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.activemq.broker.region.policy;
018    
019    import org.apache.activemq.broker.region.TopicSubscription;
020    
021    /**
022     * This PendingMessageLimitStrategy sets the maximum pending message limit value to be
023     * a multiplier of the prefetch limit of the subscription.
024     * 
025     * @org.apache.xbean.XBean
026     * 
027     * 
028     */
029    public class PrefetchRatePendingMessageLimitStrategy implements PendingMessageLimitStrategy {
030    
031        private double multiplier = 0.5;
032    
033        public int getMaximumPendingMessageLimit(TopicSubscription subscription) {
034            int prefetchSize = subscription.getConsumerInfo().getPrefetchSize();
035            return (int) (prefetchSize * multiplier);
036        }
037    
038        public double getMultiplier() {
039            return multiplier;
040        }
041    
042        /**
043         * Sets the multiplier of the prefetch size which will be used to define the maximum number of pending
044         * messages for non-durable topics before messages are discarded.
045         */
046        public void setMultiplier(double rate) {
047            this.multiplier = rate;
048        }
049    
050    }