////////////////////////////////////////////////////////////////////////////////
/// @brief barrier for synchronization
///
/// @file
///
/// DISCLAIMER
///
/// Copyright 2014 ArangoDB GmbH, Cologne, Germany
/// Copyright 2004-2014 triAGENS GmbH, Cologne, Germany
///
/// 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.
///
/// Copyright holder is ArangoDB GmbH, Cologne, Germany
///
/// @author Jan Steemann
/// @author Copyright 2014, ArangoDB GmbH, Cologne, Germany
/// @author Copyright 2013-2013, triAGENS GmbH, Cologne, Germany
////////////////////////////////////////////////////////////////////////////////

#ifndef ARANGODB_BASICS_BARRIER_H
#define ARANGODB_BASICS_BARRIER_H 1

#include "Basics/Common.h"
#include "Basics/ConditionVariable.h"

namespace triagens {
  namespace basics {

// -----------------------------------------------------------------------------
// --SECTION--                                                           Barrier
// -----------------------------------------------------------------------------

    class Barrier {

// -----------------------------------------------------------------------------
// --SECTION--                                        constructors / destructors
// -----------------------------------------------------------------------------

      public:

        Barrier (Barrier const&) = delete;
        Barrier& operator= (Barrier const&) = delete;

        Barrier (size_t);

        ~Barrier ();

// -----------------------------------------------------------------------------
// --SECTION--                                                  public functions
// -----------------------------------------------------------------------------

////////////////////////////////////////////////////////////////////////////////
/// @brief join a single task. reduces the number of waiting tasks and wakes
/// up the barrier's synchronize() routine
////////////////////////////////////////////////////////////////////////////////

        void join ();

////////////////////////////////////////////////////////////////////////////////
/// @brief wait for all tasks to join
////////////////////////////////////////////////////////////////////////////////

        void synchronize ();

// -----------------------------------------------------------------------------
// --SECTION--                                                 private variables
// -----------------------------------------------------------------------------

      private:

////////////////////////////////////////////////////////////////////////////////
/// @brief condition variable
////////////////////////////////////////////////////////////////////////////////

        triagens::basics::ConditionVariable _condition;

////////////////////////////////////////////////////////////////////////////////
/// @brief number of non-joined tasks
////////////////////////////////////////////////////////////////////////////////

        size_t _missing;
    }; 
    
// -----------------------------------------------------------------------------
// --SECTION--                                                       BarrierTask
// -----------------------------------------------------------------------------
    
    class BarrierTask {

// -----------------------------------------------------------------------------
// --SECTION--                                        constructors / destructors
// -----------------------------------------------------------------------------

      public:
        
        BarrierTask () = delete; 
        BarrierTask (BarrierTask const&) = delete;
        BarrierTask& operator= (BarrierTask const&) = delete;

        explicit BarrierTask (Barrier* barrier) 
          : _barrier(barrier) {
        }

////////////////////////////////////////////////////////////////////////////////
/// @brief destructor. joins the underlying barrier
////////////////////////////////////////////////////////////////////////////////

        ~BarrierTask () {
          _barrier->join();
        }

// -----------------------------------------------------------------------------
// --SECTION--                                                 private variables
// -----------------------------------------------------------------------------

      private:

////////////////////////////////////////////////////////////////////////////////
/// @brief the underlying barrier
////////////////////////////////////////////////////////////////////////////////

        Barrier* _barrier;

    };

  }   // namespace triagens::basics
}   // namespace triagens

#endif

// -----------------------------------------------------------------------------
// --SECTION--                                                       END-OF-FILE
// -----------------------------------------------------------------------------

// Local Variables:
// mode: outline-minor
// outline-regexp: "/// @brief\\|/// {@inheritDoc}\\|/// @page\\|// --SECTION--\\|/// @\\}"
// End: