1/*
2 * Copyright (C) 2008, 2010 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 "PurgePriority.h"
30#include <wtf/PassOwnPtr.h>
31#include <wtf/Vector.h>
32
33namespace WebCore {
34
35    class PurgeableBuffer {
36        WTF_MAKE_NONCOPYABLE(PurgeableBuffer);
37    public:
38        static PassOwnPtr<PurgeableBuffer> create(const char* data, size_t);
39
40        ~PurgeableBuffer();
41
42        // Call makePurgeable(false) and check the return value before accessing the data.
43        const char* data() const;
44        size_t size() const { return m_size; }
45
46        PurgePriority purgePriority() const { return m_purgePriority; }
47        void setPurgePriority(PurgePriority priority) { m_purgePriority = priority; }
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 !ENABLE(PURGEABLE_MEMORY)
66    inline PassOwnPtr<PurgeableBuffer> PurgeableBuffer::create(const char*, size_t) { return nullptr; }
67    inline PurgeableBuffer::~PurgeableBuffer() { }
68    inline const char* PurgeableBuffer::data() const { return 0; }
69    inline bool PurgeableBuffer::wasPurged() const { return false; }
70    inline bool PurgeableBuffer::makePurgeable(bool) { return false; }
71#endif
72
73}
74
75#endif
76