The class for read-only variables that show whether a particular feature is supported by the server. More...

#include <sys_vars.h>

Inheritance diagram for Sys_var_have:

Public Member Functions
	Sys_var_have (const char name_arg, const char comment, int flag_args, ptrdiff_t off, size_t size, CMD_LINE getopt, PolyLock lock=nullptr, enum binlog_status_enum binlog_status_arg=VARIABLE_NOT_IN_BINLOG, on_check_function on_check_func=nullptr, on_update_function on_update_func=nullptr, const char substitute=nullptr, int parse_flag=PARSE_NORMAL)

bool	do_check (THD , set_var ) override

bool	session_update (THD , set_var ) override

bool	global_update (THD , set_var ) override

void	session_save_default (THD , set_var ) override
	save the session default value of the variable in var More...

void	global_save_default (THD , set_var ) override
	save the global default value of the variable in var More...

void	saved_value_to_string (THD , set_var , char *) override
	This function converts value stored in save_result to string. More...

const uchar *	session_value_ptr (THD , THD , std::string_view) override
	A pointer to a value of the variable for SHOW. More...

const uchar *	global_value_ptr (THD *, std::string_view) override

bool	check_update_type (Item_result) override

Public Member Functions inherited from sys_var
	sys_var (sys_var_chain chain, const char name_arg, const char comment, int flag_args, ptrdiff_t off, int getopt_id, enum get_opt_arg_type getopt_arg_type, SHOW_TYPE show_val_type_arg, longlong def_val, PolyLock lock, enum binlog_status_enum binlog_status_arg, on_check_function on_check_func, on_update_function on_update_func, const char substitute, int parse_flag, sys_var persisted_alias=nullptr, bool is_persisted_deprecated=false)
	sys_var constructor More...

virtual	~sys_var ()=default

const char *	get_deprecation_substitute ()

virtual void	cleanup ()
	All the cleanup procedures should be performed here. More...

virtual sys_var_pluginvar *	cast_pluginvar ()
	downcast for sys_var_pluginvar. More...

bool	check (THD thd, set_var var)

const uchar *	value_ptr (THD running_thd, THD target_thd, enum_var_type type, std::string_view keycache_name)

const uchar *	value_ptr (THD *thd, enum_var_type type, std::string_view keycache_name)

virtual void	update_default (longlong new_def_value)

virtual longlong	get_default ()

virtual longlong	get_min_value ()

virtual ulonglong	get_max_value ()

virtual ulong	get_var_type ()
	Returns variable type. More...

virtual void	set_arg_source (get_opt_arg_source *)

virtual void	set_is_plugin (bool)

virtual enum_variable_source	get_source ()

virtual const char *	get_source_name ()

virtual void	set_source (enum_variable_source src)

virtual bool	set_source_name (const char *path)

virtual bool	set_user (const char *usr)

virtual const char *	get_user ()

virtual const char *	get_host ()

virtual bool	set_host (const char *hst)

virtual ulonglong	get_timestamp () const

virtual void	set_user_host (THD *thd)

my_option *	get_option ()

virtual void	set_timestamp ()

virtual void	set_timestamp (ulonglong ts)

virtual bool	is_non_persistent ()

bool	set_default (THD thd, set_var var)
	Update the system variable with the default value from either session or global scope. More...

bool	update (THD thd, set_var var)

SHOW_TYPE	show_type ()

int	scope () const

const CHARSET_INFO *	charset (THD *thd)

bool	is_readonly () const

bool	not_visible () const

bool	is_trilevel () const

bool	is_persist_readonly () const

bool	is_parse_early () const

bool	is_sensitive () const

bool	is_hint_updateable () const
	Check if the variable can be set using SET_VAR hint. More...

bool	is_struct ()
	the following is only true for keycache variables, that support the syntax @keycache_name.variable_name More...

bool	is_written_to_binlog (enum_var_type type)

bool	check_scope (enum_var_type query_type)
	Return true for success if: Global query and variable scope is GLOBAL or SESSION, or Session query and variable scope is SESSION or ONLY_SESSION. More...

bool	is_global_persist (enum_var_type type)

bool	is_settable_at_command_line ()
	Return true if settable at the command line. More...

bool	register_option (std::vector< my_option > *array, int parse_flags)

void	do_deprecated_warning (THD *thd)

Item *	copy_value (THD *thd)
	Create item from system variable value. More...

void	save_default (THD thd, set_var var)

bool	check_if_sensitive_in_context (THD *, bool suppress_errors=true) const

Additional Inherited Members
Public Types inherited from sys_var
enum	flag_enum { GLOBAL = 0x0001 , SESSION = 0x0002 , ONLY_SESSION = 0x0004 , SCOPE_MASK = 0x03FF , READONLY = 0x0400 , ALLOCATED = 0x0800 , INVISIBLE = 0x1000 , TRI_LEVEL = 0x2000 , NOTPERSIST = 0x4000 , HINT_UPDATEABLE = 0x8000 , PERSIST_AS_READ_ONLY = 0x10000 , SENSITIVE = 0x20000 }

enum	binlog_status_enum { VARIABLE_NOT_IN_BINLOG , SESSION_VARIABLE_IN_BINLOG }
	Enumeration type to indicate for a system variable whether it will be written to the binlog or not. More...

