/*
* 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.jackrabbit.core.observation;
import java.util.List;
import java.util.LinkedList;
import java.util.NoSuchElementException;
import java.util.Map;
import java.util.WeakHashMap;
import java.util.SortedMap;
import java.util.TreeMap;
import java.util.Date;
import java.util.Collections;
import java.text.DateFormat;
import javax.jcr.observation.Event;
import javax.jcr.observation.EventIterator;
import javax.jcr.observation.EventJournal;
import org.apache.jackrabbit.core.SessionImpl;
import org.apache.jackrabbit.core.journal.Journal;
import org.apache.jackrabbit.core.journal.RecordIterator;
import org.apache.jackrabbit.core.journal.JournalException;
import org.apache.jackrabbit.core.journal.Record;
import org.apache.jackrabbit.core.cluster.ClusterRecordDeserializer;
import org.apache.jackrabbit.core.cluster.ClusterRecord;
import org.apache.jackrabbit.core.cluster.ClusterRecordProcessor;
import org.apache.jackrabbit.core.cluster.ChangeLogRecord;
import org.apache.jackrabbit.core.cluster.LockRecord;
import org.apache.jackrabbit.core.cluster.NamespaceRecord;
import org.apache.jackrabbit.core.cluster.NodeTypeRecord;
import org.apache.jackrabbit.core.cluster.WorkspaceRecord;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* <code>EventJournalImpl</code> implements the JCR 2.0 {@link EventJournal}.
*/
public class EventJournalImpl implements EventJournal {
/**
* The logger instance for this class.
*/
private static final Logger log = LoggerFactory.getLogger(EventJournalImpl.class);
/**
* The minimum buffer size for events in {@link #eventBundleBuffer}.
*/
private static final int MIN_BUFFER_SIZE = 1024;
/**
* Map of skip maps. Key=Journal, Value=SortedMap
* </p>
* Each sorted map has the following structure:
* Key=Long (timestamp), Value=Long (revision)
*/
private static final Map<Journal, SortedMap<Long, Long>> REVISION_SKIP_MAPS = new WeakHashMap<Journal, SortedMap<Long, Long>>();
/**
* Last revision seen by this event journal.
*/
private Long lastRevision;
/**
* The event filter.
*/
private final EventFilter filter;
/**
* The journal of this repository.
*/
private final Journal journal;
/**
* The producer id to filter journal records.
*/
private final String producerId;
/**
* Target session.
*/
private final SessionImpl session;
/**
* Buffer of {@link EventBundle}s.
*/
private final List<EventBundle> eventBundleBuffer = new LinkedList<EventBundle>();
/**
* The current position of this iterator.
*/
private long position;
/**
* Creates a new event journal.
*
* @param filter for filtering the events read from the journal.
* @param journal the cluster journal.
* @param producerId the producer id of the cluster node.
* @param session target session
*/
public EventJournalImpl(
EventFilter filter, Journal journal,
String producerId, SessionImpl session) {
this.filter = filter;
this.journal = journal;
this.producerId = producerId;
this.session = session;
}
//------------------------< EventJournal >---------------------------------
/**
* {@inheritDoc}
*/
public void skipTo(long date) {
long time = System.currentTimeMillis();
// get skip map for this journal
SortedMap<Long, Long> skipMap = getSkipMap();
synchronized (skipMap) {
SortedMap<Long, Long> head = skipMap.headMap(new Long(time));
if (!head.isEmpty()) {
eventBundleBuffer.clear();
lastRevision = head.get(head.lastKey());
}
}
try {
while (hasNext()) {
EventBundle bundle = getCurrentBundle();
if (bundle.timestamp <= date) {
eventBundleBuffer.remove(0);
} else {
break;
}
}
} finally {
time = System.currentTimeMillis() - time;
log.debug("Skipped event bundles in {} ms.", new Long(time));
}
}
//------------------------< EventIterator >---------------------------------
/**
* {@inheritDoc}
*/
public Event nextEvent() {
// calling hasNext() will also trigger refill if necessary!
if (!hasNext()) {
throw new NoSuchElementException();
}
EventBundle bundle = getCurrentBundle();
// above hasNext() call ensures that there is bundle with an event state
assert bundle != null && bundle.events.hasNext();
Event next = (Event) bundle.events.next();
if (!bundle.events.hasNext()) {
// done with this bundle -> remove from buffer
eventBundleBuffer.remove(0);
}
position++;
return next;
}
//------------------------< RangeIterator >---------------------------------
/**
* {@inheritDoc}
*/
public void skip(long skipNum) {
while (skipNum-- > 0) {
nextEvent();
}
}
/**
* @return always -1.
*/
public long getSize() {
return -1;
}
/**
* {@inheritDoc}
*/
public long getPosition() {
// TODO: what happens to position when skipped
return position;
}
//--------------------------< Iterator >------------------------------------
/**
* @throws UnsupportedOperationException always.
