1/*
2 * Copyright (C) 2014-2018 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 SmallPage_h
27#define SmallPage_h
28
29#include "BAssert.h"
30#include "List.h"
31#include "Mutex.h"
32#include "VMAllocate.h"
33#include <mutex>
34
35namespace bmalloc {
36
37class SmallLine;
38
39class SmallPage : public ListNode<SmallPage> {
40public:
41 void ref(std::unique_lock<Mutex>&);
42 bool deref(std::unique_lock<Mutex>&);
43 unsigned refCount(std::unique_lock<Mutex>&) { return m_refCount; }
44
45 size_t sizeClass() { return m_sizeClass; }
46 void setSizeClass(size_t sizeClass) { m_sizeClass = sizeClass; }
47
48 bool hasFreeLines(std::unique_lock<Mutex>&) const { return m_hasFreeLines; }
49 void setHasFreeLines(std::unique_lock<Mutex>&, bool hasFreeLines) { m_hasFreeLines = hasFreeLines; }
50
51 bool hasPhysicalPages() { return m_hasPhysicalPages; }
52 void setHasPhysicalPages(bool hasPhysicalPages) { m_hasPhysicalPages = hasPhysicalPages; }
53
54 bool usedSinceLastScavenge() { return m_usedSinceLastScavenge; }
55 void clearUsedSinceLastScavenge() { m_usedSinceLastScavenge = false; }
56 void setUsedSinceLastScavenge() { m_usedSinceLastScavenge = true; }
57
58 SmallLine* begin();
59
60 unsigned char slide() const { return m_slide; }
61 void setSlide(unsigned char slide) { m_slide = slide; }
62
63private:
64 unsigned char m_hasFreeLines: 1;
65 unsigned char m_hasPhysicalPages: 1;
66 unsigned char m_usedSinceLastScavenge: 1;
67 unsigned char m_refCount: 7;
68 unsigned char m_sizeClass;
69 unsigned char m_slide;
70
71static_assert(
72 sizeClassCount <= std::numeric_limits<decltype(m_sizeClass)>::max(),
73 "Largest size class must fit in SmallPage metadata");
74};
75
76using LineCache = std::array<List<SmallPage>, sizeClassCount>;
77
78inline void SmallPage::ref(std::unique_lock<Mutex>&)
79{
80 BASSERT(!m_slide);
81 ++m_refCount;
82 BASSERT(m_refCount);
83}
84
85inline bool SmallPage::deref(std::unique_lock<Mutex>&)
86{
87 BASSERT(!m_slide);
88 BASSERT(m_refCount);
89 --m_refCount;
90 return !m_refCount;
91}
92
93} // namespace bmalloc
94
95#endif // SmallPage_h
96