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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * published by the Free Software Foundation.
 *
 * This code 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
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
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#ifndef SHARE_UTILITIES_WAITBARRIER_HPP
#define SHARE_UTILITIES_WAITBARRIER_HPP

#include "memory/allocation.hpp"
#include "utilities/waitBarrier_generic.hpp"

#if defined(LINUX)
#include "waitBarrier_linux.hpp"
typedef LinuxWaitBarrier WaitBarrierDefault;
#else
typedef GenericWaitBarrier WaitBarrierDefault;
#endif

// Platform independent WaitBarrier API.
// The WaitBarrier primary objective is to wake threads waiting in wait() fast.
// It can be arm with any int, the tag, that is not 0.
// - After arm() returns any thread calling wait(tag) with the correct tag will be blocked.
// - After disarm() is called any thread calling wait(...) will never block.
// - When wake() returns no threads are blocked any more, if it was disarmed before.
// - After calling disarm() and wake() it my be re-armed immediately.
// Wake thread:
//  - arm(tag)
//  - *work*
//  - disarm()
//  - wake()
// Wait thread:
//  - wait(tag)
template <typename WaitBarrierImpl>
class WaitBarrierType : public CHeapObj<mtInternal> {
  WaitBarrierImpl _impl;

  // Prevent copying and assignment of WaitBarrier instances.
  WaitBarrierType(const WaitBarrierDefault&);
  WaitBarrierType& operator=(const WaitBarrierDefault&);

 public:
  WaitBarrierType() : _impl() {}
  ~WaitBarrierType() {}

  // Returns implementation type.
  const char* description()    { return _impl.description(); }

  // Guarantees any thread calling wait() with same tag will be blocked.
  // Provides a trailing fence.
  void arm(int barrier_tag)    { _impl.arm(barrier_tag); }

  // Guarantees any thread calling wait() with any tag will not be blocked.
  // Provides a trailing fence.
  void disarm()                { _impl.disarm(); }

  // Guarantees any thread called wait() will be awake when it returns.
  // Provides a trailing fence.
  void wake()                  { _impl.wake(); }

  // Guarantees to return if disarm() and wake() is called.
  // Provides a trailing fence.
  void wait(int barrier_tag)   { _impl.wait(barrier_tag); }
};

typedef WaitBarrierType<WaitBarrierDefault> WaitBarrier;

#endif // SHARE_UTILITIES_WAITBARRIER_HPP