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/*
* 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 "absl/strings/string_view.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
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