WebCore/PurgeableBuffer.h

   1 /*
   2  * Copyright (C) 2008 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 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 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 PurgeableBuffer_h
  27 #define PurgeableBuffer_h
  28
  29 #include <wtf/Noncopyable.h>
  30 #include <wtf/Vector.h>
  31
  32 namespace WebCore {
  33
  34     class PurgeableBuffer : Noncopyable {
  35     public:
  36         static PurgeableBuffer* create(const char* data, size_t);
  37         static PurgeableBuffer* create(const Vector<char>& v) { return create(v.data(), v.size()); }
  38
  39         ~PurgeableBuffer();
  40
  41         // Call makePurgeable(false) and check the return value before accessing the data.
  42         const char* data() const;
  43         size_t size() const { return m_size; }
  44
  45         enum PurgePriority { PurgeLast, PurgeMiddle, PurgeFirst, PurgeDefault = PurgeMiddle };
  46         PurgePriority purgePriority() const { return m_purgePriority; }
  47         void setPurgePriority(PurgePriority);
  48
  49         bool isPurgeable() const { return m_state != NonVolatile; }
  50         bool wasPurged() const;
  51
  52         bool makePurgeable(bool purgeable);
  53
  54     private:
  55         PurgeableBuffer(char* data, size_t);
  56
  57         char* m_data;
  58         size_t m_size;
  59         PurgePriority m_purgePriority;
  60
  61         enum State { NonVolatile, Volatile, Purged };
  62         mutable State m_state;
  63     };
  64
  65 #if !PLATFORM(DARWIN) || defined(BUILDING_ON_TIGER) || PLATFORM(QT)
  66     inline PurgeableBuffer* PurgeableBuffer::create(const char*, size_t) { return 0; }
  67     inline PurgeableBuffer::~PurgeableBuffer() { }
  68     inline const char* PurgeableBuffer::data() const { return 0; }
  69     inline void PurgeableBuffer::setPurgePriority(PurgePriority) { }
  70     inline bool PurgeableBuffer::wasPurged() const { return false; }
  71     inline bool PurgeableBuffer::makePurgeable(bool) { return false; }
  72 #endif
  73
  74 }
  75
  76 #endif