PMDK C++ bindings  1.2.0
This is the C++ bindings documentation for PMDK's libpmemobj.
Public Types | Public Member Functions | Static Public Member Functions | List of all members
pmem::obj::persistent_ptr< T > Class Template Reference

Persistent pointer class. More...

#include <libpmemobj++/persistent_ptr.hpp>

Inheritance diagram for pmem::obj::persistent_ptr< T >:
pmem::detail::persistent_ptr_base< T >

Public Types

template<class U >
using rebind = pmem::obj::persistent_ptr< U >
 Rebind to a different type of pointer.
 
using persistency_type = p< T >
 The persistency type to be used with this pointer.
 
using bool_type = bool
 The used bool_type.
 
using iterator_category = std::random_access_iterator_tag
 The persistent_ptr iterator category.
 
using difference_type = std::ptrdiff_t
 The persistent_ptr difference type.
 
using value_type = T
 The type of the value pointed to by the persistent_ptr.
 
using reference = T &
 The reference type of the value pointed to by the persistent_ptr.
 
using pointer = persistent_ptr< T >
 The pointer type.
 
- Public Types inherited from pmem::detail::persistent_ptr_base< T >
typedef pmem::detail::sp_element< T >::type element_type
 Type of an actual object with all qualifier removed, used for easy underlying type access.
 

Public Member Functions

 persistent_ptr (persistent_ptr< void > const &rhs) noexcept
 Explicit void specialization of the converting constructor.
 
 persistent_ptr (persistent_ptr< const void > const &rhs) noexcept
 Explicit const void specialization of the converting constructor.
 
 operator persistent_ptr< void > () const noexcept
 Persistent pointer to void conversion operator.
 
pmem::detail::sp_dereference< T >::type operator* () const noexcept
 Dereference operator.
 
pmem::detail::sp_member_access< T >::type operator-> () const noexcept
 Member access operator.
 
template<typename = typename std::enable_if<!std::is_void<T>::value>>
pmem::detail::sp_array_access< T >::type operator[] (std::ptrdiff_t i) const noexcept
 Array access operator. More...
 
persistent_ptr< T > & operator++ ()
 Prefix increment operator.
 
persistent_ptr< T > operator++ (int)
 Postfix increment operator.
 
persistent_ptr< T > & operator-- ()
 Prefix decrement operator.
 
persistent_ptr< T > operator-- (int)
 Postfix decrement operator.
 
persistent_ptr< T > & operator+= (std::ptrdiff_t s)
 Addition assignment operator.
 
persistent_ptr< T > & operator-= (std::ptrdiff_t s)
 Subtraction assignment operator.
 
void persist (pool_base &pop)
 Persists the content of the underlying object. More...
 
void persist (void)
 Persists what the persistent pointer points to. More...
 
void flush (pool_base &pop)
 Flushes what the persistent pointer points to. More...
 
void flush (void)
 Flushes what the persistent pointer points to. More...
 
- Public Member Functions inherited from pmem::detail::persistent_ptr_base< T >
 persistent_ptr_base ()
 Default constructor, zeroes the PMEMoid.
 
 persistent_ptr_base (PMEMoid oid) noexcept
 PMEMoid constructor. More...
 
 persistent_ptr_base (element_type *ptr)
 Volatile pointer constructor. More...
 
template<typename U , typename = typename std::enable_if< !std::is_same<T, U>::value && std::is_same<typename std::remove_cv<T>::type, U>::value>::type>
 persistent_ptr_base (persistent_ptr_base< U > const &r) noexcept
 Copy constructor from a different persistent_ptr<>. More...
 
template<typename U , typename Dummy = void, typename = typename std::enable_if< !std::is_same< typename std::remove_cv<T>::type, typename std::remove_cv<U>::type>::value && !std::is_void<U>::value, decltype(static_cast<T *>(std::declval<U *>()))>::type>
 persistent_ptr_base (persistent_ptr_base< U > const &r) noexcept
 Copy constructor from a different persistent_ptr<>. More...
 
template<typename Y , typename = typename std::enable_if< !std::is_same< typename std::remove_cv<T>::type, typename std::remove_cv<Y>::type>::value && !std::is_void<Y>::value, decltype(static_cast<T *>(std::declval<Y *>()))>::type>
 operator persistent_ptr_base< Y > () noexcept
 Conversion operator to a different persistent_ptr<>. More...
 
 persistent_ptr_base (persistent_ptr_base &&r) noexcept
 Defaulted move constructor.
 
