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/*
* Copyright 2018, Intel Corporation
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* * Neither the name of the copyright holder nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/**
* @file
* Volatile resides on pmem property template.
*/
#ifndef LIBPMEMOBJ_CPP_V_HPP
#define LIBPMEMOBJ_CPP_V_HPP
#include <memory>
#include <libpmemobj++/detail/common.hpp>
#include <libpmemobj++/detail/volatile.hpp>
namespace pmem
{
namespace obj
{
namespace experimental
{
/**
* 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.
* @snippet doc_snippets/v.cpp v_property_example
*/
template <typename T>
class v {
using this_type = v<T>;
template <typename N>
friend class v;
public:
/**
* Defaulted constructor.
*/
v() noexcept : vlt{0}
{
}
/**
* Assignment operator.
*/
v &
operator=(const v &rhs)
{
/* make sure object is initialized */
(void)get();
val = rhs.val;
return *this;
}
/**
* Assignment operator.
*/
v &
operator=(const T &rhs)
{
/* make sure object is initialized */
(void)get();
val = rhs;
return *this;
}
/**
* Converting assignment operator from a different v<>.
*
* Available only for convertible types.
*/
template <typename Y,
typename = typename std::enable_if<
std::is_convertible<Y, T>::value>::type>
v &
operator=(const v<Y> &rhs)
{
/* make sure object is initialized */
(void)get();
val = rhs.val;
return *this;
}
/**
* Retrieves reference of the object.
*
* @return a reference to the object.
*
*/
T &
get() noexcept
{
PMEMobjpool *pop = pmemobj_pool_by_ptr(this);
if (pop == NULL)
return this->val;
T *value = static_cast<T *>(pmemobj_volatile(
pop, &this->vlt, &this->val, sizeof(T),
pmem::detail::instantiate_volatile_object<T>, NULL));
return *value;
}
/**
* Conversion operator back to the underlying type.
*/
operator T &() noexcept
{
return this->get();
}
/**
* Swaps two v objects of the same type.
*/
void
swap(v &other)
{
/* make sure object is initialized */
(void)get();
std::swap(this->val, other.val);
}
private:
struct pmemvlt vlt;
T val;
};
/**
* Swaps two v objects of the same type.
*
* Non-member swap function as required by Swappable concept.
* en.cppreference.com/w/cpp/concept/Swappable
*/
template <class T>
inline void
swap(v<T> &a, v<T> &b)
{
a.swap(b);
}
} /* namespace experimental */
} /* namespace obj */
} /* namespace pmem */
#endif /* LIBPMEMOBJ_CPP_V_HPP */
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