Represents and encapsulates the logic responsible for handling the auto-rejoin process within Group Replication. More...

#include <autorejoin.h>

Public Member Functions
	Autorejoin_thread (const Autorejoin_thread &)=delete
	Deleted copy ctor. More...

	Autorejoin_thread (const Autorejoin_thread &&)=delete
	Deleted move ctor. More...

Autorejoin_thread &	operator= (const Autorejoin_thread &)=delete
	Deleted assignment operator. More...

Autorejoin_thread &	operator= (const Autorejoin_thread &&)=delete
	Deleted move operator. More...

	Autorejoin_thread ()
	Initializes the synchronization primitives of the thread. More...

	~Autorejoin_thread ()
	The dtor for the thread will destroy the mutex and cond_var. More...

void	init ()
	Initializes the auto-rejoin module with a clean slate, i.e. More...

bool	abort_rejoin ()
	Aborts the thread's main loop, effectively killing the thread. More...

int	start_autorejoin (uint attempts, ulonglong timeout)
	Starts the process of auto-rejoin, launches the thread that will call attempt_rejoin() until it succeeds or until it reaches a given amount of maximum retries, waiting on a conditional variable each iteration with a given timeout. More...

bool	is_autorejoin_ongoing ()
	Returns a flag indicating whether or not the auto-rejoin process is ongoing on this thread. More...

Private Member Functions
void	autorejoin_thread_handle ()
	The thread handle, i.e. More...

void	execute_rejoin_process ()
	Handles the busy-wait retry loop. More...

Static Private Member Functions
static void *	launch_thread (void *arg)
	The thread callback passed onto mysql_thread_create. More...

Private Attributes
THD *	m_thd
	the THD handle. More...

thread_state	m_autorejoin_thd_state
	the state of the thread. More...

my_thread_handle	m_handle
	the thread handle. More...

mysql_mutex_t	m_run_lock
	the mutex for controlling access to the thread itself. More...

mysql_cond_t	m_run_cond
	the cond_var used to signal the thread. More...

std::atomic< bool >	m_abort
	flag to indicate whether or not the thread is to be aborted. More...

bool	m_being_terminated
	flag that indicates that the auto-rejoin module is in the process of being terminated. More...

ulong	m_attempts
	the number of attempts for the rejoin. More...

ulonglong	m_rejoin_timeout
	the time to wait in seconds until the next rejoin attempt. More...

Detailed Description

Represents and encapsulates the logic responsible for handling the auto-rejoin process within Group Replication.

The auto-rejoin process kicks in one of two possible situations: either the member was expelled from the group or the member lost contact to a majority of the group. The auto-rejoin feature must also be explicitly enabled by setting the group_replication_autorejoin_tries sysvar to a value greater than 0.

This thread will do a busy-wait loop for group_replication_autorejoin_tries number of attempts, waiting 5 minutes between each attempt (this wait is achieved via a timed wait on a conditional variable).

We execute the auto-rejoin process in its own thead because the join operation of the GCS layer is asynchronous. We cannot actually block while waiting for a confirmation if the server managed to join the group or not. As such, we wait on a callback invoked by an entity that is registered as a GCS event listener.

See also: Plugin_gcs_events_handler

Constructor & Destructor Documentation

◆ Autorejoin_thread() [1/3]

Autorejoin_thread::Autorejoin_thread ( const Autorejoin_thread & )

delete

Deleted copy ctor.

◆ Autorejoin_thread() [2/3]

Autorejoin_thread::Autorejoin_thread ( const Autorejoin_thread && )

delete

Deleted move ctor.

◆ Autorejoin_thread() [3/3]

Autorejoin_thread::Autorejoin_thread ( )

Initializes the synchronization primitives of the thread.

◆ ~Autorejoin_thread()

Autorejoin_thread::~Autorejoin_thread ( )

The dtor for the thread will destroy the mutex and cond_var.

Member Function Documentation

◆ abort_rejoin()

bool Autorejoin_thread::abort_rejoin ( )

Aborts the thread's main loop, effectively killing the thread.

Returns: a flag indicating whether or not the auto-rejoin procedure was ongoing at the time the abort was requested.

