atomic_bgc_ticket_guard.h

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#ifndef BINLOG_ATOMIC_BCG_TICKET_GUARD_H
#define BINLOG_ATOMIC_BCG_TICKET_GUARD_H
 
#include <functional>
#include <limits>
#include <memory>
 
#include "sql/binlog/group_commit/atomic_bgc_ticket.h"
#include "sql/binlog/group_commit/bgc_ticket.h"
#include "sql/memory/aligned_atomic.h"
 
namespace binlog {
 
class BgcTicket;
class AtomicBgcTicket;
 
class AtomicBgcTicketGuard;
 
/// @brief RAII opaque for AtomicBgcTicket (set in use/set used synchronization
/// operations in constructor/destructor)
class AtomicBgcTicketGuard {
 public:
  virtual ~AtomicBgcTicketGuard();
 
  // Remove copy-move semantics
  AtomicBgcTicketGuard(AtomicBgcTicketGuard const &) = delete;
  AtomicBgcTicketGuard &operator=(AtomicBgcTicketGuard const &) = delete;
 
  /// @brief "Next" value accessor. Before "release" operation, ticket value is
  /// set to the returned "next" ticket.
  /// @returns BgcTicket with next ticket value
  BgcTicket get_next() const;
  /// @brief "Previous" value accessor. During the "acquire" operation, ticket
  /// value is set to the returned "previous" ticket.
  /// @returns BgcTicket with previous ticket value
  BgcTicket get_prev() const;
 
  /// @brief Function used to manually manipulate the "next" ticket value. The
  /// 'set_next' function will determine the value of the ticket after the
  /// "release" operation. It can be the same value, but it might be the value
  /// incremented by one, depending on the current usage.
  /// @param next Next value for the AtomicBgcTicket referenced by this instance
  /// of the AtomicBgcTicketGuard
  void set_next(const BgcTicket &next);
 
  friend class AtomicBgcTicket;
 
 protected:
  /// @brief Constructor
  /// @param[in] bgcTicket Reference to atomic ticket instance
  /// @param[in] next_value Before "release" operation, ticket value is set to
  /// the next_value.
  AtomicBgcTicketGuard(AtomicBgcTicket &bgcTicket, const BgcTicket &next_value);
  /// @brief Constructor
  /// @param[in] bgcTicket Reference to atomic ticket instance
  /// @param[in] inc_next_before_release Before "release" operation, ticket
  /// value is set to the value+1 in case inc_next_before_release is equal to
  /// true
  AtomicBgcTicketGuard(AtomicBgcTicket &bgcTicket,
                       bool inc_next_before_release = false);
 
 protected:
  std::reference_wrapper<AtomicBgcTicket>
      m_ref;  ///< For threads to synchronize properly, AtomicBgcTicketGuard
              ///< instances must operate on the same instance of
              ///< AtomicBgcTicket. This is a reference to atomic Bgc ticket
              ///< instance, used by different instances of the BgcTicketGuard
              ///< class (e.g. front/back ticket in BgcTicketManager class)
  BgcTicket m_next_value;  ///< value to be set during the "release" op
  BgcTicket m_prev_value;  ///< previous ticket value, obtained during the
                           ///< "acquire" op
};
 
}  // namespace binlog
 
#endif  // BINLOG_ATOMIC_BCG_TICKET_GUARD_H