1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
|
// Copyright 2015 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "base/trace_event/heap_profiler_allocation_context.h"
#include <cstring>
#include "base/hash.h"
#include "base/macros.h"
namespace base {
namespace trace_event {
bool operator < (const StackFrame& lhs, const StackFrame& rhs) {
return lhs.value < rhs.value;
}
bool operator == (const StackFrame& lhs, const StackFrame& rhs) {
return lhs.value == rhs.value;
}
bool operator != (const StackFrame& lhs, const StackFrame& rhs) {
return !(lhs.value == rhs.value);
}
Backtrace::Backtrace(): frame_count(0) {}
bool operator==(const Backtrace& lhs, const Backtrace& rhs) {
if (lhs.frame_count != rhs.frame_count) return false;
return std::equal(lhs.frames, lhs.frames + lhs.frame_count, rhs.frames);
}
bool operator!=(const Backtrace& lhs, const Backtrace& rhs) {
return !(lhs == rhs);
}
AllocationContext::AllocationContext(): type_name(nullptr) {}
AllocationContext::AllocationContext(const Backtrace& backtrace,
const char* type_name)
: backtrace(backtrace), type_name(type_name) {}
bool operator==(const AllocationContext& lhs, const AllocationContext& rhs) {
return (lhs.backtrace == rhs.backtrace) && (lhs.type_name == rhs.type_name);
}
bool operator!=(const AllocationContext& lhs, const AllocationContext& rhs) {
return !(lhs == rhs);
}
} // namespace trace_event
} // namespace base
namespace BASE_HASH_NAMESPACE {
using base::trace_event::AllocationContext;
using base::trace_event::Backtrace;
using base::trace_event::StackFrame;
size_t hash<StackFrame>::operator()(const StackFrame& frame) const {
return hash<const void*>()(frame.value);
}
size_t hash<Backtrace>::operator()(const Backtrace& backtrace) const {
const void* values[Backtrace::kMaxFrameCount];
for (size_t i = 0; i != backtrace.frame_count; ++i) {
values[i] = backtrace.frames[i].value;
}
return base::SuperFastHash(
reinterpret_cast<const char*>(values),
static_cast<int>(backtrace.frame_count * sizeof(*values)));
}
size_t hash<AllocationContext>::operator()(const AllocationContext& ctx) const {
size_t backtrace_hash = hash<Backtrace>()(ctx.backtrace);
// Multiplicative hash from [Knuth 1998]. Works best if |size_t| is 32 bits,
// because the magic number is a prime very close to 2^32 / golden ratio, but
// will still redistribute keys bijectively on 64-bit architectures because
// the magic number is coprime to 2^64.
size_t type_hash = reinterpret_cast<size_t>(ctx.type_name) * 2654435761;
// Multiply one side to break the commutativity of +. Multiplication with a
// number coprime to |numeric_limits<size_t>::max() + 1| is bijective so
// randomness is preserved.
return (backtrace_hash * 3) + type_hash;
}
} // BASE_HASH_NAMESPACE
|
