utils::SharedReadablePtr< T > Class Template Reference

#include <userver/utils/shared_readable_ptr.hpp>

Detailed Description

template<typename T>
class utils::SharedReadablePtr< T >

std::shared_ptr<const T> wrapper that makes sure that the pointer is stored before dereferencing. Protects from dangling references.

Example of dangling:

// BAD! Result of `cache.Get()` may be destroyed after the invocation.
const auto& snapshot = *cache.Get();
Use(snapshot);

Such code is may work fine 99.9% of that time and, and such bugs are not detectable by most tests. This is because typically the cache data will be held by the cache itself longer than the runtime of the current handler (or whatever) that uses the data. However, 0.1% of the time there will be a crash, because at that exact time the cache will update itself, replacing the data snapshot and dropping the old shared pointer, which will turn out to be the only one.

The correct way to handle shared pointers:

// Stores the shared pointer.
const auto snapshot = cache.Get();
// We only have the right to use `*snapshot` while we hold `snapshot` itself.
Use(*snapshot);

Definition at line 41 of file shared_readable_ptr.hpp.

Public Types
using	Base = std::shared_ptr<const T>
using	MutableBase = std::shared_ptr<T>
using	Weak = typename Base::weak_type
using	Unique = std::unique_ptr<const T>
using	element_type = T

Public Member Functions
	SharedReadablePtr (const SharedReadablePtr &ptr) noexcept=default
	SharedReadablePtr (SharedReadablePtr &&ptr) noexcept=default
constexpr	SharedReadablePtr (std::nullptr_t) noexcept
SharedReadablePtr &	operator= (const SharedReadablePtr &ptr) noexcept=default
SharedReadablePtr &	operator= (SharedReadablePtr &&ptr) noexcept=default
	SharedReadablePtr (const Base &ptr) noexcept
	SharedReadablePtr (Base &&ptr) noexcept
	SharedReadablePtr (const MutableBase &ptr) noexcept
	SharedReadablePtr (MutableBase &&ptr) noexcept
	SharedReadablePtr (Unique &&ptr) noexcept
SharedReadablePtr &	operator= (const Base &ptr) noexcept
SharedReadablePtr &	operator= (Base &&ptr) noexcept
SharedReadablePtr &	operator= (const MutableBase &ptr) noexcept
SharedReadablePtr &	operator= (MutableBase &&ptr) noexcept
SharedReadablePtr &	operator= (std::nullptr_t) noexcept
const T *	Get () const &noexcept USERVER_IMPL_LIFETIME_BOUND
const T &	operator* () const &noexcept USERVER_IMPL_LIFETIME_BOUND
const T &	operator* () &&
const T *	operator-> () const &noexcept USERVER_IMPL_LIFETIME_BOUND
const T *	operator-> () &&
	operator const Base & () const &noexcept USERVER_IMPL_LIFETIME_BOUND
	operator const Base & () &&
	operator Weak () const &noexcept USERVER_IMPL_LIFETIME_BOUND
	operator Weak () &&
	operator bool () const noexcept
bool	operator== (const SharedReadablePtr< T > &other) const
bool	operator!= (const SharedReadablePtr< T > &other) const
void	Reset () noexcept

Member Typedef Documentation

Base

template<typename T>

using utils::SharedReadablePtr< T >::Base = std::shared_ptr<const T>

Definition at line 46 of file shared_readable_ptr.hpp.

element_type

template<typename T>

using utils::SharedReadablePtr< T >::element_type = T

Definition at line 50 of file shared_readable_ptr.hpp.

MutableBase

template<typename T>

using utils::SharedReadablePtr< T >::MutableBase = std::shared_ptr<T>

Definition at line 47 of file shared_readable_ptr.hpp.

Unique

template<typename T>

using utils::SharedReadablePtr< T >::Unique = std::unique_ptr<const T>

Definition at line 49 of file shared_readable_ptr.hpp.

Weak

template<typename T>

using utils::SharedReadablePtr< T >::Weak = typename Base::weak_type

Definition at line 48 of file shared_readable_ptr.hpp.

Constructor & Destructor Documentation

SharedReadablePtr() [1/6]

template<typename T>

utils::SharedReadablePtr< T >::SharedReadablePtr ( std::nullptr_t )

inlineconstexprnoexcept

Definition at line 55 of file shared_readable_ptr.hpp.

SharedReadablePtr() [2/6]

template<typename T>

utils::SharedReadablePtr< T >::SharedReadablePtr ( const Base & ptr )

inlinenoexcept

Definition at line 60 of file shared_readable_ptr.hpp.

