Partitioned_rwlock Class Reference

Implementation of read-write lock partitioned by thread id. More...

#include <partitioned_rwlock.h>

Public Member Functions
	Partitioned_rwlock ()=default
bool	init (uint parts, PSI_rwlock_key psi_key)
void	destroy ()
void	wrlock ()
void	wrunlock ()
void	rdlock (uint thread_id)
void	rdunlock (uint thread_id)

Private Member Functions
	Partitioned_rwlock (const Partitioned_rwlock &)
Partitioned_rwlock &	operator= (const Partitioned_rwlock &)

Private Attributes
mysql_rwlock_t *	m_locks_array
uint	m_parts

Detailed Description

Implementation of read-write lock partitioned by thread id.

This rwlock provides better scalability in read-heavy environments by employing the following simple trick: ) Read lock is acquired only on one of its partitions. The specific partition is chosen according to thread id. ) Write lock is acquired on all partitions.

This way concurrent request for read lock made by different threads have a good chance not to disturb each other by doing cache invalidation and atomic operations. As result scalability in this scenario improves. OTOH acquisition of write lock becomes more expensive. So this rwlock is not supposed to be used in cases when number of write requests is significant.

Constructor & Destructor Documentation

Partitioned_rwlock() [1/2]

Partitioned_rwlock::Partitioned_rwlock ( )

default

Partitioned_rwlock() [2/2]

Partitioned_rwlock::Partitioned_rwlock ( const Partitioned_rwlock &  )

private

Member Function Documentation

destroy()

void Partitioned_rwlock::destroy ( )

inline

init()

bool Partitioned_rwlock::init ( uint  parts, PSI_rwlock_key  psi_key  )

inline

Parameters

parts	Number of partitions.
psi_key	P_S instrumentation key to use for rwlock instances for partitions.

operator=()

Partitioned_rwlock & Partitioned_rwlock::operator= ( const Partitioned_rwlock &  )

private

rdlock()

void Partitioned_rwlock::rdlock ( uint  thread_id )

inline

rdunlock()

void Partitioned_rwlock::rdunlock ( uint  thread_id )

inline

wrlock()

void Partitioned_rwlock::wrlock ( )

inline

wrunlock()

void Partitioned_rwlock::wrunlock ( )

inline

Member Data Documentation

m_locks_array

mysql_rwlock_t* Partitioned_rwlock::m_locks_array

private

m_parts

uint Partitioned_rwlock::m_parts

private

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

• sql/auth/partitioned_rwlock.h