Atomic shared_ptr

std::experimental::atomic_shared_ptr - cppreference

Just::Thread uses a split reference count for atomic_shared_ptr --- the shared_ptr control block holds a count of external counters in addition to the normal reference count, and each atomic_shared_ptr instance that holds a reference has a local count of threads accessing it concurrently Atomic Operations for std::shared_ptr. There are specialisations for the atomic operations load, store, compare and exchange for a std::shared_ptr. By using the explicit variant you can even specify the memory model. Here are the free atomic operations for std::shared_ptr The only such type in the standard library is std:: shared_ptr < U >. _Atomic is a keyword and used to provide atomic types in C. Implementations are recommended to ensure that the representation of _Atomic (T) in C is same as that of std:: atomic < T > in C++ for every possible type T. The mechanisms used to ensure atomicity and memory ordering should be compatible Die teilweise Schablonenspezialisierung von std::atomic für std::shared_ptr < T > ermöglicht es Benutzern, shared_ptr-Objekte atomar zu bearbeiten. Wenn mehrere Ausführungsthreads auf dasselbe std::shared_ptr -Objekt ohne Synchronisation zugreifen und einer dieser Zugriffe eine Nicht-Konstanten-Member-Funktion von shared_ptr verwendet, tritt ein. Consistency: the atomic operations for std::shared_ptr are the only atomic operations for a non-atomic data type. Correctness : the usage of the global atomic operations is quite error-prone.

std::shared_ptr is a smart pointer that retains shared ownership of an object through a pointer. Several shared_ptr objects may own the same object. The object is destroyed and its memory deallocated when either of the following happens: the last remaining shared_ptr owning the object is destroyed Konsequenterweise sind die atomaren Operationen auf std::shared_ptr<T> mit C++20 deprecated. Wie geht's weiter? Mit C++20 lassen sich Threads kooperativ unterbrechen Eine Option ist natürlich, nur boost::shared_ptrund boost::atomic_storeanstelle von STL zu verwenden, wenn Boost eine Option ist. Es hat die gleiche Schnittstelle und ist daher leicht zu ersetzen. Dieser Artikel stammt aus dem Internet. Bitte geben Sie beim Nachdruck die Quelle an. Bei Verstößen wenden Sie sich bitte [email protected] Löschen. bearbeiten am 2021-04-30. c++ gcc shared-ptr. Describe the bug atomic<shared_ptr<Ty>> and atomic<weak_ptr<Ty>> does not work when Ty is and an array { Ty = T[] || T[N] }. No sure if this is intended. [util.smartptr.atomic] does not really specify. Code test case Godbolt example (Unc..

shared_ptr is some sort of confusing especially why we need atomic_store, atomic_load on that. It is NOT thread safe. In fact, the primary intended use of std::shared_ptr is letting multiple threads control the lifetime of the same object, but not thread-safe The Concurrency TS introduced two atomic smart pointer classes, atomic_shared_ptr and atomic_weak_ptr, as a superior alternative to the atomic access API for shared_ptr in the C++ standard. This paper highlights several issues with that specification that should be resolved before merging its contents into a future C++ standard Performance. atomic_shared_ptr<> as a distinct type has an important efficiency advantage over the functions in [util.smartptr.shared.atomic]—it can simply store an additional atomic_flag (or similar) for the internal spinlock as usual for atomic<bigstruct>. In contrast, the existing standalone functions ar Atomic shared_ptr and weak_ptr: There are now partial specializations atomic<shared_ptr<T>> and atomic<weak_ptr<T>> that allow atomic access to a shared or weak pointer. This replaces the existing free function overloads shared_ptr<T> atomic_load(const shared_ptr<T>*) etc., which were fragile and error-prone. The old free function overloads are.

