1/*
2 * Copyright (C) 2017-2019 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#pragma once
27
28#include <wtf/Assertions.h>
29#include <wtf/HashTraits.h>
30#include <wtf/UniqueArray.h>
31
32namespace WTF {
33
34class StackShot {
35 WTF_MAKE_FAST_ALLOCATED;
36public:
37 StackShot() { }
38
39 ALWAYS_INLINE StackShot(size_t size)
40 : m_size(size)
41 {
42 if (size) {
43 m_array = makeUniqueArray<void*>(size);
44 int intSize = size;
45 WTFGetBacktrace(m_array.get(), &intSize);
46 RELEASE_ASSERT(static_cast<size_t>(intSize) <= size);
47 m_size = intSize;
48 if (!m_size)
49 m_array = nullptr;
50 }
51 }
52
53 StackShot(WTF::HashTableDeletedValueType)
54 : m_array(deletedValueArray())
55 , m_size(0)
56 {
57 }
58
59 StackShot& operator=(const StackShot& other)
60 {
61 auto newArray = makeUniqueArray<void*>(other.m_size);
62 for (size_t i = other.m_size; i--;)
63 newArray[i] = other.m_array[i];
64 m_size = other.m_size;
65 m_array = WTFMove(newArray);
66 return *this;
67 }
68
69 StackShot(const StackShot& other)
70 {
71 *this = other;
72 }
73
74 void** array() const { return m_array.get(); }
75 size_t size() const { return m_size; }
76
77 explicit operator bool() const { return !!m_array; }
78
79 bool operator==(const StackShot& other) const
80 {
81 if (m_size != other.m_size)
82 return false;
83
84 for (size_t i = m_size; i--;) {
85 if (m_array[i] != other.m_array[i])
86 return false;
87 }
88
89 return true;
90 }
91
92 unsigned hash() const
93 {
94 unsigned result = m_size;
95
96 for (size_t i = m_size; i--;)
97 result ^= PtrHash<void*>::hash(m_array[i]);
98
99 return result;
100 }
101
102 bool isHashTableDeletedValue() const
103 {
104 return !m_size && m_array.get() == deletedValueArray();
105 }
106
107 // Make Spectrum<> happy.
108 bool operator>(const StackShot&) const { return false; }
109
110private:
111 static void** deletedValueArray() { return bitwise_cast<void**>(static_cast<uintptr_t>(1)); }
112
113 UniqueArray<void*> m_array;
114 size_t m_size { 0 };
115};
116
117struct StackShotHash {
118 static unsigned hash(const StackShot& shot) { return shot.hash(); }
119 static bool equal(const StackShot& a, const StackShot& b) { return a == b; }
120 static constexpr bool safeToCompareToEmptyOrDeleted = false;
121};
122
123template<typename T> struct DefaultHash;
124template<> struct DefaultHash<StackShot> {
125 typedef StackShotHash Hash;
126};
127
128template<> struct HashTraits<StackShot> : SimpleClassHashTraits<StackShot> { };
129
130} // namespace WTF
131
132