1 kumpf 1.26 //%/////////////////////////////////////////////////////////////////////////////
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2 mike 1.4 //
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3 kumpf 1.26 // Copyright (c) 2000, 2001, 2002 BMC Software, Hewlett-Packard Company, IBM,
4 // The Open Group, Tivoli Systems
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5 mike 1.4 //
6 // Permission is hereby granted, free of charge, to any person obtaining a copy
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7 chip 1.11 // of this software and associated documentation files (the "Software"), to
8 // deal in the Software without restriction, including without limitation the
9 // rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
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10 mike 1.4 // sell copies of the Software, and to permit persons to whom the Software is
11 // furnished to do so, subject to the following conditions:
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12 kumpf 1.26 //
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13 chip 1.11 // THE ABOVE COPYRIGHT NOTICE AND THIS PERMISSION NOTICE SHALL BE INCLUDED IN
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14 mike 1.4 // ALL COPIES OR SUBSTANTIAL PORTIONS OF THE SOFTWARE. THE SOFTWARE IS PROVIDED
15 // "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT
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16 chip 1.11 // LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
17 // PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
18 // HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
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19 mike 1.4 // ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
20 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
21 //
22 //==============================================================================
23 //
24 // Author: Mike Brasher (mbrasher@bmc.com)
25 //
26 // Modified By:
27 //
28 //%/////////////////////////////////////////////////////////////////////////////
29
30 #ifndef Pegasus_MessageQueue_h
31 #define Pegasus_MessageQueue_h
32
33 #include <Pegasus/Common/Config.h>
34 #include <Pegasus/Common/Message.h>
35 #include <Pegasus/Common/Exception.h>
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36 chip 1.11 #include <Pegasus/Common/IPC.h>
37 #include <Pegasus/Common/Thread.h>
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38 mike 1.4
39 PEGASUS_NAMESPACE_BEGIN
40
41 /** The MessageQueue class represents a queue abstraction and is used by
42 modules to exchange messages. Methods are provided for enqueuing,
43 dequeuing, removing, iterating messages. Some methods are virtual and
44 may be overriden but subclasses to modify the behavior.
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45 mike 1.14
46 <h1>A Word about Queue Ids</h1>
47
48 You may pass a specific queue id to the MessageQueue() constructor. The
49 default is to call MessageQueue::getNextQueueId() to obtain one. Only pass
50 queue ids generated by calling MessageQueue::getNextQueueId() to this
51 constructor. Otherwise, you might end up with two queues with the same
52 queue id.
53
54 A technique we encourage, is to declare global queue ids like this:
55
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56 mday 1.16 <pre>
57 extern const Uint32 GROCERY_QUEUE_ID;
58 </pre>
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59 mike 1.14
60 And then define them like this:
61
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62 mday 1.16 <pre>
63 const Uint32 GROCERY_QUEUE_ID = MessageQueue::getNextQueueId();
64 </pre>
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65 mike 1.14
66 And then pass them to the constructor of MessageQueue (from the derived
67 class). In this way you will secure a unique constant identifier by which
68 you may refer to a queue later on.
69
70 <h1>A Word about using the find() Methods</h1>
71
72 There are two find() methods. One that takes a queue id and one that
73 takes a name. The time complexity of the former is O(1); whereas, the
74 time complexity of the latter is O(n). Therefore, use the queue id form
75 since it is more efficient.
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76 mike 1.4 */
77 class PEGASUS_COMMON_LINKAGE MessageQueue
78 {
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79 mday 1.16 public:
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80 mike 1.4
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81 mday 1.16 /** This constructor places this object on a queue table which is
82 maintained by this class. Each message queue has a queue-id (which
83 may be obtained by calling getQueueId()). The queue-id may be passed
84 to lookupQueue() to obtain a pointer to the corresponding queue).
85
86 @param queueId the queue id to be used by this object. ONLY PASS IN
87 QUEUE IDS WHICH WERE GENERATED USING MessageQueue::getNextQueueId().
88 Otherwise, you might end up with more than one queue with the same
89 queue id.
90 */
91 MessageQueue(
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92 kumpf 1.25 const char *name,
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93 mday 1.16 Boolean async = false,
94 Uint32 queueId = MessageQueue::getNextQueueId());
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95 mday 1.23
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96 mday 1.16 /** Removes this queue from the queue table. */
97 virtual ~MessageQueue();
98
99 /** Enques a message (places it at the back of the queue).
100 @param message pointer to message to be enqueued.
101 @exception throws NullPointer exception if message parameter is null.
102 */
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103 mday 1.22 virtual void enqueue(Message* message) throw(IPCException);
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104 mday 1.16
105
106 /** allows a caller to determine if this message queue is asynchronous or
107 not .
108 */
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109 mday 1.21 virtual Boolean isAsync(void) { return _async; }
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110 mday 1.13
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111 mday 1.20
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112 mday 1.16 /** Dequeues a message (removes it from the front of the queue).
113 @return pointer to message or zero if queue is empty.
114 */
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115 mday 1.22 virtual Message* dequeue() throw(IPCException);
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116 mday 1.16
117 /** Removes the given message from the queue.
118 @param message to be removed.
119 @exception throws NullPointer if message parameter is null.
120 @exception throws NoSuchMessageOnQueue is message paramter is not
121 on this queue.
122 */
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123 mday 1.22 virtual void remove(Message* message) throw(IPCException);
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124 mday 1.16
125 /** Find the message with the given type.
