owned_buffer.h

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/*
  Copyright (c) 2021, 2024, Oracle and/or its affiliates.
 
  This program is free software; you can redistribute it and/or modify
  it under the terms of the GNU General Public License, version 2.0,
  as published by the Free Software Foundation.
 
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  as designated in a particular file or component or in included license
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  permission to link the program and your derivative works with the
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  the program or referenced in the documentation.
 
  This program is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  GNU General Public License for more details.
 
  You should have received a copy of the GNU General Public License
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  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
*/
 
#ifndef ROUTER_SRC_HTTP_SRC_HTTP_BASE_DETAILS_OWNED_BUFFER_H_
#define ROUTER_SRC_HTTP_SRC_HTTP_BASE_DETAILS_OWNED_BUFFER_H_
 
#include <string.h>
 
#include <algorithm>
#include <memory>
#include <utility>
 
#include "mysql/harness/net_ts/buffer.h"
 
namespace http {
namespace base {
namespace details {
 
template <typename T>
class ref_buffer {
 public:
  using This = ref_buffer<T>;
  ref_buffer(T &ref) : ref_{ref} {}
  ref_buffer(const ref_buffer &other) : ref_{other.ref_} {}
 
  void *data() const noexcept { return ref_.data(); }
  size_t size() const noexcept { return ref_.size(); }
 
  void reset() { ref_.reset(); }
 
  This &operator+=(size_t n) {
    ref_ += n;
    return *this;
  }
 
  operator net::const_buffer() const {
    return net::const_buffer(data(), size());
  }
 
 private:
  T &ref_;
};
 
template <typename T>
class ref_buffers {
 public:
  using This = ref_buffers<T>;
  ref_buffers(T &ref) : ref_{&ref} {}
  ref_buffers(const ref_buffers &other) : ref_{other.ref_} {}
 
  auto begin() const { return ref_->begin(); }
  auto end() const { return ref_->end(); }
 
  This &operator=(const This &t) { ref_ = t.ref_; }
 
 private:
  T *ref_;
};
 
class owned_buffer {
 public:
  owned_buffer(size_t n = 0)
      : buffer_{n ? new uint8_t[n] : nullptr},
        buffer_size_{n},
        data_movable_{buffer_.get()},
        data_size_{0} {}
 
  owned_buffer(owned_buffer &&other)
      : buffer_{std::move(other.buffer_)},
        buffer_size_{other.buffer_size_},
        data_movable_{other.data_movable_},
        data_size_{other.data_size_} {}
 
 public:  // Methods needed by net_ts stream template
  void *data() const noexcept { return data_movable_; }
  size_t size() const noexcept { return data_size_; }
 
  void reset() {
    data_movable_ = buffer_.get();
    data_size_ = 0;
  }
 
  owned_buffer &operator+=(size_t n) {
    data_movable_ = data_movable_ + n;
    data_size_ = data_size_ > n ? data_size_ - n : 0;
    return *this;
  }
 
  operator net::const_buffer() const {
    return net::const_buffer(data(), size());
  }
 
 public:  // Other methods
  size_t space_left() const { return buffer_size_ - data_size_; }
  bool empty() const { return 0 == data_size_; }
 
  size_t write(const uint8_t *source, size_t source_size) {
    const auto bytes_to_copy = std::min(source_size, space_left());
    memcpy(buffer_.get() + data_size_, source, bytes_to_copy);
    data_size_ += bytes_to_copy;
 
    return bytes_to_copy;
  }
 
 private:
  std::unique_ptr<uint8_t[]> buffer_;
  const size_t buffer_size_;
 
  uint8_t *data_movable_;
  size_t data_size_;
};
 
}  // namespace details
}  // namespace base
}  // namespace http
 
#endif  // ROUTER_SRC_HTTP_SRC_HTTP_BASE_DETAILS_OWNED_BUFFER_H_