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1 /*
2  * Copyright (C) 2007 Apple Inc.  All rights reserved.
3  *
4  * Redistribution and use in source and binary forms, with or without
5  * modification, are permitted provided that the following conditions
6  * are met:
7  * 1. Redistributions of source code must retain the above copyright
8  *    notice, this list of conditions and the following disclaimer.
9  * 2. Redistributions in binary form must reproduce the above copyright
10  *    notice, this list of conditions and the following disclaimer in the
11  *    documentation and/or other materials provided with the distribution.
12  *
13  * THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY
14  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
15  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
16  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE COMPUTER, INC. OR
17  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
18  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
19  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
20  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
21  * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
22  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
23  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
24  */
25 
26 #ifndef PageCache_h
27 #define PageCache_h
28 
29 #include "HistoryItem.h"
30 #include "Timer.h"
31 #include <wtf/Forward.h>
32 #include <wtf/HashSet.h>
33 #include <wtf/Noncopyable.h>
34 
35 namespace WebCore {
36 
37     class CachedPage;
38     class HistoryItem;
39 
40     class PageCache : public Noncopyable {
41     public:
42         friend PageCache* pageCache();
43 
44         void setCapacity(int); // number of pages to cache
capacity()45         int capacity() { return m_capacity; }
46 
47         void add(PassRefPtr<HistoryItem>, PassRefPtr<CachedPage>); // Prunes if capacity() is exceeded.
48         void remove(HistoryItem*);
get(HistoryItem * item)49         CachedPage* get(HistoryItem* item) { return item ? item->m_cachedPage.get() : 0; }
50 
51         void releaseAutoreleasedPagesNow();
52 
pageCount()53         int pageCount() const { return m_size; }
54         int frameCount() const;
55         int autoreleasedPageCount() const;
56 
57     private:
58         typedef HashSet<RefPtr<CachedPage> > CachedPageSet;
59 
60         PageCache(); // Use pageCache() instead.
61         ~PageCache(); // Not implemented to make sure nobody accidentally calls delete -- WebCore does not delete singletons.
62 
63         void addToLRUList(HistoryItem*); // Adds to the head of the list.
64         void removeFromLRUList(HistoryItem*);
65 
66         void prune();
67 
68         void autorelease(PassRefPtr<CachedPage>);
69         void releaseAutoreleasedPagesNowOrReschedule(Timer<PageCache>*);
70 
71         int m_capacity;
72         int m_size;
73 
74         // LRU List
75         HistoryItem* m_head;
76         HistoryItem* m_tail;
77 
78         Timer<PageCache> m_autoreleaseTimer;
79         CachedPageSet m_autoreleaseSet;
80      };
81 
82     // Function to obtain the global page cache.
83     PageCache* pageCache();
84 
85 } // namespace WebCore
86 
87 #endif // PageCache_h
88