126 @parameter type type of message to be found.
127 @return pointer to message if found; null otherwise.
128 */
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129 mday 1.22 virtual Message* findByType(Uint32 type) throw(IPCException);
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130 mday 1.16
131 /** Const version of findByType(). */
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132 mday 1.22 virtual const Message* findByType(Uint32 type) const throw(IPCException);
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133 mday 1.16
134 /** Find the message with the given key.
135 @parameter key key of message to be found.
136 @return pointer to message if found; null otherwise.
137 */
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138 mday 1.22 virtual Message* findByKey(Uint32 key) throw(IPCException);
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139 mday 1.16
140 /** Const version of findByKey(). */
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141 mday 1.22 virtual const Message* findByKey(Uint32 key) const throw(IPCException);
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142 mday 1.16
143 /** Finds the messages with the given type and key.
144 @param type type of message to be found.
145 @param type key of message to be found.
146 @return pointer to message if found; null otherwise.
147 */
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148 mday 1.22 virtual Message* find(Uint32 type, Uint32 key) throw(IPCException);
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149 mday 1.16
150 /** Const version of find(). */
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151 mday 1.22 virtual const Message* find(Uint32 type, Uint32 key) const throw(IPCException);
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152 mday 1.16
153 /** Returns pointer to front message. */
154 Message* front() { return _front; }
155
156 /** Const version of front(). */
157 const Message* front() const { return _front; }
158
159 /** Returns pointer to back message. */
160 Message* back() { return _back; }
161
162 /** Const version of back(). */
163 const Message* back() const { return _back; }
164
165 /** Returns true if there are no messages on the queue. */
166 Boolean isEmpty() const { return _front == 0; }
167
168 /** Returns the number of messages on the queue. */
169 Uint32 getCount() const { return _count; }
170
171 /** Retrieve the queue id for this queue. */
172 Uint32 getQueueId() const { return _queueId; }
173 mday 1.16
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174 mday 1.23 Uint32 get_capabilities(void) const
175 {
176 return _capabilities;
177 }
178
179
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180 mday 1.16 /** Prints the contents of this queue by calling the print() method
181 of each message.
182 @param os stream onto which the output is placed.
183 */
184 void print(PEGASUS_STD(ostream)& os) const throw(IPCException);
185
186 /** Lock this queue. */
187 virtual void lock() throw(IPCException);
188
189 /** Unlock this queue. */
190 virtual void unlock();
191
192 /** Provide a string name for this queue to be used by the print method.
193 */
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194 kumpf 1.25 const char* getQueueName() const;
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195 mday 1.16
196 /** This method is called after a message has been enqueued. This default
197 implementation does nothing. Derived classes may override this to
198 take some action each time a message is enqueued (for example, this
199 method could handle the incoming message in the thread of the caller
200 of enqueue()).
201 */
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202 mday 1.24 virtual void handleEnqueue() ;
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203 mday 1.16
204 /** This method <b>may</b> be called prior to enqueueing an message.
205 the message queue can inform the caller that it does not want
206 to handle the message by returning false **/
207
208 virtual Boolean messageOK(const Message *msg) { return true ;}
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209 mday 1.17
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210 mday 1.16 /** Lookup a message queue from a queue id. Note this is an O(1) operation.
211 */
212 static MessageQueue* lookup(Uint32 queueId) throw(IPCException);
213
214 /** Lookup a message given a queue name. NOte this is an O(N) operation.
215 */
216 static MessageQueue* lookup(const char *name) throw(IPCException);
217
218 /** Get the next available queue id. It always returns a non-zero
219 queue id an monotonically increases and finally wraps (to one)
220 after reaching the maximum unsigned 32 bit integer.
221 */
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222 mike 1.19 static Uint32 getNextQueueId() throw(IPCException);
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223 mday 1.16
224 protected:
225 Mutex _mut;
226 Uint32 _queueId;
227 char *_name;
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228 mday 1.23 Uint32 _capabilities;
229
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230 mday 1.16 private:
231
232
233 Uint32 _count;
234 Message* _front;
235 Message* _back;
236 Boolean _async;
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237 mday 1.12
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238 mike 1.4 };
239
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240 chip 1.11 inline const Message* MessageQueue::findByType(Uint32 type) const
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241 mday 1.16 throw(IPCException)
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242 mike 1.4 {
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243 mday 1.16 return ((MessageQueue*)this)->findByType(type);
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244 mike 1.4 }
245
246 inline const Message* MessageQueue::findByKey(Uint32 key) const
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247 mday 1.16 throw(IPCException)
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248 mike 1.4 {
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249 mday 1.16 return ((MessageQueue*)this)->findByKey(key);
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250 mike 1.4 }
251
252 inline const Message* MessageQueue::find(Uint32 type, Uint32 key) const
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253 mday 1.16 throw(IPCException)
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254 mike 1.4 {
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255 mday 1.16 return ((MessageQueue*)this)->find(type, key);
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256 mike 1.4 }
257
258 class NoSuchMessageOnQueue : public Exception
259 {
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260 mday 1.16 public:
261 NoSuchMessageOnQueue() : Exception("No such message on this queue") { }
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262 mike 1.4 };
263
264 PEGASUS_NAMESPACE_END
265
266 #endif /* Pegasus_MessageQueue_h */
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MessageQueue.h
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