write_preferring_read_write_lock.hpp

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// Copyright 2020 Open Source Robotics Foundation, Inc.
//
// 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 RCLCPP__WAIT_SET_POLICIES__DETAIL__WRITE_PREFERRING_READ_WRITE_LOCK_HPP_
#define RCLCPP__WAIT_SET_POLICIES__DETAIL__WRITE_PREFERRING_READ_WRITE_LOCK_HPP_
 
#include <condition_variable>
#include <functional>
#include <mutex>
 
#include "rclcpp/visibility_control.hpp"
 
namespace rclcpp
{
namespace wait_set_policies
{
namespace detail
{
 
 
class WritePreferringReadWriteLock final
{
public:
  RCLCPP_PUBLIC
  explicit WritePreferringReadWriteLock(std::function<void()> enter_waiting_function = nullptr);
 
 
  class RCLCPP_PUBLIC ReadMutex
  {
public:
    void
    lock();
 
    void
    unlock();
 
protected:
    explicit ReadMutex(WritePreferringReadWriteLock & parent_lock);
 
    WritePreferringReadWriteLock & parent_lock_;
 
    friend WritePreferringReadWriteLock;
  };
 
 
  class RCLCPP_PUBLIC WriteMutex
  {
public:
    void
    lock();
 
    void
    unlock();
 
protected:
    explicit WriteMutex(WritePreferringReadWriteLock & parent_lock);
 
    WritePreferringReadWriteLock & parent_lock_;
 
    friend WritePreferringReadWriteLock;
  };
 
  RCLCPP_PUBLIC
  ReadMutex &
  get_read_mutex();
 
  RCLCPP_PUBLIC
  WriteMutex &
  get_write_mutex();
 
protected:
  bool reader_active_ = false;
  std::size_t number_of_writers_waiting_ = 0;
  bool writer_active_ = false;
  std::mutex mutex_;
  std::condition_variable condition_variable_;
  ReadMutex read_mutex_;
  WriteMutex write_mutex_;
  std::function<void()> enter_waiting_function_;
};
 
}  // namespace detail
}  // namespace wait_set_policies
}  // namespace rclcpp
 
#endif  // RCLCPP__WAIT_SET_POLICIES__DETAIL__WRITE_PREFERRING_READ_WRITE_LOCK_HPP_