Public Attributes inherited from sys_var
sys_var *	next

LEX_CSTRING	name

sys_var *	m_persisted_alias
	If the variable has an alias in the persisted variables file, this should point to it. More...

bool	m_is_persisted_deprecated
	If m_persist_alias is set, and the current variable is deprecated and m_persist_alias is the recommended substitute, then this flag should be set to true. More...

enum sys_var::binlog_status_enum	binlog_status

Static Public Attributes inherited from sys_var
static const int	PARSE_EARLY = 1

static const int	PARSE_NORMAL = 2

Protected Types inherited from sys_var
typedef bool(*	on_check_function) (sys_var self, THD thd, set_var *var)

typedef bool(*	pre_update_function) (sys_var self, THD thd, set_var *var)

typedef bool(*	on_update_function) (sys_var self, THD thd, enum_var_type type)

Protected Member Functions inherited from sys_var
uchar *	session_var_ptr (THD *thd)
	A pointer to a storage area of the variable, to the raw data. More...

uchar *	global_var_ptr ()

Protected Attributes inherited from sys_var
int	flags
	or'ed flag_enum values More...

int	m_parse_flag
	either PARSE_EARLY or PARSE_NORMAL. More...

const SHOW_TYPE	show_val_type
	what value_ptr() returns for sql_show.cc More...

my_option	option
	min, max, default values are stored here More...

PolyLock *	guard
	second lock that protects the variable More...

ptrdiff_t	offset
	offset to the value from global_system_variables More...

on_check_function	on_check

pre_update_function	pre_update
	Pointer to function to be invoked before updating system variable (but after calling on_check hook), while we do not hold any locks yet. More...

on_update_function	on_update

const char *const	deprecation_substitute

bool	is_os_charset
	true if the value is in character_set_filesystem More...

struct get_opt_arg_source	source

char	user [USERNAME_CHAR_LENGTH+1]

char	host [HOSTNAME_LENGTH+1]

ulonglong	timestamp

Detailed Description

The class for read-only variables that show whether a particular feature is supported by the server.

Example: have_compression

Backing store: enum SHOW_COMP_OPTION

Note: These variables are necessarily read-only, only global, and have no command-line equivalent.

Constructor & Destructor Documentation

◆ Sys_var_have()

Sys_var_have::Sys_var_have	(	const char *	name_arg,
		const char *	comment,
		int	flag_args,
		ptrdiff_t	off,
		size_t	size,
		CMD_LINE	getopt,
		PolyLock *	lock = `nullptr`,
		enum binlog_status_enum	binlog_status_arg = `VARIABLE_NOT_IN_BINLOG`,
		on_check_function	on_check_func = `nullptr`,
		on_update_function	on_update_func = `nullptr`,
		const char *	substitute = `nullptr`,
		int	parse_flag = `PARSE_NORMAL`
	)

inline

Member Function Documentation

◆ check_update_type()

bool Sys_var_have::check_update_type ( Item_result )

inlineoverridevirtual

Implements sys_var.

◆ do_check()

bool Sys_var_have::do_check	(	THD *	,
		set_var *
	)

inlineoverridevirtual

Implements sys_var.

◆ global_save_default()

void Sys_var_have::global_save_default	(	THD *	thd,
		set_var *	var
	)

inlineoverridevirtual

save the global default value of the variable in var

Implements sys_var.

◆ global_update()

bool Sys_var_have::global_update	(	THD *	,
		set_var *
	)

inlineoverridevirtual

Implements sys_var.

◆ global_value_ptr()

const uchar * Sys_var_have::global_value_ptr	(	THD *	,
		std::string_view
	)

inlineoverridevirtual

Reimplemented from sys_var.

Reimplemented in Sys_var_have_func.

◆ saved_value_to_string()

void Sys_var_have::saved_value_to_string	(	THD *	thd,
		set_var *	var,
		char *	def_val
	)

inlineoverridevirtual

This function converts value stored in save_result to string.

This function must be called after calling save_default() as save_default() will store default value to save_result.

Implements sys_var.

◆ session_save_default()

void Sys_var_have::session_save_default	(	THD *	thd,
		set_var *	var
	)

inlineoverridevirtual

save the session default value of the variable in var

Implements sys_var.

◆ session_update()

bool Sys_var_have::session_update	(	THD *	,
		set_var *
	)

inlineoverridevirtual

Implements sys_var.

◆ session_value_ptr()

const uchar * Sys_var_have::session_value_ptr	(	THD *	running_thd,
		THD *	target_thd,
		std::string_view	keycache_name
	)

inlineoverridevirtual

A pointer to a value of the variable for SHOW.

It must be of show_val_type type (bool for SHOW_BOOL, int for SHOW_INT, longlong for SHOW_LONGLONG, etc).

Reimplemented from sys_var.

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

sql/sys_vars.h

Public Member Functions

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

◆ Sys_var_have()

Member Function Documentation

◆ check_update_type()

◆ do_check()

◆ global_save_default()

◆ global_update()

◆ global_value_ptr()

◆ saved_value_to_string()

◆ session_save_default()

◆ session_update()

◆ session_value_ptr()