*/
public void remove() {
throw new UnsupportedOperationException();
}
/**
* {@inheritDoc}
*/
public boolean hasNext() {
if (!eventBundleBuffer.isEmpty()) {
return true;
}
// try refill
refill();
// check again
return !eventBundleBuffer.isEmpty();
}
/**
* {@inheritDoc}
*/
public Object next() {
return nextEvent();
}
//----------------------< ClusterRecordProcessor >--------------------------
/**
* Implements {@link ClusterRecordProcessor} and keeps track of the number
* of events read and the timestamp of the last record processed.
*/
private class RecordProcessor implements ClusterRecordProcessor {
/**
* Number of events read so far.
*/
private int numEvents;
/**
* The timestamp of the last record processed.
*/
private long lastTimestamp;
/**
* @return the number of events read so far.
*/
private int getNumEvents() {
return numEvents;
}
/**
* @return the timestamp of the last record processed.
*/
private long getLastTimestamp() {
return lastTimestamp;
}
/**
* {@inheritDoc}
*/
public void process(ChangeLogRecord record) {
List<EventState> events = record.getEvents();
if (!events.isEmpty()) {
EventBundle bundle = new EventBundle(
events, record.getTimestamp(), record.getUserData());
if (bundle.events.hasNext()) {
// only queue bundle if there is an event
eventBundleBuffer.add(bundle);
numEvents += events.size();
lastTimestamp = record.getTimestamp();
}
}
}
public void process(LockRecord record) {
// ignore
}
public void process(NamespaceRecord record) {
// ignore
}
public void process(NodeTypeRecord record) {
// ignore
}
public void process(WorkspaceRecord record) {
// ignore
}
}
//-------------------------------< internal >-------------------------------
/**
* @return the current event bundle or <code>null</code> if there is none.
*/
private EventBundle getCurrentBundle() {
while (!eventBundleBuffer.isEmpty()) {
EventBundle bundle = eventBundleBuffer.get(0);
if (bundle.events.hasNext()) {
return bundle;
} else {
eventBundleBuffer.remove(0);
}
}
return null;
}
/**
* Refills the {@link #eventBundleBuffer}.
*/
private void refill() {
assert eventBundleBuffer.isEmpty();
try {
RecordProcessor processor = new RecordProcessor();
ClusterRecordDeserializer deserializer = new ClusterRecordDeserializer();
RecordIterator records;
if (lastRevision != null) {
log.debug("refilling event bundle buffer starting at revision {}",
lastRevision);
records = journal.getRecords(lastRevision.longValue());
} else {
log.debug("refilling event bundle buffer starting at journal beginning");
records = journal.getRecords();
}
try {
while (processor.getNumEvents() < MIN_BUFFER_SIZE && records.hasNext()) {
Record record = records.nextRecord();
if (record.getProducerId().equals(producerId)) {
ClusterRecord cr = deserializer.deserialize(record);
if (!session.getWorkspace().getName().equals(cr.getWorkspace())) {
continue;
}
cr.process(processor);
lastRevision = new Long(cr.getRevision());
}
}
if (processor.getNumEvents() >= MIN_BUFFER_SIZE) {
// remember in skip map
SortedMap<Long, Long> skipMap = getSkipMap();
Long timestamp = new Long(processor.getLastTimestamp());
synchronized (skipMap) {
if (log.isDebugEnabled()) {
DateFormat df = DateFormat.getDateTimeInstance();
log.debug("remember record in skip map: {} -> {}",
df.format(new Date(timestamp.longValue())),
lastRevision);
}
skipMap.put(timestamp, lastRevision);
}
}
} finally {
records.close();
}
} catch (JournalException e) {
log.warn("Unable to read journal records", e);
}
}
/**
* @return the revision skip map for this journal.
*/
private SortedMap<Long, Long> getSkipMap() {
synchronized (REVISION_SKIP_MAPS) {
SortedMap<Long, Long> map = REVISION_SKIP_MAPS.get(journal);
if (map == null) {
map = new TreeMap<Long, Long>();
REVISION_SKIP_MAPS.put(journal, map);
}
return map;
}
}
/**
* Simple class to associate an {@link EventState} iterator with a timestamp.
*/
private final class EventBundle {
/**
* An iterator of {@link Event}s.
*/
final EventIterator events;
/**
* Timestamp when the events were created.
*/
final long timestamp;
/**
* Creates a new event bundle.
*
* @param eventStates the {@link EventState}s that belong to this bundle.
* @param timestamp the timestamp when the events were created.
* @param userData the user data associated with this event.
* @param filter the event filter.
*/
private EventBundle(
List<EventState> eventStates, long timestamp, String userData) {
this.events = new FilteredEventIterator(
session, eventStates.iterator(),
timestamp, userData, filter, Collections.emptySet());
this.timestamp = timestamp;
}
}
}