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.cursors;
018    
019    import java.util.ArrayList;
020    import java.util.Collection;
021    import java.util.HashMap;
022    import java.util.Iterator;
023    import java.util.List;
024    import java.util.Map;
025    import org.apache.activemq.broker.region.MessageReference;
026    import org.apache.activemq.command.MessageId;
027    
028    public class OrderedPendingList implements PendingList {
029    
030        private PendingNode root = null;
031        private PendingNode tail = null;
032        private final Map<MessageId, PendingNode> map = new HashMap<MessageId, PendingNode>();
033    
034        public PendingNode addMessageFirst(MessageReference message) {
035            PendingNode node = new PendingNode(this, message);
036            if (root == null) {
037                root = node;
038                tail = node;
039            } else {
040                root.linkBefore(node);
041            }
042            this.map.put(message.getMessageId(), node);
043            return node;
044        }
045    
046        public PendingNode addMessageLast(MessageReference message) {
047            PendingNode node = new PendingNode(this, message);
048            if (root == null) {
049                root = node;
050            } else {
051                tail.linkAfter(node);
052            }
053            tail = node;
054            this.map.put(message.getMessageId(), node);
055            return node;
056        }
057    
058        public void clear() {
059            this.root = null;
060            this.tail = null;
061            this.map.clear();
062        }
063    
064        public boolean isEmpty() {
065            return this.map.isEmpty();
066        }
067    
068        public Iterator<MessageReference> iterator() {
069            return new Iterator<MessageReference>() {
070                private PendingNode current = null;
071                private PendingNode next = root;
072    
073                public boolean hasNext() {
074                    return next != null;
075                }
076    
077                public MessageReference next() {
078                    MessageReference result = null;
079                    this.current = this.next;
080                    result = this.current.getMessage();
081                    this.next = (PendingNode) this.next.getNext();
082                    return result;
083                }
084    
085                public void remove() {
086                    if (this.current != null && this.current.getMessage() != null) {
087                        map.remove(this.current.getMessage().getMessageId());
088                    }
089                    removeNode(this.current);
090                }
091            };
092        }
093    
094        public PendingNode remove(MessageReference message) {
095            PendingNode node = null;
096            if (message != null) {
097                node = this.map.remove(message.getMessageId());
098                removeNode(node);
099            }
100            return node;
101        }
102    
103        public int size() {
104            return this.map.size();
105        }
106    
107        void removeNode(PendingNode node) {
108            if (node != null) {
109                map.remove(node.getMessage().getMessageId());
110                if (root == node) {
111                    root = (PendingNode) node.getNext();
112                }
113                if (tail == node) {
114                    tail = (PendingNode) node.getPrevious();
115                }
116                node.unlink();
117            }
118        }
119    
120        List<PendingNode> getAsList() {
121            List<PendingNode> result = new ArrayList<PendingNode>(size());
122            PendingNode node = root;
123            while (node != null) {
124                result.add(node);
125                node = (PendingNode) node.getNext();
126            }
127            return result;
128        }
129    
130        @Override
131        public String toString() {
132            return "OrderedPendingList(" + System.identityHashCode(this) + ")";
133        }
134    
135        @Override
136        public boolean contains(MessageReference message) {
137            if(map.values().contains(message)) {
138                return true;
139            } else {
140                return false;
141            }
142        }
143    
144        @Override
145        public Collection<MessageReference> values() {
146            List<MessageReference> messageReferences = new ArrayList<MessageReference>();
147            for(PendingNode pendingNode : map.values()) {
148                messageReferences.add(pendingNode.getMessage());
149            }
150            return messageReferences;
151        }
152    
153        @Override
154        public void addAll(PendingList pendingList) {
155            for(MessageReference messageReference : pendingList) {
156                addMessageLast(messageReference);
157            }
158        }
159    }