1 karl 1.38 //%2006////////////////////////////////////////////////////////////////////////
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2 mike 1.4 //
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3 karl 1.32 // Copyright (c) 2000, 2001, 2002 BMC Software; Hewlett-Packard Development
4 // Company, L.P.; IBM Corp.; The Open Group; Tivoli Systems.
5 // Copyright (c) 2003 BMC Software; Hewlett-Packard Development Company, L.P.;
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6 karl 1.30 // IBM Corp.; EMC Corporation, The Open Group.
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7 karl 1.32 // Copyright (c) 2004 BMC Software; Hewlett-Packard Development Company, L.P.;
8 // IBM Corp.; EMC Corporation; VERITAS Software Corporation; The Open Group.
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9 karl 1.33 // Copyright (c) 2005 Hewlett-Packard Development Company, L.P.; IBM Corp.;
10 // EMC Corporation; VERITAS Software Corporation; The Open Group.
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11 karl 1.38 // Copyright (c) 2006 Hewlett-Packard Development Company, L.P.; IBM Corp.;
12 // EMC Corporation; Symantec Corporation; The Open Group.
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13 mike 1.4 //
14 // Permission is hereby granted, free of charge, to any person obtaining a copy
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15 chip 1.11 // of this software and associated documentation files (the "Software"), to
16 // deal in the Software without restriction, including without limitation the
17 // rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
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18 mike 1.4 // sell copies of the Software, and to permit persons to whom the Software is
19 // furnished to do so, subject to the following conditions:
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20 karl 1.38 //
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21 chip 1.11 // THE ABOVE COPYRIGHT NOTICE AND THIS PERMISSION NOTICE SHALL BE INCLUDED IN
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22 mike 1.4 // ALL COPIES OR SUBSTANTIAL PORTIONS OF THE SOFTWARE. THE SOFTWARE IS PROVIDED
23 // "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT
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24 chip 1.11 // LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
25 // PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
26 // HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
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27 mike 1.4 // ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
28 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
29 //
30 //==============================================================================
31 //
32 //%/////////////////////////////////////////////////////////////////////////////
33
34 #ifndef Pegasus_MessageQueue_h
35 #define Pegasus_MessageQueue_h
36
37 #include <Pegasus/Common/Config.h>
38 #include <Pegasus/Common/Message.h>
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39 kumpf 1.43 #include <Pegasus/Common/Mutex.h>
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40 kumpf 1.44 #include <Pegasus/Common/List.h>
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41 kumpf 1.27 #include <Pegasus/Common/Linkage.h>
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42 mike 1.4
43 PEGASUS_NAMESPACE_BEGIN
44
45 /** The MessageQueue class represents a queue abstraction and is used by
46 modules to exchange messages. Methods are provided for enqueuing,
47 dequeuing, removing, iterating messages. Some methods are virtual and
48 may be overriden but subclasses to modify the behavior.
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49 mike 1.14
50 <h1>A Word about Queue Ids</h1>
51
52 You may pass a specific queue id to the MessageQueue() constructor. The
53 default is to call MessageQueue::getNextQueueId() to obtain one. Only pass
54 queue ids generated by calling MessageQueue::getNextQueueId() to this
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55 david.dillard 1.34 constructor. Otherwise, you might end up with two queues with the same
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56 mike 1.14 queue id.
57
58 A technique we encourage, is to declare global queue ids like this:
59
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60 mday 1.16 <pre>
61 extern const Uint32 GROCERY_QUEUE_ID;
62 </pre>
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63 mike 1.14
64 And then define them like this:
65
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66 mday 1.16 <pre>
67 const Uint32 GROCERY_QUEUE_ID = MessageQueue::getNextQueueId();
68 </pre>
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69 mike 1.14
70 And then pass them to the constructor of MessageQueue (from the derived
71 class). In this way you will secure a unique constant identifier by which
72 you may refer to a queue later on.
73
74 <h1>A Word about using the find() Methods</h1>
75
76 There are two find() methods. One that takes a queue id and one that
77 takes a name. The time complexity of the former is O(1); whereas, the
78 time complexity of the latter is O(n). Therefore, use the queue id form
79 since it is more efficient.
