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
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
|
/*
*
* Copyright 2017 gRPC authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
*/
#ifndef GRPC_CORE_LIB_GPRPP_INLINED_VECTOR_H
#define GRPC_CORE_LIB_GPRPP_INLINED_VECTOR_H
#include <grpc/support/port_platform.h>
#include <cassert>
#include "src/core/lib/gprpp/memory.h"
namespace grpc_core {
// NOTE: We eventually want to use absl::InlinedVector here. However,
// there are currently build problems that prevent us from using absl.
// In the interim, we define a custom implementation as a place-holder,
// with the intent to eventually replace this with the absl
// implementation.
//
// This place-holder implementation does not implement the full set of
// functionality from the absl version; it has just the methods that we
// currently happen to need in gRPC. If additional functionality is
// needed before this gets replaced with the absl version, it can be
// added, with the following proviso:
//
// ANY METHOD ADDED HERE MUST COMPLY WITH THE INTERFACE IN THE absl
// IMPLEMENTATION!
//
// TODO(nnoble, roth): Replace this with absl::InlinedVector once we
// integrate absl into the gRPC build system in a usable way.
template <typename T, size_t N>
class InlinedVector {
public:
InlinedVector() { init_data(); }
~InlinedVector() { destroy_elements(); }
// For now, we do not support copying.
InlinedVector(const InlinedVector&) = delete;
InlinedVector& operator=(const InlinedVector&) = delete;
T& operator[](size_t offset) {
assert(offset < size_);
if (offset < N) {
return *reinterpret_cast<T*>(inline_ + offset);
} else {
return dynamic_[offset - N];
}
}
const T& operator[](size_t offset) const {
assert(offset < size_);
if (offset < N) {
return *reinterpret_cast<const T*>(inline_ + offset);
} else {
return dynamic_[offset - N];
}
}
template <typename... Args>
void emplace_back(Args&&... args) {
if (size_ < N) {
new (&inline_[size_]) T(std::forward<Args>(args)...);
} else {
if (size_ - N == dynamic_capacity_) {
size_t new_capacity =
dynamic_capacity_ == 0 ? 2 : dynamic_capacity_ * 2;
T* new_dynamic = static_cast<T*>(gpr_malloc(sizeof(T) * new_capacity));
for (size_t i = 0; i < dynamic_capacity_; ++i) {
new (&new_dynamic[i]) T(std::move(dynamic_[i]));
dynamic_[i].~T();
}
gpr_free(dynamic_);
dynamic_ = new_dynamic;
dynamic_capacity_ = new_capacity;
}
new (&dynamic_[size_ - N]) T(std::forward<Args>(args)...);
}
++size_;
}
void push_back(const T& value) { emplace_back(value); }
void push_back(T&& value) { emplace_back(std::move(value)); }
size_t size() const { return size_; }
void clear() {
destroy_elements();
init_data();
}
private:
void init_data() {
dynamic_ = nullptr;
size_ = 0;
dynamic_capacity_ = 0;
}
void destroy_elements() {
for (size_t i = 0; i < size_ && i < N; ++i) {
T& value = *reinterpret_cast<T*>(inline_ + i);
value.~T();
}
if (size_ > N) { // Avoid subtracting two signed values.
for (size_t i = 0; i < size_ - N; ++i) {
dynamic_[i].~T();
}
}
gpr_free(dynamic_);
}
typename std::aligned_storage<sizeof(T)>::type inline_[N];
T* dynamic_;
size_t size_;
size_t dynamic_capacity_;
};
} // namespace grpc_core
#endif /* GRPC_CORE_LIB_GPRPP_INLINED_VECTOR_H */
|
