////////////////////////////////////////////////////////////////////////////////
/// DISCLAIMER
///
/// Copyright 2014-2016 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
////////////////////////////////////////////////////////////////////////////////

#include "Barrier.h"
#include "Basics/ConditionLocker.h"

using namespace arangodb::basics;

////////////////////////////////////////////////////////////////////////////////
/// @brief create a barrier for the specified number of waiters
////////////////////////////////////////////////////////////////////////////////

Barrier::Barrier(size_t size) : _condition(), _missing(size) {
  TRI_ASSERT(size > 0);
}

////////////////////////////////////////////////////////////////////////////////
/// @brief destroy the barrier. this will call synchronize() to ensure all tasks
/// are joined
////////////////////////////////////////////////////////////////////////////////

Barrier::~Barrier() { synchronize(); }

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

void Barrier::join() {
  {
    CONDITION_LOCKER(guard, _condition);
    TRI_ASSERT(_missing > 0);
    --_missing;
  }

  _condition.signal();
}

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

void Barrier::synchronize() {
  while (true) {
    CONDITION_LOCKER(guard, _condition);

    if (_missing == 0) {
      break;
    }

    guard.wait(100000);
  }
}