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80 mike 1.4 */
81 class PEGASUS_COMMON_LINKAGE MessageQueue
82 {
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83 david.dillard 1.34 public:
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84 mike 1.4
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85 david.dillard 1.34 /** This constructor places this object on a queue table which is
86 maintained by this class. Each message queue has a queue-id (which
87 may be obtained by calling getQueueId()). The queue-id may be passed
88 to lookupQueue() to obtain a pointer to the corresponding queue).
89
90 @param queueId the queue id to be used by this object. ONLY PASS IN
91 QUEUE IDS WHICH WERE GENERATED USING MessageQueue::getNextQueueId().
92 Otherwise, you might end up with more than one queue with the same
93 queue id.
94 */
95 MessageQueue(
96 const char *name,
97 Boolean async = false,
98 Uint32 queueId = MessageQueue::getNextQueueId());
99
100 /** Removes this queue from the queue table. */
101 virtual ~MessageQueue();
102
103 /** Enques a message (places it at the back of the queue).
104 @param message pointer to message to be enqueued.
105 @exception NullPointer exception if message parameter is null.
106 david.dillard 1.34 @exception IPCException if socket call has an error
107 */
108 virtual void enqueue(Message* message);
109
110 /** allows a caller to determine if this message queue is asynchronous or
111 not.
112 */
113 virtual Boolean isAsync() const { return _async; }
114
115 /** Dequeues a message (removes it from the front of the queue).
116 @return pointer to message or zero if queue is empty.
117 @exception IPCException Thrown if an IPC error occurs.
118 */
119 virtual Message* dequeue();
120
121 /** Returns true if there are no messages on the queue. */
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122 kumpf 1.44 Boolean isEmpty() const { return _messageList.is_empty(); }
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123 david.dillard 1.34
124 /** Returns the number of messages on the queue. */
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125 kumpf 1.44 Uint32 getCount() const { return _messageList.size(); }
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126 david.dillard 1.34
127 /** Retrieve the queue id for this queue. */
128 Uint32 getQueueId() const throw() { return _queueId; }
129
130 Uint32 get_capabilities() const throw()
131 {
132 return _capabilities;
133 }
134
135 /** Provide a string name for this queue to be used by the print method.
136 */
137 const char* getQueueName() const;
138
139 /** This method is called after a message has been enqueued. This default
140 implementation does nothing. Derived classes may override this to
141 take some action each time a message is enqueued (for example, this
142 method could handle the incoming message in the thread of the caller
143 of enqueue()).
144 */
145 virtual void handleEnqueue() ;
146
147 david.dillard 1.34 /** This method <b>may</b> be called prior to enqueueing an message.
148 the message queue can inform the caller that it does not want
149 to handle the message by returning false **/
150
151 virtual Boolean messageOK(const Message *msg) { return true ;}
152
153 /** Lookup a message queue from a queue id. Note this is an O(1) operation.
154 @exception IPCException Thrown if an IPC error occurs.
155 */
156 static MessageQueue* lookup(Uint32 queueId);
157
158 /** Lookup a message given a queue name. NOte this is an O(N) operation.
159 @exception IPCException Thrown if an IPC error occurs.
160 */
161 static MessageQueue* lookup(const char *name);
162
163 /** Get the next available queue id. It always returns a non-zero
164 queue id an monotonically increases and finally wraps (to one)
165 after reaching the maximum unsigned 32 bit integer.
166 @exception IPCException Thrown if an IPC error occurs.
167 */
168 david.dillard 1.34 static Uint32 getNextQueueId();
169
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170 aruran.ms 1.37 /** Put the queue id into the stack.
171 */
172 static void putQueueId(Uint32 queueId);
173
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174 david.dillard 1.34 protected:
175 Uint32 _queueId;
176 char *_name;
177 Uint32 _capabilities;
178
179 private:
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180 kumpf 1.44 List<Message, Mutex> _messageList;
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181 david.dillard 1.34 Boolean _async;
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182 mike 1.4 };
183
184 PEGASUS_NAMESPACE_END
185
186 #endif /* Pegasus_MessageQueue_h */
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MessageQueue.h
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