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 * Copyright (c) 2019, Oracle and/or its affiliates. All rights reserved.

 * 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_GENERIC_HPP

#define SHARE_UTILITIES_WAITBARRIER_GENERIC_HPP

#include "memory/allocation.hpp"

#include "runtime/semaphore.hpp"

// In addition to the barrier tag, it uses two counters to keep the semaphore

// count correct and not leave any late thread waiting.

class GenericWaitBarrier : public CHeapObj<mtInternal> {

  volatile int _barrier_tag;

  // The number of threads waiting on or about to wait on the semaphore.

  volatile int _waiters;

  // The number of threads in the wait path, before or after the tag check.

  // These threads can become waiters.

  volatile int _barrier_threads;

  Semaphore _sem_barrier;

  // Prevent copying and assignment of GenericWaitBarrier instances.

  GenericWaitBarrier(const GenericWaitBarrier&);

  GenericWaitBarrier& operator=(const GenericWaitBarrier&);

  int wake_if_needed();

 public:

  GenericWaitBarrier() : _barrier_tag(0), _waiters(0), _barrier_threads(0), _sem_barrier(0) {}

  ~GenericWaitBarrier() {}

  const char* description() { return "semaphore"; }

  void arm(int barrier_tag);

  void disarm();

  void wait(int barrier_tag);

};

#endif // SHARE_UTILITIES_WAITBARRIER_GENERIC_HPP