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 
33 namespace 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;
size()44         size_t size() const { return m_size; }
45 
purgePriority()46         PurgePriority purgePriority() const { return m_purgePriority; }
setPurgePriority(PurgePriority priority)47         void setPurgePriority(PurgePriority priority) { m_purgePriority = priority; }
48 
isPurgeable()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)
create(const char *,size_t)66     inline PassOwnPtr<PurgeableBuffer> PurgeableBuffer::create(const char*, size_t) { return nullptr; }
~PurgeableBuffer()67     inline PurgeableBuffer::~PurgeableBuffer() { }
data()68     inline const char* PurgeableBuffer::data() const { return 0; }
wasPurged()69     inline bool PurgeableBuffer::wasPurged() const { return false; }
makePurgeable(bool)70     inline bool PurgeableBuffer::makePurgeable(bool) { return false; }
71 #endif
72 
73 }
74 
75 #endif
76