std::atomic_<std::shared_ptr> - cppreference

  1. std::atomic<std::shared_ptr<T>> und std::atomic<std::weak_ptr<T>> std::shared_ptr ist der einzige nichtatomare Datentyp, auf den atomare Operationen angewandt werden können. Zuerst möchte ich.
  2. /** @file bits/shared_ptr_atomic.h: 26 * This is an internal header file, included by other library headers. 27 * Do not attempt to use it directly. @headername {memory} 28 */ 29: 30 # ifndef _SHARED_PTR_ATOMIC_H: 31: #define _SHARED_PTR_ATOMIC_H 1: 32: 33: #include <bits/atomic_base.h> 34: 35: namespace std _GLIBCXX_VISIBILITY (default) 36 {37.
  3. The Atomic Shred Testo Booster Capsules contain all the strongest aphrodisiacs to help you restore your best weight room results! But you need to put in the proper efforts to get your best testosterone support in your performances. Here are a few tips to ensure you put in the most effort during your workouts: Increase Duration - The key to getting your best performances is extending the.
  4. shared_ptr<T>: the (not always) atomic reference counted smart pointer 13 Feb 2019 Introduction. This is a write-up of the behavioral analysis of shared_ptr<T> reference count in GNU's libstdc++. This smart pointer is used to share references to the same underlaying pointer. The mechanism beneath works by tracking the amount of references through a reference count so the pointer gets.
  5. atomic介绍atomic对int、char、bool等数据结构进行了原子性封装,在多线程环境中,对std::atomic对象的访问不会造成竞争-冒险。利用std::atomic可实现数据结构的无锁设计。所谓的原子操作,取的就是原子是最小的、不可分割的最小个体的意义,它表示在多个线程访问同一个全局资源的时候,能够确保所有其他的线程都不在同一时间内访问相同的资源。也就是他确保了.
  6. Bei der Eingabe der Methode wird der Parameter shared_ptr als Kopie erstellt: ref count atomic increment . Innerhalb des Methodenkörpers verschieben Sie std::move den Parameter shared_ptr in das Datenelement: ref count ändert sich nicht ! Sie stehlen nur Zeiger / Zustand: Es sind keine teuren Atomreferenzzähloperationen involviert

c++ - state of std::atomic_shared_ptr - Stack Overflo

atomic. (std::shared_ptr) std::atomic 对 std::shared_ptr<T> 的部分模板特化允许用户原子地操纵 shared_ptr 。. 若多个执行线程同时访问同一 std::shared_ptr 对象而不同步,且任何这些访问使用了 shared_ptr 的非 const 成员函数,则将出现数据竞争,除非通过 std::atomic<std::shared_ptr>> 的实例进行所有访问(或通过从 C++20 起弃用的 孤立函数 对 std::shared_ptr 进行原子访问)。. 关联 use_count 的自增保证. C++ 原子智能指针. std::atomic<std::shared_ptr> 是 C++20 进入到标准中的一个提案。. 但是目前看来实现的方案主要有:. [libstdc++/std::atomic<std::shared_prt >] (https://github.com/gcc-mirror/gcc/blob/41d6b10e96a1de98e90a7c0378437c3255814b16/libstdc%2B%2B-v3/include/bits/shared_ptr_atomic.h#L137) 内部使用 μtex μ t e x 来保护`std::shared_prt `的更新。 Other shared_ptr features still require a deallocator to be kept. The requirement that the copy constructor of D does not throw comes from the pass by value. If the copy constructor throws, the pointer would leak.] copy and converting constructors shared_ptr(shared_ptr const & r); // never throws template<class Y> shared_ptr(shared_ptr<Y> const & r); // never throws. Requires: Y* should be.

