Ioss_SerializeIO.h

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#ifndef IOSS_Ioss_SerializeIO_h
#define IOSS_Ioss_SerializeIO_h

#include <Ioss_CodeTypes.h>

namespace Ioss {
  class DatabaseIO;
} // namespace Ioss

namespace Ioss {

  /**
   * @brief Class <code>SerializeIO</code> is a sentry class which performs serialization
   * for mesh database I/O.
   *
   * This sentry guards serialization of parallel I/O routines.  At construction, it
   * blocks the processes via an MPI barrier, releasing them to execute in groups specified
   * by <code>s_groupSize</code>.  At destruction, it continues to block via MPI barriers
   * until all the processor have been released by the constructor.
   *
   * In the case where the constructor is called, and the sentry is already active and owned
   * by the processes group, the constructor and destrutor simply fall through since the
   * serialization is already in place at a higher level.
   *
   * The MPI
   *
   */
  class SerializeIO
  {
  public:
    /**
     * Creates a new <code>SerializeIO</code> instance.
     *
     * @param database_io a <code>DatabaseIO</code> variable ...
     */
    explicit SerializeIO(const DatabaseIO *database_io, int manual_owner_processor = -1);
    SerializeIO(const SerializeIO &from) = delete;
    SerializeIO &operator=(const SerializeIO &from) = delete;
    ~SerializeIO();

    inline static int getOwner() { return s_owner; }

    inline static int getRank() { return s_rank; }

    inline static int getSize() { return s_size; }

    inline static int getGroupRank() { return s_groupRank; }

    inline static int getGroupSize() { return s_groupSize; }

    static void setGroupFactor(int factor);

    inline static bool isEnabled() { return s_groupFactor != 0; }

    inline static bool inBarrier() { return s_owner != -1; }

    inline static bool inMyGroup() { return s_owner == s_groupRank; }

  private:
    const DatabaseIO *m_databaseIO; ///< Database I/O pointer
#if defined(IOSS_THREADSAFE)
    static std::mutex m_;
#endif
    bool m_activeFallThru; ///< No barries since my group is running
    int  m_manualOwner;    ///< Manually specified owner

    static int s_groupFactor; ///< Grouping factor
    static int s_size;        ///< Number of processors
    static int s_rank;        ///< My processor rank
    static int s_groupSize;   ///< Number of groups
    static int s_groupRank;   ///< My group rank
    static int s_owner;       ///< Group currently running
  };

} // namespace Ioss

#endif // IOSS_Ioss_SerializeIO_h