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.network;
018    
019    import java.util.Set;
020    import java.util.concurrent.CopyOnWriteArraySet;
021    import java.util.concurrent.atomic.AtomicBoolean;
022    import java.util.concurrent.atomic.AtomicInteger;
023    
024    import org.apache.activemq.command.ConsumerId;
025    import org.apache.activemq.command.ConsumerInfo;
026    import org.slf4j.Logger;
027    import org.slf4j.LoggerFactory;
028    
029    /**
030     * Represents a network bridge interface
031     * 
032     * 
033     */
034    public class DemandSubscription {
035        private static final Logger LOG = LoggerFactory.getLogger(DemandSubscription.class);
036    
037        private final ConsumerInfo remoteInfo;
038        private final ConsumerInfo localInfo;
039        private Set<ConsumerId> remoteSubsIds = new CopyOnWriteArraySet<ConsumerId>();
040    
041        private AtomicInteger dispatched = new AtomicInteger(0);
042        private AtomicBoolean activeWaiter = new AtomicBoolean();
043    
044        DemandSubscription(ConsumerInfo info) {
045            remoteInfo = info;
046            localInfo = info.copy();
047            localInfo.setNetworkSubscription(true);
048            remoteSubsIds.add(info.getConsumerId());
049        }
050    
051        /**
052         * Increment the consumers associated with this subscription
053         * 
054         * @param id
055         * @return true if added
056         */
057        public boolean add(ConsumerId id) {
058            return remoteSubsIds.add(id);
059        }
060    
061        /**
062         * Increment the consumers associated with this subscription
063         * 
064         * @param id
065         * @return true if removed
066         */
067        public boolean remove(ConsumerId id) {
068            return remoteSubsIds.remove(id);
069        }
070    
071        /**
072         * @return true if there are no interested consumers
073         */
074        public boolean isEmpty() {
075            return remoteSubsIds.isEmpty();
076        }
077    
078        /**
079         * @return Returns the localInfo.
080         */
081        public ConsumerInfo getLocalInfo() {
082            return localInfo;
083        }
084    
085        /**
086         * @return Returns the remoteInfo.
087         */
088        public ConsumerInfo getRemoteInfo() {
089            return remoteInfo;
090        }
091    
092        public void waitForCompletion() {
093            if (dispatched.get() > 0) {
094                if (LOG.isDebugEnabled()) {
095                    LOG.debug("Waiting for completion for sub: " + localInfo.getConsumerId() + ", dispatched: " + this.dispatched.get());
096                }
097                activeWaiter.set(true);
098                if (dispatched.get() > 0) {
099                    synchronized (activeWaiter) {
100                        try {
101                            activeWaiter.wait();
102                        } catch (InterruptedException ignored) {
103                        }
104                    }
105                    if (this.dispatched.get() > 0) {
106                        LOG.warn("demand sub interrupted or timedout while waiting for outstanding responses, expect potentially " + this.dispatched.get() + " duplicate deliveried");
107                    }
108                }
109            }
110        }
111    
112        public void decrementOutstandingResponses() {
113            if (dispatched.decrementAndGet() == 0 && activeWaiter.get()) {
114                synchronized (activeWaiter) {
115                    activeWaiter.notifyAll();
116                }
117            }
118        }
119    
120        public boolean incrementOutstandingResponses() {
121            dispatched.incrementAndGet();
122            if (activeWaiter.get()) {
123                decrementOutstandingResponses();
124                return false;
125            }
126            return true;
127        }
128    }