Why do we need atomic_shared_ptr? Just Software

We have no experience with a separate atomic_shared_ptr type and do not feel confident that we can propose the right interface for it. Given the proposed member functions, it is possible to build an atomic_shared_ptr on top of shared_ptr, but not vice versa. III. Proposed Text . Add to shared_ptr [util.smartptr.shared] the following: // [util.smartptr.shared.atomic], atomic access: shared_ptr. The Concurrency_TS offers atomic smart pointer classes atomic_shared_ptr and atomic_weak_ptr as a replacement for the use of these functions. These functions were deprecated in favor of the specializations of the std::atomic template: std::atomic<std::shared_ptr> and std::atomic<std::weak_ptr>. (since C++20) Example. This section is incomplete Reason: no example Defect reports The following. If multiple threads of execution access the same std::shared_ptr object without synchronization and any of those accesses uses a non-const member function of shared_ptr then a data race will occur unless all such access is performed through these functions, which are overloads of the corresponding atomic access functions (std::atomic_load, std::atomic_store, etc.

Atomic Smart Pointers - ModernesCpp

I am mostly interested in atomic_shared_ptr and mutex items. As you can see, atomic_shared_ptr works much faster than mutex on reading. But 2-4 times slower on writing. This means atomic_shared_ptr is useless in systems where the number of reads is approximately the same as the number of writes. Is this expected? Can anything be tuned to. Performance. atomic_shared_ptr<> as a distinct type has an important efficiency advantage over the functions in [util.smartptr.shared.atomic]—it can simply store an additional atomic_flag (or similar) for the internal spinlock as usual for atomic<bigstruct>. In contrast, the existing standalone functions are required to be usable on any arbitrary shared_ptr object, even though the vast. Shared_ptr atomic access, revision 1. 更新一下,std::atomic<std::shared_ptr<T>> 已经进入标准。 Revising atomic_shared_ptr for C++20. 编辑于 2017-12-11. 赞同 18 1 条评论. 分享. 收藏 喜欢 收起 . 继续浏览内容. 知乎. 发现更大的世界. 打开. 浏览器. 继续. 裴文谦. 又一天过去了,今天过的怎么样,梦想是不是更远了? 26 人 赞同. I'm trying to write a lock-free implementation for atomic shared pointer.Basically, there are two class templates shared_ptr and atomic_shared_ptr, each implemented in a header file of its own, for a total of two header files.The algorithm is inspired by the split reference counts idea used to implement a lock-free stack in C++ Concurrency in Action Sect. 7.2.4

std::atomic - cppreference

  1. As you may know, C++20 has added std::atomic<std::shared_ptr<T>> specialization to the standard, but sadly, most compilers have not implemented it yet. So I decided to implement it myself. I want to know if I can improve this code or not. In addition, I'm not sure if my implementations of wait(), notify_one() and notify_all() are correct using condition variable
  2. An instance of atomic_shared_ptr<T> holds: a) a pointer to atomic_shared_ptr_gref_<T>, which is a struct. consisting of a pointer to a T-type object and a global reference counter. b) a local (temporary) reference counter, which is embedded in the above pointer by using several LSBs that should be usually zero. The values of a) and b), m_ref, are atomically handled with CAS machine codes. The.
  3. std::shared_ptr teilen sich eine gemeinsame Ressource. Dabei zählt der gemeinsame Referenzzähler mit, wie viele Besitzer die Ressource hat. Wird der Smart Poi nter std::shared_ptr kopiert, erhöht sich automatisch der Referenzzähler. Beim Löschen eines std::shared_prt wird sein Referenzzähler hingegen automatisch erniedrigt. Erreicht der Referenzzähler den Wert 0, wird die Ressource.
  4. GCC Bugzilla - Bug 57250 [C++11] std::shared_ptr misses atomic_* support Last modified: 2014-11-12 23:56:45 UT
  5. In an ABI breaking release, it would be nice to reuse the low order bit of the reference count control block pointer in the shared_ptr; but even without an ABI breaking release we could do better by replacing the spinlock entirely with something like SRWLOCK on Vista and later, implementing exponential backoff, or relying on C++20 std::atomic waiting features once we have those implemented
  6. bool atomic_compare_exchange_strong(shared_ptr< _Tp > *__p, shared_ptr< _Tp > *__v, shared_ptr< _Tp > __w
  7. News und Foren zu Computer, IT, Wissenschaft, Medien und Politik. Preisvergleich von Hardware und Software sowie Downloads bei Heise Medien

