PendingMessageCursor


1   /**
2    * 
3    * Licensed to the Apache Software Foundation (ASF) under one or more contributor license agreements. See the NOTICE
4    * file distributed with this work for additional information regarding copyright ownership. The ASF licenses this file
5    * to You under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the
6    * License. You may obtain a copy of the License at
7    * 
8    * http://www.apache.org/licenses/LICENSE-2.0
9    * 
10   * Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on
11   * an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the
12   * specific language governing permissions and limitations under the License.
13   */
14  package org.apache.activemq.broker.region.cursors;
15  
16  import java.io.IOException  ;
17  import java.util.LinkedList  ;
18  
19  import org.apache.activemq.Service;
20  import org.apache.activemq.broker.ConnectionContext;
21  import org.apache.activemq.broker.region.Destination;
22  import org.apache.activemq.broker.region.MessageReference;
23  import org.apache.activemq.memory.UsageManager;
24  
25  /**
26   * Interface to pending message (messages awaiting disptach to a consumer) cursor
27   * 
28   * @version $Revision: 500862 $
29   */
30  public interface PendingMessageCursor extends Service{
31      
32      
33      /**
34       * Add a destination
35       * @param context
36       * @param destination
37       * @throws Exception
38       */
39      public void add(ConnectionContext context, Destination destination) throws Exception  ;
40  
41      /**
42       * remove a destination
43       * @param context
44       * @param destination
45       * @throws Exception
46       */
47      public void remove(ConnectionContext context, Destination destination) throws Exception  ;
48      /**
49       * @return true if there are no pending messages
50       */
51      public boolean isEmpty();
52      
53      /**
54       * check if a Destination is Empty for this cursor
55       * @param destination
56       * @return true id the Destination is empty
57       */
58      public boolean isEmpty(Destination destination);
59      
60      /**
61       * reset the cursor
62       *
63       */
64      public void reset();
65      
66      /**
67       * hint to the cursor to release any locks it might have
68       * grabbed after a reset
69       *
70       */
71      public void release();
72  
73      /**
74       * add message to await dispatch
75       * @param node
76       * @throws IOException 
77       * @throws Exception 
78       */
79      public void addMessageLast(MessageReference node) throws  Exception  ;
80      
81      /**
82       * add message to await dispatch
83       * @param node
84       * @throws Exception 
85       */
86      public void addMessageFirst(MessageReference node) throws Exception  ;
87      
88      /**
89       * Add a message recovered from a retroactive policy
90       * @param node
91       * @throws Exception
92       */
93      public void addRecoveredMessage(MessageReference node) throws Exception  ;
94  
95      /**
96       * @return true if there pending messages to dispatch
97       */
98      public boolean hasNext();
99  
100     /**
101      * @return the next pending message
102      */
103     public MessageReference next();
104 
105     /**
106      * remove the message at the cursor position
107      * 
108      */
109     public void remove();
110 
111     /**
112      * @return the number of pending messages
113      */
114     public int size();
115 
116     /**
117      * clear all pending messages
118      * 
119      */
120     public void clear();
121     
122     /**
123      * Informs the Broker if the subscription needs to intervention to recover it's state
124      * e.g. DurableTopicSubscriber may do
125      * @return true if recovery required
126      */
127     public boolean isRecoveryRequired();
128     
129     /**
130      * @return the maximum batch size
131      */
132     public int getMaxBatchSize();
133 
134     /**
135      * Set the max batch size
136      * @param maxBatchSize
137      */
138     public void setMaxBatchSize(int maxBatchSize);
139 
140     /**
141      * Give the cursor a hint that we are about to remove
142      * messages from memory only
143      */
144     public void resetForGC();
145     
146     /**
147      * remove a node
148      * @param node
149      */
150     public void remove(MessageReference node);
151     
152     
153     /**
154      * free up any internal buffers
155      *
156      */
157     public void gc();
158     
159     /**
160      * Set the UsageManager
161      * @param usageManager
162      * @see org.apache.activemq.memory.UsageManager
163      */
164     public void setUsageManager(UsageManager usageManager);
165     
166     /**
167      * @return the usageManager
168      */
169     public UsageManager getUsageManager();
170     
171     /**
172      * @return the memoryUsageHighWaterMark
173      */
174     public int getMemoryUsageHighWaterMark();
175 
176     
177     /**
178      * @param memoryUsageHighWaterMark the memoryUsageHighWaterMark to set
179      */
180     public void setMemoryUsageHighWaterMark(int memoryUsageHighWaterMark);
181 
182     
183     /**
184      * @return true if the cursor is full
185      */
186     public boolean isFull();
187     
188     /**
189      * @return true if the cursor has buffered messages ready to deliver
190      */
191     public boolean hasMessagesBufferedToDeliver();
192     
193     /**
194      * destroy the cursor
195      * @throws Exception 
196      */
197     public void destroy() throws Exception  ;
198     
199     /**
200      * Page in a restricted number of messages
201      * @param maxItems
202      * @return a list of paged in messages
203      */
204     public LinkedList   pageInList(int maxItems);
205     
206     
207 }
208
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