001/**
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017package org.apache.activemq.broker.region.virtual;
018
019import org.apache.activemq.broker.Broker;
020import org.apache.activemq.broker.ProducerBrokerExchange;
021import org.apache.activemq.broker.region.Destination;
022import org.apache.activemq.broker.region.Subscription;
023import org.apache.activemq.command.ActiveMQDestination;
024import org.apache.activemq.command.Message;
025import org.apache.activemq.filter.BooleanExpression;
026import org.apache.activemq.filter.MessageEvaluationContext;
027import org.apache.activemq.filter.NonCachedMessageEvaluationContext;
028import org.apache.activemq.plugin.SubQueueSelectorCacheBroker;
029import org.apache.activemq.selector.SelectorParser;
030import org.apache.activemq.util.LRUCache;
031import org.slf4j.Logger;
032import org.slf4j.LoggerFactory;
033
034import java.io.IOException;
035import java.util.List;
036import java.util.Set;
037
038public class SelectorAwareVirtualTopicInterceptor extends VirtualTopicInterceptor {
039    private static final Logger LOG = LoggerFactory.getLogger(SelectorAwareVirtualTopicInterceptor.class);
040    LRUCache<String,BooleanExpression> expressionCache = new LRUCache<String,BooleanExpression>();
041    private SubQueueSelectorCacheBroker selectorCachePlugin;
042
043    public SelectorAwareVirtualTopicInterceptor(Destination next, String prefix, String postfix, boolean local) {
044        super(next, prefix, postfix, local);
045    }
046
047    /**
048     * Respect the selectors of the subscriptions to ensure only matched messages are dispatched to
049     * the virtual queues, hence there is no build up of unmatched messages on these destinations
050     */
051    @Override
052    protected void send(ProducerBrokerExchange context, Message message, ActiveMQDestination destination) throws Exception {
053        Broker broker = context.getConnectionContext().getBroker();
054        Set<Destination> destinations = broker.getDestinations(destination);
055
056        for (Destination dest : destinations) {
057            if (matchesSomeConsumer(broker, message, dest)) {
058                dest.send(context, message.copy());
059            }
060        }
061    }
062
063    private boolean matchesSomeConsumer(final Broker broker, Message message, Destination dest) throws IOException {
064        boolean matches = false;
065        MessageEvaluationContext msgContext = new NonCachedMessageEvaluationContext();
066        msgContext.setDestination(dest.getActiveMQDestination());
067        msgContext.setMessageReference(message);
068        List<Subscription> subs = dest.getConsumers();
069        for (Subscription sub : subs) {
070            if (sub.matches(message, msgContext)) {
071                matches = true;
072                break;
073            }
074        }
075        if (matches == false) {
076            matches = tryMatchingCachedSubs(broker, dest, msgContext);
077        }
078        return matches;
079    }
080
081    private boolean tryMatchingCachedSubs(final Broker broker, Destination dest, MessageEvaluationContext msgContext) {
082        boolean matches = false;
083        LOG.debug("No active consumer match found. Will try cache if configured...");
084
085        //retrieve the specific plugin class and lookup the selector for the destination.
086        final SubQueueSelectorCacheBroker cache = getSubQueueSelectorCacheBrokerPlugin(broker);
087
088        if (cache != null) {
089            final Set<String> selectors = cache.getSelector(dest.getActiveMQDestination().getQualifiedName());
090            for (String selector : selectors) {
091                try {
092                    final BooleanExpression expression = getExpression(selector);
093                    matches = expression.matches(msgContext);
094                    if (matches) {
095                        return true;
096                    }
097                } catch (Exception e) {
098                    LOG.error(e.getMessage(), e);
099                }
100            }
101        }
102        return matches;
103    }
104
105    private BooleanExpression getExpression(String selector) throws Exception{
106        BooleanExpression result;
107        synchronized(expressionCache){
108            result = expressionCache.get(selector);
109            if (result == null){
110                result = compileSelector(selector);
111                expressionCache.put(selector,result);
112            }
113        }
114        return result;
115    }
116
117    /**
118     * @return The SubQueueSelectorCacheBroker instance or null if no such broker is available.
119     */
120    private SubQueueSelectorCacheBroker getSubQueueSelectorCacheBrokerPlugin(final Broker broker) {
121        if (selectorCachePlugin == null) {
122            selectorCachePlugin = (SubQueueSelectorCacheBroker) broker.getAdaptor(SubQueueSelectorCacheBroker.class);
123        } //if
124
125        return selectorCachePlugin;
126    }
127
128    /**
129     * Pre-compile the JMS selector.
130     *
131     * @param selectorExpression The non-null JMS selector expression.
132     */
133    private BooleanExpression compileSelector(final String selectorExpression) throws Exception {
134        return SelectorParser.parse(selectorExpression);
135    }
136}