C++ std::atomic(std::shared_ptr) - Gelös

A dev quickie about my opinion on the C++ Compilers lagging behind on the July 2017 addition on atomic shared pointer and the associated specialization of th.. anthonyw/atomic_shared_ptr 内部使用了一个std::atomic<struct counted_ptr>,其中struct counted_ptr是一个 96bit 的POD,其中记录了原始指针和指针的版本号,相当于使用atomic128来实现 c++ - Atomic shared_ptr for lock-free singly linked list I'm wondering if it is possible to create a lock-free, thread-safe shared pointer for any of the common architectures, like x64 or ARMv7/ARMv8 std:: atomic_... <std::shared_ptr>. If multiple threads of execution access the same std::shared_ptr object without synchronization and any of those accesses uses a non-const member function of shared_ptr then a data race will occur unless all such access is performed through these functions, which are overloads of the corresponding atomic. > std:atomic<shared_ptr<T>>) that implements the appropriate behavior. > This /should/ be part of C++20. But there is no guarantee that this is > implemented lock-free with an outer ref count. And obviously not all > compilers already support this feature at all. :-/ iirc, Peter Dimov tried really hard to get shared_ptr to support strong thread safety, but failed to do so. > Even worse, the.

Barriers and Atomic Smart Pointers in C++2

This is an atomic variant of std::shared_ptr, and can be shared by atomic and lock-free means.. More... #include <atomic_smart_ptr.h> Inheritance diagram for atomic_shared_ptr< X >: Public Member Functions: template<typename Y > atomic_shared_ptr (Y *y) atomic_shared_ptr (const atomic_shared_ptr< T > &t) noexcept template<typename Y > atomic_shared_ptr (const atomic_shared_ptr< Y > &y. All changes to the atomic_shared_ptr object itself, and all associated use_count increments, are guaranteed to be performed atomically. Associated use_count decrements take place after the atomic operation, but are not required to be part of it. Any associated destruction or deallocation operations take place after the atomic operation and are not part of it. If the compare-exchange operation. std::atomic_is_lock_free(&some_shared_ptr) Das Testprogramm unten liefert unter VC2012 das Ergebnis 0 (also std::shared_ptr ist nicht lock-free). Bei gcc 4.7 bzw. gcc 4.8 erhalte ich beim Compilieren (c++ -std=c++11) entweder Fehler: »atomic_is_lock_free« ist kein Element von »std« (ohne #include <atomic> oder (mit #include <atomic>

Why do we need atomic_shared_ptr? | Just Software

std::shared_ptr - cppreference

P0414R2 shared_ptr<T[]>, shared_ptr<T[N]> P0497R0 Fixing shared_ptr For Arrays: VS 2017 15.5 14 P0418R2 atomic compare_exchange memory_order Requirements: VS 2017 15.3 14 P0426R1 constexpr For char_traits: VS 2017 15.7 P0433R2 Integrating template deduction for class templates into the standard librar This means atomic_shared_ptr is useless in systems where the number of reads is approximately the same as the number of writes. Is this expected? Can anything be tuned to fix this? facebook/folly. Answer questions yfeldblum. High level, the principle reason to use atomic-shared-ptr is likely for the load-heavy case. For load-heavy cases, acquiring a mutex around the load can be a much heavier.

