MDL_wait Class Reference

A reliable way to wait on an MDL lock. More...

#include <mdl.h>

Public Types
enum	enum_wait_status {   WS_EMPTY = 0 , GRANTED , VICTIM , TIMEOUT ,   KILLED }

Public Member Functions
	MDL_wait ()
	Construct an empty wait slot. More...
	~MDL_wait ()
	Destroy system resources. More...
bool	set_status (enum_wait_status result_arg)
	Set the status unless it's already set. More...
enum_wait_status	get_status ()
	Query the current value of the wait slot. More...
void	reset_status ()
	Clear the current value of the wait slot. More...
enum_wait_status	timed_wait (MDL_context_owner *owner, struct timespec *abs_timeout, bool signal_timeout, const PSI_stage_info *wait_state_name)
	Wait for the status to be assigned to this wait slot. More...
enum_wait_status	observable_timed_wait (MDL_context_owner *owner, unsigned long abs_timeout, bool signal_timeout, std::function< void(unsigned long)> tracker_function, const PSI_stage_info *wait_state_name)
	Wait for the status to be assigned to this wait slot. More...

Private Attributes
mysql_mutex_t	m_LOCK_wait_status
	Condvar which is used for waiting until this context's pending request can be satisfied or this thread has to perform actions to resolve a potential deadlock (we subscribe to such notification by adding a ticket corresponding to the request to an appropriate queue of waiters). More...
mysql_cond_t	m_COND_wait_status
enum_wait_status	m_wait_status

Detailed Description

A reliable way to wait on an MDL lock.

Member Enumeration Documentation

enum_wait_status

enum MDL_wait::enum_wait_status

Enumerator
WS_EMPTY
GRANTED
VICTIM
TIMEOUT
KILLED

Constructor & Destructor Documentation

MDL_wait()

MDL_wait::MDL_wait

(

)

Construct an empty wait slot.

~MDL_wait()

MDL_wait::~MDL_wait

(

)

Destroy system resources.

Member Function Documentation

get_status()

MDL_wait::enum_wait_status MDL_wait::get_status

(

)

Query the current value of the wait slot.

observable_timed_wait()

MDL_wait::enum_wait_status MDL_wait::observable_timed_wait	(	MDL_context_owner *	owner,
		unsigned long	abs_timeout,
		bool	signal_timeout,
		std::function< void(unsigned long)>	tracker_function,
		const PSI_stage_info *	wait_state_name
	)

Wait for the status to be assigned to this wait slot.

This method varies from the above as it tracks the time waited The called can collect this time on a tracker function

Parameters

owner	MDL context owner.
abs_timeout	time after which waiting should stop.
signal_timeout	true - If in case of timeout waiting context should close the wait slot by sending TIMEOUT to itself. false - Otherwise.
tracker_function	collects the waited time at 1 sec intervals
wait_state_name	Thread state name to be set for duration of wait.

Returns

Signal posted.

reset_status()

void MDL_wait::reset_status

(

)

Clear the current value of the wait slot.

set_status()

bool MDL_wait::set_status

(

enum_wait_status

status_arg

)

Set the status unless it's already set.

Return false if set, true otherwise.

timed_wait()

MDL_wait::enum_wait_status MDL_wait::timed_wait	(	MDL_context_owner *	owner,
		struct timespec *	abs_timeout,
		bool	set_status_on_timeout,
		const PSI_stage_info *	wait_state_name
	)

Wait for the status to be assigned to this wait slot.

Parameters

owner	MDL context owner.
abs_timeout	Absolute time after which waiting should stop.
set_status_on_timeout	true - If in case of timeout waiting context should close the wait slot by sending TIMEOUT to itself. false - Otherwise.
wait_state_name	Thread state name to be set for duration of wait.

Returns

Signal posted.

Member Data Documentation

m_COND_wait_status

mysql_cond_t MDL_wait::m_COND_wait_status

private

m_LOCK_wait_status

mysql_mutex_t MDL_wait::m_LOCK_wait_status

private

Condvar which is used for waiting until this context's pending request can be satisfied or this thread has to perform actions to resolve a potential deadlock (we subscribe to such notification by adding a ticket corresponding to the request to an appropriate queue of waiters).

m_wait_status

enum_wait_status MDL_wait::m_wait_status

private

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

• sql/mdl.h
• sql/mdl.cc