persistent_ptr_baseoperator= (persistent_ptr_base &&r)
 Defaulted move assignment operator.
 
persistent_ptr_baseoperator= (persistent_ptr_base const &r)
 Assignment operator. More...
 
persistent_ptr_baseoperator= (std::nullptr_t &&)
 Nullptr move assignment operator. More...
 
template<typename Y , typename = typename std::enable_if< std::is_convertible<Y *, T *>::value>::type>
persistent_ptr_baseoperator= (persistent_ptr_base< Y > const &r)
 Converting assignment operator from a different persistent_ptr<>. More...
 
void swap (persistent_ptr_base &other)
 Swaps two persistent_ptr objects of the same type. More...
 
element_typeget () const noexcept
 Get a direct pointer. More...
 
const PMEMoid & raw () const noexcept
 Get PMEMoid encapsulated by this object. More...
 
PMEMoid * raw_ptr () noexcept
 Get pointer to PMEMoid encapsulated by this object. More...
 

Static Public Member Functions

static persistent_ptr< T > pointer_to (T &ref)
 Create a persistent pointer from a given reference. More...
 

Additional Inherited Members

- Protected Member Functions inherited from pmem::detail::persistent_ptr_base< T >
 persistent_ptr_base (element_type *vptr, int)
 Private constructor enabling persistent_ptrs to volatile objects. More...
 
template<typename U >
ptrdiff_t calculate_offset () const
 Calculate in-object offset for structures with inheritance. More...
 

Detailed Description

template<typename T>
class pmem::obj::persistent_ptr< T >

Persistent pointer class.

persistent_ptr implements a smart ptr. It encapsulates the PMEMoid fat pointer and provides member access, dereference and array access operators. The persistent_ptr is not designed to work with polymorphic types, as they have runtime RTTI info embedded, which is implementation specific and thus not consistently rebuildable. Such constructs as polymorphic members or members of a union defined within a class held in a persistent_ptr will also yield undefined behavior. This type does NOT manage the life-cycle of the object. The typical usage example would be:

#include <fcntl.h>
using namespace pmem::obj;
void
persistent_ptr_example()
{
struct compound_type {
void
set_some_variable(int val)
{
some_variable = val;
}
int some_variable;
double some_other_variable;
};
// pool root structure
struct root {
} proot;
// create a pmemobj pool
auto pop = pool<root>::create("poolfile", "layout", PMEMOBJ_MIN_POOL);
// typical usage schemes
transaction::run(pop, [&] {
proot.comp = make_persistent<compound_type>(); // allocation
proot.comp->set_some_variable(12); // call function
proot.comp->some_other_variable = 2.3; // set variable
});
// reading from the persistent_ptr
compound_type tmp = *proot.comp;
(void)tmp;
// Changing a persistent_ptr<> variable outside of a transaction is a
// volatile modification. No way to ensure persistence in case of power
// failure.
proot.comp->some_variable = 12;
}

Member Function Documentation

◆ flush() [1/2]

template<typename T>
void pmem::obj::persistent_ptr< T >::flush ( pool_base pop)
inline

Flushes what the persistent pointer points to.

Parameters
[in]popPmemobj pool

◆ flush() [2/2]

template<typename T>
void pmem::obj::persistent_ptr< T >::flush ( void  )
inline

Flushes what the persistent pointer points to.

Exceptions
pool_errorwhen cannot get pool from persistent pointer

◆ operator[]()

template<typename T>
template<typename = typename std::enable_if<!std::is_void<T>::value>>
pmem::detail::sp_array_access<T>::type pmem::obj::persistent_ptr< T >::operator[] ( std::ptrdiff_t  i) const
inlinenoexcept

Array access operator.

Contains run-time bounds checking for static arrays.

◆ persist() [1/2]

template<typename T>
void pmem::obj::persistent_ptr< T >::persist ( pool_base pop)
inline

Persists the content of the underlying object.

Parameters
[in]popPmemobj pool

◆ persist() [2/2]

template<typename T>
void pmem::obj::persistent_ptr< T >::persist ( void  )
inline

Persists what the persistent pointer points to.

Exceptions
pool_errorwhen cannot get pool from persistent pointer

◆ pointer_to()

template<typename T>
static persistent_ptr<T> pmem::obj::persistent_ptr< T >::pointer_to ( T &  ref)
inlinestatic

Create a persistent pointer from a given reference.

This can create a persistent_ptr to a volatile object, use with extreme caution.

Parameters
refreference to an object.

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