Return values

true	the auto-rejoin was ongoing
false	the auto-rejoin wasn't running

◆ autorejoin_thread_handle()

void Autorejoin_thread::autorejoin_thread_handle ( )

private

The thread handle, i.e.

setups and tearsdown the infrastructure for this mysql_thread.

◆ execute_rejoin_process()

void Autorejoin_thread::execute_rejoin_process ( )

private

Handles the busy-wait retry loop.

◆ init()

void Autorejoin_thread::init ( )

Initializes the auto-rejoin module with a clean slate, i.e.

it resets any state/flags that are checked in start_autorejoin().

See also: start_autorejoin

◆ is_autorejoin_ongoing()

bool Autorejoin_thread::is_autorejoin_ongoing ( )

Returns a flag indicating whether or not the auto-rejoin process is ongoing on this thread.

Returns: the state of the rejoin process.

Return values

true	if the auto-rejoin is ongoing
false	otherwise

◆ launch_thread()

void * Autorejoin_thread::launch_thread ( void * arg )

staticprivate

The thread callback passed onto mysql_thread_create.

Parameters

[in] arg a pointer to an Autorejoin_thread instance.

Returns: Does not return.

◆ operator=() [1/2]

Autorejoin_thread & Autorejoin_thread::operator= ( const Autorejoin_thread && )

delete

Deleted move operator.

◆ operator=() [2/2]

Autorejoin_thread & Autorejoin_thread::operator= ( const Autorejoin_thread & )

delete

Deleted assignment operator.

◆ start_autorejoin()

int Autorejoin_thread::start_autorejoin	(	uint	attempts,
		ulonglong	timeout
	)

Starts the process of auto-rejoin, launches the thread that will call attempt_rejoin() until it succeeds or until it reaches a given amount of maximum retries, waiting on a conditional variable each iteration with a given timeout.

An auto-rejoin can only start if it isn't already running or if the auto-rejoin module is not in the process of being terminated.

Parameters

[in]	attempts	the number of attempts we will try to rejoin.
[in]	timeout	the time to wait between each retry.

Returns: whether or not we managed to launch the auto-rejoin thread.

Return values

0	the thread launched successfully
!=	0 the thread couldn't be launched

See also: mysql_thread_create

Member Data Documentation

◆ m_abort

std::atomic<bool> Autorejoin_thread::m_abort

private

flag to indicate whether or not the thread is to be aborted.

◆ m_attempts

ulong Autorejoin_thread::m_attempts

private

the number of attempts for the rejoin.

◆ m_autorejoin_thd_state

thread_state Autorejoin_thread::m_autorejoin_thd_state

private

the state of the thread.

◆ m_being_terminated

bool Autorejoin_thread::m_being_terminated

private

flag that indicates that the auto-rejoin module is in the process of being terminated.

◆ m_handle

my_thread_handle Autorejoin_thread::m_handle

private

the thread handle.

◆ m_rejoin_timeout

ulonglong Autorejoin_thread::m_rejoin_timeout

private

the time to wait in seconds until the next rejoin attempt.

◆ m_run_cond

mysql_cond_t Autorejoin_thread::m_run_cond

private

the cond_var used to signal the thread.

◆ m_run_lock

mysql_mutex_t Autorejoin_thread::m_run_lock

private

the mutex for controlling access to the thread itself.

◆ m_thd

THD* Autorejoin_thread::m_thd

private

the THD handle.

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

plugin/group_replication/include/autorejoin.h
plugin/group_replication/src/autorejoin.cc

Public Member Functions

Private Member Functions

Static Private Member Functions

Private Attributes

Detailed Description

Constructor & Destructor Documentation

◆ Autorejoin_thread() [1/3]

◆ Autorejoin_thread() [2/3]

◆ Autorejoin_thread() [3/3]

◆ ~Autorejoin_thread()

Member Function Documentation

◆ abort_rejoin()

◆ autorejoin_thread_handle()

◆ execute_rejoin_process()

◆ init()

◆ is_autorejoin_ongoing()

◆ launch_thread()

◆ operator=() [1/2]

◆ operator=() [2/2]

◆ start_autorejoin()

Member Data Documentation

◆ m_abort

◆ m_attempts

◆ m_autorejoin_thd_state

◆ m_being_terminated

◆ m_handle

◆ m_rejoin_timeout

◆ m_run_cond

◆ m_run_lock

◆ m_thd