realtime_box.h

/*
 * Copyright (c) 2009, Willow Garage, Inc.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 *     * Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above copyright
 *       notice, this list of conditions and the following disclaimer in the
 *       documentation and/or other materials provided with the distribution.
 *     * Neither the name of the Willow Garage, Inc. nor the names of its
 *       contributors may be used to endorse or promote products derived from
 *       this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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 */
 
// Author: Stuart Glaser
 
#ifndef REALTIME_TOOLS__REALTIME_BOX_H__
#define REALTIME_TOOLS__REALTIME_BOX_H__
 
#include <mutex>
#include <string>
 
namespace realtime_tools
{
template<class T>
class RealtimeBox
{
public:
  explicit RealtimeBox(const T & initial = T())
  : thing_(initial) {}
 
  void set(const T & value)
  {
    std::lock_guard<std::mutex> guard(thing_lock_RT_);
    thing_ = value;
  }
 
  void get(T & ref)
  {
    std::lock_guard<std::mutex> guard(thing_lock_RT_);
    ref = thing_;
  }
 
private:
  // The thing that's in the box.
  T thing_;
 
  // Protects access to the thing in the box.  This mutex is
  // guaranteed to be locked for no longer than the duration of the
  // copy, so as long as the copy is realtime safe and the OS has
  // priority inheritance for mutexes, this lock can be safely locked
  // from within realtime.
  std::mutex thing_lock_RT_;
};
 
}  // namespace realtime_tools
 
#endif  // REALTIME_TOOLS__REALTIME_BOX_H_