dsw/cxf-topology-manager/src/main/java/org/apache/cxf/dosgi/topologymanager/exporter/EndpointListenerNotifier.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.cxf.dosgi.topologymanager.exporter;

import java.util.Dictionary;
import java.util.HashSet;
import java.util.Hashtable;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;

import org.osgi.framework.Filter;
import org.osgi.framework.FrameworkUtil;
import org.osgi.framework.InvalidSyntaxException;
import org.osgi.framework.ServiceReference;
import org.osgi.service.remoteserviceadmin.EndpointDescription;
import org.osgi.service.remoteserviceadmin.EndpointListener;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * Tracks EndpointListeners and allows to notify them of endpoints.
 */
public class EndpointListenerNotifier implements EndpointListener {
    private static final Logger LOG = LoggerFactory.getLogger(EndpointListenerNotifier.class);
    private enum NotifyType { ADDED, REMOVED };
    private Map<EndpointListener, Set<Filter>> listeners;
    private EndpointRepository endpointRepo;

    public EndpointListenerNotifier(final EndpointRepository endpointRepo) {
        this.endpointRepo = endpointRepo;
        this.listeners = new ConcurrentHashMap<EndpointListener, Set<Filter>>();
    }
    
    public static Set<Filter> getFiltersFromEndpointListenerScope(ServiceReference<EndpointListener> sref) {
        Set<Filter> filters = new HashSet<Filter>();
        String[] scopes = StringPlus.parse(sref.getProperty(EndpointListener.ENDPOINT_LISTENER_SCOPE));
        for (String scope : scopes) {
            try {
                filters.add(FrameworkUtil.createFilter(scope));
            } catch (InvalidSyntaxException e) {
                LOG.error("invalid endpoint listener scope: {}", scope, e);
            }
        }
        return filters;
    }

    public void add(EndpointListener ep, Set<Filter> filters) {
        LOG.debug("new EndpointListener detected");
        listeners.put(ep, filters);
        for (EndpointDescription endpoint : endpointRepo.getAllEndpoints()) {
            notifyListener(NotifyType.ADDED, ep, filters, endpoint);
        }
    }
    
    public void remove(EndpointListener ep) {
        LOG.debug("EndpointListener modified");
        listeners.remove(ep);
    }
    
    @Override
    public void endpointAdded(EndpointDescription endpoint, String matchedFilter) {
        notifyListeners(NotifyType.ADDED, endpoint);
    }

    @Override
    public void endpointRemoved(EndpointDescription endpoint, String matchedFilter) {
        notifyListeners(NotifyType.REMOVED, endpoint);
    }

    /**
     * Notifies all endpoint listeners about endpoints being added or removed.
     *
     * @param added specifies whether endpoints were added (true) or removed (false)
     * @param endpoints the endpoints the listeners should be notified about
     */
    private void notifyListeners(NotifyType type, EndpointDescription endpoint) {
        for (EndpointListener listener : listeners.keySet()) {
            notifyListener(type, listener, listeners.get(listener), endpoint);
        }
    }

    /**
     * Notifies an endpoint listener about endpoints being added or removed.
     *
     * @param type specifies whether endpoints were added (true) or removed (false)
     * @param endpointListenerRef the ServiceReference of an EndpointListener to notify
     * @param endpoints the endpoints the listener should be notified about
     */
    private void notifyListener(NotifyType type, EndpointListener listener, Set<Filter> filters, 
                        EndpointDescription endpoint) {
        LOG.debug("Endpoint {}", type);
        Set<Filter> matchingFilters = getMatchingFilters(filters, endpoint);
        for (Filter filter : matchingFilters) {
            if (type == NotifyType.ADDED) {
                listener.endpointAdded(endpoint, filter.toString());
            } else {
                listener.endpointRemoved(endpoint, filter.toString());
            }
        }
    }
    
    private static Set<Filter> getMatchingFilters(Set<Filter> filters, EndpointDescription endpoint) {
        Set<Filter> matchingFilters = new HashSet<Filter>();
        Dictionary<String, Object> dict = new Hashtable<String, Object>(endpoint.getProperties());
        for (Filter filter : filters) {
            if (filter.match(dict)) {
                LOG.debug("Filter {} matches endpoint {}", filter, dict);
                matchingFilters.add(filter);
            } else {
                LOG.trace("Filter {} does not match endpoint {}", filter, dict);
            }
        }
        return matchingFilters;
    }

}