Barrieren und atomare Smart Pointers in C++20 heise

  1. template<class T> void atomic_store( shared_ptr<T>* u, shared_ptr<T> r); atomic_store_explicit template<class T> void atomic_store_explicit( shared_ptr<T>* u, shared_ptr<T> r, memory_order mo); const_pointer_cast. Konstante Umwandlung in shared_ptr. template <class T, class Other> shared_ptr<T> const_pointer_cast( const shared_ptr<Other>& sp) noexcept; template <class T, class Other> shared.
  2. shared_ptr assignment. The copy assignments (1) adds the object as a shared owner of x 's assets, increasing their use_count. The move assignments (2) transfer ownership from x to the shared_ptr object without altering the use_count. x becomes an empty shared_ptr (as if default-constructed )
  3. Using shared_ptr in a multithreaded environment, Selection from C++ High Performance [Book] To understand shared pointers and thread safety, we need to recall how std::shared_ptr is typically implemented There can be multiple std::shared_ptr and whenever they access the control block to change the reference counter it's thread-safe but the std::shared_ptr itself is NOT thread-safe or atomic.
  4. 若多个执行线程访问同一 std::shared_ptr 对象而无同步,且这些访问中任一者使用 shared_ptr 的非 const 成员函数,则发生数据竞争,除非所有这种访问都通过这些作为对应原子访问函数( std::atomic_load 、 std::atomic_store 等)重载的函数进行。. 注意 shared_ptr 的控制块是线程安全的:多个线程能同时用可改.
  5. Obtains a shared_ptr that shares ownership of a resource. shared_ptr<T> lock() const noexcept; Remarks. The member function returns an empty shared_ptr object if *this has expired; otherwise it returns a shared_ptr<T> object that owns the resource that *this points to. Returns a value equivalent to the atomic execution of expired() ? shared_ptr<T>() : shared_ptr<T>(*this). Example // std.

Browse the source code of ClickHouse/contrib/boost/boost/smart_ptr/atomic_shared_ptr.hp A writer thread periodically changes the shared_ptr managed std::atomic_int value a few times and exits. When the writer thread exits, the shared_ptr held by it is destroyed, and the reader thread can no longer get a shared_ptr from its weak_ptr, which makes the reader thread to also exit. The program terminates when both the threads exit: int main() { auto sp = std::shared_ptr<std::atomic_int. This requires shared_ptr/weak_ptr implementations to protect their strong and weak refcounts with atomic operations, without the Standardese having to say this elsewhere. However, [util.smartptr.weak.obs]/5 describes weak_ptr::lock() with Returns: expired() ? shared_ptr<T>() : shared_ptr<T>(*this). Even after considering the blanket. boost/smart_ptr/shared_ptr.hpp #ifndef BOOST_SMART_PTR_SHARED_PTR_HPP_INCLUDED #define BOOST_SMART_PTR_SHARED_PTR_HPP_INCLUDED // // shared_ptr.hpp // // (C.

Atomic Smart Pointers. A std::shared_ptr consists of a control block and its resource. The control block is thread-safe, but access to the resource is not. This means modifying the reference counter is an atomic operation and you have the guarantee that the resource is deleted exactly once. These are the guarantees std::shared_ptr gives you. On the contrary, it is crucial that a std::shared. Hello, I'm trying to use the sdk toolchain to cross compile an application, but when I include a standard library that references shared_ptr_atomic.h (such as <memory>) then I get a bunch of compile errors in the form of: error: macro atomic_is_lock_free passed 2 arguments, but takes just 1 T.. shared_ptr线程安全性分析正如《STL源码剖析》所讲,源码之前,了无秘密。本文基于shared_ptr的源代码,提取了shared_ptr的类图和对象图,然后分析了shared_ptr如何保证文档所宣称的线程安全性。本文的分析基于boost 1.52版本,编译器是VC 2010。shared_ptr的线程安全性boost官方文档对shared_ptr线程安全性的. 即使它不是无锁结构,也推荐使用std::experimental::atomic_shared_ptr,而不要在普通的std::shared_ptr上使用原子自由函数,因为该类型会让代码更加清晰,确保所有的访问都是原子的,并且能避免由于忘记使用原子自由函数,从而导致数据竞争。与原子类型和操作的所有使用一样,如果使用它们是为了提高. atomic smart pointers (such as std::atomic<shared_ptr<T>> and std::atomic<weak_ptr<T>>) std::to_address to convert a pointer to a raw pointer; Changes applied to the C++20 working draft in March 2018 (Jacksonville) include: removing the need for typename in certain circumstances; new standard attributes [[no_unique_address]], [[likely]] and [[unlikely]] calendar and time-zone additions to.

