service_thd_wait.h File Reference

This service provides functions for plugins and storage engines to report when they are going to sleep/stall. More...

Go to the source code of this file.

Classes
struct	thd_wait_service_st

Macros
#define	MYSQL_THD   THD *

Typedefs
typedef enum _thd_wait_type_e	thd_wait_type

Enumerations
enum	_thd_wait_type_e {   THD_WAIT_SLEEP = 1 , THD_WAIT_DISKIO = 2 , THD_WAIT_ROW_LOCK = 3 , THD_WAIT_GLOBAL_LOCK = 4 ,   THD_WAIT_META_DATA_LOCK = 5 , THD_WAIT_TABLE_LOCK = 6 , THD_WAIT_USER_LOCK = 7 , THD_WAIT_BINLOG = 8 ,   THD_WAIT_GROUP_COMMIT = 9 , THD_WAIT_SYNC = 10 , THD_WAIT_LAST = 11 }

Functions
void	thd_wait_begin (MYSQL_THD thd, int wait_type)
	Interface for MySQL Server, plugins and storage engines to report when they are going to sleep/stall. More...
void	thd_wait_end (MYSQL_THD thd)
	Interface for MySQL Server, plugins and storage engines to report when they waking up from a sleep/stall. More...

Variables
struct thd_wait_service_st *	thd_wait_service

Detailed Description

This service provides functions for plugins and storage engines to report when they are going to sleep/stall.

SYNOPSIS thd_wait_begin() - call just before a wait begins thd Thread object Use NULL if the thd is NOT known. wait_type Type of wait 1 – short wait (e.g. for mutex) 2 – medium wait (e.g. for disk io) 3 – large wait (e.g. for locked row/table) NOTES This is used by the threadpool to have better knowledge of which threads that currently are actively running on CPUs. When a thread reports that it's going to sleep/stall, the threadpool scheduler is free to start another thread in the pool most likely. The expected wait time is simply an indication of how long the wait is expected to become, the real wait time could be very different.

thd_wait_end() called immediately after the wait is complete

thd_wait_end() MUST be called if thd_wait_begin() was called.

Using thd_wait_...() service is optional but recommended. Using it will improve performance as the thread pool will be more active at managing the thread workload.

Macro Definition Documentation

MYSQL_THD

#define MYSQL_THD   THD *

Typedef Documentation

thd_wait_type

typedef enum _thd_wait_type_e thd_wait_type

Enumeration Type Documentation

_thd_wait_type_e

enum _thd_wait_type_e

Enumerator
THD_WAIT_SLEEP
THD_WAIT_DISKIO
THD_WAIT_ROW_LOCK
THD_WAIT_GLOBAL_LOCK
THD_WAIT_META_DATA_LOCK
THD_WAIT_TABLE_LOCK
THD_WAIT_USER_LOCK
THD_WAIT_BINLOG
THD_WAIT_GROUP_COMMIT
THD_WAIT_SYNC
THD_WAIT_LAST

Function Documentation

thd_wait_begin()

void thd_wait_begin	(	MYSQL_THD	thd,
		int	wait_type
	)

Interface for MySQL Server, plugins and storage engines to report when they are going to sleep/stall.

This is currently only implemented by by the threadpool and used to have better knowledge of which threads that currently are actively running on CPUs. When not running with TP this makes a call, possibly through a service, to an empty function.

thd_wait_end MUST be called immediately after waking up again.

More info can be found in the TP documentation.

Parameters

thd	Calling thread context. If nullptr is passed, current_thd is used.
wait_type	An enum value from the enum thd_wait_type (defined in include/mysql/service_thd_wait.h) but passed as int to preserve compatibility with exported service api.

thd_wait_end()

void thd_wait_end

(

MYSQL_THD

thd

)

Interface for MySQL Server, plugins and storage engines to report when they waking up from a sleep/stall.

This is currently only implemented by by the threadpool and used to have better knowledge of which threads that currently are actively running on CPUs. When not running with TP this makes a call, possibly through a service, to an empty function.

More info can be found in the TP documentation.

Parameters

thd	Calling thread context. If nullptr is passed, current_thd is used.

Variable Documentation

thd_wait_service

struct thd_wait_service_st * thd_wait_service