pmem::obj::experimental::v< T > Class Template Reference

pmem::obj::experimental::v - volatile resides on pmem class. More...

#include <libpmemobj++/experimental/v.hpp>

Public Member Functions
	v () noexcept
	Defaulted constructor.
v &	operator= (const v &rhs)
	Assignment operator.
v &	operator= (const T &rhs)
	Assignment operator.
template<typename Y , typename = typename std::enable_if< std::is_convertible<Y, T>::value>::type>
v &	operator= (const v< Y > &rhs)
	Converting assignment operator from a different v<>. More...
T &	get () noexcept
	Retrieves reference of the object. More...
	operator T& () noexcept
	Conversion operator back to the underlying type.
void	swap (v &other)
	Swaps two v objects of the same type.

Detailed Description

template<typename T>
class pmem::obj::experimental::v< T >

pmem::obj::experimental::v - volatile resides on pmem class.

v class is a property-like template class that has to be used for all volatile variables that reside on persistent memory. This class ensures that the enclosed type is always properly initialized by always calling the class default constructor exactly once per instance of the application. This class has 8 bytes of storage overhead.

#include <fcntl.h>
#include <libpmemobj++/experimental/v.hpp>
#include <libpmemobj++/persistent_ptr.hpp>
#include <libpmemobj++/pool.hpp>
 
using namespace pmem::obj;
using namespace pmem::obj::experimental;
 
void
v_property_example()
{
    struct foo {
        foo() : counter(10)
        {
        }
        int counter;
    };
 
    // pool root structure
    struct root {
        v<foo> f;
    };
 
    // create a pmemobj pool
    auto pop = pool<root>::create("poolfile", "layout", PMEMOBJ_MIN_POOL);
    auto proot = pop.root();
 
    assert(proot->f.get().counter == 10);
 
    proot->f.get().counter++;
 
    assert(proot->f.get().counter == 11);
}

Member Function Documentation

get()

template<typename T >

T& pmem::obj::experimental::v< T >::get ( )

inlinenoexcept

Retrieves reference of the object.

Returns

a reference to the object.

operator=()

template<typename T >

template<typename Y , typename = typename std::enable_if< std::is_convertible<Y, T>::value>::type>

v& pmem::obj::experimental::v< T >::operator= ( const v< Y > &  rhs )

inline

Converting assignment operator from a different v<>.

Available only for convertible types.

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

• libpmemobj++/experimental/v.hpp