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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
     45         int capacity() { return m_capacity; }
     46 
     47         void add(PassRefPtr<HistoryItem>, PassRefPtr<CachedPage>); // Prunes if capacity() is exceeded.
     48         void remove(HistoryItem*);
     49         CachedPage* get(HistoryItem* item) { return item ? item->m_cachedPage.get() : 0; }
     50 
     51         void releaseAutoreleasedPagesNow();
     52 
     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