Consensus_leaders_handler Class Reference

Deals with the orchestration necessary to set the appropriate "consensus leaders" on GCS. More...

#include <consensus_leaders_handler.h>

Inheritance diagram for Consensus_leaders_handler:

Public Member Functions
	Consensus_leaders_handler (Group_events_observation_manager &group_events_manager)
	Register as a group event observer in group_events_manager. More...
	~Consensus_leaders_handler () override
	Unregister as a group event observer from m_group_events_manager. More...
int	after_view_change (const std::vector< Gcs_member_identifier > &joining, const std::vector< Gcs_member_identifier > &leaving, const std::vector< Gcs_member_identifier > &group, bool is_leaving, bool *skip_election, enum_primary_election_mode *election_mode, std::string &suggested_primary) override
	Executed after view install and before primary election. More...
int	after_primary_election (std::string primary_uuid, enum_primary_election_primary_change_status primary_change_status, enum_primary_election_mode election_mode, int error) override
	Sets the newly elected primary as the single preferred "consensus leader" in GCS. More...
int	before_message_handling (const Plugin_gcs_message &message, const std::string &message_origin, bool *skip_message) override
	Executed before the message is processed. More...
void	set_consensus_leaders (Member_version const &communication_protocol, bool is_single_primary_mode, Group_member_info::Group_member_role role, Gcs_member_identifier const &my_gcs_id, std::function< bool()> allow_single_leader_getter)
	Set the appropriate "consensus leaders" in GCS. More...
void	set_consensus_leaders (Member_version const &communication_protocol, bool is_single_primary_mode, Group_member_info::Group_member_role role, Gcs_member_identifier const &my_gcs_id)
	Set the appropriate "consensus leaders" in GCS. More...
Public Member Functions inherited from Group_event_observer
virtual	~Group_event_observer ()=0

Private Member Functions
void	set_as_single_consensus_leader (Gcs_member_identifier const &leader) const
void	set_everyone_as_consensus_leader () const

Private Attributes
Group_events_observation_manager &	m_group_events_manager

Static Private Attributes
static Member_version const	s_first_protocol_with_support_for_consensus_leaders

Detailed Description

Deals with the orchestration necessary to set the appropriate "consensus leaders" on GCS.

Reacts to successful primary elections by setting the newly elected primary as the single preferred "consensus leader" in GCS.

Constructor & Destructor Documentation

Consensus_leaders_handler()

Consensus_leaders_handler::Consensus_leaders_handler

(

Group_events_observation_manager &

group_events_manager

)

Register as a group event observer in group_events_manager.

First member version where we have XCom's single leader.

~Consensus_leaders_handler()

Consensus_leaders_handler::~Consensus_leaders_handler ( )

override

Unregister as a group event observer from m_group_events_manager.

Member Function Documentation

after_primary_election()

int Consensus_leaders_handler::after_primary_election ( std::string  primary_uuid, enum_primary_election_primary_change_status  primary_change_status, enum_primary_election_mode  election_mode, int  error  )

overridevirtual

Sets the newly elected primary as the single preferred "consensus leader" in GCS.

Parameters

primary_uuid	the elected primary
primary_change_status	if the primary changed after the election
election_mode	what was the election mode
error	if there was and error on the process

Returns

int 0 on success

Implements Group_event_observer.

after_view_change()

int Consensus_leaders_handler::after_view_change ( const std::vector< Gcs_member_identifier > &  joining, const std::vector< Gcs_member_identifier > &  leaving, const std::vector< Gcs_member_identifier > &  group, bool  is_leaving, bool *  skip_election, enum_primary_election_mode *  election_mode, std::string &  suggested_primary  )

overridevirtual

Executed after view install and before primary election.

Parameters

	joining	members joining the group
	leaving	members leaving the group
	group	members in the group
	is_leaving	is the member leaving
[out]	skip_election	skip primary election on view
[out]	election_mode	election mode
[out]	suggested_primary	what should be the next primary to elect

Implements Group_event_observer.

before_message_handling()

int Consensus_leaders_handler::before_message_handling ( const Plugin_gcs_message &  message, const std::string &  message_origin, bool *  skip_message  )

overridevirtual

Executed before the message is processed.

Parameters

	message	The GCS message
	message_origin	The member that sent this message (address)
[out]	skip_message	skip message handling if true

Implements Group_event_observer.

set_as_single_consensus_leader()

void Consensus_leaders_handler::set_as_single_consensus_leader ( Gcs_member_identifier const &  leader ) const

private

set_consensus_leaders() [1/2]

void Consensus_leaders_handler::set_consensus_leaders	(	Member_version const &	communication_protocol,
		bool	is_single_primary_mode,
		Group_member_info::Group_member_role	role,
		Gcs_member_identifier const &	my_gcs_id
	)

Set the appropriate "consensus leaders" in GCS.

The "consensus leaders" are set according to the following rules: a) communication_protocol is < 8.0.27: do nothing b) communication_protocol is >= 8.0.27: b1) primary_mode is SINGLE and my_role is PRIMARY: set myself, my_gcs_id, as the single preferred "consensus leader" b2) primary_mode is SINGLE and my_role is SECONDARY: do nothing b3) primary_mode is MULTI: set everyone as "consensus leader"

It inserts a default implementation of allow_single_leader_getter that verifies the current value of group_replication_paxos_single_leader var

set_consensus_leaders() [2/2]

void Consensus_leaders_handler::set_consensus_leaders	(	Member_version const &	communication_protocol,
		bool	is_single_primary_mode,
		Group_member_info::Group_member_role	role,
		Gcs_member_identifier const &	my_gcs_id,
		std::function< bool()>	allow_single_leader_getter
	)

Set the appropriate "consensus leaders" in GCS.

The "consensus leaders" are set according to the following rules: 0) If the the return result of allow_single_leader_getter lambda is false :do nothing a) communication_protocol is < 8.0.27: do nothing b) communication_protocol is >= 8.0.27: b1) primary_mode is SINGLE and my_role is PRIMARY: set myself, my_gcs_id, as the single preferred "consensus leader" b2) primary_mode is SINGLE and my_role is SECONDARY: do nothing b3) primary_mode is MULTI: set everyone as "consensus leader"

set_everyone_as_consensus_leader()

void Consensus_leaders_handler::set_everyone_as_consensus_leader ( ) const

private

Member Data Documentation

m_group_events_manager

Group_events_observation_manager& Consensus_leaders_handler::m_group_events_manager

private

s_first_protocol_with_support_for_consensus_leaders

Member_version const Consensus_leaders_handler::s_first_protocol_with_support_for_consensus_leaders

staticprivate

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The documentation for this class was generated from the following files:

• plugin/group_replication/include/plugin_handlers/consensus_leaders_handler.h
• plugin/group_replication/src/plugin_handlers/consensus_leaders_handler.cc