001/**
002 * Copyright 2015 DuraSpace, Inc.
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 *     http://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 */
016package org.fcrepo.kernel.modeshape.observer.eventmappings;
017
018import static com.google.common.collect.Multimaps.index;
019import static org.modeshape.jcr.api.JcrConstants.JCR_CONTENT;
020import static org.slf4j.LoggerFactory.getLogger;
021import static java.util.Arrays.asList;
022import static javax.jcr.observation.Event.PROPERTY_ADDED;
023import static javax.jcr.observation.Event.PROPERTY_CHANGED;
024import static javax.jcr.observation.Event.PROPERTY_REMOVED;
025
026import java.util.Iterator;
027import java.util.List;
028import java.util.function.Function;
029
030import javax.jcr.RepositoryException;
031import javax.jcr.observation.Event;
032
033import org.fcrepo.kernel.api.exception.RepositoryRuntimeException;
034import org.fcrepo.kernel.api.observer.FedoraEvent;
035import org.fcrepo.kernel.api.observer.eventmappings.InternalExternalEventMapper;
036
037import org.slf4j.Logger;
038
039import com.google.common.collect.Multimap;
040
041/**
042 * Maps all JCR {@link Event}s concerning one JCR node to one {@link FedoraEvent}. Adds the types of those JCR events
043 * together to calculate the final type of the emitted FedoraEvent.
044 * TODO stop aggregating events in the heap, if possible
045 *
046 * @author ajs6f
047 * @since Feb 27, 2014
048 */
049public class AllNodeEventsOneEvent implements InternalExternalEventMapper {
050
051    private static final List<Integer> PROPERTY_EVENT_TYPES = asList(PROPERTY_ADDED, PROPERTY_CHANGED,
052            PROPERTY_REMOVED);
053
054    private final static Logger LOGGER = getLogger(AllNodeEventsOneEvent.class);
055
056    /**
057     * Extracts an identifier from a JCR {@link Event} by building an id from nodepath and user to collapse multiple
058     * events from repository mutations
059     */
060    private static final Function<Event, String> EXTRACT_NODE_ID = ev -> {
061            final String id = FedoraEvent.getPath(ev).replaceAll("/" + JCR_CONTENT,"") + "-" + ev.getUserID();
062            LOGGER.debug("Sorting an event by identifier: {}", id);
063            return id;
064    };
065
066    @Override
067    public Iterator<FedoraEvent> apply(final Iterator<Event> events) {
068        return new FedoraEventIterator(events);
069    }
070
071    private static class FedoraEventIterator implements Iterator<FedoraEvent> {
072
073        // JCR events in a Multimap keyed by identifier
074        private final Multimap<String, Event> sortedEvents;
075
076        private final Iterator<String> ids;
077
078        public FedoraEventIterator(final Iterator<Event> events) {
079            sortedEvents = index(events, EXTRACT_NODE_ID::apply);
080            ids = sortedEvents.keySet().iterator();
081        }
082
083        @Override
084        public boolean hasNext() {
085            return ids.hasNext();
086        }
087
088        @Override
089        public FedoraEvent next() {
090            final Iterator<Event> nodeSpecificEvents = sortedEvents.get(ids.next()).iterator();
091            // we can safely call next() immediately on nodeSpecificEvents because if there was no event at all, there
092            // would appear no entry in our Multimap under this key
093            final Event firstEvent = nodeSpecificEvents.next();
094            final FedoraEvent fedoraEvent = new FedoraEvent(firstEvent);
095
096            addProperty(fedoraEvent, firstEvent);
097            while (nodeSpecificEvents.hasNext()) {
098                // add the event type and property name to the event we are building up to emit
099                // we could aggregate other information here if that seems useful
100                final Event otherEvent = nodeSpecificEvents.next();
101                fedoraEvent.addType(otherEvent.getType());
102                addProperty(fedoraEvent, otherEvent);
103            }
104            return fedoraEvent;
105        }
106
107        @Override
108        public void remove() {
109            // the underlying Multimap is immutable anyway
110            throw new UnsupportedOperationException();
111        }
112
113        private static void addProperty( final FedoraEvent fedoraEvent, final Event ev ) {
114            try {
115                if ( ev.getPath().contains(JCR_CONTENT)) {
116                    fedoraEvent.addProperty("fedora:hasContent");
117                }
118                if (PROPERTY_EVENT_TYPES.contains(ev.getType())) {
119                    final String eventPath = ev.getPath();
120                    fedoraEvent.addProperty(eventPath.substring(eventPath.lastIndexOf('/') + 1));
121                } else {
122                    LOGGER.trace("Not adding non-event property: {}, {}", fedoraEvent, ev);
123                }
124            } catch (final RepositoryException e) {
125                throw new RepositoryRuntimeException(e);
126            }
127        }
128    }
129}