ServiceDependencyImpl) aspectDependency;
            m_originalServiceRef = originalServiceRef;
        }

        private void addAspect(Component c, ServiceReference ref, Object service) {
            // Just forward "add" service dependency callback.
            m_aspectDependency.invoke(c.getCompositionInstances(), (DependencyService) c, ref, service, m_add);
        }

        private void changeAspect(Component c, ServiceReference ref, Object service) {
            // Invoke "change" service dependency callback
            if (m_change != null) {
                m_aspectDependency.invoke(c.getCompositionInstances(), (DependencyService) c, ref, service, m_change);
            }
            // Propagate change to immediate higher aspect, or to client using our aspect.
            // We always propagate our own properties, and the ones from the original service, but we don't inherit
            // from lower ranked aspect service properties.
            Dictionary props = getServiceProperties(m_originalServiceRef);
            c.setServiceProperties(props);
        }

        private void removeAspect(Component c, ServiceReference ref, Object service) {
            // Just forward "remove" service dependency callback.
            m_aspectDependency.invoke(c.getCompositionInstances(), (DependencyService) c, ref, service, m_remove);
        }

        private void swapAspect(Component c, ServiceReference prevRef, Object prev, ServiceReference currRef,
                                Object curr) {
            // Just forward "swap" service dependency callback.
            m_aspectDependency.invokeSwappedCallback(c.getCompositionInstances(), (DependencyService) c, prevRef, prev,
                    currRef, curr, m_swap);
        }
    }
}