Alternative zu std :: atomic_store (shared_ptr) für GCC

c++ documentation: Casting std::shared_ptr pointers. Example. It is not possible to directly use static_cast, const_cast, dynamic_cast and reinterpret_cast on std::shared_ptr to retrieve a pointer sharing ownership with the pointer being passed as argument. Instead, the functions std::static_pointer_cast, std::const_pointer_cast, std::dynamic_pointer_cast and std::reinterpret_pointer_cast. shared_ptr objects release ownership on the object they co-own as soon as they themselves are destroyed, or as soon as their value changes either by an assignment operation or by an explicit call to shared_ptr::reset. Once all shared_ptr objects that share ownership over a pointer have released this ownership, the managed object is deleted (normally by calling ::delete, but a different deleter.

In this post I will introduce a poor man's version of std::atomic_shared_ptr<> with a small addition that makes it harder to use incorrectly. So first of all, before we can fix anything, we need something broken, here it is. First we create a class Foo with a method Bar() that when called after destruction will have a high likelihood of causing a crash: class Foo { public: Foo() { pint. GotW #91 Solution: Smart Pointer Parameters. Herb Sutter GotW 2013-06-05. 2013-12-03. 9 Minutes. NOTE: Last year, I posted three new GotWs numbered #103-105. I decided leaving a gap in the numbers wasn't best after all, so I am renumbering them to #89-91 to continue the sequence. Here is the updated version of what was GotW #105

In this article. The shared_ptr type is a smart pointer in the C++ standard library that is designed for scenarios in which more than one owner might have to manage the lifetime of the object in memory. After you initialize a shared_ptr you can copy it, pass it by value in function arguments, and assign it to other shared_ptr instances. All the instances point to the same object, and share. Constructs a shared_ptr object, depending on the signature used: default constructor (1), and (2) The object is empty (owns no pointer, use count of zero). construct from pointer (3) The object owns p, setting the use count to 1. construct from pointer + deleter (4 template <typename X, typename T> std::shared_ptr < X > qobject_pointer_cast (const std::shared_ptr < T > &src) Returns a shared pointer to the pointer held by src. Same as qSharedPointerObjectCast(). This function is provided for STL compatibility. This function was introduced in Qt 5.14 shared_ptr的出现在某种程度上解放了c++程序员,c++11标准原生的支持了并发编程,在并发编程中shared_ptr的线程安全问题如何保证呢?先撇开shared_ptr对象的线程安全性,先看shared_ptr本身的线程安全问题。 我们知道,shared_ptr的底层实现原理是引用计数,关于这个计数是否线程安全呢,如果我们把shared_ptr. atomic shared_ptr operations se refiere a std::atomic_(store|load|exchange|compare_exchange_strong|compare_exchange_weak)(_explicit)? Plantillas de función para shared_ptr, documentadas aquí . GCC no los tiene hasta el 5. (Dato curioso: su implementación en realidad utiliza una matriz global de 16 mutexes bajo el capó). La creación de una instancia de std::atomic sobre std::shared.

Atomic operations may be implemented at the instruction layer with larger-size atomics. For example some platforms use 4-byte atomic instructions to implement AtomicI8. Note that this emulation should not have an impact on correctness of code, it's just something to be aware of. The atomic types in this module may not be available on all platforms. The atomic types here are all widely. 1. atomic_load를 사용한다. atomic_load를 사용하면 깔끔한 구현이 만들어집니다. shared_ptr의 생성과 소멸이 잦은 경우가 아니라면 성능에 큰 지장이 있지도 않을 것 같습니다. atomic_load를 살펴보면 내부에 전역 spin lock이 구현되어 있습니다. atomic_load을 사용하는 객체는. shared_ptr. ::swap. void swap (shared_ptr& x) noexcept; Swap content. Exchanges the contents of the shared_ptr object with those of x, transferring ownership of any managed object between them without destroying or altering the use count of either atomic_shared_ptr 是API的改进。 shared_ptr 已经支持原子操作,但是仅在使用适当的原子非成员函数时才支持。这很容易出错,因为非原子操作仍然可用,并且对于不精疲力尽的程序员而言,意外调用太容易了。 atomic_shared_ptr 不太容易出错,因为它不会公开任何非原子.

