This class maintains THD object of all registered threads. More...

#include <mysqld_thd_manager.h>

Public Member Functions
void	set_unit_test ()
	Internally used to bypass code. More...

void	add_thd (THD *thd)
	Adds THD to global THD list. More...

void	remove_thd (THD *thd)
	Removes THD from global THD list. More...

int	get_num_thread_running () const
	Retrieves thread running statistic variable. More...

void	inc_thread_running ()
	Increments thread running statistic variable. More...

void	dec_thread_running ()
	Decrements thread running statistic variable. More...

ulonglong	get_num_thread_created () const
	Retrieves thread created statistic variable. More...

void	inc_thread_created ()
	Increments thread created statistic variable. More...

my_thread_id	get_new_thread_id ()
	Returns an unused thread id. More...

void	release_thread_id (my_thread_id thread_id)
	Releases a thread id so that it can be reused. More...

my_thread_id	get_thread_id () const
	Retrieves thread id counter value. More...

void	set_thread_id_counter (my_thread_id new_id)
	Sets thread id counter value. More...

void	wait_till_no_thd ()
	Waits until all THDs are removed from global THD lists (all partitions). More...

void	do_for_all_thd_copy (Do_THD_Impl *func)
	This function calls func() for all THDs in every thd list partition after taking local copy of the THD list partition. More...

void	do_for_all_thd (Do_THD_Impl *func)
	This function calls func() for all THDs in all THD list partitions. More...

void	do_for_first_n_thd (Do_THD_Impl *func, uint n)
	This function calls func() for all first "n" THDs across all THD list partitions. More...

THD_ptr	find_thd (Find_THD_Impl *func)
	Returns a THD_ptr containing first THD for which operator() returns true. More...

THD_ptr	find_thd (Find_thd_with_id *func)

Static Public Member Functions
static Global_THD_manager *	get_instance ()
	Retrieves singleton instance. More...

static bool	is_initialized ()
	Checks if the singleton is not already deinitialized. More...

static bool	create_instance ()
	Initializes the thd manager. More...

static void	destroy_instance ()
	Destroys the singleton instance. More...

static uint	get_thd_count ()
	Retrieves total number of items in global THD lists (all partitions). More...

Static Public Attributes
static const my_thread_id	reserved_thread_id = 0
	Value for thread_id reserved for THDs which does not have an assigned value yet. More...

static std::atomic< uint >	atomic_global_thd_count {0U}

static const int	NUM_PARTITIONS = 8

Private Types
typedef Prealloced_array< THD *, 60 >	THD_array

typedef Prealloced_array< my_thread_id, 1000 >	Thread_id_array

Private Member Functions
	Global_THD_manager ()

	~Global_THD_manager ()

Private Attributes
THD_array	thd_list [NUM_PARTITIONS]

Thread_id_array	thread_ids

mysql_cond_t	COND_thd_list [NUM_PARTITIONS]

mysql_mutex_t	LOCK_thd_list [NUM_PARTITIONS]

mysql_mutex_t	LOCK_thd_remove [NUM_PARTITIONS]

mysql_mutex_t	LOCK_thread_ids

std::atomic< int >	atomic_num_thread_running

std::atomic< ulonglong >	atomic_thread_created

my_thread_id	thread_id_counter

bool	unit_test

Static Private Attributes
static Global_THD_manager *	thd_manager = nullptr

Friends
void	thd_lock_thread_count ()

void	thd_unlock_thread_count ()

Detailed Description

This class maintains THD object of all registered threads.

It provides interface to perform functions such as find, count, perform some action for each THD object in the list.

It also provide mutators for inserting, and removing an element: add_thd() inserts a THD into the set, and increments the counter. remove_thd() removes a THD from the set, and decrements the counter. Method remove_thd() also broadcasts COND_thd_list.

