openmp_mutex.h

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// g2o - General Graph Optimization
// Copyright (C) 2011 R. Kuemmerle, G. Grisetti, W. Burgard
// All rights reserved.
//
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// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright notice,
//   this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above copyright
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#ifndef G2O_OPENMP_MUTEX
#define G2O_OPENMP_MUTEX

#include "g2o/config.h"

#ifdef G2O_OPENMP
#include <omp.h>
#else
#include <cassert>
#endif

namespace g2o {

#ifdef G2O_OPENMP

  class OpenMPMutex
  {
    public:
      OpenMPMutex() { omp_init_lock(&_lock); }
      ~OpenMPMutex() { omp_destroy_lock(&_lock); }
      void lock() { omp_set_lock(&_lock); }
      void unlock() { omp_unset_lock(&_lock); }
    protected:
      omp_lock_t _lock;
  };

#else

  /*
   * dummy which does nothing in case we don't have OpenMP support.
   * In debug mode, the mutex allows to verify the correct lock and unlock behavior
   */
  class OpenMPMutex
  {
    public:
#ifdef NDEBUG
      OpenMPMutex() {}
#else
      OpenMPMutex() : _cnt(0) {}
#endif
      ~OpenMPMutex() { assert(_cnt == 0 && "Freeing locked mutex");}
      void lock() { assert(++_cnt == 1 && "Locking already locked mutex");}
      void unlock() { assert(--_cnt == 0 && "Trying to unlock a mutex which is not locked");}
    protected:
#ifndef NDEBUG
      char _cnt;
#endif
  };

#endif

  class ScopedOpenMPMutex
  {
    public:
      explicit ScopedOpenMPMutex(OpenMPMutex* mutex) : _mutex(mutex) { _mutex->lock(); }
      ~ScopedOpenMPMutex() { _mutex->unlock(); }
    private:
      OpenMPMutex* const _mutex;
      ScopedOpenMPMutex(const ScopedOpenMPMutex&);
      void operator=(const ScopedOpenMPMutex&);
  };

}

#endif