realtime_buffer.h
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00001 /*
00002  * Copyright (c) 2013 hiDOF, Inc.
00003  * All rights reserved.
00004  *
00005  * Redistribution and use in source and binary forms, with or without
00006  * modification, are permitted provided that the following conditions are met:
00007  *
00008  *     * Redistributions of source code must retain the above copyright
00009  *       notice, this list of conditions and the following disclaimer.
00010  *     * Redistributions in binary form must reproduce the above copyright
00011  *       notice, this list of conditions and the following disclaimer in the
00012  *       documentation and/or other materials provided with the distribution.
00013  *     * Neither the name of the Willow Garage, Inc. nor the names of its
00014  *       contributors may be used to endorse or promote products derived from
00015  *       this software without specific prior written permission.
00016  *
00017  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
00018  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
00019  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
00020  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
00021  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
00022  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
00023  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
00024  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
00025  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
00026  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
00027  * POSSIBILITY OF SUCH DAMAGE.
00028  */
00029 
00030 /*
00031  * Publishing ROS messages is difficult, as the publish function is
00032  * not realtime safe.  This class provides the proper locking so that
00033  * you can call publish in realtime and a separate (non-realtime)
00034  * thread will ensure that the message gets published over ROS.
00035  *
00036  * Author: Wim Meeussen
00037  */
00038 
00039 #ifndef REALTIME_TOOLS_REALTIME_BUFFER
00040 #define REALTIME_TOOLS_REALTIME_BUFFER
00041 
00042 #include <boost/thread/mutex.hpp>
00043 
00044 namespace realtime_tools
00045 {
00046 
00047 template <class T>
00048 class RealtimeBuffer
00049 {
00050  public:
00051   RealtimeBuffer()
00052     : new_data_available_(false)
00053   {
00054     // allocate memory
00055     non_realtime_data_ = new T();
00056     realtime_data_ = new T();
00057   }
00058 
00059   ~RealtimeBuffer()
00060   {
00061     if (non_realtime_data_)
00062       delete non_realtime_data_;
00063     if (realtime_data_)
00064       delete realtime_data_;
00065   }
00066 
00067   RealtimeBuffer(RealtimeBuffer &source)
00068   {
00069     // allocate memory
00070     non_realtime_data_ = new T();
00071     realtime_data_ = new T();
00072 
00073     // Copy the data from old RTB to new RTB
00074     writeFromNonRT(*source.readFromNonRT());
00075   }
00076 
00080   RealtimeBuffer &operator =(const RealtimeBuffer& source)
00081   {
00082     if (this == &source)
00083       return *this;
00084 
00085     // Copy the data from old RTB to new RTB
00086     writeFromNonRT(*source.readFromNonRT());
00087 
00088     return *this;
00089   }
00090 
00091   T* readFromRT()
00092   {
00093     // Check if the data is currently being written to (is locked)
00094     if (mutex_.try_lock())
00095     {
00096       // swap pointers
00097       if (new_data_available_)
00098       {
00099         T* tmp = realtime_data_;
00100         realtime_data_ = non_realtime_data_;
00101         non_realtime_data_ = tmp;
00102         new_data_available_ = false;
00103       }
00104       mutex_.unlock();
00105     }
00106     return realtime_data_;
00107   }
00108 
00109   T* readFromNonRT() const
00110   {
00111     boost::mutex::scoped_lock lock(mutex_);
00112 
00113     if (new_data_available_)
00114       return non_realtime_data_;
00115     else
00116       return realtime_data_;
00117   }
00118 
00119   void writeFromNonRT(const T& data)
00120   {
00121     // get lock
00122     lock();
00123 
00124     // copy data into non-realtime buffer
00125     *non_realtime_data_ = data;
00126     new_data_available_ = true;
00127 
00128     // release lock
00129     mutex_.unlock();
00130   }
00131 
00132   void initRT(const T& data)
00133   {
00134     *non_realtime_data_ = data;    
00135     *realtime_data_ = data;    
00136   }
00137 
00138  private:
00139   void lock()
00140   {
00141 #ifdef NON_POLLING
00142     mutex_.lock();
00143 #else
00144     while (!mutex_.try_lock())
00145       usleep(500);
00146 #endif
00147   }
00148 
00149   T* realtime_data_;
00150   T* non_realtime_data_;
00151   bool new_data_available_;
00152 
00153   // Set as mutable so that readFromNonRT() can be performed on a const buffer
00154   mutable boost::mutex mutex_;
00155 
00156 }; // class
00157 }// namespace
00158 
00159 #endif


realtime_tools
Author(s): Stuart Glaser
autogenerated on Thu Aug 27 2015 14:38:05