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