gcs_group_management_interface.h

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/* Copyright (c) 2016, 2024, Oracle and/or its affiliates.
 
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#ifndef GCS_GROUP_MANAGEMENT_INTERFACE_INCLUDED
#define GCS_GROUP_MANAGEMENT_INTERFACE_INCLUDED
 
#include "plugin/group_replication/libmysqlgcs/include/mysql/gcs/gcs_member_identifier.h"
#include "plugin/group_replication/libmysqlgcs/include/mysql/gcs/gcs_types.h"
 
#include <cstdint>
 
class Gcs_group_management_interface {
 public:
  /**
    Method that allows sending of a new group configuration. This is
    to be used when the group is blocked due to a loss of majority and
    only on one node from the new group.
 
    Implementations in each binding might have there specificities but some
    rules must be followed:
    - This should be a non-blocking call;
    - Typically, it shall cause a View Change, since we are forcing a new
      configuration.
 
    @param[in] reconfigured_group a list containing the new nodes
  */
 
  virtual enum_gcs_error modify_configuration(
      const Gcs_interface_parameters &reconfigured_group) = 0;
 
  /**
    Retrieves the minimum supported "write concurrency" value.
  */
  virtual uint32_t get_minimum_write_concurrency() const = 0;
 
  /**
    Retrieves the maximum supported "write concurrency" value.
  */
  virtual uint32_t get_maximum_write_concurrency() const = 0;
 
  /**
    Retrieves the group's "write concurrency" value.
 
    @param[out] write_concurrency A reference to where the group's
                "write concurrency" value will be written to
 
    @retval GCS_OK if successful and write_concurrency has been written to
    @retval GCS_NOK if GCS was unable to request the current "write concurrency"
                    value from the underlying implementation
  */
  virtual enum_gcs_error get_write_concurrency(
      uint32_t &write_concurrency) const = 0;
 
  /**
    Reconfigures the group's "write concurrency" value.
 
    The caller should ensure that the supplied value is between @c
    minimum_write_concurrency and @c maximum_write_concurrency.
 
    The method is non-blocking, meaning that it shall only send the request to
    an underlying GCS. The final result can be polled via @c
    get_write_concurrency.
 
    @param write_concurrency The desired "write concurrency" value.
 
    @retval GCS_OK if successful
    @retval GCS_NOK if unsuccessful
  */
  virtual enum_gcs_error set_write_concurrency(uint32_t write_concurrency) = 0;
 
  virtual ~Gcs_group_management_interface() = default;
 
  /**
   * @brief Reconfigures the group's "consensus leaders."
   *
   * Instructs the underlying GCS to use @c leader as the single preferred
   * consensus leader.
   *
   * @param leader The member you desire to act as a consensus leader.
   *
   * @retval GCS_OK if successful
   * @retval GCS_NOK if unsuccessful
   */
  virtual enum_gcs_error set_single_leader(
      Gcs_member_identifier const &leader) = 0;
 
  /**
   * @brief Reconfigures the group's "consensus leaders."
   *
   * Instructs the underlying GCS to use every member as a consensus leader.
   *
   * @retval GCS_OK if successful
   * @retval GCS_NOK if unsuccessful
   */
  virtual enum_gcs_error set_everyone_leader() = 0;
 
  /**
   * @brief Inspect the group's "consensus leader" configuration.
   *
   * @param[out] preferred_leaders The members specified as preferred leaders.
   * @param[out] actual_leaders The members actually carrying out the leader
   * role at this moment.
   *
   * @retval GCS_OK if successful, @c preferred_leaders and @c actual_leaders
   * contain the result
   * @retval GCS_NOK if unsuccessful
   */
  virtual enum_gcs_error get_leaders(
      std::vector<Gcs_member_identifier> &preferred_leaders,
      std::vector<Gcs_member_identifier> &actual_leaders) = 0;
};
 
#endif  // GCS_GROUP_MANAGEMENT_INTERFACE_INCLUDED