Member Typedef Documentation

◆ THD_array

typedef Prealloced_array<THD *, 60> Global_THD_manager::THD_array

private

◆ Thread_id_array

typedef Prealloced_array<my_thread_id, 1000> Global_THD_manager::Thread_id_array

private

Constructor & Destructor Documentation

◆ Global_THD_manager()

Global_THD_manager::Global_THD_manager ( )

private

◆ ~Global_THD_manager()

Global_THD_manager::~Global_THD_manager ( )

private

Member Function Documentation

◆ add_thd()

void Global_THD_manager::add_thd ( THD * thd )

Adds THD to global THD list.

Parameters

thd	THD object

◆ create_instance()

bool Global_THD_manager::create_instance ( )

static

Initializes the thd manager.

Must be called before get_instance() can be used.

Returns: true if initialization failed, false otherwise.

◆ dec_thread_running()

void Global_THD_manager::dec_thread_running ( )

inline

Decrements thread running statistic variable.

◆ destroy_instance()

void Global_THD_manager::destroy_instance ( )

static

Destroys the singleton instance.

◆ do_for_all_thd()

void Global_THD_manager::do_for_all_thd ( Do_THD_Impl * func )

This function calls func() for all THDs in all THD list partitions.

Parameters

func	Object of class which overrides operator()

Note: One list partition is unlocked before the next partition is locked.

◆ do_for_all_thd_copy()

void Global_THD_manager::do_for_all_thd_copy ( Do_THD_Impl * func )

This function calls func() for all THDs in every thd list partition after taking local copy of the THD list partition.

It acquires LOCK_thd_remove to prevent removal of the THD.

Parameters

func	Object of class which overrides operator()

◆ do_for_first_n_thd()

void Global_THD_manager::do_for_first_n_thd	(	Do_THD_Impl *	func,
		uint	n
	)

This function calls func() for all first "n" THDs across all THD list partitions.

Parameters

func	Object of class which overrides operator()
n	number of elements we want to call func for

◆ find_thd() [1/2]

THD_ptr Global_THD_manager::find_thd ( Find_THD_Impl * func )

Returns a THD_ptr containing first THD for which operator() returns true.

Parameters

func	Object of class which overrides operator()

Returns: THD_ptr

Return values

THD_ptr{THD*}	When matching THD is found.
THD_ptr{nullptr}	When THD is not found.

◆ find_thd() [2/2]

THD_ptr Global_THD_manager::find_thd ( Find_thd_with_id * func )

◆ get_instance()

static Global_THD_manager * Global_THD_manager::get_instance ( )

inlinestatic

Retrieves singleton instance.

◆ get_new_thread_id()

my_thread_id Global_THD_manager::get_new_thread_id ( )

Returns an unused thread id.

◆ get_num_thread_created()

ulonglong Global_THD_manager::get_num_thread_created ( ) const

inline

Retrieves thread created statistic variable.

Returns: ulonglong Returns the total number of threads created after server start

◆ get_num_thread_running()

int Global_THD_manager::get_num_thread_running ( ) const

inline

Retrieves thread running statistic variable.

Returns: int Returns the total number of threads currently running

◆ get_thd_count()

static uint Global_THD_manager::get_thd_count ( )

inlinestatic

Retrieves total number of items in global THD lists (all partitions).

Returns: uint Returns the count of items in global THD lists.

◆ get_thread_id()

my_thread_id Global_THD_manager::get_thread_id ( ) const

inline

Retrieves thread id counter value.

Returns: my_thread_id Returns the thread id counter value

Note: This is a dirty read.

◆ inc_thread_created()

void Global_THD_manager::inc_thread_created ( )

inline

Increments thread created statistic variable.

◆ inc_thread_running()

void Global_THD_manager::inc_thread_running ( )

inline

Increments thread running statistic variable.

◆ is_initialized()

static bool Global_THD_manager::is_initialized ( )

inlinestatic

Checks if the singleton is not already deinitialized.

◆ release_thread_id()

void Global_THD_manager::release_thread_id ( my_thread_id thread_id )

Releases a thread id so that it can be reused.

Note that this is done automatically by remove_thd().

◆ remove_thd()

void Global_THD_manager::remove_thd ( THD * thd )

Removes THD from global THD list.

Parameters

thd	THD object

◆ set_thread_id_counter()

void Global_THD_manager::set_thread_id_counter ( my_thread_id new_id )

Sets thread id counter value.

