/home/breidi/Dropbox/signalserver/include/misc/databuffer.h

Go to the documentation of this file.

/*
    This file is part of the TOBI SignalServer.

    Commercial Usage
    Licensees holding valid Graz University of Technology Commercial
    licenses may use this file in accordance with the Graz University
    of Technology Commercial License Agreement provided with the
    Software or, alternatively, in accordance with the terms contained in
    a written agreement between you and Graz University of Technology.

    --------------------------------------------------

    GNU General Public License Usage
    Alternatively, this file may be used under the terms of the GNU
    General Public License version 3.0 as published by the Free Software
    Foundation and appearing in the file gpl.txt included in the
    packaging of this file.  Please review the following information to
    ensure the GNU General Public License version 3.0 requirements will be
    met: http://www.gnu.org/copyleft/gpl.html.

    In case of GNU General Public License Usage ,the TOBI SignalServer
    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
    along with the TOBI SignalServer. If not, see <http://www.gnu.org/licenses/>.

    Copyright 2010 Graz University of Technology
    Contact: SignalServer@tobi-project.org
*/

#ifndef DATABUFFER_H
#define DATABUFFER_H

#include <boost/circular_buffer.hpp>
#include <boost/thread/mutex.hpp>
#include <boost/thread/condition_variable.hpp>

namespace tobiss
{

template<class T>
class DataBuffer
{
public:
  typedef boost::circular_buffer<T> container_type;
  typedef typename container_type::size_type size_type;
  typedef typename container_type::value_type value_type;
  typedef typename boost::call_traits<value_type>::param_type param_type;

  class buffer_overrun : public std::runtime_error { public:  buffer_overrun( ):runtime_error("Attempted to insert into full DataBuffer."){ } };
  class buffer_underrun : public std::runtime_error { public:  buffer_underrun( ):runtime_error("Attempted to read from an empty DataBuffer."){ } };

  explicit DataBuffer( size_type capacity ) : unread_(0), container_(capacity) { }  

  void resize( size_type capacity )
  {
    boost::mutex::scoped_lock lock( mutex_ );
    container_.resize( capacity );
    lock.unlock( );
  }

  size_type getNumAvail(  )
  {
    boost::mutex::scoped_lock lock( mutex_ );
    assert( unread_ <= container_.size() );
    return unread_;
    // the mutex is unlocked by scoped_lock's destructor.
  }

  void blockWhileEmpty( )
  {
    boost::mutex::scoped_lock lock( mutex_ );
    cond_not_empty_.wait( lock, boost::bind( &DataBuffer<value_type>::is_not_empty, this ) );
    lock.unlock( );
  }

  void blockWhileFull( )
  {
    boost::mutex::scoped_lock lock( mutex_ );
    cond_not_full_.wait( lock, boost::bind( &DataBuffer<value_type>::is_not_full, this ) );
    lock.unlock( );
  }

  void insert_blocking( param_type item )
  {
    boost::mutex::scoped_lock lock( mutex_ );
    cond_not_full_.wait( lock, boost::bind( &DataBuffer<value_type>::is_not_full, this ) );
    container_.push_front( item );
    unread_++;
    lock.unlock( );
    cond_not_empty_.notify_one( );
  }

  void insert_throwing( param_type item )
  {
    boost::mutex::scoped_lock lock( mutex_ );
    if( is_not_full() )
    {
      container_.push_front( item );
      unread_++;
      lock.unlock( );
      cond_not_empty_.notify_one( );
    }
    else
    {
      lock.unlock( ); // This unlock() is redundant. The scoped_lock's destructor should take care of unlocking the mutex.
      throw buffer_overrun( );
    }
  }  

  void insert_overwriting( param_type item )
  {
    boost::mutex::scoped_lock lock( mutex_ );
    container_.push_front( item );
    if( is_not_full() )
      unread_++;
    lock.unlock( );
    cond_not_empty_.notify_one( );
  }

  void getNext_blocking( value_type *pItem )
  {
    boost::mutex::scoped_lock lock( mutex_ );
    cond_not_empty_.wait( lock, boost::bind( &DataBuffer<value_type>::is_not_empty, this ) );
    *pItem = container_[--unread_];
    lock.unlock( );
    cond_not_full_.notify_one( );
  }  

  void getNext_throwing( value_type *pItem )
  {
    boost::mutex::scoped_lock lock( mutex_ );
    if( is_not_empty() )
    {
      *pItem = container_[--unread_];
      lock.unlock( );
      cond_not_full_.notify_one( );
    }
    else
    {
      lock.unlock( ); // This unlock() is redundant. The scoped_lock's destructor should take care of unlocking the mutex.
      throw buffer_underrun( );
    }
  }

  void peekNext_blocking( value_type *pItem )
  {
    boost::mutex::scoped_lock lock( mutex_ );
    cond_not_empty_.wait( lock, boost::bind( &DataBuffer<value_type>::is_not_empty, this ) );
    *pItem = container_[unread_-1];
    lock.unlock( );
  }  

  void peekNext_throwing( value_type *pItem )
  {
    boost::mutex::scoped_lock lock( mutex_ );
    if( is_not_empty() )
    {
      *pItem = container_[unread_-1];
      lock.unlock( );
    }
    else
    {
      lock.unlock( ); // This unlock() is redundant. The scoped_lock's destructor should take care of unlocking the mutex.
      throw buffer_underrun( );
    }
  }

  bool dropOldest()
  {
    boost::mutex::scoped_lock lock( mutex_ );
    if( is_not_empty() )
    {
      unread_--;
      lock.unlock( );
      cond_not_full_.notify_one( );
      return true;
    }
    lock.unlock( );
    return false;
  }

  void clearAll()
  {
    boost::mutex::scoped_lock lock( mutex_ );
    unread_ = 0;
    lock.unlock( );
    cond_not_full_.notify_one( );
  }

private:
  DataBuffer( const DataBuffer& );            // No Copy Constructor!
  DataBuffer &operator=( const DataBuffer& ); // No Assignment Operator!

  bool is_not_empty( ) const { return unread_ > 0; }
  bool is_not_full( ) const { return unread_ < container_.capacity( ); }

  size_type unread_;
  container_type container_;

  boost::mutex mutex_;
  boost::condition_variable cond_not_empty_;
  boost::condition_variable cond_not_full_;
};

}

#endif