rescue_task.h

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#ifndef MYSQL_CSA_SERVICE_RESCUE_TASK_H
#define MYSQL_CSA_SERVICE_RESCUE_TASK_H
 
#include <future>
#include "mysql/utils/return_status.h"
#include "sql/rpl_rli.h"
 
namespace mysql::csa {
 
/// Types of rescue operations
enum class Rescue_operation_type {
  rollback  // rollback conflicting transaction
};
 
/// Rescue task to rollback conflicting transaction
class Rescue_task {
 public:
  /// Constructor
  /// @param rli RLI attached to the transaction to rescue
  /// @param op_type Rescue operation type
  /// @param action_promise Promise used to synchronize thread waiting for
  /// rescue operation to finish
  /// @param job_id Job internal identifier
  Rescue_task(Relay_log_info *rli, Rescue_operation_type op_type,
              std::promise<bool> &action_promise, int job_id);
  /// Default constructor, required by synchronized queue
  Rescue_task() = default;
  /// Perform rescue operation
  void operator()();
  /// Sets promise value, e.g. in case when task cannot be executed (stop)
  void set_promise();
 
 private:
  /// Rolls back transaction attached to RLI
  void rollback_trx();
  /// RLI attached to the transaction to rescue
  Relay_log_info *m_rli{nullptr};
  /// Rescue operation type
  Rescue_operation_type m_rescue_operation_type{
      Rescue_operation_type::rollback};
  /// Promise to synchronize on after operation is done
  std::optional<std::reference_wrapper<std::promise<bool>>> m_action_promise;
  /// Job internal identifier
  int m_job_id{0};
};
 
}  // namespace mysql::csa
 
#endif  // MYSQL_CSA_SERVICE_RESCUE_TASK_H