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