Checkable_rwlock Class Reference

This has the functionality of mysql_rwlock_t, with two differences: More...

#include <rpl_gtid.h>

Classes
class	Guard
	RAII class to acquire a lock for the duration of a block. More...

Public Types
enum	enum_lock_type {   NO_LOCK , READ_LOCK , WRITE_LOCK , TRY_READ_LOCK ,   TRY_WRITE_LOCK }

Public Member Functions
	Checkable_rwlock (PSI_rwlock_key psi_key=0)
	Initialize this Checkable_rwlock. More...
	~Checkable_rwlock ()
	Destroy this Checkable_lock. More...
void	rdlock ()
	Acquire the read lock. More...
void	wrlock ()
	Acquire the write lock. More...
void	unlock ()
	Release the lock (whether it is a write or read lock). More...
bool	is_wrlock ()
	Return true if the write lock is held. More...
int	trywrlock ()
	Return 0 if the write lock is held, otherwise an error will be returned. More...
int	tryrdlock ()
	Return 0 if the read lock is held, otherwise an error will be returned. More...
void	assert_some_lock () const
	Assert that some thread holds either the read or the write lock. More...
void	assert_some_rdlock () const
	Assert that some thread holds the read lock. More...
void	assert_some_wrlock () const
	Assert that some thread holds the write lock. More...
void	assert_no_wrlock () const
	Assert that no thread holds the write lock. More...
void	assert_no_rdlock () const
	Assert that no thread holds the read lock. More...
void	assert_no_lock () const
	Assert that no thread holds read or write lock. More...

Public Attributes
bool	m_dbug_trace
	If enabled, print any lock/unlock operations to the DBUG trace. More...

Private Member Functions
int32	get_state () const
	Read lock_state atomically and return the value. More...

Private Attributes
std::atomic< int32 >	m_lock_state
	The state of the lock: 0 - not locked -1 - write locked >0 - read locked by that many threads. More...
mysql_rwlock_t	m_rwlock {}
	The rwlock. More...

Detailed Description

This has the functionality of mysql_rwlock_t, with two differences:

1. It has additional operations to check if the read and/or write lock is held at the moment.
2. It is wrapped in an object-oriented interface.

Note that the assertions do not check whether this thread has taken the lock (that would be more complicated as it would require a dynamic data structure). Luckily, it is still likely that the assertions find bugs where a thread forgot to take a lock, because most of the time most locks are only used by one thread at a time.

The assertions are no-ops when DBUG is off.

Member Enumeration Documentation

enum_lock_type

enum Checkable_rwlock::enum_lock_type

Enumerator
NO_LOCK
READ_LOCK
WRITE_LOCK
TRY_READ_LOCK
TRY_WRITE_LOCK

Constructor & Destructor Documentation

Checkable_rwlock()

Checkable_rwlock::Checkable_rwlock ( PSI_rwlock_key  psi_key = 0 )

inline

Initialize this Checkable_rwlock.

~Checkable_rwlock()

Checkable_rwlock::~Checkable_rwlock ( )

inline

Destroy this Checkable_lock.

Member Function Documentation

assert_no_lock()

void Checkable_rwlock::assert_no_lock ( ) const

inline

Assert that no thread holds read or write lock.

assert_no_rdlock()

void Checkable_rwlock::assert_no_rdlock ( ) const

inline

Assert that no thread holds the read lock.

assert_no_wrlock()

void Checkable_rwlock::assert_no_wrlock ( ) const

inline

Assert that no thread holds the write lock.

assert_some_lock()

void Checkable_rwlock::assert_some_lock ( ) const

inline

Assert that some thread holds either the read or the write lock.

assert_some_rdlock()

void Checkable_rwlock::assert_some_rdlock ( ) const

inline

Assert that some thread holds the read lock.

assert_some_wrlock()

void Checkable_rwlock::assert_some_wrlock ( ) const

inline

Assert that some thread holds the write lock.

get_state()

int32 Checkable_rwlock::get_state ( ) const

inlineprivate

Read lock_state atomically and return the value.

is_wrlock()

bool Checkable_rwlock::is_wrlock ( )

inline

Return true if the write lock is held.

Must only be called by threads that hold a lock.

rdlock()

void Checkable_rwlock::rdlock ( )

inline

Acquire the read lock.

tryrdlock()

int Checkable_rwlock::tryrdlock ( )

inline

Return 0 if the read lock is held, otherwise an error will be returned.

trywrlock()

int Checkable_rwlock::trywrlock ( )

inline

Return 0 if the write lock is held, otherwise an error will be returned.

unlock()

void Checkable_rwlock::unlock ( )

inline

Release the lock (whether it is a write or read lock).

wrlock()

void Checkable_rwlock::wrlock ( )

inline

Acquire the write lock.

Member Data Documentation

m_dbug_trace

bool Checkable_rwlock::m_dbug_trace

If enabled, print any lock/unlock operations to the DBUG trace.

m_lock_state

std::atomic<int32> Checkable_rwlock::m_lock_state

private

The state of the lock: 0 - not locked -1 - write locked >0 - read locked by that many threads.

m_rwlock

mysql_rwlock_t Checkable_rwlock::m_rwlock {}

private

The rwlock.

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

• sql/rpl_gtid.h