Session_sysvars_tracker Class Reference

Inheritance diagram for Session_sysvars_tracker:

Classes
struct	sysvar_node_st
class	vars_list

Public Member Functions
	Session_sysvars_tracker (const CHARSET_INFO *char_set)
	Constructor. More...
	~Session_sysvars_tracker () override
	Destructor. More...
void	reset ()
	Prepare/reset the m_registered_sysvars hash for next statement. More...
bool	enable (THD *thd) override
	It is responsible for enabling this tracker when a session starts. More...
bool	check (THD *thd, set_var *var) override
	Check if any of the system variable name(s) in the given list of system variables is duplicate/invalid. More...
bool	update (THD *thd) override
	Once the value of the @session_track_system_variables has been successfully updated, this function calls Session_sysvars_tracker::vars_list::update updating the hash in orig_list which represents the system variables to be tracked. More...
bool	store (THD *thd, String &buf) override
	Store the data for changed system variables in the specified buffer. More...
void	mark_as_changed (THD *thd, LEX_CSTRING tracked_item_name) override
	Mark the system variable with the specified name as changed. More...
void	claim_memory_ownership (bool claim) override
Public Member Functions inherited from State_tracker
	State_tracker ()
	Constructor. More...
virtual	~State_tracker ()=default
	Destructor. More...
bool	is_enabled () const
	Getters. More...
bool	is_changed () const

Static Public Member Functions
static bool	server_init_check (const CHARSET_INFO *char_set, LEX_STRING var_list)
	Method used to check the validity of string provided for session_track_system_variables during the server startup. More...
static const uchar *	sysvars_get_key (const uchar *entry, size_t *length)
	Supply key to the hash implementation (to be used internally by the implementation). More...

Private Attributes
vars_list *	orig_list
	Two objects of vars_list type are maintained to manage various operations on variables_list. More...
vars_list *	tool_list

Additional Inherited Members
Protected Attributes inherited from State_tracker
bool	m_enabled
	Is tracking enabled for a particular session state type ? More...
bool	m_changed
	Has the session state type changed ? More...

Detailed Description

Session_sysvars_tracker

This is a tracker class that enables & manages the tracking of session system variables. It internally maintains a hash of user supplied variable names and a boolean field to store if the variable was changed by the last statement.

Constructor & Destructor Documentation

Session_sysvars_tracker()

Session_sysvars_tracker::Session_sysvars_tracker ( const CHARSET_INFO *  char_set )

inline

Constructor.

~Session_sysvars_tracker()

Session_sysvars_tracker::~Session_sysvars_tracker ( )

inlineoverride

Destructor.

Member Function Documentation

check()

bool Session_sysvars_tracker::check ( THD *  thd, set_var *  var  )

inlineoverridevirtual

Check if any of the system variable name(s) in the given list of system variables is duplicate/invalid.

When the value of @session_track_system_variables system variable is updated, the new value is first verified in this function (called from ON_CHECK()) and a hash is populated in tool_list.

Note

This function is called from the ON_CHECK() function of the session_track_system_variables' sys_var class.

Parameters

thd	The thd handle.
var	A pointer to set_var holding the specified list of system variable names.

Returns

true Error false Success

Implements State_tracker.

claim_memory_ownership()

void Session_sysvars_tracker::claim_memory_ownership ( bool  claim )

inlineoverridevirtual

Reimplemented from State_tracker.

enable()

bool Session_sysvars_tracker::enable ( THD *  thd )

overridevirtual

It is responsible for enabling this tracker when a session starts.

During the initialization, a session's system variable gets a copy of the global variable. The new value of session_track_system_variables is then verified & tokenized to create a hash, which is then updated to orig_list which represents all the systems variables to be tracked.

Parameters

thd	The thd handle.

Returns

true Error false Success

Implements State_tracker.

mark_as_changed()

void Session_sysvars_tracker::mark_as_changed ( THD *  thd, LEX_CSTRING  tracked_item_name  )

overridevirtual

Mark the system variable with the specified name as changed.

Parameters

thd	Current thread
tracked_item_name	Name of the system variable which got changed.

Implements State_tracker.

reset()

void Session_sysvars_tracker::reset

(

void

)

Prepare/reset the m_registered_sysvars hash for next statement.

server_init_check()

static bool Session_sysvars_tracker::server_init_check ( const CHARSET_INFO *  char_set, LEX_STRING  var_list  )

inlinestatic

Method used to check the validity of string provided for session_track_system_variables during the server startup.

store()

bool Session_sysvars_tracker::store ( THD *  thd, String &  buf  )

overridevirtual

Store the data for changed system variables in the specified buffer.

Once the data is stored, we reset the flags related to state-change (see reset()).

Parameters

	thd	The thd handle.
[in,out]	buf	Buffer to store the information to.

Returns

false Success true Error

Implements State_tracker.

sysvars_get_key()

const uchar * Session_sysvars_tracker::sysvars_get_key ( const uchar *  entry, size_t *  length  )

static

Supply key to the hash implementation (to be used internally by the implementation).

Parameters

	entry	A single entry.
[out]	length	Length of the key.

Returns

Pointer to the key buffer.

update()

bool Session_sysvars_tracker::update ( THD *  thd )

overridevirtual

Once the value of the @session_track_system_variables has been successfully updated, this function calls Session_sysvars_tracker::vars_list::update updating the hash in orig_list which represents the system variables to be tracked.

Note

This function is called from the ON_UPDATE() function of the session_track_system_variables' sys_var class.

Parameters

thd	The thd handle.

Returns

true Error false Success

Implements State_tracker.

Member Data Documentation

orig_list

vars_list* Session_sysvars_tracker::orig_list

private

Two objects of vars_list type are maintained to manage various operations on variables_list.

tool_list

vars_list * Session_sysvars_tracker::tool_list

private

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

• sql/session_tracker.cc