sys_var Class Reference

#include <set_var.h>

Inheritance diagram for sys_var:

Collaboration diagram for sys_var:

Public Types
enum	flag_enum {   GLOBAL, SESSION, ONLY_SESSION, SCOPE_MASK = 1023,   READONLY = 1024, ALLOCATED = 2048, INVISIBLE = 4096 }
enum	binlog_status_enum { VARIABLE_NOT_IN_BINLOG, SESSION_VARIABLE_IN_BINLOG }

Public Member Functions
	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)
virtual void	cleanup ()
virtual sys_var_pluginvar *	cast_pluginvar ()
bool	check (THD *thd, set_var *var)
uchar *	value_ptr (THD *thd, enum_var_type type, LEX_STRING *base)
virtual void	update_default (longlong new_def_value)
bool	set_default (THD *thd, set_var *var)
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_struct ()
bool	is_written_to_binlog (enum_var_type type)
virtual bool	check_update_type (Item_result type)=0
bool	check_type (enum_var_type type)
bool	register_option (std::vector< my_option > *array, int parse_flags)
void	do_deprecated_warning (THD *thd)

Public Attributes
sys_var *	next
LEX_CSTRING	name
enum sys_var::binlog_status_enum	binlog_status

Static Public Attributes
static const int	PARSE_EARLY = 1
static const int	PARSE_NORMAL = 2

Protected Types
typedef bool(*	on_check_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
virtual uchar *	session_value_ptr (THD *thd, LEX_STRING *base)
virtual uchar *	global_value_ptr (THD *thd, LEX_STRING *base)
uchar *	session_var_ptr (THD *thd)
uchar *	global_var_ptr ()

Protected Attributes
int	flags
	or'ed flag_enum values
int	m_parse_flag
	either PARSE_EARLY or PARSE_NORMAL.
const SHOW_TYPE	show_val_type
	what value_ptr() returns for sql_show.cc
my_option	option
	min, max, default values are stored here
PolyLock *	guard
	second lock that protects the variable
ptrdiff_t	offset
	offset to the value from global_system_variables
on_check_function	on_check
on_update_function	on_update
const char *const	deprecation_substitute
bool	is_os_charset
	true if the value is in character_set_filesystem

Detailed Description

A class representing one system variable - that is something that can be accessed as @global.variable_name or @session.variable_name, visible in SHOW xxx VARIABLES and in INFORMATION_SCHEMA.xxx_VARIABLES, optionally it can be assigned to, optionally it can have a command-line counterpart with the same name.

Definition at line 54 of file set_var.h.

Member Enumeration Documentation

enum sys_var::binlog_status_enum

Enumeration type to indicate for a system variable whether it will be written to the binlog or not.

Definition at line 67 of file set_var.h.

Constructor & Destructor Documentation

sys_var::sys_var	(	sys_var_chain *	chain,
		const char *	name_arg,
		const char *	comment,
		int	flags_arg,
		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 constructor

Parameters

chain	variables are linked into chain for mysql_add_sys_var_chain()
name_arg	the name of the variable. Must be 0-terminated and exist for the liftime of the sys_var object.

See Also

my_option::name

Parameters

comment

shown in mysqld –help,

See Also

my_option::comment

Parameters

flags_arg	or'ed flag_enum values
off	offset of the global variable value from the &global_system_variables.
getopt_id	-1 for no command-line option, otherwise

See Also

my_option::id

Parameters

getopt_arg_type

See Also

my_option::arg_type

Parameters

show_val_type_arg	what value_ptr() returns for sql_show.cc
def_val	default value,

See Also

my_option::def_value

Parameters

lock	mutex or rw_lock that protects the global variable in addition to LOCK_global_system_variables.
binlog_status_enum

See Also

binlog_status_enum

Parameters

on_check_func	a function to be called at the end of sys_var::check, put your additional checks here
on_update_func	a function to be called at the end of sys_var::update, any post-update activity should happen here
substitute	If non-NULL, this variable is deprecated and the string describes what one should use instead. If an empty string, the variable is deprecated but no replacement is offered.
parse_flag	either PARSE_EARLY or PARSE_NORMAL

Definition at line 135 of file set_var.cc.

Member Function Documentation

virtual sys_var_pluginvar* sys_var::cast_pluginvar ( )

inlinevirtual

downcast for sys_var_pluginvar. Returns this if it's an instance of sys_var_pluginvar, and 0 otherwise.

Reimplemented in sys_var_pluginvar.

Definition at line 103 of file set_var.h.

virtual void sys_var::cleanup ( )

inlinevirtual

All the cleanup procedures should be performed here

Reimplemented in Sys_var_charptr.

Definition at line 98 of file set_var.h.

bool sys_var::is_struct ( )

inline

the following is only true for keycache variables, that support the syntax @keycache_name.variable_name

Definition at line 127 of file set_var.h.

Here is the caller graph for this function:

uchar * sys_var::session_value_ptr ( THD *  thd, LEX_STRING *  base  )

protectedvirtual

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 in Sys_var_gtid_purged, Sys_var_charptr_func, Sys_var_gtid_specification, Sys_var_tz, Sys_var_struct, Sys_var_have, Sys_var_session_special_double, Sys_var_session_special, Sys_var_bit, Sys_var_plugin, Sys_var_set, Sys_var_flagset, Sys_var_max_user_conn, Sys_var_dbug, Sys_var_external_user, Sys_var_proxy_user, Sys_var_enum, and sys_var_pluginvar.

Definition at line 201 of file set_var.cc.

Here is the call graph for this function:

uchar* sys_var::session_var_ptr ( THD *  thd )

inlineprotected

A pointer to a storage area of the variable, to the raw data. Typically it's the same as session_value_ptr(), but it's different, for example, for ENUM, that is printed as a string, but stored as a number.

Definition at line 174 of file set_var.h.

Here is the caller graph for this function:

bool sys_var::set_default	(	THD *	thd,
		set_var *	var
	)

Update the system variable with the default value from either session or global scope. The default value is stored in the 'var' argument. Return false when successful.

Definition at line 251 of file set_var.cc.

---

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

• sql/set_var.h
• sql/set_var.cc