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
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
|
#include "buffer.hh"
#include <algorithm>
#include <cassert>
#include <cstring>
#include <memory>
#include <utility>
namespace {
class FixedBuffer : public Buffer {
public:
explicit FixedBuffer(size_t size) : size_(size) {}
void const* rptr(size_t& avail, size_t need) override {
if (rptr_ < wptr_) {
avail = wptr_ - rptr_;
} else if (rptr_ == wptr_ && !full_) {
avail = 0;
} else {
avail = (data_.get() + size_) - rptr_;
if (avail < need && rptr_ > data_.get()) {
rotate();
return rptr(avail, need);
}
}
return rptr_;
}
void consume(size_t size) override {
if (size == 0)
return;
if (rptr_ < wptr_) {
assert(std::cmp_greater_equal(wptr_ - rptr_, size));
rptr_ += size;
if (rptr_ == wptr_)
reset();
} else {
assert(rptr_ != wptr_ || full_);
assert(std::cmp_greater_equal((data_.get() + size_) - rptr_, size));
rptr_ += size;
if (rptr_ == data_.get() + size_) {
rptr_ = data_.get();
if (rptr_ == wptr_)
reset();
}
}
}
void* wptr(size_t& avail, size_t need) override {
if (wptr_ == nullptr) {
data_ = std::make_unique_for_overwrite<char[]>(size_);
rptr_ = wptr_ = data_.get();
}
if (wptr_ < rptr_) {
avail = rptr_ - wptr_;
} else if (rptr_ == wptr_ && full_) {
avail = 0;
} else {
avail = (data_.get() + size_) - wptr_;
if (avail < need && rptr_ > data_.get()) {
rotate();
return wptr(avail, need);
}
}
return wptr_;
}
void commit(size_t size) override {
if (size == 0)
return;
if (wptr_ < rptr_) {
assert(std::cmp_greater_equal(rptr_ - wptr_, size));
wptr_ += size;
if (wptr_ == rptr_) {
full_ = true;
}
} else {
assert(rptr_ != wptr_ || !full_);
assert(std::cmp_greater_equal((data_.get() + size_) - wptr_, size));
wptr_ += size;
if (wptr_ == data_.get() + size_) {
wptr_ = data_.get();
if (wptr_ == rptr_)
full_ = true;
}
}
}
[[nodiscard]] bool full() const override { return rptr_ == wptr_ && full_; }
[[nodiscard]] bool empty() const override { return rptr_ == wptr_ && !full_; }
private:
void reset() {
rptr_ = wptr_ = data_.get();
full_ = false;
}
void rotate() {
if (rptr_ < wptr_) {
size_t size = wptr_ - rptr_;
memmove(data_.get(), rptr_, size);
wptr_ = data_.get() + size;
} else {
size_t to_move = (data_.get() + size_) - rptr_;
if (wptr_ + to_move > rptr_) {
auto tmp = std::make_unique_for_overwrite<char[]>(to_move);
memcpy(tmp.get(), rptr_, to_move);
memmove(data_.get() + to_move, data_.get(), wptr_ - data_.get());
memcpy(data_.get(), tmp.get(), to_move);
} else {
memmove(data_.get() + to_move, data_.get(), wptr_ - data_.get());
memcpy(data_.get(), rptr_, to_move);
}
wptr_ += to_move;
}
rptr_ = data_.get();
}
size_t const size_;
std::unique_ptr<char[]> data_;
char* rptr_{nullptr};
char* wptr_{nullptr};
bool full_{false};
};
class DynamicBuffer : public Buffer {
public:
DynamicBuffer(size_t start_size, size_t max_size)
: start_size_(start_size), max_size_(max_size) {}
void const* rptr(size_t& avail, size_t /* need */) override {
avail = wptr_ - rptr_;
return rptr_;
}
void consume(size_t size) override {
assert(std::cmp_greater_equal(wptr_ - rptr_, size));
rptr_ += size;
if (rptr_ == wptr_) {
reset();
}
}
void* wptr(size_t& avail, size_t need) override {
avail = end_ - wptr_;
if (avail < need) {
if (end_ == nullptr) {
size_t size = std::min(max_size_, std::max(need, start_size_));
data_ = std::make_unique_for_overwrite<char[]>(size);
end_ = data_.get() + size;
rptr_ = wptr_ = data_.get();
avail = end_ - wptr_;
} else if (std::cmp_greater_equal(rptr_ - data_.get(), need - avail)) {
memmove(data_.get(), rptr_, wptr_ - rptr_);
wptr_ = data_.get() + (wptr_ - rptr_);
rptr_ = data_.get();
avail = end_ - wptr_;
} else if (std::cmp_less(end_ - data_.get(), max_size_)) {
size_t current_size = end_ - data_.get();
size_t new_size = std::min(
max_size_, current_size + std::max(need - avail, current_size));
auto tmp = std::make_unique_for_overwrite<char[]>(new_size);
memcpy(tmp.get(), rptr_, wptr_ - rptr_);
end_ = tmp.get() + new_size;
wptr_ = tmp.get() + (wptr_ - rptr_);
rptr_ = tmp.get();
data_ = std::move(tmp);
avail = end_ - wptr_;
}
}
return wptr_;
}
void commit(size_t size) override {
assert(std::cmp_greater_equal(end_ - wptr_, size));
wptr_ += size;
}
[[nodiscard]] bool full() const override {
return rptr_ == data_.get() && wptr_ == end_ &&
std::cmp_equal(end_ - data_.get(), max_size_);
}
[[nodiscard]] bool empty() const override { return rptr_ == wptr_; }
private:
void reset() {
if (std::cmp_greater(end_ - data_.get(), start_size_)) {
data_ = std::make_unique_for_overwrite<char[]>(start_size_);
}
rptr_ = wptr_ = data_.get();
}
size_t const start_size_;
size_t const max_size_;
std::unique_ptr<char[]> data_;
char* end_{nullptr};
char* rptr_{nullptr};
char* wptr_{nullptr};
};
} // namespace
std::unique_ptr<Buffer> Buffer::fixed(size_t size) {
return std::make_unique<FixedBuffer>(size);
}
std::unique_ptr<Buffer> Buffer::dynamic(size_t start_size, size_t max_size) {
return std::make_unique<DynamicBuffer>(start_size, max_size);
}
|
