1 // Copyright 2015 The Chromium Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
4
5 #include "base/trace_event/heap_profiler_allocation_context.h"
6
7 #include <cstring>
8
9 #include "base/hash/hash.h"
10 #include "base/macros.h"
11
12 namespace base {
13 namespace trace_event {
14
operator <(const StackFrame & lhs,const StackFrame & rhs)15 bool operator < (const StackFrame& lhs, const StackFrame& rhs) {
16 return lhs.value < rhs.value;
17 }
18
operator ==(const StackFrame & lhs,const StackFrame & rhs)19 bool operator == (const StackFrame& lhs, const StackFrame& rhs) {
20 return lhs.value == rhs.value;
21 }
22
operator !=(const StackFrame & lhs,const StackFrame & rhs)23 bool operator != (const StackFrame& lhs, const StackFrame& rhs) {
24 return !(lhs.value == rhs.value);
25 }
26
27 Backtrace::Backtrace() = default;
28
operator ==(const Backtrace & lhs,const Backtrace & rhs)29 bool operator==(const Backtrace& lhs, const Backtrace& rhs) {
30 if (lhs.frame_count != rhs.frame_count) return false;
31 return std::equal(lhs.frames, lhs.frames + lhs.frame_count, rhs.frames);
32 }
33
operator !=(const Backtrace & lhs,const Backtrace & rhs)34 bool operator!=(const Backtrace& lhs, const Backtrace& rhs) {
35 return !(lhs == rhs);
36 }
37
AllocationContext()38 AllocationContext::AllocationContext(): type_name(nullptr) {}
39
AllocationContext(const Backtrace & backtrace,const char * type_name)40 AllocationContext::AllocationContext(const Backtrace& backtrace,
41 const char* type_name)
42 : backtrace(backtrace), type_name(type_name) {}
43
operator ==(const AllocationContext & lhs,const AllocationContext & rhs)44 bool operator==(const AllocationContext& lhs, const AllocationContext& rhs) {
45 return (lhs.backtrace == rhs.backtrace) && (lhs.type_name == rhs.type_name);
46 }
47
operator !=(const AllocationContext & lhs,const AllocationContext & rhs)48 bool operator!=(const AllocationContext& lhs, const AllocationContext& rhs) {
49 return !(lhs == rhs);
50 }
51
52 } // namespace trace_event
53 } // namespace base
54
55 namespace std {
56
57 using base::trace_event::AllocationContext;
58 using base::trace_event::Backtrace;
59 using base::trace_event::StackFrame;
60
operator ()(const StackFrame & frame) const61 size_t hash<StackFrame>::operator()(const StackFrame& frame) const {
62 return hash<const void*>()(frame.value);
63 }
64
operator ()(const Backtrace & backtrace) const65 size_t hash<Backtrace>::operator()(const Backtrace& backtrace) const {
66 const void* values[Backtrace::kMaxFrameCount];
67 for (size_t i = 0; i != backtrace.frame_count; ++i) {
68 values[i] = backtrace.frames[i].value;
69 }
70 return base::PersistentHash(values, backtrace.frame_count * sizeof(*values));
71 }
72
operator ()(const AllocationContext & ctx) const73 size_t hash<AllocationContext>::operator()(const AllocationContext& ctx) const {
74 size_t backtrace_hash = hash<Backtrace>()(ctx.backtrace);
75
76 // Multiplicative hash from [Knuth 1998]. Works best if |size_t| is 32 bits,
77 // because the magic number is a prime very close to 2^32 / golden ratio, but
78 // will still redistribute keys bijectively on 64-bit architectures because
79 // the magic number is coprime to 2^64.
80 size_t type_hash = reinterpret_cast<size_t>(ctx.type_name) * 2654435761;
81
82 // Multiply one side to break the commutativity of +. Multiplication with a
83 // number coprime to |numeric_limits<size_t>::max() + 1| is bijective so
84 // randomness is preserved.
85 return (backtrace_hash * 3) + type_hash;
86 }
87
88 } // namespace std
89