Chromium의 base::scoped_refptr? - dydtjr1128&#39;s Blog[C++ job interview Q&A] What are the smart pointers in C++

std::shared_ptr is a smart pointer that retains shared ownership of an object through a pointer. Several shared_ptr objects may own the same object. The object is destroyed and its memory deallocated when either of the following happens: the last remaining shared_ptr owning the object is destroyed; ; the last remaining shared_ptr owning the object is assigned another pointer via operator= or. std::shared_ptr < T > のstd::atomicの部分テンプレート特殊化により、ユーザーはshared_ptrオブジェクトをアトミックに操作できます。. 複数の実行スレッドが同じstd::shared_ptrオブジェクトに同期せずにアクセスし、それらのアクセスのいずれもstd::shared_ptrの非constメンバ関数を使用すると、そのような. 由于shared_ptr的操作主要含有两个步骤:复制指针和引用计数加一,所以这两步在多线程中会有问题。. 所以对于多线程读写shared_ptr结论是:. 同一个shared_ptr被多线程读,线程安全;. 同一个shared_ptr被多线程写,不是线程安全;. 共享引用计数的不同的shared_ptr被多.

std::shared_ptr of an instance of type T. Exceptions. May throw std::bad_alloc or any exception thrown by the constructor of T. If an exception is thrown, this function has no effect. Notes. This function is typically used to replace the construction std:: shared_ptr < T > (new T (args.. The class template atomic_shared_ptr provides thread-safe atomic pointer operations over a std::shared_ptr. It provides a better alternative to the non-member shared_ptr atomic access functions. Member functions (constructor) constructs an atomic_shared_ptr object (public member function) operator= stores a value into an atomic_shared_ptr object (public member function) is_lock_free. checks if.

C++ unique/shared ptr custom deleters – Alex HoughtonPassing smart pointers shared_ptr and unique_ptr | byModern (Effective) C++ - Pimpl Idiom from C++11 onwards

shared_ptr type class. To implement operator= for a class like this has two issues: 1) operator= for an atomic shared_ptr can only be best effort. If another thread wins out, so be it. I'm going to, for the purposes of this discussion, assume that this is OK, and that if you don't like it, you'll use compare_and_set/swap to do a better job In July 2017, the C++ standard committee created a draft for the next version of the C++ standard, initially known as C++2a. In September 2020, the C++ standard committee approved this draft, and sent it to ISO for approval as C++20. This page shows the status of libc++; the status of clang's support of the language features is here Where weak_this is the hidden mutable std::weak_ptr member of std::shared_from_this.The assignment to the weak_this member is not atomic and conflicts with any potentially concurrent access to the same object. This ensures that future calls to shared_from_this() would share ownership with the shared_ptr created by this raw pointer constructor.. The test ptr->weak_this.expired() in the. boost/shared_ptr.hpp #ifndef BOOST_SHARED_PTR_HPP_INCLUDED #define BOOST_SHARED_PTR_HPP_INCLUDED // // shared_ptr.hpp // // (C) Copyright Greg Colvin and Beman Dawes. 我之前以为atomic<std::shared_ptr>这个helper struct里面的load和store是lockfree的,发现并不是 folly里面的的atomic shared ptr是,但当前的project不大可能引入了。 各位都用的是lockfree的不?都是啥library里的? - 来自「最水木 for iPhone 6s」 - C 和 C++ 参考手册. 来自cppreference.com. C++ 参考手册 C++98, C++03, C++11, C++14, C++17, C++20, C++2

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