1 /**************************************************************
2  *
3  * Licensed to the Apache Software Foundation (ASF) under one
4  * or more contributor license agreements.  See the NOTICE file
5  * distributed with this work for additional information
6  * regarding copyright ownership.  The ASF licenses this file
7  * to you under the Apache License, Version 2.0 (the
8  * "License"); you may not use this file except in compliance
9  * with the License.  You may obtain a copy of the License at
10  *
11  *   http://www.apache.org/licenses/LICENSE-2.0
12  *
13  * Unless required by applicable law or agreed to in writing,
14  * software distributed under the License is distributed on an
15  * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
16  * KIND, either express or implied.  See the License for the
17  * specific language governing permissions and limitations
18  * under the License.
19  *
20  *************************************************************/
21 
22 
23 
24 #ifndef SD_SLIDESORTER_REQUEST_QUEUE_HXX
25 #define SD_SLIDESORTER_REQUEST_QUEUE_HXX
26 
27 #include "SlsRequestPriorityClass.hxx"
28 #include "cache/SlsCacheContext.hxx"
29 #include "taskpane/SlideSorterCacheDisplay.hxx"
30 #include <drawdoc.hxx>
31 #include "osl/mutex.hxx"
32 
33 
34 namespace sd { namespace slidesorter { namespace cache {
35 
36 class RequestData;
37 
38 /** The request queue stores requests that are described by the RequestData
39     sorted according to priority class and then priority.
40 */
41 class RequestQueue
42 {
43 public:
44     RequestQueue (const SharedCacheContext& rpCacheContext);
45     ~RequestQueue (void);
46 
47     /** Insert a request with highest or lowest priority in its priority
48         class.  When the request is already present then it is first
49         removed.  This effect is then a re-prioritization.
50         @param rRequestData
51             The request.
52         @param eRequestClass
53             The priority class in which to insert the request with highest
54             or lowest priority.
55         @param bInsertWithHighestPriority
56             When this flag is <TRUE/> the request is inserted with highes
57             priority in its class.  When <FALSE/> the request is inserted
58             with lowest priority.
59     */
60     void AddRequest (
61         CacheKey aKey,
62         RequestPriorityClass eRequestClass,
63         bool bInsertWithHighestPriority = false);
64 
65     /** Remove the specified request from the queue.
66         @param rRequestData
67             It is OK when the specified request is not a member of the
68             queue.
69         @return
70             Returns <TRUE/> when the request has been successfully been
71             removed from the queue.  Otherwise, e.g. because the request was
72             not a member of the queue, <FALSE/> is returned.
73     */
74     bool RemoveRequest (CacheKey aKey);
75 
76     /** Change the priority class of the specified request.
77     */
78     void ChangeClass (
79         CacheKey aKey,
80         RequestPriorityClass eNewRequestClass);
81 
82     /** Get the request with the highest priority int the highest priority class.
83     */
84     CacheKey GetFront (void);
85 
86     // For debugging.
87     RequestPriorityClass GetFrontPriorityClass (void);
88 
89     /** Really a synonym for RemoveRequest(GetFront());
90     */
91     void PopFront (void);
92 
93     /** Returns <TRUE/> when there is no element in the queue.
94     */
95     bool IsEmpty (void);
96 
97     /** Remove all requests from the queue.  This resets the minimum and
98         maximum priorities to their default values.
99     */
100     void Clear (void);
101 
102     /** Return the mutex that guards the access to the priority queue.
103     */
104     ::osl::Mutex& GetMutex (void);
105 
106 private:
107     ::osl::Mutex maMutex;
108     class Container;
109     ::boost::scoped_ptr<Container> mpRequestQueue;
110     SharedCacheContext mpCacheContext;
111 
112     /** A lower bound of the lowest priority of all elements in the queues.
113         The start value is 0.  It is assigned and then decreased every time
114         when an element is inserted or marked as the request with lowest
115         priority.
116     */
117     int mnMinimumPriority;
118     /** An upper bound of the highest priority of all elements in the queues.
119         The start value is 1.  It is assigned and then increased every time
120         when an element is inserted or marked as the request with highest
121         priority.
122     */
123     int mnMaximumPriority;
124 };
125 
126 
127 } } } // end of namespace ::sd::slidesorter::cache
128 
129 #endif
130