ut::Seq_lock< T > Class Template Reference

A class that allows to read value of variable of some type T atomically and allows the value to be changed, all using lock-free operations. More...

#include <ut0seq_lock.h>

Inheritance diagram for ut::Seq_lock< T >:

Public Member Functions
	Seq_lock ()=default
template<typename... Args>
	Seq_lock (Args... args)
template<typename Op >
void	write (Op &&op)
	Writes a new value for the variable of type T. More...
template<typename Op >
auto	read (Op &&op) const

Private Attributes
T	m_value
	Stored value. More...
std::atomic< uint64_t >	m_seq {0}
	Sequence count. More...

Additional Inherited Members
Private Member Functions inherited from ut::Non_copyable
	Non_copyable (const Non_copyable &)=delete
Non_copyable &	operator= (const Non_copyable &)=delete
	Non_copyable ()=default
	~Non_copyable ()=default

Detailed Description

template<typename T>
class ut::Seq_lock< T >

A class that allows to read value of variable of some type T atomically and allows the value to be changed, all using lock-free operations.

The type T has to be composed of std::atomic fields only. That is because read(op_r) might read it in parallel to write(op_w). Other than that you are allowed to use any type. Inspired by https://www.hpl.hp.com/techreports/2012/HPL-2012-68.pdf Figure 6.

Constructor & Destructor Documentation

Seq_lock() [1/2]

template<typename T >

ut::Seq_lock< T >::Seq_lock ( )

default

Seq_lock() [2/2]

template<typename T >

template<typename... Args>

ut::Seq_lock< T >::Seq_lock ( Args...  args )

inline

Member Function Documentation

read()

template<typename T >

template<typename Op >

auto ut::Seq_lock< T >::read ( Op &&  op ) const

inline

write()

template<typename T >

template<typename Op >

void ut::Seq_lock< T >::write ( Op &&  op )

inline

Writes a new value for the variable of type T.

The op can use memory_order_relaxed stores. NOTE: The user needs to synchronize all calls to this method.

Member Data Documentation

m_seq

template<typename T >

std::atomic<uint64_t> ut::Seq_lock< T >::m_seq {0}

private

Sequence count.

Even when the value is ready for read, odd when the value is being written to.

m_value

template<typename T >

T ut::Seq_lock< T >::m_value

private

Stored value.

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

• storage/innobase/include/ut0seq_lock.h