SharedReadablePtr() [3/6]

template<typename T>

utils::SharedReadablePtr< T >::SharedReadablePtr ( Base && ptr )

inlinenoexcept

Definition at line 62 of file shared_readable_ptr.hpp.

SharedReadablePtr() [4/6]

template<typename T>

utils::SharedReadablePtr< T >::SharedReadablePtr ( const MutableBase & ptr )

inlinenoexcept

Definition at line 64 of file shared_readable_ptr.hpp.

SharedReadablePtr() [5/6]

template<typename T>

utils::SharedReadablePtr< T >::SharedReadablePtr ( MutableBase && ptr )

inlinenoexcept

Definition at line 66 of file shared_readable_ptr.hpp.

SharedReadablePtr() [6/6]

template<typename T>

utils::SharedReadablePtr< T >::SharedReadablePtr ( Unique && ptr )

inlinenoexcept

Definition at line 68 of file shared_readable_ptr.hpp.

Member Function Documentation

Get()

template<typename T>

const T * utils::SharedReadablePtr< T >::Get ( ) const &

inlinenoexcept

Definition at line 95 of file shared_readable_ptr.hpp.

operator bool()

template<typename T>

utils::SharedReadablePtr< T >::operator bool ( ) const

inlineexplicitnoexcept

Definition at line 113 of file shared_readable_ptr.hpp.

operator const Base &() [1/2]

template<typename T>

utils::SharedReadablePtr< T >::operator const Base & ( ) &&

inline

Definition at line 107 of file shared_readable_ptr.hpp.

operator const Base &() [2/2]

template<typename T>

utils::SharedReadablePtr< T >::operator const Base & ( ) const &

inlinenoexcept

Definition at line 105 of file shared_readable_ptr.hpp.

operator Weak() [1/2]

template<typename T>

utils::SharedReadablePtr< T >::operator Weak ( ) &&

inline

Definition at line 111 of file shared_readable_ptr.hpp.

operator Weak() [2/2]

template<typename T>

utils::SharedReadablePtr< T >::operator Weak ( ) const &

inlinenoexcept

Definition at line 109 of file shared_readable_ptr.hpp.

operator!=()

template<typename T>

bool utils::SharedReadablePtr< T >::operator!= ( const SharedReadablePtr< T > & other ) const

inline

Definition at line 117 of file shared_readable_ptr.hpp.

operator*() [1/2]

template<typename T>

const T & utils::SharedReadablePtr< T >::operator* ( ) &&

inline

Definition at line 99 of file shared_readable_ptr.hpp.

operator*() [2/2]

template<typename T>

const T & utils::SharedReadablePtr< T >::operator* ( ) const &

inlinenoexcept

Definition at line 97 of file shared_readable_ptr.hpp.

operator->() [1/2]

template<typename T>

const T * utils::SharedReadablePtr< T >::operator-> ( ) &&

inline

Definition at line 103 of file shared_readable_ptr.hpp.

operator->() [2/2]

template<typename T>

const T * utils::SharedReadablePtr< T >::operator-> ( ) const &

inlinenoexcept

Definition at line 101 of file shared_readable_ptr.hpp.

operator=() [1/5]

template<typename T>

SharedReadablePtr & utils::SharedReadablePtr< T >::operator= ( Base && ptr )

inlinenoexcept

Definition at line 75 of file shared_readable_ptr.hpp.

operator=() [2/5]

template<typename T>

SharedReadablePtr & utils::SharedReadablePtr< T >::operator= ( const Base & ptr )

inlinenoexcept

Definition at line 70 of file shared_readable_ptr.hpp.

operator=() [3/5]

template<typename T>

SharedReadablePtr & utils::SharedReadablePtr< T >::operator= ( const MutableBase & ptr )

inlinenoexcept

Definition at line 80 of file shared_readable_ptr.hpp.

operator=() [4/5]

template<typename T>

SharedReadablePtr & utils::SharedReadablePtr< T >::operator= ( MutableBase && ptr )

inlinenoexcept

Definition at line 85 of file shared_readable_ptr.hpp.

operator=() [5/5]

template<typename T>

SharedReadablePtr & utils::SharedReadablePtr< T >::operator= ( std::nullptr_t )

inlinenoexcept

Definition at line 90 of file shared_readable_ptr.hpp.

operator==()

template<typename T>

bool utils::SharedReadablePtr< T >::operator== ( const SharedReadablePtr< T > & other ) const

inline

Definition at line 115 of file shared_readable_ptr.hpp.

Reset()

template<typename T>

void utils::SharedReadablePtr< T >::Reset ( )

inlinenoexcept

Definition at line 119 of file shared_readable_ptr.hpp.

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

• userver/utils/shared_readable_ptr.hpp