/*

 * Copyright (C) 2007 Apple Inc.  All rights reserved.

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions

 * are met:

 * 1. Redistributions of source code must retain the above copyright

 *    notice, this list of conditions and the following disclaimer.

 * 2. Redistributions in binary form must reproduce the above copyright

 *    notice, this list of conditions and the following disclaimer in the

 *    documentation and/or other materials provided with the distribution.

 *

 * THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY

 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE

 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR

 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE COMPUTER, INC. OR

 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,

 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,

 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR

 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY

 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT

 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE

 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 

 */

#ifndef PageCache_h

#define PageCache_h

#include "HistoryItem.h"

#include "Timer.h"

#include <wtf/Forward.h>

#include <wtf/HashSet.h>

#include <wtf/Noncopyable.h>

namespace WebCore {

    class CachedPage;

    class Frame;

    class HistoryItem;

    class Page;

    class PageCache : public Noncopyable {

    public:

        friend PageCache* pageCache();

        static bool canCache(Page*);

        void setCapacity(int); // number of pages to cache

        int capacity() { return m_capacity; }

        void add(PassRefPtr<HistoryItem>, Page*); // Prunes if capacity() is exceeded.

        void remove(HistoryItem*);

        CachedPage* get(HistoryItem* item);

        void releaseAutoreleasedPagesNow();

        int pageCount() const { return m_size; }

        int frameCount() const;

        int autoreleasedPageCount() const;

    private:

        typedef HashSet<RefPtr<CachedPage> > CachedPageSet;

        PageCache(); // Use pageCache() instead.

        ~PageCache(); // Not implemented to make sure nobody accidentally calls delete -- WebCore does not delete singletons.

        static bool canCachePageContainingThisFrame(Frame*);

        void addToLRUList(HistoryItem*); // Adds to the head of the list.

        void removeFromLRUList(HistoryItem*);

        void prune();

        void autorelease(PassRefPtr<CachedPage>);

        void releaseAutoreleasedPagesNowOrReschedule(Timer<PageCache>*);

        int m_capacity;

        int m_size;

        // LRU List

        HistoryItem* m_head;

        HistoryItem* m_tail;

        Timer<PageCache> m_autoreleaseTimer;

        CachedPageSet m_autoreleaseSet;

     };

    // Function to obtain the global page cache.

    PageCache* pageCache();

} // namespace WebCore

#endif // PageCache_h