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
|
/*
* Copyright 2016 The WebRTC Project Authors. All rights reserved.
*
* Use of this source code is governed by a BSD-style license
* that can be found in the LICENSE file in the root of the source
* tree. An additional intellectual property rights grant can be found
* in the file PATENTS. All contributing project authors may
* be found in the AUTHORS file in the root of the source tree.
*/
#include "rtc_base/copy_on_write_buffer.h"
#include <stddef.h>
#include <algorithm>
#include <cstring>
#include <utility>
#include "absl/strings/string_view.h"
#include "rtc_base/checks.h"
namespace webrtc {
CopyOnWriteBuffer::CopyOnWriteBuffer() : offset_(0), size_(0) {
RTC_DCHECK(IsConsistent());
}
CopyOnWriteBuffer::CopyOnWriteBuffer(const CopyOnWriteBuffer& buf)
: buffer_(buf.buffer_), offset_(buf.offset_), size_(buf.size_) {}
CopyOnWriteBuffer::CopyOnWriteBuffer(CopyOnWriteBuffer&& buf) noexcept
: buffer_(std::move(buf.buffer_)), offset_(buf.offset_), size_(buf.size_) {
buf.offset_ = 0;
buf.size_ = 0;
RTC_DCHECK(IsConsistent());
}
CopyOnWriteBuffer::CopyOnWriteBuffer(absl::string_view s)
: CopyOnWriteBuffer(s.data(), s.length()) {}
CopyOnWriteBuffer::CopyOnWriteBuffer(size_t size)
: buffer_(size > 0 ? new RefCountedBuffer(size) : nullptr),
offset_(0),
size_(size) {
RTC_DCHECK(IsConsistent());
}
CopyOnWriteBuffer::CopyOnWriteBuffer(size_t size, size_t capacity)
: buffer_(size > 0 || capacity > 0 ? new RefCountedBuffer(size, capacity)
: nullptr),
offset_(0),
size_(size) {
RTC_DCHECK(IsConsistent());
}
CopyOnWriteBuffer::~CopyOnWriteBuffer() = default;
bool CopyOnWriteBuffer::operator==(const CopyOnWriteBuffer& buf) const {
// Must either be the same view of the same buffer or have the same contents.
RTC_DCHECK(IsConsistent());
RTC_DCHECK(buf.IsConsistent());
return size_ == buf.size_ &&
(cdata() == buf.cdata() || memcmp(cdata(), buf.cdata(), size_) == 0);
}
void CopyOnWriteBuffer::SetSize(size_t size) {
RTC_DCHECK(IsConsistent());
if (!buffer_) {
if (size > 0) {
buffer_ = new RefCountedBuffer(size);
offset_ = 0;
size_ = size;
}
RTC_DCHECK(IsConsistent());
return;
}
if (size <= size_) {
size_ = size;
return;
}
UnshareAndEnsureCapacity(std::max(capacity(), size));
buffer_->SetSize(size + offset_);
size_ = size;
RTC_DCHECK(IsConsistent());
}
void CopyOnWriteBuffer::EnsureCapacity(size_t new_capacity) {
RTC_DCHECK(IsConsistent());
if (!buffer_) {
if (new_capacity > 0) {
buffer_ = new RefCountedBuffer(0, new_capacity);
offset_ = 0;
size_ = 0;
}
RTC_DCHECK(IsConsistent());
return;
} else if (new_capacity <= capacity()) {
return;
}
UnshareAndEnsureCapacity(new_capacity);
RTC_DCHECK(IsConsistent());
}
void CopyOnWriteBuffer::Clear() {
if (!buffer_)
return;
if (buffer_->HasOneRef()) {
buffer_->Clear();
} else {
buffer_ = new RefCountedBuffer(0, capacity());
}
offset_ = 0;
size_ = 0;
RTC_DCHECK(IsConsistent());
}
void CopyOnWriteBuffer::UnshareAndEnsureCapacity(size_t new_capacity) {
if (buffer_->HasOneRef() && new_capacity <= capacity()) {
return;
}
buffer_ =
new RefCountedBuffer(buffer_->data() + offset_, size_, new_capacity);
offset_ = 0;
RTC_DCHECK(IsConsistent());
}
} // namespace webrtc
|
