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     */
017    package org.apache.camel.processor.aggregate;
018    
019    import java.util.AbstractCollection;
020    import java.util.Collection;
021    import java.util.Iterator;
022    import java.util.LinkedHashMap;
023    import java.util.Map;
024    
025    import org.apache.camel.Exchange;
026    import org.apache.camel.Expression;
027    import org.apache.commons.logging.Log;
028    import org.apache.commons.logging.LogFactory;
029    
030    /**
031     * A {@link Collection} which aggregates exchanges together using a correlation
032     * expression so that there is only a single message exchange sent for a single
033     * correlation key.
034     *
035     * @version $Revision: 53289 $
036     */
037    public class DefaultAggregationCollection extends AbstractCollection<Exchange> implements AggregationCollection {
038    
039        private static final transient Log LOG = LogFactory.getLog(DefaultAggregationCollection.class);
040        private Expression<Exchange> correlationExpression;
041        private AggregationStrategy aggregationStrategy;
042        private Map<Object, Exchange> map = new LinkedHashMap<Object, Exchange>();
043    
044        public DefaultAggregationCollection() {
045        }
046    
047        public DefaultAggregationCollection(Expression<Exchange> correlationExpression, AggregationStrategy aggregationStrategy) {
048            this.correlationExpression = correlationExpression;
049            this.aggregationStrategy = aggregationStrategy;
050        }
051    
052        protected Map<Object, Exchange> getMap() {
053            return map;
054        }
055    
056        @Override
057        public boolean add(Exchange exchange) {
058            Object correlationKey = correlationExpression.evaluate(exchange);
059            Exchange oldExchange = map.get(correlationKey);
060            Exchange newExchange = exchange;
061    
062            if (oldExchange != null) {
063                Integer count = oldExchange.getProperty(Exchange.AGGREGATED_COUNT, Integer.class);
064                if (count == null) {
065                    count = 1;
066                }
067                count++;
068                newExchange = aggregationStrategy.aggregate(oldExchange, newExchange);
069                newExchange.setProperty(Exchange.AGGREGATED_COUNT, count);
070            }
071    
072            // the strategy may just update the old exchange and return it
073            if (newExchange != oldExchange) {
074                if (LOG.isDebugEnabled()) {
075                    LOG.debug("put exchange:" + newExchange + " for key:"  + correlationKey);
076                }
077                if (oldExchange == null) {
078                    newExchange.setProperty(Exchange.AGGREGATED_COUNT, Integer.valueOf(1));
079                }
080                map.put(correlationKey, newExchange);
081            }
082    
083            onAggregation(correlationKey, newExchange);
084    
085            return true;
086        }
087    
088        public Iterator<Exchange> iterator() {
089            return map.values().iterator();
090        }
091    
092        public int size() {
093            return map.size();
094        }
095    
096        @Override
097        public void clear() {
098            map.clear();
099        }
100    
101        public void onAggregation(Object correlationKey, Exchange newExchange) {
102        }
103    
104        public Expression<Exchange> getCorrelationExpression() {
105            return correlationExpression;
106        }
107    
108        public void setCorrelationExpression(Expression<Exchange> correlationExpression) {
109            this.correlationExpression = correlationExpression;
110        }
111    
112        public AggregationStrategy getAggregationStrategy() {
113            return aggregationStrategy;
114        }
115    
116        public void setAggregationStrategy(AggregationStrategy aggregationStrategy) {
117            this.aggregationStrategy = aggregationStrategy;
118        }
119    }