source: XIOS/dev/dev_trunk_omp/extern/src_ep_dev/ep_barrier.hpp @ 1646

#ifndef EP_BARRIER_HPP_INCLUDED
#define EP_BARRIER_HPP_INCLUDED

#ifdef _usingEP

namespace ep_lib
{

  class ep_barrier
  {
    private:
      int nbThreads;          //<The number of threads for this barrier
      int currentNbThread;    //<The current number of threads waiting
      bool sense;             //<Direct barrier feedback protection
      omp_lock_t mutex;       //<To have an atomic int

      ep_barrier(ep_barrier&){}
      ep_barrier& operator=(ep_barrier&){return *this;}

    public:
      /** Constructor with the number of threads */
      explicit ep_barrier(const int inNbThreads)
          : nbThreads(inNbThreads), currentNbThread(0), sense(false) {
          omp_init_lock( &mutex );
      }

      /** Destructor, release the omp lock */
      ~ep_barrier(){
          omp_destroy_lock( &mutex );
      }

      /** Perform a barrier */
      void wait(){
          const bool mySense = sense;
          omp_set_lock( &mutex );
          const int nbThreadsArrived = (++currentNbThread);
          omp_unset_lock( &mutex );

          if(nbThreadsArrived == nbThreads) {
              currentNbThread = 0;
              sense = !sense;
              #pragma omp flush
          }
          else {
              volatile const bool* const ptSense = &sense;
              while( (*ptSense) == mySense){
              }
          }
      }


      /** Change the number of threads */
      void setNbThreads(const int inNbThread){
          omp_set_lock( &mutex );
          nbThreads = inNbThread;
          omp_unset_lock( &mutex );
      }
  };


}
#endif


#endif // EP_BARRIER_HPP_INCLUDED