Only used in testing for now.

Parameters

new_id The next ID to hand out (if it's unused).

◆ set_unit_test()

void Global_THD_manager::set_unit_test ( )

inline

Internally used to bypass code.

It enables unit test scripts to create dummy THD object for testing.

◆ wait_till_no_thd()

void Global_THD_manager::wait_till_no_thd ( )

Waits until all THDs are removed from global THD lists (all partitions).

In other words, get_thd_count() to become zero.

Friends And Related Function Documentation

◆ thd_lock_thread_count

void thd_lock_thread_count ( )

friend

◆ thd_unlock_thread_count

void thd_unlock_thread_count ( )

friend

Member Data Documentation

◆ atomic_global_thd_count

std::atomic< uint > Global_THD_manager::atomic_global_thd_count {0U}

static

◆ atomic_num_thread_running

std::atomic<int> Global_THD_manager::atomic_num_thread_running

private

◆ atomic_thread_created

std::atomic<ulonglong> Global_THD_manager::atomic_thread_created

private

◆ COND_thd_list

mysql_cond_t Global_THD_manager::COND_thd_list[NUM_PARTITIONS]

private

◆ LOCK_thd_list

mysql_mutex_t Global_THD_manager::LOCK_thd_list[NUM_PARTITIONS]

private

◆ LOCK_thd_remove

mysql_mutex_t Global_THD_manager::LOCK_thd_remove[NUM_PARTITIONS]

private

◆ LOCK_thread_ids

mysql_mutex_t Global_THD_manager::LOCK_thread_ids

private

◆ NUM_PARTITIONS

const int Global_THD_manager::NUM_PARTITIONS = 8

static

◆ reserved_thread_id

const my_thread_id Global_THD_manager::reserved_thread_id = 0

static

Value for thread_id reserved for THDs which does not have an assigned value yet.

get_new_thread_id() will never return this value.

◆ thd_list

THD_array Global_THD_manager::thd_list[NUM_PARTITIONS]

private

◆ thd_manager

Global_THD_manager * Global_THD_manager::thd_manager = nullptr

staticprivate

◆ thread_id_counter

my_thread_id Global_THD_manager::thread_id_counter

private

◆ thread_ids

Thread_id_array Global_THD_manager::thread_ids

private

◆ unit_test

bool Global_THD_manager::unit_test

private

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

sql/mysqld_thd_manager.h
sql/mysqld_thd_manager.cc

Public Member Functions

Static Public Member Functions

Static Public Attributes

Private Types

Private Member Functions

Private Attributes

Static Private Attributes

Friends

Detailed Description

Member Typedef Documentation

◆ THD_array

◆ Thread_id_array

Constructor & Destructor Documentation

◆ Global_THD_manager()

◆ ~Global_THD_manager()

Member Function Documentation

◆ add_thd()

◆ create_instance()

◆ dec_thread_running()

◆ destroy_instance()

◆ do_for_all_thd()

◆ do_for_all_thd_copy()

◆ do_for_first_n_thd()

◆ find_thd() [1/2]

◆ find_thd() [2/2]

◆ get_instance()

◆ get_new_thread_id()

◆ get_num_thread_created()

◆ get_num_thread_running()

◆ get_thd_count()

◆ get_thread_id()

◆ inc_thread_created()

◆ inc_thread_running()

◆ is_initialized()

◆ release_thread_id()

◆ remove_thd()

◆ set_thread_id_counter()

◆ set_unit_test()

◆ wait_till_no_thd()

Friends And Related Function Documentation

◆ thd_lock_thread_count

◆ thd_unlock_thread_count

Member Data Documentation

◆ atomic_global_thd_count

◆ atomic_num_thread_running

◆ atomic_thread_created

◆ COND_thd_list

◆ LOCK_thd_list

◆ LOCK_thd_remove

◆ LOCK_thread_ids

◆ NUM_PARTITIONS

◆ reserved_thread_id

◆ thd_list

◆ thd_manager

◆ thread_id_counter

◆ thread_ids

◆ unit_test